1. Importance of Leak Testing
- Closed System Requirement: For proper operation, the refrigerant must remain sealed within the system.
- Consequences of Leaks: If refrigerant leaks out, the system will not operate efficiently.
2. Popular Methods of Leak Testing
Standing Pressure Test with Dry Nitrogen:
- Gas Used: Always use dry nitrogen to avoid introducing water vapor into the system.
- Why Not Compressed Air? Compressed air contains water vapor, which we want to eliminate from the system.
Standing Pressure Test with R22 or Another Refrigerant as a Tracer Gas:
- Use a small amount of refrigerant along with nitrogen to detect leaks.
Vacuum Hold Test:
- Check if the system can maintain a vacuum, indicating no leaks.
3. Detailed Procedure: Standing Pressure Test with Nitrogen
Advantages: High pressure helps to find very small leaks.
Disadvantages: Small leaks might take time to show up on a pressure gauge.
Understanding Test Pressures:
- Example Data Plate: Shows low side (150 PSIG) and high side (300 PSIG) test pressures for R22 equipment.
- R410A System: High side pressures exceed 300 PSIG, so typical test pressures are higher (250 PSIG for the low side).
- General Rule: Test at twice the working pressure of the system.
Steps for Testing:
- Charge with Nitrogen: Use consistent pressures (150 PSIG for R22, 250 PSIG for R410A).
- Procedure: Charge the system carefully to reach the exact test pressure.
- Bubble Solution: Apply to connections to visually check for leaks.
4. Duration of Pressure Test
Small Systems: 1-2 hours.
Larger Systems: Overnight.
Outcome:
- No Pressure Drop: Indicates no leaks.
- "If and Only If" (IFF): No leaks mean you can proceed to evacuation and charging.
5. Risks of Skipping Proper Leak Testing
- Inadequate Evacuation: Leads to improper system operation.
- Moisture Introduction: Can occur if the system isn't leak-free before evacuation.
- Time Wastage: Skipping proper leak testing means you might have to redo the work.
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