What exactly is the back pressure of a safety valve? Why is it related to the outlet pipe of the safety valve?
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Is the back pressure of a safety valve the pressure in the safety valve’s discharge system? Is it true that the longer the outlet pipe of the safety valve, the greater the pressure drop in that pipe, and thus the higher the backpressure on the safety valve?
The back pressure of a safety valve is the pressure acting at the outlet of the safety valve. Back pressure is divided into static back pressure and dynamic back pressure. Static back pressure refers to the pressure at the valve outlet when the safety valve has not activated ； Dynamic back pressure refers to the frictional pressure drop caused by fluid flow after the safety valve activates. I recall that there are guidelines stating that the outlet pipe of a safety valve should not be too long, as this is related to the issue of back pressure. This post was last edited by LXD on 2007-12-16 15:12]
It is friction that causes an increase in the pressure at the outlet of the safety valve; the sum of the pressure at the safety valve’s outlet and the set pressure difference equals the inlet pressure. This pressure represents the safe operating pressure for the equipment or pipeline, and it must not be exceeded.