Lamps are for inside use or for a purpose, e.g. table lamps, wall lamps and hanging lamps. And generally stationary.
Lanterns are portable for outdoors and usually require a handle or bail to carry.
However, people seem to use the terms interchangeably!
Mantle refers to the way it hangs like a cloak above the flame.
Modern gas mantles are usually sold as fabric items, which, because of impregnation with metal nitrates (either THORIUM Oxide, or YTTRIUM Nitrate and Europium Nitrate), produce a bright light.
To produce a mantle, cotton or other cellulose fibre is woven or knitted into a net bag, impregnated with soluble nitrates of the chosen metals, and then heated.
‘The Cure’
When the mantle is heated for the very first time in a flame (‘the cure’), the mantle fabric burns away in seconds, leaving a brittle and very fragile ceramic shell or lattice in the shape of the original fabric. This remaining brittle frame is of very high melting point and is what produces light from the heat of the flame whenever used. Light is produced when this lattice is heated to glowing by the gas combustion, although the mantle itself does not burn.
The mantles use the heat of a flame (in modern portable applications produced using kerosene or LPG) to heat up to around 1000 degrees Celsius. At this temperature they are sufficiently hot to radiate an intense white light as a consequence of the rare earth elements (yttrium or thorium) in the mantle.
How does the mantle help?
The mantle aids the combustion process by keeping the flame small and more contained, and at higher fuel flow rates than in a simple lamp. This concentration of combustion inside the mantle improves the transfer of heat from the flame to the mantle.
Since Thorium is radioactive, and produces a radioactive gas, radon-220, as one of its decay products, there are concerns about the safety of thorium mantles, although there is only a negligible amount of Thorium content in each mantle. Normal use, however, poses minimal health risk. Some safety agencies make recommendations about their use. These issues have meant that some brands are now only available in yttrium or sometimes zirconium, although they can be either more expensive or less efficient.
Sometime around 1990, the Coleman Company replaced the thorium in their mantles with YTTRIUM, a non-radioactive compound. This development was based in part on the discovery that incandescent mantles of improved strength and durability can be manufactured by employing yttrium oxide as the primary metal oxide instead of thorium oxide.
The yttrium mantle is said to produce about 20% less light, but lasts longer. It has been further discovered that by employing a critical ratio of cerium oxide to the yttrium oxide, higher illuminating power can be obtained.
A soft mantle is essentially a bag with either a drawstring or some type of fitting that attaches the mantle to the burner. The fabric of a hard mantle is supported by a metal frame that gives it a dome-like shape.
Olive oil should NEVER be used in a high-pressure lamp. It’s too viscous to work with the high-pressure system, which needs to compress the fuel and force it through a tiny nozzle. The thicker oil just cannot function in high-pressure lamps.
Radiation from the use of thorium mantles is apparently miniscule.
The hazards are in the manufacturing process.
A study in 1981 estimated that the dose from using a thorium mantle every weekend for a year would be tiny in comparison to the normal annual background radiation dose, although this assumes the thorium remains intact rather than airborne.
The radioactivity is a major concern for people involved with the manufacture of mantles and an issue with contamination of soil around some former factory sites.
One area of concern is the possible release of thorium-bearing dust if the mantle shatters due to mechanical impact. When using any kind of fuel lamp, adequate ventilation is a must.
RECOMMENDED PRECAUTIONS FOR USERS:
- Always service your lamp outdoors or in a well-ventilated space, away from children and other people.
- Store new mantles in a sealed container.
- Do NOT ingest mantle or mantle ash.
- Carefully brush the ash and debris from the old mantle into a bag and seal.
- Place bag into proper waste receptacle.
- Do NOT breathe in the smoke when ‘burning in’ a new mantle.
- Wash hands afterwards
