EXTRACTS FROM ANNUAL REPORTS

The necessary qualities in the petrol are partly obtained by selection of base stocks and by specialist refining techniques, such as hydroforming, but additives are also extremely important. The organic compounds of lead used as octane rating improvement additives are startlingly effective: as little as 0.05 % of one of them in petrol can increase the octane number by up to 15 units.

For many years, tetraethyl lead was the only additive used to increase petrol octane ratings but recently tetramethyl lead has also been widely used. Tetramethyl lead is the more volatile of the two, and its volatility helps to give better additive distribution in the more volatile portion of the petrol and a more even spread of additives throughout the engine. In this way, a mixture of tetramethyl and tetraethyl lead can contribute to better all round performance.

So today's petrol is designed, by selection of components, refining methods and additives, to meet all quality requirements. It resists oxidation or reaction with metals in motor car fuel systems, and its volatility is right for the vehicles and climate in which it is used. Its anti-knock value is satisfactorily high.

This result is the culmination of a continuing process. One stage began several years ago with oil industry specialists forecasting what engine requirements would be today, and with a research programme designed to find the best way of meeting these requirements. The process continued with the planning and installation of new refinery equipment, eventually producing materiaJ to ~eet the established needs; and with a series of provmg tnals in laboratories and outside them that covered hundreds of thousands of miles of road testing before a gallon of the new product was sold. And the process goes on i;iow wi!h continuing examination of problems and solut10ns still years ahead.

Each major producer of petrol has developed its own individual solutions to the technical problems of fuel for motor cars, and each will continue to do so. The best standards of the whole petroleum industry ensure that these solutions provide fuel that will allow the full potential performance of any care engine to be realised.

Extracts

from Annual Reports

BLACKPOOL

N. K. Whitehead

The total quantity of petroleum spirit, including mixtures of petroleum authorised to be kept at 295 premises in the Borough, was I, 162,671 gallons. The spectacular jump in gallonage licensed is due to the installation of a half million gallon plant installed for the storage of P.F.D., a petroleum spirit used for the manufacture of town gas. Two other new types of licence were also introduced during the year. One was for multi-storey car parks to cover petrol in the fuel tanks of vehicles using the parks and the other was for tenpin bowling centres to provide for the keeping of petroleum mixtures required to refurbish the surface of the bowling lanes.

The testing of tanks and pipelines which have been underground upwards of twenty years has continued. The necessary tests on the electrical equipment and circuits used on petrol pumps were carried out by the Inspection Department of the North Western Electricity Board.

Mr. Whitehead reports there were no accidents involving petroleum on licensed premises. However, one accident occurred to two men who were installing underground cables. Jn attempting to defrost sand left in a concrete mixer, the men poured into the mixing tub petrol which they ignited with a match. The resulting flames burned the men about the face, hands and arms. Another incident which could have had serious consequences, occurred at a school when petrol was discharged from a road tanker to the boiler installation in mistake for heating oil. Fortunately, the mistake was discovered early and steps were immediately taken to avoid a disaster.

BOSTON E. J. Latham

120 licences were issued for the storage of 185,220 ga.llons of petroleum spirit, 10,850 gallons of pet~~leum mixtures and 712 lb. of carbide of calcium. 74 v1s1ts of inspection were made.

BRISTOL K. L. Holland, M.B.E.

Mr. Holland reports that each licensed installation has been regularly inspected and whilst minor faults are inevitable, a satisfactory standard in general has been maintained by each licensee.

During the year, 29 new licences for the storage of petroleum spirit and/or mixture were granted and 32 were returned for cancellation. The total number of licensed premise~ sta~ds at 685. These comprise 480 bulk storage mstallat10ns 1~ underground tanks (of which 60 al~o had a can store hcence); 199 can stores and 6 carbide of calcium stores.

8

Of the I 03 existing underground storage tanks which were tested at a pressure of I 0 lbs. per square inch by means of an inert gas in accordance with licensing conditions, 10 proved defective. In addition, 45 new tanks were tested prior to being licensed. observed. Three road delivery tankers were intercepted and examined. Mr. Harvey reports a serious fire during the hours of darkness which completely gutted a garage and comments that with present day methods of install~tion the petrol in underground tanks was not involved.

CAMBRIDGE F. W. Cartwright 210 petrol and carbide stores were licensed during the year, covering a total of 894,358 gallons of storage. 61 underground petrol storage tanks have been tested for soundness of which 58 were found to be in order. Three leaking tanks were condemned and put out of use.

Mr. Cartwright comments that in common with many other local authorities it has been decided that the Petroleum (Regulation) Acts, 1928 and 1936 and the Petroleum Spirit (Motor Vehicles, etc.) Regulations, 1929, should be applied to basement and multi-deck car parks. Architects and others have been advised of the need for ensuring that safety precautions, inherent to the storage of petroleum spirit be embodied in the design and construction of such premises. An application for a licence to install a manned self service filling station, the first in Ca~bridge, has been received and, subject to certain special safety precautions, has been approved in principle.

CHESTERFIELD J. A. Norris 145 licences to store petroleum spirit were issued, six being in respect of new stores. The total amount of ~etroleum spirit and petroleum mixtures covered by these licences is 287,424 gallons. 622_ visits were made to licensed premises. 13 new tanks were mstalled. Nine old tanks which have been in the ground for twenty years or more were re-tested. Two were found to be unsatisfactory and were rendered safe.

DERBY W. H. Matthews . At the close of the year there were 276 licensed premises w1_th authorised storage of petroleum spirit, petroleum mixtures and carbide of calcium. 13 licences were issued for new installations. A total of I 019 visits to licensees' premises were made, of which 804 'visits were day-to-day ~ttendances for supervision of new constructions and installations, and i 15 visits were to existing places to observe that the requirements of the Act and the local a~thorities' conditions of licence continued to be complied with. 21 tanks which had been installed for more than twenty years were subjected to pressure test; seven were condemned as unfit for further storage use.

DUDLEY G. H. Harvey There are 147 premises licensed for the storage of petroleum spirit/mixtures. 234 visits were made to ensure that full compliance with the licence conditions were being GLASGOW T. Cairns

The quantity of petroleum spirit stored under licence in the city is 3,876,085 gallons and the quantity of carbide of calcium is 1,414 tons 15 cwts. 76 lb. A total of 1,241 licences were issued.

Of 183 underground tanks pressure tested for soundness, 19 were found to be faulty and were rendered free of petroleum spirit vapour by steaming, 68 other tanks were abandoned and also made safe by steaming. 71 petrol road tankers were inspected when mak!ng deliveries. One tanker company was warned for parking their empty vehicles unattended in open spaces in the city.

Mr. Cairns reports that a seri?us accident was proba~ly avoided by prompt action when it was known that a filling station had been selling petrol instead of paraffin for use in room heaters. Warnings were broadc~st an_d a!l th_e petrol sold was subseq~1ently traced. On mvest1gat1011, 1t transpired that the delivery had been n:ade by a tanker driver who was unfamiliar with the station and also t~at the pump attendant was not sure of the tank layout. Five hundred gallons of petrol had been deliver~d on t.oP. of forty gallons of paraffin oil. Arising fr.om tht? and sumlar confused deliveries of petrol and diesel ml, the. local authority introduced additional conditions of_ li~ence requiring the painting of ground manhole .covets, Ill an endeavour to prevent further incidents of tlus nature.

One accident causing injury was reported to H.M. Inspector of Explosives. A young woman employed as ~ petrol pump attendant was filling the tank of a rear engined foreign car wh~n ther~ was an. over.flo':' of petrol caused possibly by an air-lock m ~he .fillmg pipe, the petrol spilled on to the hot engine and ignited. Further spillage was caused when the attendant threw down the. h?se, damaging it on the concrete kerb. Petrol became ignited under the car and around the woman's feet; she was detained in hospital with first and second degree burns to her legs.

Jn all 5,288 inspections were made .in respect of t_he enforcement of tbe Petroleum Act requirements. ~firm of garage proprietors were prosecuted under a hce1:ce condition for failing to render underground tanks ft ee from danger from fire and were .fined £5. Another person was fined £20 for the unautbonsed storage of petroleum spirit, no licence being in force.

KIDDERMINSTER R. L. Bloor

A total of 249 visits we_re made to _the 86 premises licensed for the storage of petroleui:1 spmt .or petrole~1m mixtures, either to ensure that new mstallat1ons at filling stations were being completed to tbe necessary safety

standards or to ensure that the older ones were being maintained in a satisfactory condition, and that licence conditions were being observed. The redevelopment of the town centre has meant that several underground storage tanks have had to be rendered safe before removal; where they were to remain on site, they have been filled with sand and cement slurry.

LANCASTER A. F. Bambridge 210 licensed premises were visited. 85 licences were issued for the storage of 289,885 gallons of petroleum spirit and mixtures and one licence for the storage of 112 lbs. of carbide of calcium. 14 'old'tanks were tested for leakage, two failing the test. In both instances the tanks were installed in the early 1920's. Mr. Bambridge refers to his Council's membership of the Association and comments on the useful information he has received through the media of 'The Bulletin'.

LEEDS R. French, M.B.E. There are 1,035 licensed stores in the City, of these 26 are over 10,000 gallons capacity. The quantities range from two gallons to 4l million gallons. A total of 2,449 visits have been made including 787 routine visits which are taken at station level, and 1,662 specific inspections. There were 125 tanks tested during the year; of these 17 failed the test. Legal proceedings were taken in one instance. This concerned the failure of a firm to immunise an underground tank for explosive risk, despite repeated notices. The court ordered the work to be done within one week. This was complied with and the case withdrawn. Mr. French comments that for the first time in the history of the city, the total licensed storage capacity for flammab_le li~uids coming with the jurisdiction of petro-leum legislation exceeded 5,000,000 gallons. In fact, it has rise~ from below that figure to over 8,000,000 gallons during the _last twelve months. This gives an indication of the rapid growth of the oil industry which at the moment shows no sign of abating. A few years ago it was standard practice to install 500 gallon tanks and it was something out of the ordinary if a ta~k of I ,OOO gallons capacity was used; today, however, it is ~ot uncommon for tanks of 4,000 to 5,000 gallons capacit~ to be provided. This is a good point from a Fire Prevention angle, as the frequency of delivery by tank ~ag~ns can _be reduced, thus nsk in transit and delivery. considerably reducing the

MANCHESTER J. R. Roberts, M.B.E. Mr. Roberts observes that in the congested city area the comequences of careless storage of petroleum spirit could be disastrous and the most stringent conditions of _licence are imposed. A total of 3,420 visits were made to hcen~e? storage places and to other places where petroleum spmt might be kept. 1, 133 licences were granted. The installation of 42 new tanks for the underground storage of petrol was supervised at all stages, air pressure tests being applied to determine freedom from leakage. Disused petrol tanks are required to be made safe and 61 such tanks were filled with water,sand or a weak cement mixture. One prosecution was taken against a asbestos manufacturers for keeping (Toluene) for use in a manufacturing firm of cotton a_n? petroleu~1 spmt process without a licence. A fine of £20 was imposed.

