Two-fuel Carburetters and Fittings. VIII.
Page 13
If you've noticed an error in this article please click here to report it so we can fix it.
Some American Conceptions of Paraffin-carburetter Requirements: Water Injection, Two Float Chambers, and An Efficient Vaporizer.
The conditions of the fuel market operating to direct public attention to the desirability of adopting means whereby other fuels than petrol may be utilized exist almost universally. An active search for a suitable two-fuel carburetter is being instituted in the United States. During a recent discussion of the situation before the Society of Automobile Engineers, it was agreed in the first place that alcohol as a fuel offered no immediate relief. For internal-combustion engines, it would require a compression pressure of more..than double that for which automobile and heavy-vehicle engines are designed. The possibilities of benzoic are thoroughly appreciated, and methods of improving the means of distribution of this fuel were discussed. It was pointed out that the public is already being forced to use paraffin, which it is buying mixed with petrol in the standard cans and at petrol prices.
The Rittman Process.
Much is expected from the Rittman process, a method of " cracking " petroleum, which is stated to yield 200 per cent, more petrol from crude oil than any other method. There are seven plants in the United States which have up to the present adopted this process, but the total output of these is not yet sufficient to affect the price or the available quantities to an appreciable degree.
The opinion was expressed that low-grade-fuel carburetters were desirable and, whenever necessary, the engines should be modified so that they will burn this fuel. Even in the event of an early easing of the situation in the petrol market, it is nevertheless pointed out that if both petrol and paraffin are in use as fuels, the public in general will turn to the cheaper fuel, and this will act as an automatic check on the price of both.
The principal difficulty in the way of the immediat,e universal adoption of paraffin is that of starting the engine, owing to the fact that paraffin will not vaporize at low temperatures. For the time being, it is pointed out, petrol can still be used for starting, and the design of the induction manifold revised, so that, after a short period of running on the spirit, sufficient heat is available to vaporize the paraffin.
Some Carburetters Described.
Several two-fuel carburetters were described. The Higgins uses water injection as an. aid to efficiency. There are three compartments in this carburetter, which we illustrate ; that at the left-hand is for paraffin, the central one being for water, and that on the right for petrol. The last-named chamber is filled by hand pump, and the petrol in it used for starting purposes. The various chambers are thereafter kept supplied with fuel at the proper levels by mechanicallyoperated plunger pumps The Western carburetter has two float chambers, one for each fuel, with dashboard control for both. The induction manifold is completely surrounded by the exhaust pipe, thus heating and vaporizing the mixture. With thiscaburetter, the engine is started on petrol, paraffin being turned on and the petrol turned off after a few minutes, when a suitable amount of heat to vaporize the heavy fuel is available.
Our third illustration shows a special type of vaporizer, which is stated to be particularly efficient and to have one or two special properties, rendering it suitable for use in this respect. This vaporizer may be used in conjunction with any form of petrol carburetter, and if the usual two-way taps for thutting off the petrol and supplying paraffin instead are fitted, at may be used as a tweefuel fitting.
The disability of the two-fuel carburetter with one float chamber only was mentioned, and it is one to which we have referred once or twice in the course of this series. With a single float chamber it is essential that, a short time before the engine is stopped, the paraffin be turned off and petrol re-admitted ; this ensures that there is petrol in the float chamber in readiness for the next start. This precaution, of course, only applies when it is the user's intention tc stop for a long time, as, in the case of a short stop, it is generally found that the engine will start up again on paraffin as a fuel.