【2026 Safety Protection】Difference Between PSV and PRV
Thread Content
Pressure Safety Valves (PSV) are also commonly referred to as simply Safety Valves. They are used to relieve pressure from equipment that operates with gases. Generally, the valve opens suddenly, in an instant.
Pressure Relief Valves (PRV) are also commonly referred to as simply Relief Valves. They are a type of Safety Valve. They are used to relieve pressure from equipment that handles liquids. Generally, the valve opens in a relatively gradual and proportional manner.
The function of both PSV and PRV is to relieve excess pressure from the system by opening automatically, and they close automatically once the pressure in the system returns to normal.
The most common type of safety valve used in industries is spring loaded safety valve.
The valve features a spring that is connected to an adjusting screw. This screw can be adjusted to compress the spring, thereby allowing for flexible control over the spring force. The spring is attached to a disc via a spindle; it is at this position that the fluid enters the valve when the system is under excessive pressure.
If the pressure force is less than the spring force, then the fluid will not be able to move the disc. This situation represents normal operating conditions. If the pressure force is equal to the spring force, then the disc begins to move. The fluid flows from the equipment into the valve and then starts to flow out of the system.
In the case of a PSV, when the pressure force exceeds the spring force, the valve opens immediately and a ‘pop’ sound is produced; whereas a PRV opens in proportion to the increasing pressure. It can be said that its opening is relatively gradual compared to that of a PSV.
The escaping fluid causes a decrease in pressure. When the pressure force becomes smaller than the spring force once again, the disc returns to its original position and seals the equipment.
The following response is for reference: A Pressure Safety Valve (PSV) is designed for compressible fluids like gases, vapors, or steam. Pressure safety valves (PSVs) are specifically designed for compressible fluids such as gases, steam, or vapors.
When system pressure reaches the set limit, it wastes no time – it “pops” open instantly to release all the excess pressure, and then snaps shut once conditions return to normal. When system pressure reaches the set value, it immediately opens up to release the excess pressure, and closes again quickly once the pressure returns to normal levels.