The Vaporizing Of Paraffin for High-Speed Motors
(Electric Ignition Type)

VAPORIZATION IN THE HIGH-SPEED MARINE ENGINE. 83 and 'also of the snifting gravity feed type, only øJbout ■one-fifth of the total air passes through the vaporizer with the throttle full open. As in Figs. 61 to 63, the vaporizing surface is obtained from a nest of tubes v, which are arranged for easy access for cleaning, the upper tube plate is also arranged with a gland-packed joint n to allow for differential expansion. In this case the mixture flows through the tubes, and not around them, as the former example of this type ; for starting, these tubes can either be heated from the outside by a burner applied at the flue s, or petrol can be used. As in Fig. 64, the petrol or paraffin is supplied under a slight pressure-head, and passing the regulator k1 is admitted by the combined air and fuel valve e1 in varying quantity, according to the opening of the throttle t1 ; a correspond- ingly varying supp]y of extra air is admitted past the liand- regulated shutter sleeve a1 and sliding disc a2, the latter being pinned to a stem having at one end a steadying piunger. The weak feature in all exhaust-heatecl vaporizer -engines is tlieir inability to run for prolonged periods with a clear exhaust under a light load, and although this fault can be compensated for to some extent by retarding the ignition, thereby raising the terminal pressure and causing the engine to exhaust at a higher temperature, this, nevertheless, lias a prejudicial effect ■on the engine, as it undtily heats the exhaust valve. In some large engines of the wrifer’s design, the necessary adjustment of the ignition periods is automatically -effected by the varying vacuum produced by the partial closing of the regulator controlling the mixture supply, through the agency of a piunger acting against a spring.