Process plants convert raw materials into useful products through heating and cooling. For most, this results in fluidic process media. A combination of process equipment, such as piping, vessels, pumps, compressors and valves; all of which have different characteristics; transport the fluids from the start to the end of a process.

Fluids at different phases and temperatures have an associated operation pressure. Operation pressure poses a hazard to the process equipment, as exceeding their designed operation pressure threshold may lead to violent busting/explosions. A hazard which is most commonly is monitored with a Pressure Safety Valve (PRV) or Pressure Relieve Valve (PRV).

What is the difference between PRV and PSV?

Firstly, what is a Pressure Safety Valve (PRV) or Pressure Relieve Valve (PRV)? PRV/PSV is a device used to mitigate an overpressure condition.

Secondly, according to API standards, a PSV is used for gas and a PRV for liquids. The difference is the naming scheme for different standards and specifications.

Dual Medium Safety Relief Valve

At Pinnacle Process Safety and Valves (PPSV) we have a dual medium safety relief valve or SRV. This innovation, is certified for liquid, gas, or steam scenarios.

The 1900 DM trim is engineered to perform on liquid and gas media including two-phased fluid applications.


API standard for dual media requires that no modification is done to the PRV/PSV when switching fluids, the following certifications apply to the 1900 DM:

  • Certified for gas and liquid on the same certification
  • ASME VIII CC 2787
  • API 520

Should you wish to find out more or have any enquiries on process instruments, valves, fire and gas detectors RFQs, Tenders and Projects, please contact us on:

Phone: (+27) 011 450 4885

Cell/WhatsApp: (+27) 072 474 8143

Email: or

Written by: Garth Matsebele

Acknowledgement to Baker Hughes, 2020, 1900 Series Dual Media

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