A pressure regulator is a valve that automatically cuts off the flow of a liquid or gas at a certain pressure. Regulators are used to allow high-pressure fluid supply lines or tanks to be reduced to safe andor usable pressures for various applications ie Oxy-fuel welding and cutting, propane and LP Gas applications, Oil and Gas Industry, Mining Industry. Gas pressure regulators are used to regulate the gas pressure and are not appropriate for measuring flow rates. A pressure regulator's primary function is to match the flow of gas through the regulator to the demand for gas placed upon the system. If the load flow decreases, then the regulator flow must decrease also. If the load flow increases, then the regulator flow must increase in order to keep the controlled pressure from decreasing due to a shortage of gas in the pressure system. Thes regulators are available in Two stages first called First stage Reulator & than second stage Regulator. These regulators are available in two types the one is adjustable type & another is Preset type.