A carbide lamp is a lamp which is designed to burn acetylene, a gas which will burn hot and bright in the right conditions. These types of lamps were originally designed for mining, and although they have been largely replaced by electric lamps, some people still use carbide lamps for caving, camping, and mining operations. Antique versions can be purchased at auction or through an antique store, while new versions are available from outdoor suppliers who sell camping equipment and related supplies.
The design of a carbide lamp includes two chambers connected with a valve. When the valve is opened, water can drip from the upper chamber into the lower chamber, which is filled with calcium carbide. This causes a chemical reaction which generates acetylene, with the gas flowing out of a nozzle in front of the lamp. The acetylene can be lit with a match or similar device, generating a bright flame. Often, a reflector is mounted on the lamp to scatter the light.
There are some potential safety risks with the lamp. It is important to make sure that the nozzle is clear so that the gas can escape, or the lamp may explode from the buildup of pressure inside. It is also critical to be able to control the valve which drips water, as this controls the amount of gas produced inside the chambers. When the carbide lamp is not in use, the valve needs to close securely so that flammable gas is not generated. These lamps also get very hot, which can become a safety issue.
The light produced by a carbide lamp is bright, white, and even. The even nature of the light can be very useful in underground settings where lights with filaments and lenses can cast peculiar shadows. Shadows may obscure important visual information or make a space look and feel confusing, which can be disorienting underground when people lack frames of reference which they can use to figure out where they are.
Calcium carbide to run carbide lamps is manufactured industrially. It can be obtained through a number of companies. Many stores which sell new calcium carbide lamps also sell calcium carbide refills, or can point people to potential sources. For people buying antique lamps, it is critical to clean and inspect the lamp, taking special care to check the valve and nozzle, before fueling the lamp and testing it out. It is also advisable to test a carbide lamp in a controlled environment with a fire extinguisher within reach in case there is a problem.