Refrigeration Operator B case studies
Refrigeration Operator B · Put your knowledge to work in context.
The Refrigeration Operator B credential sits within the Operating Engineer family of certifications administered in Ontario by the Technical Standards and Safety Authority (TSSA). It is aimed at people who operate and monitor refrigeration plants - industrial process cooling, food storage, ice rinks, HVAC chillers and similar systems - and who need a formal operating qualification rather than an engineering degree. The Refrigeration Operator B case studies are 5 cases and about 3,707 words.
1Ammonia plant: rising discharge pressure on a hot afternoon
At a cold-storage warehouse in Mississauga, a two-stage ammonia plant with two 250 kW screw compressors and an evaporative condenser normally runs at about 1,050 kPa gauge discharge, which corresponds to roughly 25 °C condensing. On a July afternoon the outdoor wet-bulb is 21 °C and the discharge pressure has climbed to 1,380 kPa gauge.
765 words, about 4 min2R-123 centrifugal chiller with climbing purge run-time
An office tower in Ottawa is cooled by a 1,400 kW low-pressure centrifugal chiller using R-123, with a water-cooled condenser, a purge unit and an evaporator that runs in a vacuum at about 40 kPa absolute (5 °C). The purge run-time log, normally about 3 minutes a day, now shows 35 minutes a day and is still climbing.
745 words, about 4 min3Reciprocating compressor tripping on oil failure after an outage
At a food processing plant, a 110 kW reciprocating compressor using R-404A and POE oil tripped on its oil-failure switch three times in one morning. The compressor had been shut down for a three-day maintenance outage while the oil was changed (55 L of the specified oil) and the oil filter replaced.
773 words, about 4 min4Passing relief valve and a supervisor's instruction to isolate it
At a small arena, an ammonia plant serves the ice pad. On a Friday evening the operator notices frost and a plume at the discharge stack of the high-pressure receiver's relief valve, and a sharp ammonia smell in the machine room.
714 words, about 4 min5Logbook request, an unqualified apprentice and an overdue TSSA order
On a Sunday at a cold-storage facility, the shift operator holds a Refrigeration Operator certificate and is the only certificate holder on site; the chief engineer is on vacation for two weeks. The plant serves a -25 °C freezer and a 2 °C cooler.
710 words, about 4 min