76 Section E
Refrigerant Leaks
A system with R-134a and Ester oil will become saturated with moisture much
faster than a system with R-12 and mineral oil. The compressor in an R-134a
system will have to be replaced if the product has had a low side leak.
R-134a refrigerant molecules are smaller than R-12 molecules. This means that
R-134a will pass more minor leaks and the rate of flow will be greater than for R-
12. Therefore, it is now more important than ever to follow good brazing practices.
Use a good grade of silver solder. 45% silver solder is recommended.
Leak Detection
R-134a system leaks can be pinpointed by means of an electronic leak detector or
by bubble solution.
Electronic leak detectors for R-134a service are currently available from several
manufacturers. The least expensive models are non-selective detectors that will
detect any type of emission or vapor present, regardless of its chemical
composition. Some non-selective detectors designed for use with R-12 may have
a much lower sensitivity when used with R-134a. However, newly designed
detectors with good R-134a sensitivity are now available. Be sure to consult with
the manufacturer before selecting or using a non-selective detector with R-134a.
Halogen-specific detectors use a specialized
sensor that allows detection of compounds
containing chlorine, fluorine, bromine, and iodine
without being activiated by other species. The
major advantage of this type of detector is a
reduction in the number of “nuisance alarms”.
Halogen-specific detectors are generally more
expensive than non-selective detectors but
feature higher sensitivity.
R-134a properties
The properties of R-134a are very similar to
those of R12. The principal data for the two
refrigerants are shown in the chart below.
REFRIGERANTS
R-12 R-134a
NAME
Dichlorodifluoro-
methane
1,1,1,2--Tetra-
fluoromethane
Formula CCI
2
F
2
CH
2
F-CF
3
Molecular Weight (g/mol) 120.93 102.3
Ozone Depletion Potential
(ODP)
1 0
Global Warming Potential
(GWP)
3.1 0.3
Boiling Point °F
-21.6 -15.7
Vapor Pressure (77°F) 80 psig 82 psig
Flammability None None
Solubility of Water in
Refrigerant (wt% @ 77°F)
0.009 0.11
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