"This ensures that backpressure does not increase the opening
backpressure effects on opening pressure."
The above snip is from API-520 Part 1
My doubt is, For a conventional PSV we are going to change the PSV Spring force load as per the back pressure at the outlet of PSV.
In case of balanced bellow type PSV, the snip states that when back pressure increases, the PSV opening pressure(=set pressure0 decreases. How the PSV Set pressure changes?
Can anyone explain your understanding for the red font text?
Edited by Danish John Paul, 01 October 2020 - 12:15 AM.