NEWCASTLE-UNDER-LYME D. Hall Licences granted by the department authorised th~ storage of 919,682 gallons of petroleum spirit. . 5,258 gallons of petroleum mixture and 190 I bs. of carbide of calcium. This compares with an approximate 200,000 gallons a little more than ten years ago. Mr. Hall refers to the honou~ accorded him of being elected the first Chairman of the Association for Petroleum Acts Administration and suggests that this honour must be shared by his local authority which became a member _of the West Midlands Petroleum Group shortly after its inception.

OXFORD R. E. Dust 165 premises were licensed for the storage of gallons of petroleum spirit or mixtures and five 704,981 for the storage of carbide of calcium. 680 visits of inspection to licensed 78 minor contraventions were found, premises were made. these being promptly corrected by the licensees concerned. 22 underground petrol storage tanks, havin~ been installed 20 years or more, were pressure tested durmg the year. Seven were found to be unsound, and were at once put out of use. Arising out of an accidental spillaae of some 200 gallons of petrol at a filling station, a petr~I company, a tanke1: driver and the station manager were prosecuted for contravention of the Petroleum Spirit (Conveyance by_ Road) Regulations, 1957. Pleas of guilty were entered m each case, and fines of £20, £20 and £10 respectively w~r~ imposed. (This case was reported in full in 'The Bulletm Volume 3, No. 4, pages 145 and 146-Ed.).

PLYMOUTH R. Billings A total of 240 premises were licensed to store petroleum spirit, mixtures and carbide of calcium. 14,279,739 gallons of petroleum spirit was stored together with 477,000 gallons of liquid petroleum distillate. Mr. Billings observes

10

tha~ from the report on various Plymouth docks activities dunng the year, it is recorded that over 640,000 tons of petroleum products came into the city, which is 44,000 tons more than in the previous year. This seems to indicate a large increase in such activity and the importance of Plymouth as an importing and distributing centre for petroleum products through the South-Western area.

L.egal proceedings were taken against a petrol filling station owner and employee following the latter lighting a fire to burn waste paper adjacent to a petrol pump. Fines of £5 and £3 respectively were imposed for this rash act and lack of supervision by the licensee of the premises.

ROWLEY REGIS

F. T. Harrison

126 premises were licensed for the storage of 205,474 gallo~s of petroleum spirit and mixtures. Two licences wer~ issued fc;ir the storage of I ton 4 cwts. of carbide of ca_lc1um. Dunng the year 493 visits were made to premises. ~me pre~sure tests were applied to existing tanks and six defective tanks were removed or filled in.

SCUNTHORPE

F. J. Bowyer 112 . . . . prem1s~s were licensed for the storage of petroleum spmt and mixtures, the total quantity being 1 487 610 g·1llo d f · ' ' < • ns an our premises were licensed to store C'1rbide of ~alcium, the total being 3,714 lbs. Sixteen new t~nks have ee!1 test.ed and 23 old tanks retested after a ten year period, six tanks failed on test and were removed.

SEISDON R.D.C. E. H. Roberts f92 premises are licensed under this Act for the storage 0 petroleum .spirit: 22 of these are public filling stations ~nd 70 are private mstallations. Conditions of licence are c~se~ _on the Horne Office Model Code with additional insndih?ns to govern the use of petroilers. A total of 165 r pect10ns were made under this Act. 12 tanks and pipemes were _tested. Mr. Roberts acknowledges the value of mef!Ibersh1p of the Midlands Petroleum Acts Adminis~adti~n. Group, now the Association for Petroleum Acts m1111stration.

SHEFFIELD C.R. Wells

The t?tal quantity of Petroleum Spirit now beina kept ~~fer licence in t.he city amounts to 3,336,40 I i<1llons eh. together with 202 tons of carbide of calcium, necessitated the issue of 964 petroleum licences.

The total number of visits made by petroleum officers fc;>r_ all purposes was 3,062, of which 1.302 were periodical ~~s~ts ~~ensure that licence conditions were being observed, v1s1ts were to apply leakage tests to tanks which were ~O years. old or more. 1,068 visits were to supervise new mstal_l~t1ons, alteration or additions to existing stores. 497 v1s1ts were made to investigate complaints by members of the public, police, fire brigade and gas hoard, ahout smells of petrol in the cellars or basements of all kinds of properties, and 46 petrol tankers were inspected and found to be in compliance with the Regulations.

Of the 110 old petrol tanks which were tested for soundness during the year, 10 were found to be defective and have ~een replaced, taken out and scrapped, or made safe by fillmg them with sand, cement slurry or water.

SMETHWICK T. J. Metcalfe

140 licences covering the keeping in approved stores of 1_84,698 gallons of petroleum spirit and mixtures, and one licence to keep for sale 112 lbs. of carbide of calcium were issued.

Licensed stores were inspected on 224 occasions and a further 295 visits were made to check progress on the construction of new, or modification of existing stores. Soundness tests were applied to 11 petrol tanks which had been immured for 20 years or more, 9 being passed as fit for further use and two being required to be lifted and removed.

The only accident involving premises licensed under the Acts was the knocking over of an electrically operated petrol pump by a skidding motor car. No fire resulted and no one was injured.

STAFFORD K. C. Hughes

83 premises were licensed during the year, permitting ~h_e storage of a total of 257 ,350 gallons of petroleum spmt or mixtures. Seven new tanks were installed and ten old tanks aged 20 or more vears have been pressure tested with nitroaen to ensure continuing freedom from leaks. All were b found to be sound. Mr. Hughes comments on the need for legislation to control the storage and conveyance of the many substances and mixtures whic~ •. although just as volatile and flammable as petroleum spmt, _d.o, not satisfy the present definition of 'Petroleum Spmt as expressed in the Act.

ST. HELENS W. C. Adamson

416,364 gallons or petroleum spi 1.·it is kept under lice~ce. 163 licences being issued. 577 v1s1ts t~ hcei:sed premises were made, 38 persons being warned for_ m111or. breaches of the law. 52 storage tanks were tested, lour being found unsatisfactory.

Mr. Adamson reports that for the second time in .so1~1e two years in St. Helens, a ten years old boy risked his l~fe by dropping a lighted firework into the petrol tank ol :1 disused van on waste ground near his home. He received burns about the head and was detained in hospital. Arrangements were made with the Cleansing Superintendent for his department to remove any unwanted motor

11

vehicle free of charge and publicity through the local press was given to this offer, at the same time emphasis being placed on the dangers of petrol tanks on such vehicles.

WALSALL

H. Griffiths

At the end of the year there were two hundred and sixty-seven petrol licences and one carbide of calcium licence in force.

Throughout the year 235 inspections have taken place at a number of the premises to ensure that conditions of licence are being adhered to, and where necessary work has been carried out by the responsible persons to achieve this.

Numerous plans have been examined and recommendations made in respect of proposed new Petroleum Filling Stations in the Borough.

WEST HARTLEPOOL

A. F. Brunner

Mr. Brunner refers to the storage of 7-! million gallons of light petroleum distillate at the Northern Gas Board's Central Production Station. The tanker 'M.T. Orkanger' carrying the first delivery of feedstock for the new Production Station arrived at Hartlepool Deep Water Berth in May. Delivery into one of the three mammoth storage tanks, via a half mile length of pipeline, of thjs first consignment of about 7,000 tons of distillate was the culmination of much activity which had engaged the interest of the department for over two years. 99 premises with a gross storage capacity of 7,747,383 gallons are licensed. 421 visits of inspection were made. The periodic testing of underground storage tanks which have been installed for twenty years or more is now an established duty. Eleven such tanks were tested, satisfactory results were obtained in every instance.

Two suspected petrol leaks were investigated. In the first instance a supposed 'petrol smell' was traced to a fractured gas main; in the second, suspected petrol losses at a filling station were found to be due to book-keeping errors.

WORCESTER

J. Beer

The number of licences issued for the storage of petroleum and/or carbide of calcium was 148. The licensed storage was 5, 183,952 gallons of petroleum spirit, including mixtures and 25 cwt. of carbide of calcium. A total of 365 inspections were made for the purpose of ascertaining that new installations were satisfactorily constructed and that at premises already licensed the conditions attached to the respective licences were duly observed.

M r. Beer welcomes the visit to Worcester by Mr. W. McCarthy, an lnspector recently appointed by the Home Office, to act as a Liaison Officer between the Explosives branch of the Home Office and local authorities administering the Petroleum and Explosives Acts.

A reminder that the licensing of petroleum stores by local authorities is by no means a modern development was given recently in a centenary booklet published by the firm of Caffyns Ltd., garage proprietors in Kent and Sussex. A copy of the actual licence is reproduced here.

Oldest Surviving Petroleum Licence

Eastbourne

As will be seen, the licence was issued in Eastbourne in 1871 and authorised William Morris Caffyn, an Ironmonger and grandfather of the present Chairman of the company, Alderman Sydney M. Caffyn, C.B.E., to keep an unspecified quantity of petroleum "In a shed at the back of his house in Seaside Road". The conditions under which the petroleum (presumably burning oil for !amps) was to be stored were simply, "That no other mfl.amma?le_ or substance be kept, or or ?ther art1fic_ial light of any description be at ttme mtroduced mto any part of the premises in which the above-mentioned Petroleum shall be kept". The signatures appended were of six members of the local board, several of whose names are well-remembered in the district.

In the words of the author of the booklet "The conditions (or lack of them) would not a modern Inspector ! " While conceding this point, most Inspectors would sur_ely agree that by segregating the from the dy.iellmg-house a_nd_ banning naked lights the. hcel?-ce con tamed the two mam mgredients on which later llcensmg has been Not a few must also be surprised that licences were issued at all so many years before the advent of the motor-car.

. We are grateful to Caffyn for the information given and for perrruss1on to reproduce the licence.

