CIRO System Operations & Maintenance — Questions and Answers
Question 1: What is the purpose of purging non-condensable gases from an ammonia system?
- To remove air and other gases that reduce condenser efficiency, increase discharge pressure, and waste energy (Correct answer)
- To add refrigerant to the system
- To remove oil from the system
- To test the system for leaks
Correct answer: To remove air and other gases that reduce condenser efficiency, increase discharge pressure, and waste energy
Air and non-condensable gases accumulate in the condenser, occupying space that should be used for condensing refrigerant. This raises head pressure, reduces capacity, and increases energy consumption.
Question 2: How often should ammonia system safety valves be tested or replaced?
- Relief valves must be tested or replaced at intervals specified by jurisdiction and RAGAGEP, typically every 5 years (Correct answer)
- Never; safety valves are permanent
- Only after an ammonia leak occurs
- Every month
Correct answer: Relief valves must be tested or replaced at intervals specified by jurisdiction and RAGAGEP, typically every 5 years
IIAR and ASHRAE standards require periodic testing or replacement of pressure relief valves (typically every 5 years) to ensure they will open at the correct pressure in an emergency.
Question 3: What is the purpose of an oil drain on an ammonia system evaporator?
- To periodically drain accumulated compressor oil from the evaporator, which reduces heat transfer efficiency when it coats tube surfaces (Correct answer)
- To drain condensed water
- To remove excess refrigerant
- To drain cleaning solution
Correct answer: To periodically drain accumulated compressor oil from the evaporator, which reduces heat transfer efficiency when it coats tube surfaces
Oil carried into evaporators by the refrigerant accumulates on heat transfer surfaces, acting as an insulator and reducing cooling capacity. Regular oil draining maintains efficient heat transfer.
Question 4: What daily operational checks should an industrial refrigeration operator perform?
- Check pressures, temperatures, oil levels, sight glasses, compressor operation, and log all readings (Correct answer)
- Only check if the system is running
- No daily checks are required
- Only check the thermostat setting
Correct answer: Check pressures, temperatures, oil levels, sight glasses, compressor operation, and log all readings
Daily rounds include recording suction/discharge pressures, oil pressure/level/temperature, superheat, subcooling, condenser/evaporator conditions, compressor vibration/noise, and any leaks or abnormalities.
Question 5: What is the importance of maintaining proper water treatment in evaporative condensers?
- Preventing scale buildup, biological growth (Legionella), and corrosion that reduce heat transfer efficiency and system reliability (Correct answer)
- Water treatment is optional
- Only aesthetics are affected
- Treatment only prevents freezing
Correct answer: Preventing scale buildup, biological growth (Legionella), and corrosion that reduce heat transfer efficiency and system reliability
Evaporative condensers recirculate water that can develop scale, biological contamination (including Legionella), and corrosion without proper chemical treatment, all of which degrade heat transfer and can pose health risks.
Question 6: What is the procedure for adding ammonia charge to a system?
- Connect the ammonia supply to the system's charging valve, introduce refrigerant in the liquid phase to the receiver or high side, following safety procedures (Correct answer)
- Pour ammonia into the compressor
- Add ammonia through the suction line as vapor only
- No specific procedure is required
Correct answer: Connect the ammonia supply to the system's charging valve, introduce refrigerant in the liquid phase to the receiver or high side, following safety procedures
Ammonia charging must follow strict safety procedures: proper PPE, connecting to designated charging connections, introducing liquid to the high side (receiver), monitoring charge weight, and checking for leaks.
CIRO System Operations & Maintenance
What is the purpose of purging non-condensable gases from an ammonia system?