Question

In a vacuum degassisng process, a setpoint change was introduced to the level in the pressure tank and the pressure was maintained constant ( it changes because of proces intercation)

my question is that the pressure control valves opens to compensate for the decrease of pressure but it reaches 100% of opening (i.e. fully opened) for 2 min. What does this indicate and what are the results of such valve respond ?

Answer 1

As you mentioned that setpoint change was introduced to the level in the pressure tank and the pressure was maintained constant. Suppose you have increased set point for level then automatically pressure will also increase rapidly. If it increases fast then that will be dangerous for the tank and other equipments. To avoid this risk, pressure valve opens 100% to remove pressure rapidly until new equilibrium gets set. This is for safety provision.

Second reason as I can say that, it will remove gases by opening 100% valve to help maintaining vacuum. Suppose sudden pressure increased in tank then as pressure increases, solubility of gases increases and you will not get proper degassing results.so to avoid this scenerio, it opens fully to decrease pressure rapidly.

Hope this will be helpful for you.