Torch, also known as welding torch, refers to the use of oxygen and low-pressure acetylene as a heat source, welding or preheating of ferrous metal or non-ferrous metal workpiece tools. Gas welding operation is the main tool. The role of the torch is to combustible gas and oxygen by a certain percentage of uniform  mixed to a certain speed from the nozzle spurt, forming a certain rate, a certain composition, suitable for welding requirements and stable combustion of the flame. The quality of the welding torch directly affects the welding quality of the welding. Therefore, the welding torch is required to have a good performance of adjusting the ratio of the oxygen to the combustible gas and the flame energy rate so that the mixed gas is ejected at a speed equal to or greater than the burning speed to stabilize the flame Burning. At the same time also requires the torch weight to light, should be easy to use, safe and reliable.