Refrigeration system isolation valves are specially designed with a back-seat, as well as a front-seat. For what purpose are these valves designed in this way?

Correct Answer: Option C — permit repacking the valve stem under pressure without shutting down

Refrigeration service valves feature a dual-seating design incorporating both front-seat and back-seat arrangements. Back-seating the valve isolates the packing gland from system pressure, allowing maintenance personnel to safely replace the stem packing without pumping down the system.