EPA Section 608 Universal Certification ExamType I (Small Appliances)Hard
A technician is connecting a recovery machine to a small appliance. To prevent air and non-condensables from entering the recovery cylinder, what critical step must be performed before opening the valves to the recovery cylinder?
- AConnect a desiccant dryer in-line with the recovery hoses.
- BHeat the recovery cylinder to increase its internal pressure.
- CPurge the recovery hoses with nitrogen.
- DEvacuate the recovery hoses and manifold gauge set.
Show answer & explanationAnswer & explanation
Correct answer: D. Evacuate the recovery hoses and manifold gauge set.
Before connecting to a system, the recovery hoses and manifold gauge set should be evacuated to a deep vacuum. This removes any air or moisture from these components, preventing them from contaminating the recovered refrigerant in the cylinder.
Why the other options are wrong
- A. A desiccant dryer removes moisture, but evacuation also removes air (non-condensables) which is crucial for efficient recovery.
- B. Heating the recovery cylinder would increase its pressure, making it harder to pull refrigerant in and potentially dangerous.
- C. Purging with nitrogen can introduce nitrogen into the system, which is a non-condensable. Evacuation is preferred.
Preventing Non-Condensables in Recovery
To maintain the purity of recovered refrigerant and ensure efficient recovery, non-condensable gases (like air) must be removed from the recovery setup.
- Non-condensables raise system pressure and reduce efficiency.
- Evacuate recovery hoses and manifold before connecting.
- Always use a vacuum pump for evacuation.
- Moisture is also considered a contaminant.
Memory trick: Before you 'pull,' pull a 'vacuum' on your lines, or 'air' will spoil your finds!