12

f=c }iMt, the Local Board for the District of Eastbourne, in the County of Sus"6x, being the Local Authorit.r t. -.it. to ~t Licenses under the Act of Parliament hereinafter mcntione<l, upon application to 110 duly made by 'I/Uk~ /l/t1VUJ Or /If· of .&~ /f:.-,c ff~)

in the sai<l. District, un<l.cr the Provisions of au Act of

PllJ'liamcnt of the Session hol<l.cn in the 25th &nu 2Gth. Y cars of the Ucign of Her Majesty Queen

Victoria, chapter 66, intitulc<l. "An Act for the safo keeping of l'ctroleum," an<l. un<l.er the Provisions of

the "Petroleum Act, 1868," Do hereby, under and by virtue of the Provisions of the said Acts (but •qbjcct to the Conditions hcrcii1altcr expressed), liceme the said //;iL<P,.;.. h-t. ...vc ... : e#r to keep Petroleum in a certain place within the said Parish, not situate in any Harbour within the

jurisdiction of a Harbour Authority as defmed bJ the sai<l. Acts, to wit,

v;; m d/t~~t cvf /ft~ /

.. /,~( 7~· ~-..c<W .;n ....d.e-c'-4..dv

/Rf>a,<?

in the sai<l. District: Provided always, that this Licen&e i• granted upon the following Conditions, viz.:-

" That no other inflammable or explo•ivo substance be kept, or Candle or ether artificial light of any

description be at any time introduced into any part of the premises in which the above-mentioned.

l'etroleum shall be kept."

GIVEN under the ,//f/

Seal of the sai<l. Local Board an<l. the hands of Five Members thereof thi1

day of _/~,...~/

in the Year of our Loni One

'Ihousa.nd Eight Hundred and p.-re..,,f nu)

7£/. vd tY'r/I~ ~~7·'~

13

Association of Municipal Corporations

INFLAMMABLE SUBSTANCES (WORKING PARTY), STANDING ADVISORY COMMITTEE ON DANGEROUS SUBSTANCES

Report of Fire Service Committee

The following letter was received from the Home Office:

26th April, 1965.

Following a recent reorganisation within the Home Office, we have been examining the work of the various committees which have been concerned over the past few years with the transport and handling of dangerous substances. These are the Working Party on Inflammable Substances, composed of representatives of the Home Office, the Scottish Home and Health Department and other interested Government Departments and the local authority associations; the Working Party on the Marking of Road Tank Vehicles, composed of representatives from the Home Office and the trade interests concerned; and the working groups on acety-lene, petroleum and explosives, composed of H.M. Inspectors of Explosives and representatives from industry. In addition to the work of these various bodies you will be well aware that there is an urgent need for immediate attention to be given to the question of extending the scope of the existing regulations concerned with the carriage by road of dangerous substances.

In order, therefore, to co-ordinate more closely the work of the various committees already mentioned and to provide suitable machinery for consultation with the interests chiefly concerned on the need for further measures to control the carriage of dangerous substances by road, the Secretary of State has decided that the Working Party on Inflammable Substances should be reconstituted as the Standing Advisory Committee on Dangerous Substances and that its terms of reference, which will now be extended, should be as follows: (i) to advise the Secretary of State on questions falling within his sphere of responsibility which relate to the control, in the interests of the safety of the public, of dangerous substances, with particular reference to:

(a) the carriage of dangerous substances (other than radio-active materials) by road, and (b) the storage of dangerous substances (except in premises covered by the Factories Act, 1961, and the Offices, 1963); Shops and Railway Premises Act. .

(ii) for the foregoing purpose, to have power to set up sub-committees to deal with particular problems. and to co-opt as members of such sub-committees representatives of industrial and commercial interests and of any other bodies concerned.

It is proposed that the membership of the new Committee, whose Chairman will be Mr. McConnell, should, as in the case of the present Working Party on Inflammable Substances, be limited to the Home Offic~, the

Scottish Home and Health Department and other mterested Government Departments, the local authori~y

Associations (including the Greater London C<?u~cil) and the Dock and Harbour Authorities Associat10n.

The Committee will not be further enlarged by the addition of members representing industrial and commercial interests. Instead, it is suggested that the Cc;im-mittee should concern itself with broad issues of policy. determining priorities of work, considering final reports, etc., and that it should leave the detailed work on par-ticular problems to special sub-committees to be set up as the need arises. These sub-committees will be better able than the main Committee to undertake the detailed, often technical, examination required. It is at t~is level that industrial and commercial (and other) mter~sts could most conveniently be brought into cons~ltat10n.

Although some re-adjustment of representation and terms of reference will be needed we expect that some, if not all, of the various committees and working groups described above will be able to continue their work as sub-committees of the new Advisory Committee. It is to be understood, of course, that bodies represented on the main Committee will have the right to be represented on sub-committees as they think fit. The first task of the Advisory Committee, however, will doubtless be to set up sub-committee machinery to examine how best to extend the existing regulations on the carriage of dangerous substances by road to a much wider range of substances; none of the existing working groups is wholly appropriate for this urgent and immediate task.

I should be grateful if you would be good enough to let me know as soon as possible whether you agree in principle with these proposals and to advise me about your representation on the new Committee.

A similar letter has been sent to the C.C.A., U.D.C.A ..

R.D.C.A., Counties of Cities Association, ConYention of Royal Burghs, Association of County Councils of

Scotland, Greater London Council and Dock and

Harbour Authorities Association.

Subject to reconsideration of sub-para. (b) of para. I of the proposed terms of reference, we have accepted those proposals. As regards that sub-paragraph, this Association and some of the other local authority Associations have in the past argued strongly that control over the storage of dangerous substances should be by reference to

14

the degree of hazard of each substance and not in relation to the type of premises in which the substances are stored. ~here. are large numbers of factories and shops where !1censmg_ under the Petroleum (Consolidation) Act, 1928, is op~rat1ve and there is, in our view, no reason why such premises should be exempt from the consideration now to be given to the need for control of other dangerous -substances. We have referred to the Home Office, for consideration by the new Advisory Committee, the following letter from the Town Clerk of Bath:

12th July, 1965. .

... Arising out of a recent accident in the West Country involving a bulk liquid tanker, the Bath Accident Prevention Council consider that in addition to adequate marking of vehicles carrying dangerous liquids by road, -such vehicles should be required to carry an outfit of thick blankets of inert material such as asbestos/glass fibre, sufficient to reduce leakage rates arising from any accident. In the case of corrosive fluids, suitable protective clothing to be worn by those who have to do cleaning up operations should also be carried on these vehicles.

Municipal Review Supplement, October, 1965.

TANKER'S LOAD WAS NOT MARKED

The problems of dangerous loads being transported !hr?ugh~ut the country were illustrated at a special service mc1dent m Essex, reports Mr. J. Ellis, Chief Fire Officer for the county. A loaded butane tanker trailer had been rnmm_ed in a level crossing by a diesel shunting engine at Harwich Quay. 1:ot~l w7ight o.f the tanker was no md1cation of its contents, says 33t Mr. tons but Ellis. there was "It was rather illuminating to find that in the first half of September a total of 70 consignments of highly inflammable liquids, poisons, toxic or pharmaceutical materials were registered. No doubt a considerable percentage of these leave the port by road".

The attention of the working party on inflammable and dangerous loads is being drawn to the incident. The tanker trailer contained 18 tons of butane, and had just been towed off the British Railways ferry. The towing vehicle had connected up the trailer and was proceeding from the quay when it halted momentarily across the permanent way on a sleeper crossing. The shunting engine rammed the tanker just below tank level so that the tank was not fractured and although the buffers displaced a valve manifold and pipework and became wedged in the chassis, the pipes did not fracture.

The officer in charge found that to separate the trailer and engine it was necessary to remove the engine buffers. Hoses were laid out to provide cover while this was done. Two of the holding nuts were so rusted that they had to be cut by hammer and chisel. The trailer was then eased to give a slight clearance by deflating the tyres on the far side to tilt up the part in contact with the engine. The engine was then gently driven away. The trailer tyres were re-inflated, the trailer was jacked up to a level position with timber under the wheels, the towing unit was then coupled and the trailer was removed to a safe standing position. With acknoirledgements to 'Fire'-

Examination of L.P.G. Liquid Measuring Devices

By Malcolm W. Jensen, National Handbook 99, 23rd April, 1965, (Order from the Superintendent Bureau of Standards 21 pages, 35 cents. of Documents, U.S. Government Printing Office, from local U.S. Department Washington, D:C.204ffi02, o)r of Commerce Field 0 ces · This publication details the v?lumetri~ method o~testing L.P. Gas liquid-measuring devices. Thts method is more accurate and more nearly approximates the actual _operl;ltion of the measuring device than does the grav1m.etnc method. Descriptions of apparatu_s, met~ods of cahb_ration, step-by-step proce?ures for mspectmg and testmg commercial devices are given, and a report form plus proproced ure for completing it are suggested. Safety pre~au: tions are included as a 'Hazardous Substance. Warmn~ and as particular procedures to be followed durmg certam steps in the test. This handbook will be of interest not only to Weights and Measures officials but to those of manufacturing. commercial and indust;ial firms interested in the measurement of liquefied petroleum gas. Note.-Foreign remittances must be in U.S. Exchange and should include an additional one-fourth of the publication price to cover mailing costs.

15

THE WAR AGAINST

POLLUTION The oil industry has long been aware of the problems of pollution connected with the processing of crude oil on a. scale vast enough to meet the growing energy demands of Europe. Seven major oil companies, including Esso, have now formed a Study Group whose primary concern is to seek ways to solve these problems on a practical basis_

Ever since man began to burn fuel to keep himself warm, cook food and smelt metals, pollution has been an inescapable and undesirable aspect of progress. Pollution was never a serious problem for small nomadic communities; but with the growth of cities, civilizations and a great variety of industrial processes, the problem has become critical. In the industrialized countries, governments, local authorities and responsible organizations are seeking ways in which the pollution of both air and water can be arrested or-ideally-reduced. The urgency of the task is increased by the knowledge that the population of the world will have doubled by the end of the century. Unless effective anti-pollution measures are universally accepted in the near future, the situation will be even more acute when there are twice as many people.

