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The Diminutive Durr Carburetter.

2nd May 1912, Page 4
2nd May 1912
Page 4
Page 4, 2nd May 1912 — The Diminutive Durr Carburetter.
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A Description of a Small floatless Atomizer which is Specially Intended for the Use of Heavy Liquid Fuels.

It may be only coincidence that the recent labour troubles in the coal-mining industry, which have served to focus public attention on liquid-fuel possibilities, have been followed by renewed activity on the part of inventors of heavy-oil vaporizers. Suffice it to say, however, that, during the past week or two, we have had several new devices of the kind brought to our notice. The public advent of the Purr carburetter in this country is at any rate not ill-timed ; its evolution has, we are informed, proceeded over a period of several years. If all that its inventor tells us about it be true, this latest type of vaporizer is "the goods," as our American friends concisely put it.

Apart from the claims as to the economy of the Ditrr's operation, we can unhesitatingly testify to its extreme simplicity, its handiness and exceptional compactness. All there is of it is illustrated in the photograph which we reproduce on this page ; we do not remember previously to have examined a vaporizer of quite such small overall dimensions for its capacity. The size which we illustrate is for use with a 15 h.p. engine, and it is exactly 21 in. in height and 1i in. in diameter.

Our line illustrations herewith will amply serve to demonstrate the form of this atomizer's few parts. It will be seen that no float is employed ; the fuel is fed to the bottom of the circular easing under

pressure from the supply tank in the normal way, but its supply is thereafter controlled by means of a suction-operated needle valve. The weight of the needle and its component valve when at rest suffices to seal the fuel supply. The needle is directly acted upon by the partial vacuum in the induction pipe, which latter is in

direct communication with the top of the fuel-control valve ; the latter is in one piece with the needle valve itself, and its periphery is a working fit inside the casing. The needle is drilled with a duct for the liquid fuel, which is sucked right up through it when it is lifted from its seat. Air enters the bottom of the casing under the fuel-control valve and thence is drawn through suitable small boles at high velocity into the top of the fuel outlet. The needle itself in reality performs most of the functions of the more-cornmonly-used jet. The effective atomization is actually secured at the coned top of the needle-cum-jet owing to the intimate admixture of the separated small streams of high-velocity air and the uprising fuel. This method of atomizing is a simple one, but it is not, we believe, entirely novel. It may well be quite effective with all forms of liquid fuel from benzol to lowgravity petrol ; the inventor claims that. it is. It certainly secures a practical form of design which for compactness is very hard to beat. Tt is perhaps by virtue of its neat method of control that this ingenious litle contrivance merits most attention. Obviously for varying engine speeds under load some provision must be made for the admission of excess of air. In the Purr such an arrangement has been neatly combined with a positive stop to limit the lift, of the fuelcontrol valve. An inner sleeve, screwed externally to rotate in the threaded interior of the casing, covers and uncovers a port to the outside air, so regulating the amount of air which may additionally be sucked up with the already highly-atomized and aerated fuel. At the same time that this sleeve rotates, it rises or falls, as the case may be, by virtue of its threaded housing ; its bottom end being of such a diameter as to serve as a stop to the fuel-control valve, and the lift of the needle, so the supply of pure fuel is correspondingly altered. As additional air is admitted, so is the range of lift for the needle valve increased. As the suction on the jet itself becomes less, so the fuel-supply capacity is increased.

At the time of going to press we have no opportunity practically to test the straightforward and not unusual claims on behalf of the Dfirr, which are made by Mr. C. P. Wenzel, who has the exclusive rights for this country. We are in a, position, however, to quote the results of certain tests which we understand have been made with it at the Central Technical Institute at Darmstadt.

On a 10 h.p. stationary engine, over a. period of five weeks, a consumption was registered of 172 grammes (6.06 ozs.) of crude benzol per horse-power-hour. Comparative tests on a car and subsequently on a brake test of the same engine, gave the following results. The engine was a 50 h.p. four-cylinder. An ordinary wellknown make of carburetter is said to have yielded 62 b.h.p. and to have used 280 grammes (9.87 ozs.) of ordinary petrol per horse-power hour. A Diirr carburetter under similar conditions gave 71.9 b.h.p

and used 215 grammes (7.85 ozs.) of 780 s.g. heavy oil. The petrol cost 38 marks per 100 kilos. (is. 71d. per gallon), whilst the benzol cost 20 marks (101c1. per gallon). The results claimed on behalf of the Burr are therefore : more horse-power for the same engine ; lower consumption ; use of a fuel of about half the cost.

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People: C. P. Wenzel
Locations: Darmstadt

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