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Pressure Test and Leak Checking
WARNING
To avoid possible explosion, the line from the nitrogen cylinder must include a pressure regulator and a pressure
relief valve.
CAUTION
Never exceed 800 psi (5516 kPa) due to the possibility of rupturing hoses or line-set connections.
4.
Open the hand valve a minimal amount on the line coming from the nitrogen cylinder.
5.
Once the regulator on the nitrogen tank is set, open the high-pressure valve on the gauge manifold. Pressurize the
refrigerant lines and the evaporator(s) to 500 psig (3447 kPa). To reach 500 psig (3447 kPa), you may need to further
open the hand valve on the nitrogen cylinder.
6.
The needle(s) will rise as pressure enters the line set and evaporator(s). Once the point of the predetermined pressure
has been reached, close the gauge valve(s). Monitor the gauge reading(s) after the pressure has stabilized (should be
less than a minute). The pressure should be left in the system for a minimum of 15 minutes.
•
If the gauge pressure drops, there is a leak in the system. Refer to "Leak Check" on page 12 to determine the
location of the leak(s).
•
If the gauge pressure remains constant, close the valve on the nitrogen cylinder and disconnect it from the
gauge manifold. Proceed to "Evacuation" on page 13.
.
WARNING
When using high-pressure nitrogen in the system, wear safety glasses and gloves.
Secure the hose end to prevent injury to personnel or damage to property. Do not point the hose toward personnel or
property.
To prevent inhalation, the nitrogen should NOT be expelled into a confined space where personnel are working; the
work area should be well ventilated.
If the nitrogen is mixed with refrigerant , contact with an open flame or hot surface could create PHOSGENE GAS,
which can cause respiratory problems or death.
Leak Check
IMPORTANT: Do not use a vacuum as a leak detection technique as moisture could be drawn into the system.
•
A rapid drop in gauge pressure indicates a large leak or several small ones.
•
A slow drop in gauge pressure indicates small leak(s).
Open both gauge valves and pressurize the system again to maintain a positive pressure on the lines and evaporator while
checking for leaks. Use the following techniques to locate leaks.
•
Large leaks can often be detected by listening for a hissing sound or felt by placing your hand around the leaking
fitting. NOTE: If pipe insulation encases a leaking fitting, the escaping nitrogen can be forced down the insulation to a
remote location, giving a false indication of the leak location.
•
Apply a soap solution on all connections and joints. Bubbles indicate leaks, so mark these locations. Clean off the soap
solution when leak checking is complete.
CAUTION
Care must be taken to ensure soap solution does not ingress into a leaking fitting(s) and contaminate the system.
•
If the leaks cannot be located with the previous methods, an electronic leak detector should be used. For this
procedure, add a trace of R-410A refrigerant to the nitrogen in the system (if permitted by current EPA regulations).
NOTE: Ensure the electronic leak detector you use is capable of sensing HFC-type refrigerants.
Repeat the procedures above until all leaks are found and repaired. After repair, repeat the steps in "Pressure Test" on page 11.
When pressure-testing is completed, remove the nitrogen source at the outdoor unit service valves and re-install the two
Schrader valve cores. Torque the cores to 3 in-lbs (23-34 N-cm).
12
DuraSea Condenser Installation, Start-Up & Service Manual
L-3153
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