735/740 series needle valves are of the rising stem type and are designed to shut off the flow of the process media to the pressure instrument, thereby allowing the instrument to be isolated from the pressure media or removed from service. Needle valves may also be used to throttle flow and aid in dampening pulsations. Trerice Needle Valves are constructed from brass, carbon steel and stainless steel for use on a variety of pressure media. It is recommended to place a needle valve, ball valve or gauge cock in line before every pressure gauge installation.