BACKCAPS A Taurus back cap applies pressure to the end of the collet and force it to the collet body. The pressure keeps the tung-sten in place and seals the torch from the atmosphere. Three backcaps are available: short, medium and long. They serve the same purpose but for different applications. When operating in a restricted area with limited space, the short back cap will be fitted. However, the tungsten length must be in proportion to the size of the back cap. VALVES The Taurus valve allows the oprator to open the gas flow before and close it after a welding operation. The valve fits on to the torch body.