Hey im an apprentice instrument technician just wondering there are a lot of various information about this I just feel paranoid about damaging a dp transmitter. I only work on natural gas for medium

remove from service
1. open equalize valves
2. close LP and HP block valves
3. open vent

return to service
1. close vent
2. open equalize valves
3. open LP and HP block valves
4. close equalize

?

 

That's correct. DP transmitters aren't as "sensitive" to incorrect valving as they used to be--and they would "blow out" in the drop of a hat thirty years ago. But, you got it--on removing from service, equalize the pressure between the two sides by opening both equalizing valves, close the HP and LP block valves, and open the vent between the equalizing valves. On returning to service, close the vent between the two equalizing valves, open the equalizing valves (if they're not already open), open the HP and LP block valves, and close both equalizing valves.