PLANNING AND THE PETROLEUM 0FFICER-W. C. R. DALE

3. The Petroleum Spirit (Motor Vehicles, etc.) Regulations, 1928

By virtue of these Regulations, made under Section 10 of the Act, petroleum spirit kept for private use (nor for sale) in connection with motor vehicles, motor boats, lawn mowers, electricity · generators; etc., is exempted from the provisions of Sections 1-9 of the Act (i.e. including the licensing provisions) subject to the conditions laid down in the Regulations. (If these cannot be observed, a licence must still be obtained). The maximum quantity which may be kept in this way is 60 gallons, and foi: this purpose the amount kept in storage places 20 feet apart or less is added together. As the petrol tank of a motor vehicle is a place for this purpose it follows that an indoor car park with a capacity of more than (say) 20 cars, will require to be licensed. Apart from the tanks of motor vehicles, petroleum spirit kept in this way must be stored in suitable metal containers, properly labelled and these must not exceed 2 gallons in capacity when specific notice is given to the licensing authority and special structural conditions are observed. The storage place (e.g. a garage) must be properly ventilated, and if it adjoins a house or assembly ha!J, then either (i) the partition between must be constructed of non-flammable materials with no opening or (ii) petroleum spirit must be kept only in the fuel tank of a motor vehicle and in not more than two two-gallon vessels. The Regulations also contain certain other detailed conditions.

The Transporting of Petroleum Spirit . The Petroleum Spirit (Conveyance by Road) Regulat10ns made under Section 6 apply to the conveyance by road of more than 32 gallons of petroleum spirit or petroleum mixtures (excluding the contents of the petrol tank of a motor vehicle). This quantity is increased to 50 gallons if the petroleum spirit is in a single securely closed steel barrel, but is reduced below 32 gallons in certain other circumstances. The Regulations deal mainly wit h the construction of the vehicle, and with safety precautions, of which two call for particular comment. Regulation 7 provides that a vehicle carrying petroleum spirit (or mixture) shall, except when it is in a licensed store or other approved place, be constantly attended by the driver or by another person over the age of 18 years. This is a question of fact- in one particular case (Swansea) the driver was in a cafe 92 yards away, and although he claimed he could see the vehicle, he was held to have contravened the Regulation. Regulation 16 provides for the precautions to be taken when a delivery is made from a vebicle into a storage tank when a Certificate has to be signed and handed to the person in charge of tbe vehicle before delivery can begin, and tanks must be dipped, connections checked, and other precautions taken.

Special Regulations have also beeft made for the Conveyance by Road of Gas Cylinders (1931), Compressed Gas Cylinders used as fuel for motor vehicles (1940) and Carbon Disulphide (1958). There are also special provisions as to the loading of ships with petroleum spirit (Sections 7 and 8) and the transporting o.f petroleum spirit by canal (Section 9). Miscellaneous

Section 5 deals with the labelling ofcontainers in which petroleum spirit is kept, and it is an offence to sell petroleum spirit in a container which does not comply with the requirements of this Section.

Sections 13 and 14 deal with explosions at licensed premises, or on ships or vehicles carrying petroleum spirit. The occupier must report any explosion involving petroleum spirit and causing loss of life or personal injury,. to the Home Secretary, who may order an inquiry to be held.

Sections 16, 17 and 18 deal with the powers oflnspectors ~nder. the Explosives Act, and of Inspectors appointed by hcensmg authorities, including the right to purchase and test samples, to examine places and vessels where petroleum spirit is kept by a dealer or by a person using it for trade or industry, and to obtain search warrants and seize petroleum spirit kept without a licence. It shall be noted. however, that there is no general rigbt of entry for inspectors, and that this must therefore be included in the licence conditions.

A1;11ong other statutory provisions, Section 73 of the Public H~alth Act, 1961, deals with derelict petrol tanks, and reqmres the occupier of premises containing such a tank to take reasonable steps to prevent it from becoming ~ dang~r. Officers of licensing authorities have a right of mspection, and may require certain safety measures to be taken. By liaising with his colleagues in other departments, the petroleum officer will also discover other Acts of Parliament,. such as the Town and Country Planning Act, 1962, which, although they do not specifically relate to petroleum spirit, contain provisions which may help to solve a particular problem.

