Hi All,
I am trying to understand what is wrong with a control valve that does not seem to seal properly since a recent rebuild (see attached image). The valve is a globe valve that is being used to control the level in a Knock Out Pot. The control scheme is On/Off.
Previously this valve would open and close every hour or so, but now the close command is given, but the level continues to fall for hours sometimes hitting the LL trip point. Eventually, the valve seals up and the level rises again, but not in the linear way it would previously. When the LL trip is hit the level rises just as quickly as it used to in a linear way.
During a previous rebuild the decision was made by the team on site to modify the plug to shorten the long nose by cutting it. The logic was that there was dirt getting clogged in the outlet due to the long nose, resulting in erosion of the seat and poor sealing performance (after two years operation). Performance after this modification was normal.
After the most recent rebuild no modifications were made to the plug, but the performance is now much worse.
Do you think I should plan in for the valve to be pulled out again and inspected?
Is there an issue with the air pressure regulator?
I am trying to understand what is wrong with a control valve that does not seem to seal properly since a recent rebuild (see attached image). The valve is a globe valve that is being used to control the level in a Knock Out Pot. The control scheme is On/Off.
Previously this valve would open and close every hour or so, but now the close command is given, but the level continues to fall for hours sometimes hitting the LL trip point. Eventually, the valve seals up and the level rises again, but not in the linear way it would previously. When the LL trip is hit the level rises just as quickly as it used to in a linear way.
During a previous rebuild the decision was made by the team on site to modify the plug to shorten the long nose by cutting it. The logic was that there was dirt getting clogged in the outlet due to the long nose, resulting in erosion of the seat and poor sealing performance (after two years operation). Performance after this modification was normal.
After the most recent rebuild no modifications were made to the plug, but the performance is now much worse.
Do you think I should plan in for the valve to be pulled out again and inspected?
Is there an issue with the air pressure regulator?
