GB394736A - Improvements in or relating to testing combustible fluids - Google Patents

Abstract

<PICT:0394736/III/1> Fuels and other combustible liquids are tested to ascertain the temperatures at which they ignite spontaneously in heated air, and the intervals at various temperatures between contact with and ignition or explosion in the heated air. Fuels are thus graded according to their suitability for use in compression ignition engines. Using the apparatus shown, the iron explosion cylinder 1 is heated by electric coils 5 to the highest investigation temperature, e.g. 600 DEG C., the heater turned off, a charge of cold air drawn in through an opening in the cover 12 by a pump attached to a pipe 14, and when the temperature of the air reaches a maximum and begins to fall a fuel charge is forced in through a passage 20 and a valve 21 so as to form a conical spray which does not touch the heated sides of the cylinder. The moment of injection is recorded electrically through the lifting of the valve 21 raising a tappet pin 24 which moves a block 25 pivoted on pins 26 so that contacts 29, 30 are separated and an electric circuit broken. The moment of ignition or explosion of the fuel is similarly recorded through the lifting of a valve and pin raising a lever 36 on pivots 37 so as to separate contacts 38, 39. The explosion cylinder is then cleared by sucking in fresh air, and the test is repeated at successively lower tempera <PICT:0394736/III/2> tures of say 10-20 DEG C. The recording device comprises a paper strip which is moved along an insulating trough so as to be pierced at one side by sparks from a fixed sparking point 49 of the injection timing circuit and at the other by sparks from a vibrating sparking point 50 of the ignition timing circuit. The circuits for the injection and ignition recording are in parallel, and comprise low tension coils 42, 43 respectively with associated high tension coils 47, 48, tremblers 41, 420, and contact breakers 28, 36; the coils are earthed at one end 44, the L.T. coils being connected at the other end through a switch 45 to a battery 46, and the H.T. coils to the sparking points 49, 50. The point 50 is on a reed 59 vibrated by a circuit comprising the reed 59, an adjustable contact 60, electromagnetic coils 61, a switch 62, and a battery 63. The pump for injecting the fuel is of the kind in which a small charge of fuel is forced by a plunger past a spring-loaded non-return valve in the pipe leading to the injection nozzle, the plunger being operated with a given force by the fall of a pivoted weighted lever.