PLANNING AND THE PETROLEUM OFFICER

W. C.R. Dale, A.F.l.P., Greater London Council

Introduction

If the effect of fire is to be minimised, adequate fire prevention safeguards must be built into a structure or storage at the construction stage. This means that a petroleum officer'.s consideration of a proposal at the planntng or drawmg board stage is of prime importance and my purpose is to indicate what I deem to be the most important points to bear in mind during this consideration.

Objectives

To minimise the effect of fire, one must do two things: (a) use every endeavour to prevent outbreak of fire; (b) make ad.eq~iate pr~vi sio n to localise any outbreak and to limit any nsk to persons· included in this would be ensuring that there is adequate provision for summoning the Fire Brigade. ·

When dealing with flammable liquids there is one further thing that must be done and that is to prevent outflow. lt could be argued that this falls within the first

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two objectives but it is of such importance that it should stand as an objective on its own. It is no good making the storage area safe if petrol is permitted to flow out to be ignited or to spread fire elsewhere whenever things go wrong.

Prevention of outbreak of fire

Turning firstly to prevention of outbreak there are some e~ementary facts to be remembered. lt is only the vapour given off by a flammable liquid that burns and this vapour will burn onlv if the concentration of it in air falls within the explosive- (or flammable) range of that vapour. For petrol vapour, the range volume by volume extends from about I % at the lower ~nd to 8 % at the ~pper end; for acetylene the range is wider from about 2.5 % to 80 %. Even when one has an explosive concentration of vapour one needs to heat the vapour above its auto-ignition temperature before it will ignite. The auto-ignition temperature o~ p~trol vapour is about 300°C. These elementary facts 111d1cate two separate approaches which can be made to prevent ignition of vapours from flammable liquids.

Ventilation .. T~e first approach is to ensure by means of good vent1lat10n th~t vapour can never be present in explosive concentration. The simplest way of achieving this is to ~rrange all sto_rages in the open air. It is pertinent at this ,,tage to ment10.n that petrol vapour becomes fully toxic at a concent~at1on of 0.5 % with air, i.e. about half the low~r explosive limit. A man can be killed as easily by gassmg. as by burning him to death. One would, however, be seekmg ventilation to prevent much lower concentration of vapour than this.

Exclusion of ignition sources . ~~e other path to follow is to avoid the presence of any igmtioi~ source within any area where an explosive concehn.tr11atwn of vapour may w 1c must b b. possibly occur. In defining areas

rr po 1 ics. exposure . . ' F ear 1trary, one enters the realms of practical or most risks a distance of 20 feet from the pomt · 1s · ' . a 111ce round number of about the nght ~ime~sions. For large risks, such as bulk distributing fi ep~ s, a fig~1re of 50 feet is more appropriate. Having xe ;n arb1t\ary figure, no relaxation of it should be ag~~el 'Jtherw1se a series of waivers might in the ultimate w itt e own the figure to nothing.

Jgnition sources

Likely ignit!on sources must now be considered. There are some obvious ones like fire, flame and lighted cigarette~. Ther.e are also some exotic ones like potassium and sodium which burst into flames when exposed to air. The Home Office Code conditions take cognizance of all these.

Electrical heating apparatus

Of pa~ticular interest in the context of excluding ignition s.ources is th.e prohibition in the Code relating to 'artificial hght, electncal apparatus or appliances likely to ignite fl~mm~ble.vapour'. Use of the word 'likely' shows that discretion is called for. Jn considering how to apply this discretion, electrical apparatus and appliances can conveniently be divided into two types, namely heating appliances and other apparatus.

With electrical heating appliances a limit must be fixed on the temperature which exposed surfaces can obtain. For reasons already discussed, the limit of 300°C. suggests itself. Some petroleum spirits such as hexane, cyclohexane and heptane have auto-ignition temperature below 300°C. and where these substances are met ~ suitable adjustment of the general figure of 300°C. will be necessary. In a cellulose space, a lower figure of I 80°F. is required because of the tendency of cellulose deposits to 'fume off' above this temperature. The housing or frame enclosing heaters should be similar to those for other electrical appliances with which it is now convenient to deal.

