When starting a reciprocating refrigeration compressor that has been shut down for a period of time, you should manually throttle which valve?

Correct Answer: Option D — suction valve

Manually throttling the suction valve during cold startups prevents sudden liquid slugging and dampens massive pressure surges from flooding the compressor crankcase. This standard marine operating procedure protects internal valves, pistons, and connecting rods from catastrophic hydraulic shock until system equilibrium is restored.