The patent: 1937 Ehrich & Graetz Although a patent often differs in detail, sometimes significantly so, from the design’s production version, the Rapid pre-heater’s components closely resemble those depicted in the patent drawing. The air inlet holes numbered 13 in component No.8 in the patent drawing. More graphically depicted, acupuncture needles inserted in the holes to illustrate (circled) how they are angled to emerge in the inlet of the component, fed by pressurised air from the top of the fuel tank. The fuel/air outlet bore is close to the 0.32mm diameter of the kerosene stove jet pricker inserted here. Component No.15 housing the fuel/air mixing tract (No.17 in the patent drawing) has a larger still diameter outlet than component No. 8 beneath it. The final jet orifice has a 0.18mm bore, much like the lantern’s jet nipple. A strength of this design is that the pre-heater is not engaged/shut off with a sealing ‘pip’ attached to a sprung-loaded capping lever, but has a positive needle valve control for on/off and points in-between to control the pre-heater’s flame size. A claim in the patent text is that if the pre-heater’s final outlet jet becomes blocked, the fuel/air supply can be shut off with the valve control and the jet can be manually pricked. The slot numbered 24 in the patent drawing is incorporated in the base rim of the flame tube to accommodate the pricker. The issue then becomes locating a pricker of 0.18mm gauge. I serviced the pre-heater as part of THIS Aladdin Petromax 828 restoration project. John
Great! This came out beautifully. It's through posts like this, where each item is taken apart and described in detail, that I can learn the most. Tkanks
@Knee I’m glad that’s of interest Stanislaw. The completed Aladdin Petromax 828 (sold in the UK between 1937-1939) is HERE. John