Electrical apparatus

In deciding the proper type of housing or enclosure for electrical apparatus regard must be had to the area in which the apparatus is to be installed.

Occasionally, as in the case of submersible pumps, it may be necessary to install electrical equipment in a space where vapour at or above the explosive range is always present; this is usually known as a 'Division O' area. Needless to say, equipment installed in a 'Division O' area must not only be of a safe type but must be as fool-proof as human ingenuity can make it.

Generally, however, it is convenient to think in terms of three areas: a 'danger area' (or Division I area) where there is a constant risk of the formation of a fully explosive concentration of vapour; a 'safe area', where no vapour will be present, and an 'intermediate area' (or Division 2 area) between the other two areas where vapour. ~ay occasionally be present but save under freak cond1t1011s the concentration of it is unlikely to build up to anything approaching the lower explosive limit. Becaus.e. petrol vapour is heavier than air, one passe~ from a D1v1s1?n l area to a Division 2 area more quickly upwards in a vertical direction than in a horizontal direction. Pits and chambers below ground will frequently be Division l areas althouoh the area above them can be regarded as a b Division 2 area.

Jn a Division I area one should permit only such apparatus as is Flameproof (Group II gases), lntrin~ically Safe (Pentane Class) or pressurised. As an alternative to Flameproof (Group II gases) it is customary to accept the American equivalent of apparatus approved by Underwriters Laboratory Incorporated for Class 1 Group D (Hazardous location).

If one examines the concepts underlying the various methods of protecting electrical apparatus whi~h hav_e just been mentioned, it becomes apparent that with suitable combination of Flameproof, [ntrinsically Safe and pressurised equipment, one can arrange to install vir.tually any electrical equipment in a Division I area. There 1s a da~ger here. Before one decides how electrical apparatus 10 a Division 1, or for that matter in a Division 0 or 2 ar.ea, is to be protected, one should first decide wh~ther , .havm_g paid due regard to efficiency and other cons1derat1ons, 1t is in fact necessary to install the equipment in such an area at all.

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ln a Division 2 area, it is reasonable to accept vapour tight equipment as an alternative to Flameproof, Intrinsically Safe or pressurised equipment. Hitherto, there has been no hard and fast national standard laid down for vapour tight and similar equipment, but a British Standards Committee has been set up to remedy the omission. The sooner their findings are promulgated, the better.

In a 'Safe area' anything will go so far as electrical equipment is concerned.

Limiting the effect of fire

Attention can now be directed to measures to limit the extent of a fire and to minimise the risk to persons. Naturally one's first concern will be with persons and the way in which they can best be helped is to ensure that they always have easy and safe means of escape from storage areas and buildings which might be threatened.

To limit spread of fire, firebreaks must be established. Distance itself provides an effective firebreak if there are no combustibles in the intervening space. Where adequate safety distances cannot be achieved the use of fire-resisting walls or partitions offer an alternative. Any openings in these walls must be dealt with; windows can be glazed with :fire-resisting glass in :fire-resisting framing fixed shut or if openings are necessary for ventilation, these openings can be protected by hopper type fire-resisting baffles; small personnel doors can be rendered fire-resisting and selfclosing; and large doorway openings can be fitted with :fire-resisting shutters held open only by fusible links.

It is further essential to exclude any avoidable clutter of combustible from a storage area. This means that kiosks and canopies which it is not worthwhile requiring to be of :fire-resisting construction should be made only of incombustible materials or at least of materials having a low surface spread of flame (i.e. Class 2 in British Standard 476, Part I). The same should apply to the exposed lining of any fire-resisting wall or partition.

One should also ensure that adequate portable fireextinguishers are readily available to deal with an outbreak of fire at its initial stages and means should be available for summoning the fire brigade.

Prevention of outflow

The final objective to consider before looking at invividual cases is the question of prevention of outflow. In the case of can stores this is achieved simply by providing a retaining well well is usually to the set at store. The capacity of this retaining I 00 % of the capacity of the store. However, in cases where the whole contents of the store may be deposited into the well in one fell swoop and a margin for a layer of foam is desired it would not be unreasonable to ask for I I 0 % of the store capacity.