At present one of the most heavily populated and heavily industralized areas of the world is Western Europe. Ultimately in Europe there may be an effective supra-national authority to direct the war against pollution. Meanwhile individual countries have introduced and are introducing legislation designed to restrict pollution from both industrial and domestic sources (in this connection it is interesting to note that Great Britain was the first European country to produce an anti-pollution law in the form of the Town lmprovement Clauses Act of 1847). At the same time, responsible sections of industry are making voluntary and collective efforts to attack the pollution problem in a number of ways.

The oil industry, as a major supplier of energy, has long b~en acutely conscious of the increase in pollution created directly or indirectly by the steadily growing demands for energy. Indeed, several of the major oil companies have spent large sums in research on projects connected with ~he problem. Esso, for example, has carried out extensive investigations connected with smoke control and with methods of reducing the amount of sulphur oxides and sulphuric acid emitted into the atmosphere from the waste gases of large industrial furnaces.

As far as the contamination of the sea is concerned, some of the major oil companies, including Esso, have developed me~hods to completely eliminate the dumping of slops and residues from oil tankers in a concerted effort to keep the coastlines of the world clean.

These are voluntary efforts on the part of the oil industry .. As such t.hey hav_e been welcomed by the press, have received public acclaim and have, without doubt, encouraged other sections of industry to see what can be done in different spheres.

It is worth emphasizing, however, that the oil companies who have been closely concerned with the development of such anti-pollution measures do not adopt a 'holier-thanthou' attitude. They know that if much has been done already, there is much that remains to be done. They are aware also that what is really needed is a joint attack u~on the problem, a sharing of data and information, a pool mg of experience and research.

It was in this frame of mind that in April, 1963, siJC major oil companies operating in Western Europe formed an organization to carry the war against pollution one stage further. The organization is called CONCA WEa contraction for The Oil Refining Companies' International Study Group for Clean Air and Water Conserl'ation (West em Europe). The objectives of CONCA WE are: (I) the collection and dissemination to members of information on the pollution of air, water and soil attributable to the oil _refining industry; (2) the formation of active co-operat10n in anti-pollution measures between member companies: (3) the provision of funds for research in this field; ( 4) the propagation of the results of this work together with the observations and experience of the Study Group.

The founder members consisted of Esso, B.P., Caltex~ Gulf Eastern, Mobil and Shell. Just over a year later, in September, 1964, the membership was increased to seven by the addition of Compagnie Fram:;aise de Raffinage. Each of the member companies pays a fixed annual subscription to CONCA WE plus an additional sum based on its proportion of Eu~opean oil refining capacitt In t_his way funds are provided for the various ant1-pollut10n studies and projects. The headquarters of the Study Group are at The Hague, where representatives of the member companies meet regularly to plan the Group's activities; and to exchange views and information.

At present, t~e Group is concerned only with J?Ollu!ion problem~ r~sultmg from the refining and process~ng s1d~s. of the 011 industry. ln the realm of air pollut1on, this embraces such subjects as reviewing methods for getting: the best possible atmospheric dispersion of flue gases from existing refinery stacks; finding out what are the most ef!ecti~e type~ .of stack or chimney to use for varying: cl1mat1c cond1t1ons; how to reduce and disperse refinery smells; and the study of the behaviour of gases rising from refinery flares. It also includes the techniques used for making air pollution surveys on the sites of new refinery projects, and the study of the relationship between industrial air pollution and corrosion.

In the province of water pollution, subjects that are now being intensively studied include: the behaviour of orn when it is spilled into soil and soil/water combinations; the means available for the prevention and detection of leaks in oil pipelines; and methods of ensuring that refinery effiuents do not contaminate the waters into which they are discharged.

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Besides undertaking studies on its own initiative, :WE acts as a clearing house for the exchange of about anti-pollution research and achievemen!s w1th111 the oil industry. It also aims whenever !O encourage the study of pollution problems at umvers1t1es, not only in order to increase general knowledge and but also to increase ultimately the number of mformed scientists available to advise governments and local authorities.

In the last fifteen years the refining capacity of Western Europe has &rown at a fantastic rate. It is now eight times th_an 1t was in 1950. Each year, with the continued mcrease 111 the demand for oil products, many existing refineries increase their capacity and new refineries come on stream. In 1950 the total European refining capacity was about 46 million tons: it is now rapidly approaching 4_00 million tons. Bearing these figures in mind, the s1gnficance of CONCA WE is self-evident.

The war against pollution is a war that must inevitably intensify as time passes. The oil industry is fully alive to the need for urgent action-particularly through the medium of CONCA WE-and is determined to remain in the vanguard of the growing movement to solve these problems in the European area on a practical basis. From Esso Magazine, Autumn 1965.

Council Meeting

Report of a meeting of the Council of the Association held at Dudley on Tuesday, the 16th November, 1965

Present

D. Hall (Chairman) with Messrs. E. V. Beeby, J. Beer, R. L. Bloor, G. N. Dean, J. W. Frid, H. Griffiths, R. P. Holdaway, C. T. Peacock, R. E. J. Roden, J. A. Sharp, B. W. C. Thacker and the Honorary Secretary.

Apologies

Received from Mr. M. Gee and Mr. C. R. Peskett.

BUSINESS

Management Procedure-Standing Orders

The members had before them proposed Standing Orders for the Council, Secretary and Editor. Mr. Holdawa)'. suggested amendments to cover (a) Immediate Past Chairman), (b) Representation on other bodies, (c) Insurance for the Editor against libel proceedings. In the case of (a) this was agreed. In the case of (b) the Hon. Secretary was instructed to write to the Home wi.th a view to securing representation on the Standrng Advisory Committee on Dangerous Substances. In 1 he case of_( c) the Hon. Secretary was asked to ascertain the cost of msurance. The Standing Orders thus amended were adopted.

Underground Car Parks final draft of recommendations for this type of premises was considered. Two small amendments having been accepted, the Council agreed the amended recommendations should be circulated for the Annual Meeting.

Cash Registers, Telephones, etc., in Kiosks

Mr. Sharp submitted a report and discussion ensued but as agreement was not forthcoming, Mr. Sharp was requested to submit a further report to the Chairman. Limiting Devices

Mr. Bloor reported on a query from Mr. E. H. Roberts (Seisdon R.D.C.) concerning limiting devices. The ultimate conclusion being that the decision for acceptance or non-acceptance of these devices lay entirely with the Local Authority concerned.

Expenses

The Chairman read Resolutions passed at the preceding Council Meeting and explained at length the scale of charges for expenses for (a) Members attei;iding Meetings and (b) for Branch Representatives attendmg Council meetings.

Affiliation Fee

The Honorary Secretary expressed doubts as to whether this term was fully understood as some fees ha_d been paid by full members. The Chairman satisfactorily explained.

Correspondence

A letter was read from Mr. Bloor asking about cars offered for sale parked in service areas and over the storage tanks. It was resolved to submit the question to the appropriate Sub-Committee.

Reference was made to correspondence between the Clerk of Staines U.D.C. and Mr. Beer concerning Licence Fees. It was agreed that this was hardly a matter for the Association, but that the subject should be brought to the notice of the Urban District Councils' Association.

Applications for Membership

The Hon. Secretary submitted 15 applications for membership or associate membership. It was resolved that all applications be accepted.

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Application Forms for Branch Membership

The specimen drawn up by 1\fr. R. E. Dust (Oxford) was considered. After certain amendments had been agreed, the Chairman undertook to make some copies, it being understood that Branches would be responsible for providing their own forms on the lines now agreed.

The Bulletin-Advertisements

Mr. Dean reported on the information and advice he had obtained and the members were of the opinion that a notice should appear in the next issue of 'The Bulletin· inviting advertisements.

Mid-Week School, 1966

The Hon. Secretary informed the Council of the dates agreed for the 1966 school. They are Tuesday, Wednesday and Thursday, the 17th, 18th and 19th May, 1966.

It was decided that a meeting of the School Subcommittee should be held as soon as possible.

SOUTH EAST MIDLAND

The second Meeting of the South East Midland Branch of the Association was held at Cambridge on Thursday, 16th September, 1965. It was through the courtesy of Mr. F. W. Cartwright, Chief Inspector for the City that facilities were afforded to the Branch, and the business meeting was held at the Town Hall. It was attended by the Chairman of the Branch, Mr. E. A. Melbourne of Saffron Walden; the Secretary, Mr. R. E. Dust of Oxford, the Treasurer, the Branch Representative on the Council and 16 other members.

The Secretary undertook to circularise all members with a copy of the Draft Rules for consideration at the next meeting.

The first part of the morning was taken up by the business meeting, this being followed by a demonstration and talk by Mr. Cartwright of his by now famous micrometer point gauge used in the ullage testing of underground petrol tanks. (Full details of this instrument are given in the Bulletin for January, 1964, Vol. 2, No. 3). The remarkable accuracy of it made a profound impression

The Minutes of the last meeting (at Oxford on the 20th May) were read out and the Secretary reported that he had written to the Secretary of the Association asking Council to agree to the amendment of the Draft Rules of the Branch

BRANCH MEETINGS

on all those present and great credit must go to Mr. Cartwright, not only for his inventiveness, but also for the presentation of his talk. It was followed by a practical demonstration of the instrument at an underground tank in the· City which was attended by

to allow officers of local authorities who were engaged in the administration of the Petroleum Acts to become members of the Branch notwithstanding the fact that they were not members of the Association.

The Secretary had .replied that the Council had agreed to the amendment of Rule 3 of the Draft Rules as follows:

"The following paragraph be added to Rule 3:

"In addition, any person employed in the administration of the Petroleum Acts shall be eligible for membership of the Branch provided his Local Authority or any one of its officers is in membership of the Association as provided above". everyone present at the meeting. The afternoon period was filled by a talk and demonstration by Mr. Ronald Perry of the Penetone Co., Ltd .• Runneymeade Works, Egham, Surrey· manufacturers of the product 'Slix', of which much has b~en written already in The Bulletin. Both lecture and demonstration were held\ at the City Fire Headquarters by courtesy of the Cambridgeshire and Isle of Ely Chief Fire Officer and, after a full explanation of the nature of the product and its precise function, a practical demonstration showing 'Slix' in. action was enjoyed by all and illustrated once again the great value of actually seeing what the product can and' can not do.

Arrangements for the next meetina were left to the Secretary and ~hairman but a suggestion from Mr. Melbourne that 1t be held at Saffron Walden in Essex. was warmly welcomed by all those present.

YORKSHIRE

A meeting of the Yorkshire Branch was held at Leeds City Fire Brigade Headquarters, Leeds, on Monday, 27th September, 1965.

