The ST33-A0### line of pressure relief safety valve are brass constructed, have a threaded male NPT inlet connection with a stainless steel pull ring for manual pressure relief. The brass body, brass valve seat, and the zinc plated steel spring resist corrosion and can be used in operating temperatures up to 250°F. The safety valve is rated by the American Society of Mechanical Engineers (ASME) with a UV mark for pressure vessel safety. The preset pressure rating is accurate to within 3% and the silicone O-ring provide a leak proof seal.

Pressure Relief Valve Application

Relief valves release excess pressure or vacuum from a system. The valve opening allows fluids or gases to escape decreasing pressure, and closing once pressure reaches a level below the preset limit. This works inversely for vacuums where gas is allowed to pass into the system until the low-pressure limit is reached and the valve closes. A relief valves may an adjustment setting allowing modification to the pressure ratings where the valve opens, making it versatile for multiple applications. Relief valves are rated accordingly by the volume of liquid or gas they can pass and whether the construction material is suitable for a fluid or gas, which may either be corrosive in nature or operate at an extreme temperature. Relief valves are often found in a variety of applications including air compressors, petrochemical and chemical manufacturing, natural gas processing, and even power generation.

National Pipe Taper (NPT) are a standardized fitting that is commonly used for joining pipe. Due to the tapered threads (wider diameter at the base of the threads, similar to a trapezoid) the male fitting will tighten the further it is threaded into the female. NPT follows the technical standards provided by the American National Standard Pipe Thread standards, often called national pipe thread, which is often where the confusions with NPT arises, as NPT is specifically an acronym that refers to tapered pipe.