H. BECKINGHAM

At 15.00 hours on the 19th I held a consultation with Mr. Ellis, Area Manager for the Esso Petroleum Co., Ltd., and Mr. Hawkins, the Deputy City Surveyor. The result of our discussion was a joint publication which was distributed to the press and the B.B.C.

Two hourly gas tests were continued on the sewerage lines and the City Surveyor obliged me by cutting into the manholes, allowing a direct constant flow of water from the River Petteril.

At 17.30 hours on the 18th I made an appeal through the Medium of Border T.V. for any information which the public could supply in respect of any known petrol leakage.

I also requested the Police to use the Public Address System in an effort to warn the public of the danger which at that time existed. This was repeated between 23.00 hours and 23.59 hours.

At 07.00 hours on the 19th the readings of the sewerage pipe atmosphere began to show negative readings. At this time I requested the Police again to use the Public Address System to tell the public that small domestic appliances could be used for their needs, but they should refrain from lighting domestic fires.

At 12.00 hours on the 19th complete negative readings were obtained and I declared the area safe.

CHEAP PRODUCTION OF AEROSOLS

Paper presented by H. Beckingham, M.I.Fire E. Chief Fire Officer, Warrington at the International Fire Exhibition and Conference held recently at Olympia, London

BRING NEW FIRE HAZARDS

The development of aerosols in Britain is progressing rapidly. A production of a half million packages in 1950 grew to 12 million in 1957. In 1964 the figure was quite staggering-I JO million packages were produced by reputable firms. This figure does not include those produced by non-reputable firms.

Aerosols are not new a patent for a type of aerosol was grai:ited in 1862. T~day, however, aeroso!s are _big busmess based, in some cases possibly, on nsk agamst reward. · An aerosol, sometimes called a 'pressure pack', is normally a metal or glass container, in which is a liquid ~roduct and a propellant. This propellant is usually a hqu~fied gas, the vapour of which supplies H~e pressure to eject the product in the form of a spray, which may be very fine, for example in the case of insecticides, or a quite coarse spray where a surface coating is required, for example hair lacquer and moth proofer. . There are basically two types of pressure pac~. Th~ fir_st is the. two-phase system which consists of a s1!1gle hqu1d or solid phase and a single gaseous phase, and is the most common type. The liquid or solid phase is either the product alone or a mixture of the product and the liquid pr_opellant. In certain cases the liquid product may contam _some propellant, although where a solid is used it consists of only the product.

When the actuator button is depressed the pressure created by the liquid gas propellant ejects the liquid phase out ~hr~ugh the valve. The decrease in pressure allows the_ hq ~1d gas propellant to further vaporise in order" to mamtam sufficient pressure to eject all of the product.

The second type is the three-phase system consisting of either two liquid phases which could be emulsified or one liquid and one solid phase in addition to the liquefied gas propellant. The operation of the actuator valve allows the pressure exerted by the propellant vapour in the space above the product to force up the dip tube and out of the. valve. The ~iquid propel Ian~ continues to vaporise dunng the operation of the valve m order to maintain the pressure.

It can be seen then that each aerosol is, in fact, a pressure pack containing essentially a product and propellant and it is therefore possible to have a flammable or nonflammable product combined with a flammable or nonflammable propellant.

The most common products are based on hydrocarbon oils, kerosine, alcohols or water. The propellant may bepropane or butane (highly flammable) or non-flammable propellant, the most common being the fluorohydrocarbons, or commonly called 'Arctons'. All are liquefied gases.

A very small number of aerosols may use a gas such as nitrogen or carbon dioxide; even nitrous oxide has been used. The completed aerosol may, therefore result in being a dangerous hazard to the consumer or 'one which could be considered quite safe to the consumer during personal use.

It should be noted here that the hazard relating to aerosols must be considered in relation to three headings: (a) Consumer; (b) Transport of packages; (c) Storage of aerosols.

The main hazards of aerosols can be further classified as follows:

(l) The danger that the product, when expelled into the air, may ignite from an ignition source in the vicinity and thereby cause injury to the consumer or cause a fire;

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~2) The danger of the aerosol being placed where it can be heated and explode. Aerosol containers may explode very violently under these circumstances; (3) An aerosol container leaking and allowing a flammable gas to escape and become ignited by a source of ignition or alternatively a flammable product to escape and therefore create a fire hazard. Corrosion is a factor which is directly related to this hazard.

