If this a not a custody transfer meter you can go to 200" or above. BUT - you loose accuracy. That is why most custody transfer contracts are written to current AGA regulations which are normally a max of 100" w.c. Knowledable buyers and sellers both actually prefer flows 20 to 80 w.c...
Do you have any purging experience at all? What is the natural gas processing max design of the unit is mmscf/d? What is the dimension of the contactor and flash tank? Is any other vessels (charcoal filter, etc..) on the TEG unit. What will the operating pressure of the contactor be? Will due...
I'm no engineer but 30 years experience. PSV's are PSV's. They are not intented to be used for blow down valves. PSV valves are normally very expensive and have an almost zero bubble shut off. So, if used for more than a PSV, and lets say it leaks for any reason. If there is no other PSV...