WHAT IS THE DIFFERENCE BETWEEN A THERMAL RELIEF VALVE AND PRESSURE SAFETY VALVE?

Question

hey guys/gals.........

i was having a terrible confusion in the basic difference between a TRV and a PSV.............

SP PLZZZ BAIL ME OUT.............asap.............

....ash

Answer 1

In a liquid filled system, small temperature increases will cause large pressure increases. A Thermal Relief Valve (TRV) operates the same way as a Pressure Safety Valve (PSV) due to expansion of Liquids.

It is smaller than a Pressure Safety Valve (PSV) used for gases because, the volume of liquid required to decrease the pressure when it operates is much less than the volume of gas relieved by a PSV.

(A thermal relief valve doesn't actually operate on Temperature. It operates on the Pressure increase due to Temperature increase).

Relief valves are also used to 'Break' an excess vacuum in a tank by admitting a gas of the same type as the vapour in the tank (or an Inert gas like Nitrogen).  This system is used to prevent Implosion of the tank. (There are also two-way PSV's used in low pressure/vacuum systems which will relieve excess pressure and break excess vacuum as necessary).

There are a number of different types of Safety Valve ...Conventional, Bellows and Pilot-operated valves...etc.

Answer 2

THERMAL RELIEF VALVE  works on temperature.

PRESSURE SAFETY VALVE works on pressure.