Aerosols being a comparatively new hazard in almost every home in Britain, there are often notices outlining certain precautions, but it is found that very few people read the labels and even fewer people take any notice or act upon them.

Even so, in Britain, there have not been a great number of serious accidents resulting in injury or fire directly <:aused by aerosols. But a number of incidents have occurred-women have been burned. while using aerosol hair sp~ays, pressure pack containers have exploded when stored 111 cupboards or shop windows and an aerosol of insecticide was placed in the steam from a boiling kettle and exploded.

Nearly all these cases result from negligence of the consumer. It is, however, safe to say that many aerosols ~re. l~azardous. Flames 24ins. long may be p~oduced by 1g111t111g the vapour of certain types of domestic aerosols. When heated, an aerosol will explode with a violence which has to be seen and heard to be appreciated.

Larger manufacturers of aerosols are aware of the problems of pressure packs and are doing all they can to produce a safe product. Formulation of contents is extremely important and is calculated after a great deal of research. Containers are tested with the product at an ambient temperature for eight months, and also for eight months at an elevated temperature of around 35 deg. C. to assimilate the worst type of storage conditions.

Because equipment for today's 'pressure filling method' ?f containers costs only about £1,000 there has been an mflux on the market of small firms which have not the knowledge of the larger firms and are onlv interested in making quick money: Thus another hazard is produced.

There is always, of course a market for the cheapest possible product. Unfortu~ately the cheaper pressure packages are often the most hazardous. At one time 90 per cent of aerosols were produced by the facturer; today that figure may be down as larger manulow as 40 to 50 p~r cent; the remainder being produced by the small, possibly non-reputable firms.

Transp<?rt and storage of aerosols is a subject on its own and is one further problem producing new hazards to the modern fire service· there is a need for the control of storage of aerosols, with adequate marking requirements.

In many other countries there are legal requirements where There .regulations is mention exist specifically for pressure packs. of aerosols by the British Transport Commission in its list of dangerous goods, and conditions of acceptance by merchandise trains relating to substances giving off flammable vapours.

The manufacturers of products containing nitrocellulose or cellulose derivatives are governed by the Nitro Cellulose Regulations, but there are no restrictions on storing containers. But if the product contains a petroleum derivative it will come within the Petroleum Act, 1928, and storage will be governed by this Act-eveo on retailers' premises.

Perhaps the time has come for more consideration on the use, transport and storage of pressure packs. Britain is behind many other countries in this respect.

In the meantime aerosols must be used with care. Do not use them near open flames and do not smoke whilst using them. Store them away from heat, hot cupboards and sunlight. Take care when disposing of finished aerosol containers-they can explode when heated, even though apparently empty. Never pierce a container.

All aerosols are not dangerous when in use, but if in doubt take care. All aerosols are dangerous if heated.

Certain aerosols may have pure butane in the dip tube and on the first actuation of the valve this highly flammable gas is expelled, so shake the aerosol before use. Never use an aerosol upside down.

Aerosols are so easy to operate that a little thought is well worthwhile.

With acknoll'ledgement to 'The Municipal Journal.

SELF SERVICE

• .. at Southwark

By W. H. Collier Senior Petroleum Inspector, Greater London Council

A recent newspaper article "~ead-lin~d" the forthcoming opening by Gem Self-Service .stat10ns at Abb<?tts Langley, Herts., of the fi~st of their ~,hree ne"'. fill!ng stations as "Another round 111 petrol ~ar , empha~1s be111g placed on the considerable saving 111 costs, which 'Yas expected to lead to a reduction of 6d. per gall~n.

Me!lt~on was also made in the article of another stat10n, Stirling Moss's garage at Southwark Bridge i!1 Greater London, which was to be converted to self-service.

Although self-service might ultimate_ly lead to reducti<;m in the price of petrol, one of the pnme reasons for its introduction must surely be to overcome the current shortage of labour. The fact of a shortage. of labour wo~1ld not be of direct concern to a local authority endeavouring to secure the safe keeping of petroleum spir_it but might nevertheless colour its approach to a self-service proposal. It will never be known whether the Greater London Council was influenced in this way when it indicated that in principle it would be prepared to agree under the Petroleum Acts to the company's proposals in respect of Stirling Moss's garage. Final conversion of the station has still to be completed and detailed approval of the equipment given, but it is not anticipated that there will now be any insuperable difficulties.

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