What is Difference between pressure relief valve and pressure safety valve


Whenever,we talk about the pressure in the process industries we come across two types of safety equipments and that is pressure safety valves and pressure relief valves.

Psv and prv are widely used terminology in the industry.Such terms are often used interchangely because people think that both are same.

Although their functions are same but there are certain differences.

If you want to learn it’s difference in detail then

Must Read: Difference between safety valve and relief

Let us understand what is the Difference between pressure safety valve (PSV ) and Pressure Relief Valve (PRV ).

Difference between pressure safety valve and pressure relief valve


  • It directly open at set pressure.
  • It can open manually by by easing gear.
  • Setting pressure is just above the working pressure and not more than 3 percent above the approved working pressure.


  • Opening is proportion to the increase in pressure.
  • It can not open manually.
  • Setting pressure is 10 percent above the working pressure.

On basis of operations

Pressure Safety Valve- This term used to describe for protecting a vessel filled with compressible fluid or gas.

The opening is sudden for such a valve.

The valve opens almost completely when the set pressure of the valve is reached.

Pressure relief valve :-This term is used to describe for protecting a vessel filled with liquid.

The opening of a such valve is proportional to increase in pressure of liquid filled vessel

Thus,the valve opening is not suddenly,but gradual if pressure increased gradually.

Difference between pressure safety valve(psv ) and pressure relief valve (prv )

Relief valve wikipedia