25/07/2026
PRV vs PSV β Understanding the Difference in Process Plants
In every pressure system, protecting equipment and personnel from overpressure is critical. Two of the most important safety devices used in process industries, oil & gas, chemical plants, and CBG (Compressed Biogas) plants are the Pressure Relief Valve (PRV) and the Pressure Safety Valve (PSV).
Although their names sound similar, they serve different purposes.
πΉ What is a PRV (Pressure Relief Valve)?
A Pressure Relief Valve (PRV) is primarily designed for liquid service. It opens gradually (modulating action) as the system pressure increases above the set pressure. The valve releases only the amount of fluid required to maintain a safe operating pressure and closes gradually when the pressure returns to normal.
Key Features:
β Used mainly for liquids (water, oil, slurry, chemicals)
β Gradual opening and closing
β Controls system pressure continuously
β Prevents damage to pumps, pipelines, and liquid systems
Common Applications:
β’ Pump discharge lines
β’ Hydraulic systems
β’ Water pipelines
β’ Slurry transfer systems
β’ Liquid storage tanks
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πΉ What is a PSV (Pressure Safety Valve)?
A Pressure Safety Valve (PSV) is designed for gas, steam, and vapour service. It operates with a pop action, opening fully and instantly when the pressure exceeds the set limit. This rapid release protects equipment from catastrophic overpressure.
Key Features:
β Used for gases, steam, and vapours
β Opens instantly (Pop Action)
β Provides emergency pressure relief
β Protects pressure vessels and critical equipment
Common Applications:
β’ Pressure vessels
β’ Digesters
β’ Biogas holders
β’ Compressors
β’ Boilers
β’ Steam systems
β’ Gas pipelines
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πΉ PRV vs PSV β Quick Comparison
PRV
- Medium: Liquid
- Operation: Gradual (Modulating)
- Function: Pressure control
- Application: Pumps & liquid systems
PSV
- Medium: Gas/Steam/Vapour
- Operation: Instant (Pop Action)
- Function: Emergency pressure protection
- Application: Pressure vessels & gas systems
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πΉ Importance in CBG Plants
In a CBG (Compressed Biogas) plant, both valves play an essential role in ensuring safe and reliable operation.
PRV is typically