Empty Refillable Recovery tanks should be evacuated to __ inches of mercury before being put into service.
A) 0
B) 4
C) 27
D) 29.9
The correct answer and explanation is :
Correct Answer:
D) 29.9 inches of mercury
Explanation:
When preparing an empty refillable recovery tank for service, it must be properly evacuated to 29.9 inches of mercury (Hg) to ensure that all air, moisture, and non-condensable gases are removed before introducing refrigerant. This process is crucial for the following reasons:
- Prevention of Contamination:
- Air and moisture in the recovery tank can cause contamination of the refrigerant.
- Moisture reacts with refrigerants like R-134a, R-410A, or R-22 to form acids, which can damage the refrigeration system.
- Avoiding System Malfunctions:
- Non-condensable gases, such as air, reduce the efficiency of the refrigeration system by increasing head pressure and affecting heat exchange.
- Compliance with Industry Standards:
- EPA and HVAC industry guidelines mandate proper evacuation before using recovery tanks to ensure safe and efficient refrigerant handling.
- Better Refrigerant Recovery Efficiency:
- A fully evacuated tank creates a vacuum, allowing refrigerant to flow in more efficiently during the recovery process.
- This minimizes refrigerant loss and ensures compliance with environmental regulations.
Why 29.9 inches of Hg?
29.9 inches of mercury (Hg) represents a deep vacuum, close to absolute zero pressure. This level ensures that almost all air and moisture are removed from the recovery tank. Any residual gases or moisture left in the tank can degrade the refrigerant and lead to system inefficiencies or failures.
Thus, before putting an empty refillable recovery tank into service, it should be evacuated to 29.9 inches of mercury to maintain refrigerant purity, prevent system damage, and ensure efficient HVAC operations.
Here is an illustration of an HVAC technician evacuating a refillable recovery tank using a vacuum pump. The pressure gauge is showing -29.9 inches of mercury, ensuring proper evacuation before putting the tank into service.