A Mixing Valve for Gas Fuel
Page 27
If you've noticed an error in this article please click here to report it so we can fix it.
A Compact Device Suitabli for Engine Testing and Stationary Plant Use ACONVENIENT*fuel for bench testing a reconditioned engine, the running-in of a new engine, or the continuous operation of a stationary unit, is to be found in mains gas. In order to use this fuel in the most efficient manner, it is essential to have a means for correctly proportioning the air-gas mixture at various throttle openings. The demand for such an instrument has been met by the G.M. Carburetter Co„ Alta Works, 27-31, Gartside Street, Manchester, 3, with a device known as the G.M. gas carburetter.
This instrument, as will be seen from an accompanying drawing, comes into the mixing-valve class, the valve, in this case, being gravity loaded. The effective weight of the valve must be such as virtually to balance the gas pressure, so that it remains on its seating when no demand is being made on the instrument. A " flooding" lever is provided, and this has the effect of raising the valve to permit a quantity of gas to enter the body of the carburetter and so provide for an easy start. The main supply of air comes in, via the valve, with the gas, but there is an extra-air device which is referred to as an adjustable pressure compensator. All G.F. models are so designed as to operate direct off the mains without the need for a separate pressure-reducing governor., In models known as GFC/S and GFC/RI there is a safety blow-off valve incorporated. Its purpose is to release the pressure within the instrument in the event of a blow-back, and so protect it from damage, and to guard against blown-out manifold gaskets. It also serves as a means .for effecting a quick change-over from gas to liquid fuel, or vice versa.
To make the intitrument almost universal in its application, a number of .different types of adapter is available, and these are shown in a second drawing. There are several different models, from one for use only with gas, to that fitted with the safety blow-off valve and quick change-over device. Full information relative to types and priqes may be obtained from the maker.
We have seen one of these G.M. carburetters in use on a Fordson engine, and its operation was in every way satisfactory.