Trailer Vans for Disinfestation by the use of cyanide gas
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nURING the past few years, Cranes (Dereham) , Ltd., South Green Works, Dereham, Norfolk, has built a number of disinfestation vans, based on its trailer chassis, for municipal authorities in different parts of the country. Many of them have been purchased in connection with the five-year building plan now being carried out, which entails the demolition of old houses and the construction of new buildings, to which the inhabitants are removed. To ensure that the furniture is completely disinfested after leaving the old dwellings, many of which are pest-ridden, the councils employ these vans, which are taken to a depot and pumped full cf cyanide gas.
The process employed is one patented. by Mr. H. W. Seymour, Chiswell House, 133-139, Finsbury Pavement, London, E.C.2, who, we learn, has the controlling rights. After the gas has entered the van body and sufficient time has elapsed to ensure that the furniture is properly, fumigated, hot air is pumped in so as to aerate the interior and remove all traces of the gas. The process ensures that there is no risk of contagion when the load is delivered to the new dwellings.
These vans have been supplied based on four-wheeled trailers for use behind lorries and tractors and as semitrailers for attachment to such vehicles as the Scammell mechanical horse and the Karrier Cob.
In all cases, the construction of the body is much the same. A frame of channel steel is used to carry the body and it is cranked to ensure a low-load
ing height at the rear. The standard body entails the use of an outer framework of studs morticed into longituclinals, which, at the top, support ash cambers for the roof. The sides and roof are covered with tongued and grooved matchboarding, whilst the latter is rendered watertight by Oil. dressed canvas.
The whole body is lined, with the exception of the floor, with thin metal sheets. The floor consists of two thicknesses of fin, deal, with Rnbberoid sandwiched between them. The doors are at the rear and hinged vertically, the halves meeting in the centre and being provided with rubber-covered steel flanges to ensure complete gas tightness; rubber is also used to cover the hinges. The doors are held in the closed position by a number of turn screws and a small inspection door at the front is made gas tight in the same way. Inlets are fitted at the front of:the trailer for coupling up to the gas plant, and an outlet is provided at the top at the rear, this being opened when the hot air is pumped in, and through which the cyanide gas escapes.