ADVANCED LEAK DETECTION
Leakage that avoids detection by the basic field test (SL)
must be determined by Nitrogen pressurization (PDL),
run-vibration (VDL), or by adding heat (TDL).
For advanced leak detection the electronic halogen detector
cannot be used. We shall rely on the super sensitive microfoamers
unique to the BIG BLU fluid coating.
TESTING FOR
PRESSURE DEPENDENT LEAKAGE (PDL)
| On newly connected field
installations, always proceed to the PDL Test. The
old habit of pressure checking with Refrigerant Gas,
besides being taboo, is more expensive, more time
consuming and less reliable . On existing systems, the technician must properly remove and store any refrigerant charge. |
1. Pressurize the low side to 150 psi and the high
side to 450 psi using dry Nitrogen or Helium. If the high and
low sides cannot be split by way of isolation valves,
pressurize the entire system to about 300 psi.
2. Always conduct proper bubble testing by thoroughly
saturating all surfaces with BIG BLU. Allow up to 15 minutes
reaction time for the microfoamers to expand into visible
white "cocoon" structures. Use an inspection mirror
to view undersides and a light source for dark areas.
3. Starting at the compressor, coat all suspected
surfaces. Continue to coat all suction line connections back
to the evaporator section.
4. Spray coat all fittings starting with the discharge
line at the compressor to the condenser coil. Spray coat all
the soldered condenser coil U-joints.
5. From the condenser, continue to spray coat all
liquid line connections including the receiver (valves,
seams, pressure taps and any mounting hardware). Continue the
liquid line search back to the evaporator section.
6. Any control line taps to the sealed system must be
spray coated the entire length of their run all the way back
to the bellow device.
7. Expose the evaporator section and coat all
connections, valves and U-joints.
Our first sequence of search started with the compressor and
suction line due to their large surface areas. The next sequence
begins with the discharge line, across the condenser to the
liquid line connection at the evaporator section. The evaporator
section is the last and least desirable component to pressure
test in the field.
This completes the PDL Test.
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