Industrial Refrigeration IV - Plant Operation and Safety
Operating discipline and emergency response
Plant operation questions blend procedure with consequence. Normal running means rounds: log suction and discharge pressures, oil levels, liquid levels, water treatment, and watch for frost lines, vibration, and leaks. Startup and shutdown follow a written sequence - valves lined up, compressor unloaded, pumps running before the chiller is loaded, hot gas isolated before entering the machine room. Pump-down, lockout/tagout, confined-space permits, and hot-work permits are control measures, not paperwork.
Ammonia safety numbers are exam favorites: 25 ppm is the 8-hour TLV, 35 ppm the short-term limit, and 300 ppm the IDLH; ammonia can be smelled well below 25 ppm. Know alarm and ventilation requirements, the location of eyewash and safety showers, escape respirators versus SCBA, and the rule that only trained, equipped personnel respond. Machine rooms need adequate exits and ventilation and must not be used for storage.
Traps: sending untrained staff in to "check" a leak; venting liquid ammonia to atmosphere; assuming a purge vent is harmless; ignoring creeping discharge pressure because "it always runs that way" (non-condensables or a fouled condenser).
Worked example: an operator smells ammonia near a pump seal. Correct order: notify, evacuate and isolate the area, don proper PPE and respiratory protection, stop the source if it can be done safely, ventilate, then repair under permit. Documenting the event is part of the response, not an afterthought.