Ashereng
Yes, it sounds confusing doesn't it? Let me try again.
A PVST isn't carried out on a closed valve, therefore on a process trip in FL position, the valve is closed and remains closed. Dito on valve failure.
However, a PVST is carried out on a valve in the open position and in the...
Ashereng
Thanks for your reply. For our spring return valves the actuator's spring(s) trigger the respective FO & FC valves to their failure positions accordingly.
However my concern is that the FL actuators may fail in a semi closing position with mitigating circumstances as the FL...
Hi
Does anyone have any ideas how to hook-up a pneumatic Fail Last Double acting actuator so that if performing a PVST that it shall return to the Fail Open position again on loss of air or power?
Thanks in advance
Graham
