History of Petromax

Kerosene Pressure Lantern Principles of Operation

Auer von Welsbach invented the principle of the gas flame heated incandescent mantle light in 1885. In the blue flame of a Bunsen burner he heated a woven fabric which glowed six times more brightly than the flame itself. The fabric was hung above the burner, the sole source of heat, in a shape which inspired the name of "mantle" (i.e., a cloak). The mantle was composed of a loosely woven cotton mesh, soaked in a liquid solution of thorium and cerium nitrate. Upon igniting a mantle for the first time, the cotton burnt away, leaving a rigid, brittle "skeleton" of thorium and cerium oxides. These oxides emitted brilliant light when heated to very high temperatures -- the principle of incandescence. This newfound principle was revolutionary, especially in the application of street lighting, and quickly became widespread throughout the industrialized world.

Before long, the idea of using liquid fuels for this type of lighting was explored. By the end of the 19th century, the first alcohol and kerosene fueled incandescent lamps had been developed. These liquid fuel lamps used pressure to force the fuel towards the burner, and the heat of the burner's flame to vaporize the liquid fuel. They are thus often termed "pressure lamps / lanterns". One of the first and most successful kerosene fueled pressure lanterns was invented in 1910 by Max Graetz – the world famous Petromax. The Petromax lantern, and its smaller cousin the Geniol lantern, remain popular to this day, both in the private sector and for professional applications.

Principle of Petromax The Petromax lantern acts as a small "gasworks". The fuel tank is pressurized to approximately 2 atmospheres (2 bar, or 30 psi) with air introduced by a built-in hand pump. This pressure is then used to force the liquid kerosene up into the vaporizer (or "generator", as it is sometimes called). Initially, the vaporizer must be pre-heated to gasify the liquid kerosene within it, prior to igniting the lantern's mantle. This preheating may be accomplished by burning alcohol poured in to a preheating cup located at the base of the vaporizer. Alternately, a built-in kerosene-fueled blowtorch, the "Rapid" preheater located on the side of most Petromax lanterns, may be used to heat the vaporizer. Once in operation, the heat from the lantern's blue flame (encased within the mantle) is used to gasify the liquid kerosene rising through the vaporizer. The liquid kerosene boils away into vapor at approximately 250° C (480° F), about halfway up the height of the vaporizer -- see illustration. The gaseous kerosene continues its journey through the vaporizer's circular loop, increasing in temperature, until it exits the small orifice in the vaporizer's nipple at nearly the speed of sound (1000 ft./sec.). Upon exiting the nipple, the gaseous fuel begins to expand and combine with air in small square chamber at the side of the lantern's inner casing. The expansion of the gas and turbulent mixing with the air are responsible for the hissing noise of the Petromax lantern while in operation. The gaseous kerosene and air are swept into the mixing tube where the two are thoroughly combined in the turbulent flow. This ensures complete combustion of the mixture upon exiting the ceramic nozzle, resulting in a hot, clean blue flame.

These principles of operation are generally applicable to any incandescent pressure lantern or lamp (e.g. – Coleman, Tilley, etc.), although fuel types, vaporization temperatures, and operating pressures / procedures may vary.

Thanks to John Baldessari and all the other kind helpers for this translation!

Copyright Jürgen Breidenstein jb@hytta.de | All rights reserved. Images: Graetz-Nachrichten

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  History of Petromax