We have an application at our chemical plant that we'd like to replace. Process pressure is maybe 10psig max. The following setup is part of an autovent system.
It is mounted to a relatively large Bettis single acting actuator on a Tricentric butterfly valve that is maybe 24" dia. Current setup is an old I/P connected to a volume booster or ratioing box with a through shaft. On top of that is a positon transmitter with 3 limit switches and a beacon. We'd like to replace the setup with a digital HART positoner with a position transmitter and limit switches. I realize we'll probably need to keep the volume booster.
Currently, the DCS outputs 4-20 to the I/P, which changes the air signal to volume booster that actually puts air on the actuator. The position transmitter puts out 4-20 which is read back to the DCS. A loop isolator is also in this loop. A safety system reads the other side of the loop isolator to pick up the valve position. And last, we have 2 closed and 1 open limit switch all wired back to the safety system. (We do 2 out of 3 voting on the limit switches.)
Anyone make such an animal that isn't so piecemeal? If necessary we can put a Rosemount TriLoop on the 4-20 from the DCS to the positioner to pick off the valve position to send to the safety system.
(I left out the 2, 1" quick exhausting air relays and solenoids...you can hear this thing across the plant when it trips.) Please reply to the group rather than emailing your answers.
Thanks, KT