THE IMPORTANCE OF SENSITIVITY
Sensitivity is the measure of performance in
leak finding devices.
High sensitivity means "fine" leak detection. Low
sensitivity is considered "gross" detection.
| Refrigeration Technologies has developed
a fluid coating of remarkable leak reactant sensitivity. Progressive compositions trademarked as "BIG BLU" are now capable of magnifying micro-gas leakage as small as 0.65 oz./yr into visible foam "cocoons." Our research work has been verified and published in several distinguished scientific journals.* *Reference: American Society for Non-Destructive Testing "The Study of Leak Detection Fluids." Materials Evaluation. Vol. 49 No. 8 Pages 1035 - 1037, August 1991 |
 The
super sensitivity of the Big Blu fluid is demonstrated |
The advent of fine electronic sensing devices proves that microscopic leaks do in fact exist, and leaks larger than 0.5 oz./yr. can be detrimental to the operation of any refrigeration system. Bubble testing is gross because only large leaks (above 4.2 oz./yr) and leaks of proper position can be detected. This can be demonstrated when a fitting is electronically sensed as leaking, but secondary application of a bubble solution to confirm the site yields no bubble or foam formation. The question immediately confronting the technician is: 1. Did the electronic give a false reading? or Does the bubble solution lack the sensitivity to show the leak? Refrigeration Technologies has conducted extensive studies investigating all the faults of bubble leak testing. The failure of bubble solutions lies in their composition. Most are based on shampoo, bubble bath or dish washing soap and usually contain artificial thickeners, fluorescent dyes, or glycerin that dramatically kill leak sensitivity. |
THE SIX CLASSES OF LEAKS
Refrigeration Technologies has determined six
(6) types of leaks, you will
at sometime during your servicing experience, come to know.
| Class 1 | Standing Leaks (SL) are leaks that can be detected while the unit is at rest (off) and fully equalized. This shall include freezer evaporator coils warmed up by defrost. SL leaks, fortunately, are the most common of all. |
| Class 2 | Pressure Dependent Leaks (PDL) are leaks that can only
be detected as the pressure is built.
Nitrogen or Helium is used to pressurize low sides to 150
psi and high sides to 450 psi. Never
use C02 or Oxygen. PDL testing should be conducted if no leaks are discovered by the SL test. |
| Class 3 | Temperature Dependent Leaks (TDL) are leaks associated with the heat of expansion. TDL usually occurs from high ambient air, condenser blockage or during defrost. |
| Class 4 | Vibration Dependent Leaks (VDL) occur only during unit operation. The mechanical strain of motion, rotation, refrigerant flow, or valve actuation are all associated with VDL. |
| Class 5 | Combination Dependent Leaks (CDL) are flaws that require two or more conditions in order to induce leakage. For example, temperature, vibration and pressure cause the discharge manifold on a semi-hermetic compressor to expand and seep gas. |
| Class 6 | Cumulative Micro-Leaks (CML) are all the individual leaks that are too small to detect with standard tools. The total loss over many years of operation slightly reduces the initial gas charge. In practice, a system having many fittings, welds, seams or gasket flanges; the greater the amount of CML. |
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