PSV and PRV are both types of pressure relief valves used in industrial applications to protect equipment, pipelines, and systems from overpressure conditions. While they serve a similar purpose, there are some differences between the two:

1. PSV (Pressure Safety Valve):

   • A PSV is a type of pressure relief valve designed to protect equipment and systems from overpressure by relieving excess pressure to the atmosphere.
   • PSVs are typically designed to open fully at a predetermined set pressure and reseal once the pressure drops below a certain level.
   • PSVs are often used in critical applications where safety is paramount, such as in oil and gas processing, chemical plants, power generation, and pressure vessels.
   • PSVs are subject to strict regulations and codes, including ASME Boiler and Pressure Vessel Code, API standards, and local jurisdictional requirements.

2. PRV (Pressure Relief Valve):

   • A PRV is a general term used to describe any type of pressure relief valve that protects equipment or systems from overpressure conditions.
   • PRVs may include various types of relief valves, such as pressure safety valves (PSVs), pressure reducing valves (PRVs), and pressure regulating valves (also sometimes referred to as PRVs).
   • PRVs may have different operating characteristics and may be used for different purposes, such as controlling downstream pressure, maintaining system pressure within a specific range, or protecting equipment from overpressure.

In summary, the main difference between PSV and PRV lies in their specific function and application. PSV refers specifically to pressure safety valves designed to protect against overpressure events and ensure safety in critical applications. PRV, on the other hand, is a broader term that encompasses various types of pressure relief valves used for different purposes, including pressure safety, pressure reduction, and pressure regulation.