On petrol filling stations, outflow can be prevented by dishing the storage, filling and vehicle charging areas. Obviously these areas will have to be drained and this drainage must be passed through a petroleum interceptor to prevent outflow of petroleum spirit into the sewers. All gullies connected to a petroleum interceptor should be of trapped type. Filling stations

A lot more could be said in regard to the objectives, but it is appropriate now to consider the conditions that result from the application of the objectives to particular types of storages. It is convenient to start with filling stations.

Storage tanks

All objectives are best met if storage tanks on filling stations are situate underground and not above-ground. This almost invariably coincides with the wishes of the filling station proprietor so the point need not be developed.

The storage tank should be constructed of !in. mild steel plate with welded seams and for convenience should be provided with a manhole. There will be some danger to the tank shell from the dipstick so a plate having minimum dimensions of about 14ins. by 4ins., commonly known as an impact plate, should be provided beneath the dipping opening. Before being installed in a manner which can be considered later, the tank should have all rust and scale removed and then be coated with bitumen or similar anti-corrosive coatings.

Tank fittings

On a storage tank, one needs a suction pipe, a vent pipe and a combined dip and filling pipe. The dip and filling pipe should in all cases be 2 inches longer than the suction pipe so as to ensure the maintenance of a liquid seal on it. Occasionally, on safety grounds, an off-set filling pipe may. be necessary. Whenever an off-set filling pipe is pr~v1ded, no dipping opening or other opening from which petrol can flow when the tank is overfilled should be permitted. There are a number of contents gauges which are just as accurate as dipsticks. One word of warning, however, many contents gauges have reference to the specific gravity of the liquid being measured so that if !he grade calibrated. is changed, the gauge may need to be re-

The suction pipe is normally sealed from atmosphere by valv~s and equipment in the petrol pump. There is a possible path of outflow via the air separator vent of the p~mp but provision is this outlet. normally made in the pump to block

The vent pipe must connect the tank directly to atmosphere. It should be the only pipe that does so. To prevent the possibility of flash back to the tank via the vent pipe, safety gauze must be fitted in the upper orifice of the pipe. 1J?1mense quantities of vapour are discharged from the pipe when the tank is being filled. It would be best if this vapour were discharged upwards to aid dispersal but general practice unfortunately does not follow this ideal be~ause it is alleged t~at rain water may get into the tank. I! JS therefore essential to enst~re that vent pipes are so situate as to enable vapour to disperse rapidly. The upper orifices of the vent pipes should be well removed from openings into buildings and dangerous electrical equipment. In this context a roof, other than an imperforate concrete roof, may well be an opening into a building. Incidentally it might be of interest to mention that the weight of vapour laden air in a vent pipe is such that for

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every !Oft. of height of vapour in the vent pipe, petrol is rai~ed 0.1 inch in the dip pipe. Thus after a tank wagon delivery when the vent pipe is full of vapour one would expect the level of petrol in the dip pipe to be higher than when only fresh air is in the vent pipe after operation of the petrol pump.

Th.e installation of tanks is not strictly within the scope of this paper but may I put in a personal plea for concrete encasement of tanks. In my opinion, rendered brick chambers filled with sand lead to early corrosion of tanks. Most sand has sulphur present in it. Rendering on the inside of the brick walls of the chamber may soon be pushed off by sub-surface water pressure and once water enters the chamber you have ideal conditions for corrosion. If you ~ust have. a chamber, I suggest you build the walls of v1.brated reinforced concrete and then permit in-filling only with puddled clay having a specific resistance in excess of 3,000 ohms per centimetre cube and of such nature that it will. not permit the incubation of sulphate reducing bactena after test lasting 42 days.

There is a modern trend towards remote pumping; this n~eans that petrol is pumped under pressure towards island dispensers mstead of being sucked as at present. Within my t~rms of reference, I should refer to the need for ensunng that ~n impact check valve is always inserted in the pressure hne at the base of each dispenser so as to ensure tha~ petrol is not sprayed all over the forecourt if, or should .1t be when, the dispenser is knocked over by a clumsy dnver. · d ~II petrol pumps should be fitted with limiting or pre-set evices to prevent continuous outflow of petrol from them.