The Chairman, Mr. R. M. Sample (Scarborough) introduced the Assistant Chief Fire Officer of Leeds, Mr. F. Scott, who welcomed all members present, and gave apologies for absence from the Chief Officer, Mr. R. French. He then wished the meeting well.

\'linutes

The Minutes of the last meeting were taken as read, moved by Mr. Wood and seconded by Mr. Sykes.

\Iembership

The Secretary then stated that seven new members had joined since the last meeting. There was no outstanding correspondence. ~

Mr. C. T. Peacock then introduced Mr. R. P. Thom, Senior Sales Engineer, British Insulated Callender's Cables, Ltd., who gave a very interesting talk about Mineral Insulated Copper Sheath Cables, their use, construction and associated fittings.

Mr. Thorn described various types and sizes of cables, and gave a very interesting description of the manufacture of these. He stressed that the cables were designed to work at a temperature of 42°F. above the ambient temperature and could, therefore, feel hot to the touch. This was not a~. indication of overloading but normal working cond1ti?ns. He also pointed out that as the cables were subjected to a temperature of 55°C. during manufacture, th_ey were capable of withstanding very high temperatures without loss of efficiency or destruction. , ~r. Thom then went on to describe the flameproof httmgs used with this type of cable, and indicated that all these were marked with the letter 'F'.

The Secretary then introduced Mr. F. Clark. M.I.E.E., H.M. Inspector of Factories (Electrical Section), Leeds, ~tnd called upon him to present his paper entitled:

THE INSTALLATION AND MAINTENANCE OF ELECTRICAL APPARATUS IN FLAMMABLE OR EXPLOSIVE ZONES

. Tl~e. !lumber of industries and processes where the poss1b1~1ty of a flammable or explosive risk arises is mcreasmg steadily and there are in consequence more cases today than formerly where engineers and designers have ~o consider the hazards that may arise from electrical machinery, apparatus, instruments, installations, etc. 1 propose to cover a number of points of general interest, hut time limitation will not permit a complete coverage of this subject.

Most of the applications to be considered here are conce_rned with the risk of fire or explosion in connection with the use of flammable liquids and vapours, but some refere1~ce will also be made to explosive dusts and to e xplos1ves proper.

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The flash point of a liquid may be defined as the lowest temperature at which an explosive vapour can be produced when exposed to a source of ignition which does not materially raise the temperature of the liquid. The F.P. must not be confused with the ignition temperature and careful study of the flammable limits should also be made. Two other factors of great importance are the most incendive concentration of a vapour and the most easily ignited concentration. In testing apparatus it is also important to know the concentration that will produce the highest internal pressure following ignition.

Although petroleum spirit is given, by statute, a flash point less than 73°F., this is a very arbitrary figure without any real practical value. The important factor is really the temperature at the working point together with details of the actual process-a liquid may be vapourised by normal evaporation at temperatures exceeding its flash point but it can be more readily vapourised, or atomised, by mechanical means, such as spraying, and the end result is the same.

We have available today in this country a number of well-tried methods of providing safe conditions in the fields we are now considering, viz:

I. The use of flameproof apparatus and wiring. 2. The use of intrinsically safe electrical apparatus and wiring. 3. Pressurisation of apparatus. 4. Segregation and isolation of apparatus from the danger Zone.

Items I and 2 are covered by British Standards and Codes of Practice but the Standards of other countries may vary to some extent and German and U.S.A. techniques show appreciable variations.

Flameproof Apparatus

Flameproof apparatus cov~rs

mos~, of the app_Iicati~ns concerned and may be described as apparatus m which an internal explosion will not ignite the ~urroundiJ?-g atmosphere when the latter is equally explosive, nor w~ll the explosion distort the apparatus". ~uch apparatus :-v1ll have been designed in accordance with the appr?pnate British Standard will have been tested by the M1mstry of Power at Buxto~ and will have been given a certificate covering a certain group or groups of gases. All equipment must carry the registered ftameproof symbol and the Group Number.

Such a certificate does not mean that the appratus is suitable for use in an atmosphere continuously in the flammable range and, in fact, British Standards indicate quite clearly that for such situations other safeguards are necessary.

For practical purposes, the various ranges offlameproof apparatus are separated into four Groups, as follows:

Group I: Methane-this has little general application in industry and is chiefly concerned with coal mines. The use of methane in the gas industry is a recent development and represents the only appreciable application of Group I outside coal mining.

Group II: Pentane-this covers must of the usual industrial solvents and vapours including Petroleum, Benzene, Acetone, M.E.K., Cellulose, Ethyl Ether, Methyl Alcohol, Ammonia, etc.

Group III: Coal gas and Coke Oven Gas.

Group IV: Acetylene, Carbon Disulphide, Hydrogen, Ethyl-nitrate.

Safety is ensured by carrying out tests in which the apparatus is filled with the most incendive concentration and then placed in a chamber filled with the most easily ignited concentration. Limits are laid down for the minimum width of the flanges of the apparatus and the maximum gap between these flanges. Although these gaps act as flame traps and prevent the transmission of a flame or incendive particle they are not provided as pressure relief devices but are intended as maximum working tolerances over the life of the apparatus. Any well designed piece of flameproof equipment will have no measurable gap when new and may even be hermetically sealed by the use of spigotted and gasketted joints-the general use of gaskets on straight flanges cannot at the present time be accepted owing to possible variants, but research in this field is active. The rate of rise of pressure when internal ignition occurs is so rapid that the flange gaps give no measurable relief. The tests require certain working conditions to be complied with and a motor, for instance, would have to be complete with all windings, etc., and would have to be driven at normal speed. This is a fairly recent addition to B.S. 229 following a number of puzzling failures of certified equipment. This failing was eventually traced to pressure piling or gas c?mpre~sion which resulted in an explosion pressure many times higher than normal. It is felt that the tests are still inadequate in certain vital ways since they do not cover simulated fault conditions where an internal short-circuit has occurred. There can be little doubt that without careful attention to circuit protection and possibly fault limitation, certified apparatus, especially motors and switchgear, may not be satisfactory under fault conditions on heavy duty systems.

British flameproof apparatus is designed generally to a basis of flange width of 1 inch, although in certain cases this may be iin. Initially the gap width is determined experimentally by using an 8 litre sphere with equatorial flanges. The flange gaps are reduced progressively until no outside ignition occurs when a factor of safety is applied, normally 2. Rates of pressure rise are measured and ignition of the most incendive mixture or that giving the maximum pressure is done by spark or fuse.

The maximum permitted gaps for flanged joints are:

Group I: Methane-0.02in.

Group/!: Pentane-0.016in.

Group Ill: Town Gas-0.008in.

Group IV: Hydrogen-none given (but approximately 0.004in.).

Group IV is an excluded group for which no certificates have been given. The gap clearance for this Group are too small for normal manufacturing techniques although with screwed flanges having accurately cut machine threads this exclusion is now being overcome.

The function of the gap as a flame trap is not fully understood and for some time it was assumed to be a straightforward theory involving cooling of the ~ame by the metal flanges. This theory is now known to be mcorrect and non-metallic flanges will give a similar effect to metal. It appears probable that a layer of gas is maintained over each surface of the flanges and that these layers of gas quench the flame by inhibiting chain carriers; cooling, therefore, is effected by two layers of gas by surface contact.

Under normal conditions, the internal pressure will not exceed 140 p.s.i. after an internal explosion but turbulence and pressure piling have resulted in pressures of the order of 280 p.s.i. being recorded.

Oil-filled switchgear raises certain difficulties since the gas resulting from the cracking of switch oil by arcing, known as arc gas, may comprise 15 /~ acetylene and 85 % hydrogen, both excluded gases in Group IV, where the flange gap would be about 0.004 ins. On this acco.unt there has been some doubt in the minds of British engmeers on the integrity of such gear. Continental practice-Germa!lon the other hand, accepts the oil immersion of switch contacts as an adequate safeguard and pays literall)'. .no attention to the connections, bus-bars, cables, etc. Bn~1sh tests now use hydrogen as the filling media for the switch oil tank.

U .S.A. practice requires, in general, smaller !?aps between flanges than B.S. 229 but the testing technique may be less severe. Under extreme conditions with gaps at maximum limits it is sometimes possible to observe what appears to be a blue flash being emitte~ from. t.he F.P. enclosure and both Continental and Amencan cnttcs. have regarded this as unsatisfactory. Careful investigat.ion has shown that this feature is not a hazard and the optical effect is probably produced by molecular disturbance as the gas is emitted.

Installation

A chain is only as strong as its weakest link and it is necessary to preserve the same standards of safety throughout all parts of an installation in the danger zone. Wiring may be enclosed in screwed steel conduit or armoured cables, M.LC.C. cables or armoured P.V.C. cables may be used. Conduits over 1 inch in diameter are capable of transmitting flame and pressure piling could also occur. For such large conduits sealing boxes should be used. In addition, all connections to F.P. apparatus must be made via separate terminal boxes.

Cables and wiring accessories are not included in the certification although recent tests have included a number of cable glands.

Details of wiring requirements, installation and maintenance of flameproof and intrinsically safe equipment are given in British Standard Code of Practice No. 1003. It is important to remember that proper segregation must be provided between hazardous and non-hazardous sections. of an installation. Stopper boxes or F.P. terminal or cable boxes are used for such duties.

Circuit protection must be given very close attention. Syste~ ratings and fault duties must be kept to the lowest practical val~es with, where necessary, fault limitation such as by impedance earthing. Normally, apparatus cannot be opened until the system has been made dead and fuse gear should therefore be enclosed in separate co!11part~1ents having interlocking features associated with smtable 1solators-B.S. 116 limits the maximum ratina of F.P. oil-filled switchgear to 50 M.V.A. 0

Portable flameproof apparatus is only permitted under certain conditions and such equipment must be supplied by screened cable and provided with effective earthleakage protection.

Most flammable vapours are also toxic and effective measures are therefore necessary to provide adequate ventilation at all times. For most applications a dilution of 10,000 cubic feet of air per gallon of solvent or liquid vapourised will reduce the concentration below the minimum toxic value. This value is always considerably less than the lower flammable limit.

All installations must be tested at regular intervals and such tests should cover insulation resistance and earth continuity. Whilst suitable insulation testers are available with intrinsically safe certification at 500 volts such apparatus is not generally available for earth continuity testing, except for lighting circuits, and power circuits will normally have to be tested with the system dead. .

