The function of a pressure controls valve is to reduce the water pressure within the system. The valve works by constricting the diaphragm, reducing the pressure inside to 50 to 80 psi. The reduction in water pressure eases the pressure on the pipes. It also helps the valve open, allowing more water to flow. The pressure can be adjusted by turning an adjustment screw. You can lower or increase the water pressure as required.

Many codes and standards address the design, installation, and use of pressure relief valves. One of the most widely used codes is the ASME Code, or Boiler and Pressure Vessel Code. Although most of these codes are voluntary, they are widely used in the industry and are often written into purchasing specifications. In the U.S. and Canada, the ASME Code is mandatory. It is also a good idea to review the latest standards before purchasing a valve.

Another type of pressure control valve is a self-actuated valve. The mechanism uses a pitot tube that allows a process fluid to pressurize a diaphragm. This diaphragm opens and closes depending on the process fluid pressure. An electro-pneumatic valve is also available. The control and driver circuits are built into the throttle valve assembly, eliminating the need for separate electronics modules.