These torches are either air or water cooled. Air-cooled torches are designed for welding light gauge materials where low current values are used. A circulating stream of water flows around the torch to keep it from overheating. The tungsten electrode, which supplies the welding current, is held rigidly in the torch by means of a collet that screws into the body of the torch. A variety of collet sizes are available so different diameter electrodes can be used.
Gas is fed to the weld zone through a nozzle, which consists of a ceramic cup.
Gas cups are threaded into the torch head to provide directional and distributional control of the shielding gas. The cups are interchangeable to accommodate a variety of gas flow rates. Gas cups vary in size. The size you should use depends upon the type and size of torch and the diameter of the electrode. Pressing a control switch on the torch starts the flow of both the current and gas.