The Use of Compressed Gas
Page 62
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in France
11 gas as fuel for heavy vehicles have been conducted for some years past by the Soci6te du Gas de Paris, 6, Rue Conclorcet, Paris, with conclusive results as to the practical possibilities of this fuel. A special mixing valve designed by M. A. Pignot, research engineer to the Paris Gas Co., has contributed largely to the success of these experiments.
The Pignot appliance, which is quite simple, comprises a cylindrical mixing chamber, with a cover held in place by a stirrup and screw. Within the chamber is an automatic valve, the stem of which is provided with guides above and beneath. The gas and air enter the mixing chamber by the concentric passages clearly indicated in the accompanying drawing, the supply of gas being' reguWed by a throttle valve operated as usual from the accelerator pedal.
The throttle lever has an extension actuating a sleeve on the exterior of the air tube, the sleeve being pierced with four holes corresponding to four diametrically opposed air ports in the tube. The air apertures are triangular.
In order to ensure that the speed of the entering air shall not be greater than that of the gas, the orifices are screened with wire gauze, which has a braking effect on the air. It should be noted that the length of the connecting link between the throttle lever and the air sleeve is variable, thus permitting the richness of the mixture to be regulated.
The experiments were conducted with several different vehicles, one being Rochet-Schneider coach with a 3.8litre four-cylindered engine. In this case compressed gas was carried in six light steel cylinders, each of which bad a volumetric capacity of 48 litres, making 228 litres in all. The gas was stored at a pressure of 200 kg. per sq. cm. (2,840 lb. per sq. in.). About 58 cubic tn. of gas were thus carried. An expansion chamber 300 mm. in diameter and 60 mm. deep was introduced between the gas cylinders and the mixing valve.
Vehicles running on town gas have been entered by the Paris Gas Co. in the annual French Rallye des Carburants Nationaux each year since 1927, amongst them being buses of the standard Paris type. A Rochet-Schneider lorry with a power unit similar to the one mentioned above took part in last year's A.C.F. Rallye des Carbu rants Nationaux, or "other fuels rally."
The consumption of gas on this trial, which was of a severe nature, including mountain work, ranged from 34.7 cubic m. to 40.4 cubic m. per 100 kilometres (62.13 miles). The vehicle ran under load, its total laden weight on certain sections of the 3,000-kilometre run being about 5 tons, and the average working radius, with one charge of gas, was in the neighbourhood of 120 kilometres (74i miles).
In his summing up of last year's trial, M. Delpeyroux, chief of the A.C.F. research laboratory, remarked that the vehicles running on town gas had once again proved that this fuel could be used advantageously to replace petrol in a great number of public services.