[EricH]

Originally Posted by Max Boord

We had a pressure vent valve in place on both but where required to add a ball valve in addition to our vent valve on our off board setup.

The compressor's vent valve (solid brass, trips automatically, also known as "Pressure Relief Valve") or the "Pressure Vent Plug" (better known as "dump valve" and activated manually)? The compressor's pressure relief valve, I'll buy. But R89 specifically calls for the pressure vent plug, NOT the relief valve. It's not shown on any diagram (in that part of the circuit, at least).