Siting of petrol pumps and tanks t So k far h a s · is · pos.sible pumps and the opening to p~trol banks 2 ~ ould be sited in the open air and should be set 1 ac . f~et from the public highway. In well ventilated ocat1ons 1t may t b . t b no e unreasonable to permit the pumps 0 e ~nd e

r canopies or even buildings provided that the canopies and buildings are of suitable construction Tank 1

0 penll1gs ~nd the tank wagon stand should, h~wever, a ways be 111 th ~ op . d 1 . . . f yard fo. th. - en air an t 1e m1mmum size o open 1 is purp:)se should be 30ft. by 16ft. f Sto~~ge btanks should be sited as far away as possible f~~~nof e basements of buildings. If they are within 20 should ~ dase~ 1 ent the usual 9in. concrete encasement Ever eff<e ou led and the mix improved to 1 : 11- : 3-t. y ort should be made to ensure that the bottom of any storage tank is at least 18ins. below a nearby basement. 1 n certain sto ag t k · r. f an cas · . es it may be necessary to 111 a basement. This, however, . include the will require ~ec~a b encasement. of the tank and enclosure of the tank oc. i Ya mec~an1cally ventilated walkway with adequate retall1 ng capacity and fire separation.

Buildings near tanks and pumps

It is essential to establish a fire break between buildings ~ md any petrol storage or vehicle charging area. Tf distance itself does not _provide a sufficient fire break, this can be d.o.ne by ensuring that any exposed walls and other part1t1ons of the buildings are of two-hour fire-resisting construction and that any openings in these exposed walls are dealt with as already discussed. It is also essential that any exposed supports for the building (and buildings on stilts are not unusual these days) should have a similar standard of fire-resistance.

There is, however, little point in applying this standard to small single storey kiosks and service buildings. Provided that there is adequate means of escape for personnel, it is only necessary to ensure that these buildinas are of incombustible construction. ""

Drainage of filling stations

It has already been mentioned that the drainage of filling stations should be taken via trapped gullies through a petroleum interceptor. The point should, however, be emphasised that in a vehicle charging area, there is constant spillage. Tarmac does not stand up well to petrol and permits seepage of petrol through it. Thus the area within a twelve foot radius of any petrol pump should be paved with concrete.

Brick stores

Petroleum spirit and particularly petroleum mixture is not always kept in bulk in tanks ; it is alS) kept in cans, drums and barrels. This type of storage is often associated with use in a factory in such things as spraying, mixing and dipping rooms. The powers an Inspector has under the Petroleum (Consolidation) Act, 1928, enable him to control such use, but it is not appropriate to deal with this aspect in the context of this paper.

All objectives will be met if arrangements are made for cans, drums and barrels containing petroleum spirit and mixture to be kept in a store situate in the open air constructd with 9 inch walls and 5 inch reinforced concrete roof. The door of the store should be fire-resisting and normally kept locked, a retaining well not more than 2 feet deep should be provided to the store and ventilation arranged by gauze protected air bricks at high and low levels in at least three walls. The store is best detached from other buildings but objection need .not be r.aised to its being attached to a building on one side provided the separation is imperforate and of a four ~o~ir stan.da~d of fire resistance. Exposed openings to buddmgs w1th111 20 feet of the store should be protected as has already been discussed for filling stations.

Some people prefer a roof of light con

s ~ruction

. to .a store such that it will disintearate and provide a rehef Ill the event of explosion. The desirability of thi~ w.ill obviously be decided by the proximity ~f other budd

.1~g

s but the best of both worlds might be achieved by requmng the roof to be constructed of narrow 5 inch reinforced concrete slabs lightly cemented together.

Iron stores

For small storaaes up to 50 gallons, considerable relaxation may be allo~ed. A galvanised iron. bin (16 S. W .G) in the open air should be a

d~qu a te

p~·o".1ded .that the. bm has retaining capacity. The distance w1th111 which opemngs to buildings need protection can comfortably be reduced to 10 feet. The store should, however, be 20 feet from the public way and adjoining property to ensure observance of our fire, flame, etc., conditions.

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