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14th November 1947
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Page 33, 14th November 1947 — OUTPUT
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and sizes of these tanks in use, but basically they are similar. Usually they comprise a tank which houses the part to be cleansed, and a. pump which supplies paraffin at pressure to a spray gun operating in the tank. After the paraffin has been used, it drains back through a filter to a sump for further use. By this means, the dirt and oil from the assembly are retained in a sludge trap and the paraffin can be used again and again until it becomes absorbed in the dirt.

Larger concerns find degreasing by the use of solvents or washing .solutions to be more economical. The economy of a trichlorethylene plant was proved by an Army workshop in an overseas area, which employed over 100 civilians in stripping and cleaning used engine (Above) Departing from normal procedure, the police workshops stripped an engine to Siltiff the accumulation of grease and carban befote and after passing through the degreasing plant. In the lower illustration the grease has been dissolved and carbon reduced to a substance suficiently wfi la be remixed by a sash tool. (Right) Cranshaws Chemical Colander," thE first known trichlorethylene plant which was produced by 1.C.1. in 1927.

assemblies as they arrived at the workshop. The section was in a filthy state, and cases of dermatitis and accident's which resulted in blood poisoning were frequent.

An improvised degreasing plant, employing trichlorethylene as a solvent, was installed to clean the engines as they arrived. The outcome of this experiment was that the staff was reduced to 25, and skin troubles were eliminated. Further, the accident rate per ceni was reduced to the normal level for the remainder of the workshop.

The earliest known trichlorethylene degreasing plant was produced by Imperial Chemical Industries, Ltd , in 1927 and was then called " Cranshaw's Chemical Colander." This plant, forMing the simplest means for solvent degreasing, employed a Bunsen burner for heating at the base of the container, and was cooled by a set of water-cooled coils housed in the lid.

Prototype of Solvent Plants A small quantity of trichlorethylene was pouted into the container and the component to be degreased was placed on top. The lid of the container was then closed and heat from the Bunsen burner applied to the base. Vapour rising from the solvent heated up the unit being degreased and passed on to the water-cooled coil in the lid, where it condensed. The liquid formed by condensation dropped back over the greasy unit and increased the washing action.

When it was considered that the article had been sufficiently "cooked," the Bunsen burner was removed and the water cooling transferred to a coil housed in the base of the plant. This was a protracted method of degreasing, as a long period elapsed between heating up the solvent and the finish of the cooling action. Moreover, degreasing was liable to occur in patches, because of the solvent "rain," and crevices in the casting remained untouched. • The plant produced in 1930, and still in favour, employs a cooling system which controls the vapour at a constant level near the top of the plant. Heat imparted to the plant is sufficient to keep the trichlorethylene as a vapour while work is being lowered into the tank or withdrawn, and as the vapour condenses before reaching the top, no solvent is lost. This form of plant is made in various sizes to suit the purpose of the workshop or factory, and 12,000 have been supplied since 1930.

Precautionary Measures

Trichlorethylene is a safe solvent,-because it involves no risk of either fire or explosion. To prohibit smoking in the area of the plant is a precautionary measure against phosgene gas, which results from the combination of nicotine and fumes from the plant.

Degreasing components by soaking in solutions of. water and a cleaning compound is a popular practice in the larger vehicle repair workshops. An advantage of this method is that certain cleaners not only degrease engine parts, but decarbonize them at the same time.

Plants of this kind consist of two heated tanks for cleaning and rinsing the unit to be degreased. Heating is generally by gas, thermostatically controlled, or by steam if available. Air passing through the heating chamber and forced up through the tank, agitates the solution and provides a " scrubbing " action.

For the smaller workshop, a single tank, which has a dividing wall across the centre, forming two compartments for cleaning and rinsing respectively, is available, making a compact and inexpensive unit. Details of these equipments are available from Hope, Hartope and Co., Ltd., 2, The Broadway, Hammersmith, London, W.6, which has developed the system after a considerable amount of research on the subject, and produces Graking X.L.C. fluid ri57 • A Special type of degreasing outfit on these lines has been designed for use in the Metropolitan Police vehicle repair shops at Hendon. Using a solution of Graking X.L.C. fluid in the cleaning tank, heavy carbon on valves, pistons and other components is softened sufficiently in an hour to enable it to be brushed off with a sash tool. Both tanks, which are steam heated, arp agitated by mechanical means. Rinsing the parts is done in the space of a few minutes, and the Basol solution ensures that they will not rust.

It is general practice in this workshop to strip the electrical parts from an engine, and leave it to soak in the solution overnight. The following morning the engine is rinsed off and all traces of carbon and oil are removed, leaving the assembly in a fit state to be dismantled.

Trichlorethylene degreasing plants are offered by Imperial Chemical Industries, Ltd!, being made in the company's department at G. A. Harvey and Co., Ltd., Woolwich Road, London, S.E.7. The latter concern also

manufactures the larger patterns. Smaller plants may be supplied by the Petroleum Engineering and Trading Co, Ltd., 62, Desborough Road, High Wycombe, Bucks.

Distributors of paraffin pressure-cleaning tanks include Harvey Frost and Co., Ltd., Bishop's Stortford, Herts, and Mann, Egerton and Co., Ltd., Norwich.

The Weaver steam jenny, which is made by the Weaver Manufacturing and Engineering Co., Ltd, Magna Works, Kathie Road, Bradford, has uses besides degreasing. A stronger compound employed with this equipment will strip the paint from chassis or bodies without detriment to the metal work.

Laycock Niagara washing plants for dual spray guns are manufactured by the Laycock Engineering Co., Ltd.. Victoria Works, Millhouses, Sheffield, 8. Other vehicle washing plants are offered by the Equipment and Engineering Co., Ltd., Strand, London, W.C.2; Kerry's, Ltd., Warton Road, London, E.15; B.E.N. Patents, Ltd, High Wycombe, Bucks; V. L. Churchill and Co., Ltd., Walnut Tree Walk, London, S.E.11; and Messrs Williams and James, Chequers Bridges, Gloucester.

The special degreasing plant in use in the Metropolitan Police Vehicle Repair Depot was designed and produced in the depot.

Tags

Organisations: Metropolitan Police
People: Victoria Works

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