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- For other meanings, including oxy-gas torches, see Blowtorch (disambiguation).
Early blowlamps used liquid fuel, carried in a refillable reservoir attached to the lamp. Modern blowtorches are mostly gas-fuelled. Their fuel reservoir is disposable or refillable by exchange. The term "blowlamp" usually refers to liquid-fuelled torches and is still used in the UK. Liquid-fuelled torches are pressurised by a piston hand pump, gas torches are self-pressurised by the fuel's evaporation.
Fuel torches are used in a vast range of sizes and output power. The term blowtorch is applied to the smaller and lower temperature ranges of these. Blowtorches are typically a single hand-held unit, with their draught supplied by a natural draught of air. Larger torches may have a heavy fuel reservoir placed on the ground, connected by a hose. This is common for butane- or propane-fuelled gas torches, but it has also applied to older, large liquid paraffin (kerosene) torches such as the Wells light.
Many torches now use a hose-supplied gas feed, often mains gas. They may also have a forced air supply, from either an air blower or an oxygen cylinder. Both of these larger and more powerful designs are less commonly described as blowtorches, the term blowtorch usually being reserved for the smaller and less powerful self-contained torches. The archaic term "blowpipe" is sometimes still used in relation to oxy-acetylene welding torches.
The blowlamp is ancient in origin as a tool of gold and silversmiths. They began as a literal "blown lamp", a wick oil lamp with a mouth-blown tube alongside the flame. This type of lamp, with a spirit fuel, continued into use for such small tasks into the late 20th century.
The first known blowlamp patent is from France and is dated January 7, 1791.
Another early blow pipe patent comes from USA and is dated May 13, 1856.
In 1882, a new vaporizing technique was developed by C. R. Nyberg in Sweden, and the year after, the production of the Nyberg blow lamp started. It was quickly copied or licensed by many other manufacturers.
After the Korean War in the 1950s, propane caused many changes in the blowlamp industry worldwide, and by the 1970s most manufacturers of the old type of blowlamp, using gasoline or kerosene as fuel, had disappeared. There remain several manufacturers producing brass blow lamps in India, China and North Korea for markets where propane gas is difficult to obtain or too expensive to be viable.
The blowtorch is commonly used where a diffuse (wide spread) high temperature naked flame heat is required but not so hot as to cause combustion or welding temperature applications: soldering, brazing, softening paint for removal, melting roof tar, or pre-heating large castings before welding such as for repairing. It is also common for use in weed control by controlled burn methods, melting snow and ice from pavements and driveways in cold climate areas, especially the USA and Canada road repair crews may use a blowtorch to heat asphalt or bitumen for repairing cracks in preventative maintenance. It is also used in cooking; one common use is for the creation of the layer of hard caramelized sugar in a crème brûlée.
Types and variants
The blowtorch is referred to in industry and trade as per the fuel consumed by the tool:
- Liquid, with ambient atmospheric air after vaporizing it using a coiled tube passing through the flame. They take time to start, needing pre-heating with burning methylated spirit:
In both sorts the fuel tank often is small and serves also as the handle, and usually is refuelled by changing the fuel tank with the liquefied gas in it.
The forms with gaseous fuel are sometimes fed from a liquid petroleum gas cylinder via a hose.
A flame gun is a large type of blowlamp with built-in fuel tank, used for various purposes: weed control by controlled burn methods, melting snow and ice off walk and driveways in the winter, starting a fire, etc. It is commonly confused in word usage with a flamethrower.
- BBC - Food, Caramelising with a blowtorch.
- Popular Mechanics October 1, 1926, pp 685. "Blowtorch Made from Gasoline Lamp" by LB Robbins: Google books: 
- Pressure Lamps International 
- Blow Lamps Unlimited 
- Southern Steam Trains 
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