EPA Section 608 Universal Certification ExamType III (Low-Pressure Appliances)Medium
A technician is performing a recovery from a low-pressure chiller. To prevent air from entering the recovery unit and subsequently into the chiller, what action should be taken when connecting the recovery hoses?
- AConnect the hoses and immediately open the chiller's high-pressure isolation valve.
- BFill the recovery hoses with liquid refrigerant from a separate cylinder before connection.
- CEvacuate the recovery hoses and manifold before opening the chiller's service valves.
- DPurge the recovery hoses with nitrogen before connecting them to the chiller.
Show answer & explanationAnswer & explanation
Correct answer: C. Evacuate the recovery hoses and manifold before opening the chiller's service valves.
Evacuating the recovery hoses and manifold removes any air or non-condensable gases present in them before they are connected to the chiller, preventing these contaminants from entering the system.
Why the other options are wrong
- A. Opening the high-pressure valve immediately without evacuating the hoses would draw air into the chiller.
- B. Filling hoses with liquid refrigerant is not a standard or safe procedure for preventing air ingress and could cause slugging or over-pressurization.
- D. Purging with nitrogen would introduce another non-condensable gas that would need to be removed later.
Preventing Air During Recovery Connection
Before connecting recovery hoses to a refrigeration system, it is crucial to remove any air or non-condensable gases from the hoses to prevent contamination of the system.
- Air in hoses can introduce non-condensables.
- Evacuation creates a vacuum, removing air.
- This step is critical for system integrity.
Memory trick: Vacuum the hoses, or air will lose!