I need to pull open the bottom plate of an oil separator in order to check the buoy mechanism and mesh. The separator is located in the discharge line. In order to isolate the oil separator, I´m planning to shut down the compressors and close all of their discharge service valves. That should take care of the upstream side. But downstream the separator, the only service valve available is that at the remote condenser inlet. There is a discharge differential pressure regulator right downstream from the oil separator. It´s my understanding that this valve when energized, remains 100% open. It begins to close and create a pressure differential when de-energized during defrost. My question is: is it possible to somehow shut tight this regulator whith the system off, in order to isolate the oil separator from the condenser inlet side? Thank you.