EPA Section 608 Universal Certification ExamCoreHard
A technician is working on a centrifugal chiller that uses R-123. Due to the very low operating pressure, which of the following is the most significant concern when operating this type of system?
- AHigh discharge pressure causing compressor overload.
- BRefrigerant migration to the compressor oil.
- CAir and moisture infiltration into the system.
- DExcessive superheat leading to poor cooling.
Show answer & explanationAnswer & explanation
Correct answer: C. Air and moisture infiltration into the system.
Centrifugal chillers using very low-pressure refrigerants like R-123 operate below atmospheric pressure on the low side. This creates a constant risk of air and moisture being drawn into the system through leaks, which are non-condensable and can severely impair efficiency and lead to acid formation.
Why the other options are wrong
- A. High discharge pressure is a concern for most systems, but not specific to 'very low operating pressure' systems, which primarily face suction side issues.
- B. Refrigerant migration is a general concern, but not the *most significant* for very low-pressure systems compared to air/moisture infiltration.
- D. Excessive superheat is a symptom of various issues, but air/moisture infiltration is a more fundamental problem for these systems.
Low-Pressure Chiller Concerns
Centrifugal chillers using very low-pressure refrigerants operate below atmospheric pressure on the low side. The most significant concern for these systems is the infiltration of air and moisture through leaks, as these are non-condensable contaminants that degrade performance and can cause system damage.
- Operate below atmospheric pressure.
- Leaks draw in air/moisture.
- Non-condensables reduce efficiency.
- Moisture leads to acid formation.
Memory trick: Below zero, air and water flow.