Intrinsically Safe Apparatus

Intrinsic safety is a term covering apparatus and circuits of low power and of such design and construction that any ~parking which may occur during normal operations is mcapable of igniting the prescribed inflammable vapour ~or whi_ch it _is cert!fied. Such apparatus is frequently used m conJunct10n with flameproof apparatus such as for ~ontrol. and interlock circuits, relays, telephones, gauges, mspect1on or emergency lights and instruments. . 1!1 Int~insically safe apparatus must be tested by the Safety !'-f mes Res~arc~ Establishment at Sheffield but prehmmary exammat10n of apparatus and drawings is done by the Electrical Branch of the Factory Inspectorate and the ce~tificates are issued by H.M. Chief Inspector of Factories.

The general requirements are dealt with in British Standard 1259 and the gases are now codified by Classes and not by Groups as for flameproof gear. The categories are: (a) Pentane Class: covering pentane, petroleum, butane, hexane, iso-hexane, heptane, acetone, carbon monoxide, cyclohexane, cyclohexene and benzene. (b) Ethylene Class: covering ethylene (c) Hydrogen Class: covering hydrogen, town gas, coke oven gas, and blue water gas.

Details of certificates issued by H.M. Chief Inspector of Factories are published by H.M.S.O. in a booklet known ~1s Form 931. This also covers "approved" apparatus, 1.e. apparatus which can be accepted as safe without recourse to test. Such apparatus is of extremely small power and limited application.

There are several important factors to be considered in connection with intrinsic safety design which affect the incendivity of a spark; they are: inductance, current and voltage of circuit, the contact materials and rate of contact separation of the electrodes.

Other factors are also important including means of damping or absorbing arc energy. The energy released in an I.S. circuit is represented theoretically by the formula t Li2 joules (where L = inductance in henrys and i = current in amperes) but experience has shown that a truer representation is given by t Li!.79 up to about I henrys. For methane the limitation of energy is approximately 0.003 to 0.005 joules whilst for pentane the value would be reduced by 15 % or so.

It will be obvious from this that intrinsically safe apparatus is always of low power and also usually of low voltage too-otherwise the current becomes very small in value. Transistorised equipment is lending itself to this subject with great facility. Not only are the power supplies for transistorised amplifiers and gating circuits conveniently low but such apparatus can with ease be encapsulated in expoxy resin to provide great standards of reliability and robustness.

With the exception of very low inductance circuits it is standard practice to provide some approved forms of energy shunt across the contacts, such as a resistor, capacitor or non-linear resistor (Metrosil).

Included among apparatus that is approved but not tested are lighting fittings provided with an air-driven turbo-generator which is pressurised by the driving air during the time that current is being generated. Such apparatus is suitable for all groups but some care is needed in providing a clean and dry air supply or corrosion of turbo impellor occurs.

Pressurised Systems

Although there is a good deal of flameproof and intrinsically safe apparatus available today there are many applications where other solutions have to be found. ~he design of a machine motor or generator ma~ be so spe~1alised that replacement with flameproof gear is no~ p~ss1ble. It is also necessary to do this for Gr<?UP IV appl_1cat10nshydrogen, acetylene, carbon disulphide, ethyl mtrate, etc. For some of these cases pressurisation has been developed.

It may be possible to use a simple pipe ventilated motor in a hazardous zone provided that safegua~ds _are taken to ensure a "clean air" inlet, that the exhaust 1s piped away from the zone of risk and that additional safeguards are taken to provide an adequate _purge bef~r~ the ~otor can be started. This would reqmre an add1t10nal mdependently-driven fan together with interlocking features to prevent misuse.

A more convenient method which can be applied readily to motors, switch cubicles, lighting fittings, etc., is to use a completely independent ventilating system whereby clean air at a pressure of 2 to 4 inches water gauge is applied to the apparatus. Pressure or air flow switches must be fitted to the exhaust ducting of such schemes interlocked with the main supply circuitbreaker or contactor to ensure that:

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(a) The equipment call:not be starte<;f or until it has been pressurised for sufficient time to give an effective purge, and (b) if the pressurising air supply fails, or if a cubicle is opened or a lighting glass fitting broken the supply will be disconnected instantly.

Since the air pressure switch or relay will be liable to be exposed to the "hot" vapour it is necessary to provide an intrinsically safe circuit for this part of the apparatus. It will be seen that by this means a pipe-ventilated motor of normal design, and price, can be used for, say, a hydrogen risk provided the pressurisation scheme is properly engineered with intrinsically safe relays, with Class IV certificates, on all exhaust ductings or pipes. Many firms now provide pressurised apparatus as standard lines which can be used with great economic advantage. It will be appreciated that all non-flameproof and non-LS. equipment must be segregated and placed in safe zones.

For excluded gases such as acetylene and carbon disulphide further precautions are necessary. Usually, segregated apparatus, completely separated from the "hot zone", can be used and pressurised schemes will only be possible where some indirect method of operation is available for the pressure switches or relays. Remote pressure gauges with capillary connections offer one solution as does a mechanical linkage scheme between "hot" and .. safe" zones. This can be done with a metal bellows arrangement to enable the pressure from the "hot zone" to be transmitted without direct vapour connections.

In some cases complete control or switch rooms are pressurised and such techniques are widely used in refinery, gas works and chemical plants.

The only problems arising in such cases concern the fresh air supply and means of access and egress for personnel. The first point is covered on refineries by erecting a stack pipe some 20 feet high for the air inlet, but this procedure would not be satisfactory for vapours lighter than air. The second point is covered by providing air lock entry doors, one of the .most examples being the revolving door. Static pressurisation systems have not given complete satisfaction since migration or percolation of the flammable vapour has occurred into the apparatus so pressurised.

Segregation of Apparatus

Although interesting at first consideration the practice of segregating the electrical apparatus from the "hot zone" usually presents many difficulties not at first apparent. A motor driving a machine may be placed in a room separate from the hazardous zone with a glanded shaft passing through an impervious wall, but some means must be provided for stopping the machine and very often for starting also. Where an intrinsically safe certificate is available then the l.S. apparatus can be used for the control circuit but where none is available some ingenuity is required for providing safe couplings. Pneumatic hydraulic and mechanical means are available but theless difficulties arise and careful consideration is required.

Perhaps the commonest field for segregation is. in lighting, and fluorescent are often acceptable if behind sealed screens of wired glass not less than :i.- mch thick.

Explosives

Flameproof apparatus in general is not and such equipment does not offer the right solution where explosive dusts or explosives are involved.

The real problem in these cases is the exclusion of the dust or explosive from the enclosure of the apparatus. Robust industrial apparatus constructed to dust C!r watertight requirements of British Standards the normal solution allied with a sound system of mamtenance and cleanliness. Pressurised schemes are also acceptable.

The ignition energy for dusts is relatively high, when compared with inflammable vapours, bl!t a broken lamp and an exposed filament or a shorted flexible cable ing a handlamp will cause trouble if the dust is in the explosive range. This concentration is a very heavy one and would be quite unacceptable in any w?rks since visibility would cease. It is usual for dust explos10ns to be initiated by a primary explosion which may not be very serious but this causes so much latent dust is raised in a heavy cloud and is then tgmted in a secondary, explosion of great severity. Flour, sugar, grain, wood, aluminium and magnesium produce .explosive dusts of great destruction power and whole -flour mills, etc.-have been destroyed by such explostons.

Much attention must be given to the of the plant. Segregation must be applied where possible and pressure reliefs provided. It is also possible to use explosion detectors which act on rate of rise of P'.essure and suppress incipient explosions by dousing with carbon dioxide.

Dusts are separated into three Classes: I, 2 and 3 in descending order of incendivity or explosibility.

Class I includes such dusts as aluminium powder, bitumen, cellulose acetate, cocoa, cotton, flour. rice, starch, sugar, tea, wood flour and others.

Class 2 includes cork, grass, heather, paper dust, sawdust and others.

Class 3 includes aluminium grain, blacking, carbon. coal, peat, tobacco.

Ammonia

One explosive vapour with unusual properties is amm?nia and users of refrigerating plant utilising compressors have found that given the right cond1t10ns. serious and destructive explosions can occur.

The lower flammable limit of NH:i in air is about. I 5 but the toxic limit is much less and a concentrat10n ot 0.1 % can be detected readily owing to the great dis-_ comfort it causes. Ammonia is included in Group I I ot flameproof apparatus but for large continuously manned plants it may not be practicable, or necessary, to use all flameproof apparatus. By using a very sensitive detector. which is intrinsically safe, it is possible to cut off all power circuits whenever ammonia is present in the atmosphere of the engine room.

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An emergency lighting circuit, separate from the power circuit, and a flameproof exhaust fan should be provided in addition to permit access for possible repairs with respirators where necessary, and to clear the fumes as quickly as possible.

Recent Development

A better degree of standardisation among contributing countries to the International Electrical Commission (l.E.C.) has already taken place and dangerous or flammable areas are now classified as:

Division 0-where dangerous atmospheres are continuously present.

Division I-where a dangerous atmosphere is likely under normal conditions, and

Division 2-where a dangerous atmosphere would only occur under abnormal conditions.

Only intrinsically safe or pressurised electrical apparatus and instruments would be acceptable in Division 0.

Normal flameproof and intrinsically safe apparatus would be satisfactory in Division 1.

Division 2 is a zone where a good deal of relaxation is permitted. Standards have been laid down in this country covering Division 2 zones which permit totally enclosed and spark-proof electrical apparatus for certain Division 2 zones where clearances are adequate, normally more than 25 feet from source of vapour.

I consider that the classification can usefully be extended by including Division 3 to indicate completely safe zones.

References

B.S. 229:

B.S. 889:

B.S. 1259:

Flameproof Apparatus. Ditto. Intrinsically-safe electrical apparatus and circuits. B.S. 1538: Intrinsically-safe transformers. B.S.C.P. 1003: Installation and Maintenance of Flameproof and Intrinsically-safe Electrical Equipment for Industries other than Coal Mining. Factories Act, 1961. Electricity (Factories Act) Special Regulations, 1908 and 1944. Safeguards against the Explosion Hazard in Industry by F. H. Mann-Electrical Times, 6s. Od. net. Factory Form 931-List of Certificates received by H.M.

Chief Inspector of Factories in respect of Intrinsical/ysaje and Approved Electrical Apparatus. The Institute of Petroleum Electrical Code, 5s. Od. net.

