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Leak Detection
The new non-chlorine based refrigerants [HP - 62/R 404A] require special leak detection devices other than
what has been standard for the CFC’s.
While the instruments for leak detection are different, the processes have not changed.
Basics to remember:
1. Look for signs of oil when you visually start your leak check process. Oil is carried with the refrigerant. If
the oil has leaked out so will the refrigerant.
2. Refrigerant vapor is heavier than air. When leak checking suspect areas, probe below the joints or connec-
tions.
A. Always check the high-side of the system with the compressor operational.
B. Check the low-side of the system, with the system idle.
C. Following a & b will normally allow the highest pressure on each portion of the system for the best
detection.
3. Systems short of refrigerant will show improper operational results in both the freeze and harvest cycles.
Many systems will appear normal in higher operating temperatures and change drastically in cooler con-
denser temperatures.
4. Many new and reworked leak detection instruments have the ability to detect CFC’s, HCFC’s and the new
HFC’s by making a simple switch selection. This type of detector will be more sensitive on one setting than
the other. This results in finding some leaks that are so small it may take years before the actual leak rate
would create adverse operating conditions in the product.
A bubble test and/or additives with UV lamp may be the best team for the most positive leak testing results.
5. Never pressurize a system with oxygen or a mixture of refrigerant and air. Either of these methods may
cause a system explosion to occur.
6. Pressurizing systems to leak test should only be done with dry nitrogen. Be sure the regulator setting does
not exceed the recommended system pressure.
CAUTION: A full cylinder of nitrogen will have pressure of approximately 2700 PSI.
7. Failure to correct leaks will also cause shorter compressor life as a result of the higher operating tempera-
tures. Always leak check the total system as one located leak may not be the only leak.
SYSTEM EVACUATION & RECHARGING
Should service work ever be required on a product where the sealed refrigeration is opened for any reason, the
refrigerant must be reclaimed, drier/filter replaced, evacuated and recharged. The old method of “purging” is
NOT ACCEPTABLE. Always evacuate the system through both the high and low side service valves. Be certain
both valves are completely open when evacuating and the drier/filter has been replaced.
SELF-CONTAINED PRODUCTS
Every effort should be made to never have the system open to the atmosphere for longer than 15 minutes, and
the replacement of the drier/filter is no longer an option, [IT IS MANDATORY].
A good vacuum is not always easy to measure, however the goal is to have less then 1% non-condensible va-
pors in the system at the completion of the evacuation. Basic guidelines with a good pump would be to evacu-
ate a selfcontained product 30 to 45 minutes and a remote product no less than 60 minutes.