Question Period

An interesting point was raised by Station Officer Roast of the Bradford City Fire Brigade, who pointed out to the meeting that the corners of the normal glands used by B.l.C.C. for copper sheath mineral insulated cables were chamfered, but the flameproof glands were not, so that it was possible to ascertain by touch where flameproof glands were fitted or not.

Following further questions, Mr. Wood proposed a vote of thanks to the speakers and this was seconded by Mr. Sykes.

Next Meeting

The venue of the next meeting was proposed and seconded, to be in Scarborough in April, 1966.

There being no other business, the Chairman brought the meeting to a close by thanking the Leeds City Fire Brigade for the facilities and hospitality provided.

MIDLAND

A joint meeting of East and West Midlands Petroleum Officers was held in Dudley, on the 12th October, 1965.

The Chairman of the Association (Mr. D. Hall) introduced the Deputy Mayor of Dudley, Councillor W. G. K. Griffiths, J.P., and invited him to open the proceedings.

In a warm welcome to members, the Deputy Mayor expressed his pleasure in being asked to welcome them and open their meeting. He realised the great importance of the work of Petroleum Officers and ventured the opinion that perhaps at some future period, Petroleum Officers might be called upon to supervise atomic installations. He wished the meeting success. . .

The Chairman thanked Councillor Griffiths on behalf of the members. The business of the meeting then continued.

Present were 41 members and 4 visitors. Apologies were received from 27 members.

Branch Formation

The Chairman explained why the representatives the East and West Midlands had been called together m a joint meeting. He said that the question to be decided first was whether there should be one or two Branches.

After long discussion, Mr. J. Beer _Proposed and Mr. T. J. Metcalfe seconded "that a Midlands Branch be formed". Jn an amendment Mr. K. C. Hughes "that a West Midlands Branch be formed comp.nsmg the areas of Herefordshire, Shropshire, Staffordshire, Warwickshire and Worcestershire". This was duly seconded but on being put to the vote, was lost. The original proposition was then carried.

Election of Officers

The following officers of the Midlands Branch were then elected:

Chairman: Mr. J. S. Forman (Solihull C.B.)

Vice-Chairman: Mr. K. C. Hughes (Stafford M.B.C.)

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Hon. Sec./Treasurer: Mr. G. H. Harvey (Dudley C.B.)

Hon. Auditor: Mr. T. J. Metcalfe (Smethwick C.B.)

In the course of the meeting it was constantly stressed that the formation of Branches was highly desirable to give members greater opportunities of attending meetings nearer to their own areas, thus saving considerable travelling and expense. The hope was expressed that in due course a Branch in the East Midlands would be formed and to this end endeavours would be made to find a venue for a meeting of the East Midlands Petroleum Officers.

In the afternoon under the Chairmanship of Mr. J. S. Forman, members re-assembled to receive a talk by Mr. G. F. Stokes, Station Officer, Walsall Fire Brigade, entitled:

FIRE EXTINGUISHERS AT PETROL FILLING STATIONS

As you may well be aware there are many various types of fire extinguishers and consequently it is not easy for the inexperienced person to tell the precise difference between one extinguisher and another.

To some a two-gallon water gas or soda acid type extinguisher and a similar size foam extinguisher look almost identical. Some extinguishers have lengths of discharge hose attached and some of the same type have not. Some have to be turned upside down to be operated whilst a similar type are operated in the upright position by striking a knob on the top. It is these little differences which tend to confuse people unless they are properly trained in the use of the particular extinguishers which they may be called upon to use.

It is therefore vitally important that the Petroleum Officer, the Licensee and his staff should be fully conversant with the types of fire appliances likely to be provided on petrol filling stations.

The Model Code has been amended and now recommends the following scale of fire appliances as a guide. 1. Foam or dry powder extinguishers of approved type and two gallons or 10 lbs. capacity respectively should be provided on the basis of two extinguishers for up to four pumps connected to underground tanks; three for five to eight pumps and one more for every three pumps in addition.

It also recommends an ample supply of sand and an implement for its convenient application. The sand which should be kept as dry as possible for obvious reasons, is particularly useful for absorbing and smothering small spillages of petrol and oil and also for preventing freely flowing petrol from spreading and running into drains.

In the case of a storage place other than underground tanks, the Mode! Code further recommends that at least one 2-gallon foam extinguisher or one JO lbs. dry powder extinguisher should be provided for any quantity of petroleum spirit up to 100 gallons and for larger quantities it may be necessary to provide more extinguishers, or one or more foam engines of 10 or 30 gallons capacity may be required.

All extinguishers shall be situated within a reasonable distance from any tanks, pumps or other place in which petroleum spirit is kept or handled. A suggested reasonable distance is not more than 50 feet.

It follows that all fire fighting equipment n:ust .alwa~s be easily and immediately accessible and mau~tamed. m proper working order. The provision of fire fightmg equ~pment is one thing, ensuring that it is always in g.ood wo~kmg order, is vital. Care and maintenance of eqmpment is of paramount importance but it is all too frequen~ly n~glected. One cannot afford to be caught with fire extmgh1shers which will not function properly in an emergency.

Most of the reputable firms supplying fir~ fighting equipment offer a regular maintenance service for a nominal charge and Petroleum Officers should encourage licensees to take advantage of such service.

The particular choice of fire extinguishers to be provided on a petrol filling station may be governed by local conditions of licence but where this is not so l would suggest that as far as the main risk is concerned all extinguishers should be of the same type, i.e. all foam or all dry powder since under certain conditions the effectiveness of foam may be impaired by the additional use of dry powder due to chemical reaction between the powder and the foam.

Two-gallon Foam Extinguisher Chemical Foam

This type of extinguisher consists of a cylindrical ~ontainer filled to an indicated level with a solution of sodmm bicarbonate which also contains a stabilising medium.

An inner container is filled with a solution of aluminium sulphate. When the extinguisher is operated the two solutions mix together to produce foam and a gascarbon dioxide-which expels the foam. The ratio of expansion of the foam is about eight times the water capacity of the extinguisher.

A jet of at least 20 feet should be obtained and the duration of discharge of the contents should not be less than 30 seconds nor more than 90 seconds.

The most common method of operating a chemical foam extinguisher is by turning it upside down but in some cases it may be necessary to release a seal on top of the inner container before inverting. Mechanical Foam

This type of extinguisher is similar in size to the chemical extinguisher and may be red or blue in colour. The resulting foam is produced from a foam compound and water as distinct from the interaction of chemical solutions in the case of chemical foam. Gas Cartridge Type

The air foam concentrate is held either in a sealed plastic bag or as a solution with the water. When the pressure charge is pierced by striking the knob the plastic bag is ruptured, thus forcing the concentrate into the water cont~ine~ in the body of the extinguisher. The foam solution 1s then expelled via a dip tube and a short length of hose to the nozzle at which point it is aerated to produce foam. Stored Pressure Type

This type contains a premixed solution of foam compound and water in a hermetically sealed container which protects the contents from evaporation and is pressurised with either compressed air or nitrogen. The pressure is indicated on a pressure gauge.

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Operation is by pressing a release handle which causes the solution to be expelled via a diptube and hose to the nozzle where it is aerated to produce foam in the same way as the gas cartridge type.

Discharge can be stopped by returning the handle to its normal position.

Both the foregoing types are operated in the upright position and with the hose attachment makes handling and control of the foam jet much easier. Ratio of expansion is the same as the chemical type.

Care and Maintenance Chemical Foam Extinguisher

Open up annually and check that:

I. Both containers are filled to the correct levels. 2. The nozzle, vent holes and internal strainer are not clogged. 3. Washers in good condition. 4. Any releasing device moves freely. 5. No corrosion is present either internally or externally.

Extinguishers should be discharged at least once every two years.

Mechanical Foam Extinguishers (Gas cartridge type)

Open up annually and check that:

I. The water level is correct. 2. The nozzle, internal diptube and strainer, vent holes are not clogged. 3. The plunger moves freely. 4. Washers and hose are in good condition. 5. No corrosion is present either internally or externally. 6. The gas cartridge is weighed to detect any loss.

This type of extinguisher should be discharged at least once every five years.

Stored Pressure Type . Bein~ pressurised this type cannot be opened up for 111spect1on. They should be inspected quarterly and the following points noted: 1. Check pressure by means of the pressure gauge and any loss made good. 2. Nozzle is not clogged and hose in good condition. 3. No external corrosion is visible.

Each extinguisher should be tested annually by discharge.

Dry Powder Extinguishers

I?uring the past few years dry powder extinguishers have achieved a high standard of reliability and are particularly ~ffect~ve in extinguishing "running fires" and open surface fires mvolving flammable liquids. I have witnessed a number of impressive demonstrations in the use of these extinguishers.

The main constituent of the powder is sodium bicarbonate to. which is added a waterproofing agent such as a ~etalhc stearate to prevent moisture absorption and assist its free flowing. The powder is non toxic and a non conductor of electricity.

There are two types of dry powder extinguishers: (a) Those with the gas stored in a sealed cartridge and (b) Those with the gas stored within the body of the extinguisher and fitted with a pressure gauge.

Both types of extinguisher are operated in the upright position either by striking a knob in the case of the cartridge type or by a squeeze grip handle for the stored pressure type. The powder is then expelled from the extinguisher via the discharge tube and nozzle which in the case of the larger types can be opened or closed as required.

A 20 lbs. dry powder extinguisher is considered to be equivalent to one 2-gallon foam extinguisher. This size has a range of about 20-25 feet and a duration of 20 seconds. Care and Maintenance Gas Cartridge Type

Dry powder extinguishers should be checked annually as follows: 1. Weighed to ensure that they contain the correct amount of powder 2. Nozzle, vent holes, and internal discharge tube, are not clogged. 3. Cap washer and hose in good condition. 4. Plunger and squeeze grip nozzle control move freely. (This nozzle control must not be oiled or greased). 5. Check that the powder is free from caking. 6. Weigh gas cartridge to detect any loss. 7. Check for external corrosion.

This type of extinguisher should be totally discharged at least once every five years. Stored Pressure Type

Being pressurised this type cannot be opened up for inspection. 1. They should be weighed quarterly and if a loss of weight is detected the supplier should be consulted. 2. Any loss of pressure should be made good. 3. Nozzle and squeeze grip handle in good order. 4. No sign of external corrosion.

Each extinguisher should be totally discharged every five years.

The effectiveness of a portable fire extinguisher ultimately depends on its regular and proper maintenance plus the ability of the person using it and many_ fires have been nipped in the bud by the prompt and efficient use of these extinguishers.

The use of dry powder, a colour code for extin~t~i~hers, the effect of frost on extinguishers and the poss1b1hty of the development of an all-purpose ext_inguisher for filling stations were among the many questions ably answered by Station Officer Stokes and Sub-Officer J. R. Lewis.

At tea, kindly provided by the General Purposes Committee of the Dudley Town Council, members were again joined by the Deputy Mayor who said he hoped both Association and Branch meetings would continue to be held in Dudley. Mr. K. C. Hughes proposed a vote of thanks to the Dudley Council for the facilities and hospitality extended to members, and to the Deputy Mayor for his interest and attendance. The vote of thanks was heartily endorsed.

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Through the Pipeline: by Otto

WHAT'S TO DO ABOUT FIBREGLASS ?

Fibreglass comprises a mat of glass fibres impregnated with a suitable resin. The glass fibres are, of course, incombustible but the same is not generally true of the resin, even though the particular type of resin used may vary between one manufacturer and another.

On a filling station forecourt, it is essential that the amount of combustible material present should be kept to a minimum. This follows the time-old adage of keeping any potential fire in a risk area as small as is practicable. This does not mean that it is necessary for everything in the area to be incombustible within the meaning attributed to that term by B.S.476 Part I. It means rather that any combustible material allowed should only burn slowly and be unlikely to permit a flash of fire across its surface. Accepting this criterion a reasonable standard to apply would be that none of the materials allowed on the forecourt should have a surface spread of flame classification inferior to Class 2 (low surface spread of flame) in B.S.476 Part I. This standard should apply to petrol pump housings, canopies and other structures, not required to be fire-resisting.

The question arises as to how fibreglass fits into the picture. The standard fibreglass sheet usually has a Class 3 (medium) surface spread of flame characteristic but by the addition of certain fire-retarding agents it is possible to produce what is known as a self extinguishing grade of fibreglass. "Self extinguishing" fibreglass sheet almost invariably has a Class 2 surface spread of flame classification.

A few countries, like Belgium and Portugal, permit the carrying tank of tank wagons to be constructed <?f fibreglass. As there have been suggestions that this c?untry should follow suit it may be worth while to ':"hat objections there might be to this. The mam Objections can be discussed under three heads as follows: 1. Fibreglass does not conduct electricity very well; It has a specific resistance of about 1010 ohms per cent1meter cube. It would not therefore serve any useful purpose to earth the carrying tank during filling as is practice today. Modern thinking on static generation has, however, changed and the need for a tank made. of_ conductive material is not now regarded as essential If other precautions are taken. 2. Physical. Fibreglass will burn and no one can relish thought of a large quantity of an inflammable liquid bemg enclosed in a combustible container. One can imagine arising where fire fighters may have alternative to wait until a fire burning through a hbreglass carrymg tank has released its contents. d.oes not have a very high impact resistance. Dropping a 3m. diameter steel ball weighing 1,800 gm. through 10 ems. on to some sheets of fibreglass has produced star fractures. Whether or not petrol could escape through these star fractures must be a matter of luck.

J. Chemical. Fibreglass, or at least the resin i! contains, is destroyed by some chemicals including chlormated hydrocarbons, benzene and alcohol. Many petrols, of course, contain benzene and some in this country alcohol; these petrols would therefore tend to destroy a fibreglass carrying tank. As for chlorinated two of these, trichlor ethylene and carbon tetrachlonde, are frequently carried in fire extinguishers on tank wagons.

A fair assessment at the present time might be that the case for permitting fibreglass carrying tanks has not yet been made. An open mind must, however, be kept on !he subject because resins may change and manufacturmg methods will improve. Thus, future development may overcome the snags which exist at present.

The case for underground fibreglass petrol m.ight more easily be established because many of the obJect10ns to fibreglass carrying tanks do not apply with the same force. So far as chemical attack is concerned, the answer may lie in accepting a tank for a given number. of years, to be determined according to the characteristics of the fibreglass used, and after that period requiring abandonment of the tank without option.

HOW DOES THAT AUTOMATIC NOZZLE WORK?

In simplicity an automatic nozzle is a nozzle which is fitted with a device to prevent overfilling of a vehicle's tank. The nozzle may or may not be fitted with a latch to hold open its dispensing lever and thereby avoid the need for full manual control.

All the automatic nozzles in current production. work in much the same way. It is well known that if one arranges for liquid to flow rapidly past a small hole then air or liquid is sucked out of that hole or in other words a venturi is created. In the case of an automatic nozzle, the venturi created by petrol rapidly flowing past a small hole is made to suck air out of a small chamber sealed on one side by a diaphragm. A depression would occur in this chamber were it not for an air bleed hole. Attached to the air bleed hole is a length of small bore copper tube extending down to near the end of the nozzle spout. As liquid rises in a vehicle's filling pipe it covers the nozzle spout and eventually the end of the copper tube attac.hed to the air bleed hole. When this occurs, air flow to relieve the depression in the chamber is stopped. The partial vacuum formed in the chamber causes the diaphragm on one side of the chamber to move. Movement of the diaphragm displaces a fulcrum point on which the normal control lever of the nozzle bears. Without a fulcrum point, the lever can no longer exert pressure on the stem of the main control valve to hold it open and the valve snaps shut under the influence of its spring.

Wark is done in securing movement of the diaphragmand nothing in this world is free. The work is paid for by loss of pressure and a reduction in overall flow rate through the nozzle; in simplicity, to obtain the linear flow

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necessary .to create the venturi requires constriction of the cross-sectional area of the liquid flow path with consequent loss. o~ hydraulic efficiency. In general, the greater the constnct10n, the greater the liquid velocity and the lower the. overall flow rate required to make the device work. It is pertinent to recall that some automatic nozzles require a flow of 4! gallons a minute before they will work; the more usual figure is, however, lf gallons per minute.

~hese facts are important in the light of the safeguard winch the cut-off device is intended to provide in selfse_rvice applications. It is to be hoped that serious attempts will be made by manufacturers to secure an operating flow bel?w one gallon per minute. If this so restricts the pump delivery rate that five gallons per minute cannot be exceeded then this too will be a further safeguard, having regard to the awkwardness of the fillling arrangements on some vehicles.

On conventional stations the automatic nozzle without a retaining lat~h is passively regarded by authorities as a bonus precaut10n against spilling; although there are those who .a~e conc.erned at the false security created by nozzles requmng a high flow rate to operate. This, however, was n<;>t the role cast for automatic nozzles; they were designed with a retaining latch to dispense with the need for full manual control.

There are some sophisticated designs of automatic nozzle which incorporate: (a) an ~nchor spring to prevent the nozzle accidentally fallmg out of a vehicle's filling pipe. (b) a .specially made retaining latch such that the operatmg lever is released when the nozzle hits the ground or part of a vehicle, and (c) a break off section which prevents damage to the pump or. h<?se. should a vehicle drive away with the nozzle still m its filling pipe.

It is c.;l~ime? that these safeguards take care of most eventualities .likely to arise in the use of latched open nozzles and 1t may be agreed that this is true provided that:

(a) the minimum setting on the retaining latch ensures a flow rate of twice that necessary to operate the cut off device; and (b) th.e pump to which the nozzle is attached is fitted with an effective limiting device and is situate in an area drained to a petroleum interceptor.

Certainly the only final device that could be incorporated would be one to ensure cut-off immediately the nozzle leaves or falls from the vehicle filling pipe.

HOW BIG IS THAT LEAK ?

Faced with a leaking tank one is inclined to imagine that there will be an immediate loss of all its contents and that the bigger the tank, the larger the amount of petrol immediately at hazard. Fortunately, rapid loss of contents can only follow catastrophic failure of a tank and this is a very rare bird indeed. The more usual pattern particularly with underground tanks is outflow from a small hole caused by corrosion over a number of years. The rate of leakage of air or liquid through the hole does not depend directly on the capacity of the tank; instead, it is a function of the size of the hole and the pressure within the tank.

For the sake of argument, let us assume that a holed tank is subjected to a pressure test of 10 lbs. per square inch and that the hole in the wall of the tank is circular and has a diameter of 12 thousandths of an inch. Under these conditions, while the pressure remains at 10 lbs. per square inch, 2! cubic feet of air (or nitrogen) would be lost per hour, causing a drop in pressure oft lb. per square inch per hour in a 500 gallon tank or t lb. per square inch per hour in a 1,000 gallon tank. It is interesting to note that under the specified conditions a 5,000 gallon tank would lose only approximately 1 lb. per square inch of pressure in 24 hours and many argue that this makes the standard pressure test unsatisfactory on large tanks, particularly when regard is also paid to the difficulties of accurately determining variations arising from changes in temperature and barometric pressure.

In considering what would happen if liquid instead of air were in the holed tank, one embraces Torricelli's Theorem and hopefully murmurs that v2 = 2gh, trusting that v = velocity of outflow in feet per second, g = the acceleration of gravity (i.e. 32.2 ft/sec2) and h = the depth of the hole beneath the surface of the liquid in feet. If the velocity determined is multiplied by the cross-sectional area of the hole, the rate of leakage can be ascertained. Taking the worst case in a full 5,000 gallon tank where the hole at the very bottom of the tank is 8 feet below the surface of the liquid, one concludes that the rate of leakage would be 0.4 gallons per hour or about 10 gallons per day. On average the tank will only be half full and the ayerage head of liquid will therefore be 4 feet. From this one deduces that the average rate of leakage in the conditions specified would be about 5 gallons per day and that the tank would take 1,000 days to empty.

Before too much comfort is derived from these figures, it should be pointed out that the leak will continue until someone stops use of the tank. Addin~ 5,000 gallons of petrol to the ground ev~ry 1,00~ days 1~ a dangerous as well as an expensive pastime, particular!~ 1f one remembers that one gallon of petrol w~rnld be sufficient to produce a.n even explosive concentrat10n throughout the whole air space of a basement r~om measuring 30 feet !ong by. 10 feet wide by 10 feet high. But then any filling station proprietor would notice a loss of 5 gallons per day-or would he?

All calculations have presumed that there is no impediment to liquid flowing through the hole. This is not always the case. In waterlogged ground. it often occurs that the level of water outside the tank is higher than petrol inside. Under these conditions, no petrol is lost but water flows into the tank. One may confidently predict that any filling station proprietor will ultimately become aware of water in his tank.

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