Multi F Installation Manual

43
Refrigerant Piping Connections
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MULTI
F
MAX
MULTI
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Leak Test Procedure, continued.
7. While operating the pressure gauge system, observe the connections for any leaks. If bubbles appear at any of the connections (indoor,
BD, and outdoor units) or refrigerant piping joints, a leak is present.
8. Make a note of where the leaks are, and remove the soap with a clean cloth.
9. Disengage the nitrogen pressure by loosening the charge hose connector at the nitrogen cylinder. After the system pressure is back to
normal range, disconnect hose from the cylinder.
10. Repair the connections and piping where bubbles / leaks were observed. When finished, repeat leak testing using the liquid soap method
and nitrogen cylinder.
11. After system is leak free, depressurize by loosening the charge hose connector at the nitrogen cylinder. When system pressure returns to
normal, disconnect the hose from the cylinder.
Essential Points for Leak Testing
The key to successful testing is strict adherence to the leak testing procedure.
1. The liquid and gas piping in each refrigerant system should be pressurized with nitrogen gas in accordance with the steps listed below.
Step 1: Pressurize to 43.5 psi for three (3) minutes or more. (Will identify if major leaks are present in the system.)
Step 2: Pressurize to 217.6 psi for three (3) minutes or more. (Will identify if major leaks are present in the system.)
Step 3: Pressurize to 551.1 psi for approximate twenty-four (24) hours. (Will identify if minor leaks are present in the system.)
Pressurizing the system to 551.1 psi does not guarantee the identification of minor leaks if the pressure is maintained for only a short time. It
is recommended that the system remain pressurized for at least 24 hours.
Example:
'XULQJ/HDN7HVWSVLDW)
7ZHQW\IRXU+RXUV/DWHUSVLDW)
Although the pressure dropped from 551.1 psi to 543.9 psi, it can
be assumed that there are no leaks because pressure can also drop
due to the change in outdoor temperature.
3 minutes
5 minutes
24 hours
Step 1
Step 2
Step 3
(Time)
Outdoor Temperature (°F
3.8 (551.1)
3.75 MPa
(543.9 psi)
3.5 (507.6)
3.0 (435.1)
2.5 (362.6)
2.0 (290.1)
1.5 (217.6)
1.0 (145.0)
0.5 (72.5)
0.0 (0.0)
Step 1: 0.3 MPa (43.5 psi) at 3 minutes
Step 2: 1.5 MPa (217.6 psi) at 5 minutes
Step 3: 3.8 MPa (551.1 psi) at 24 Hours
MPa (psi)
77°F
68°F
59°F
Piping system should not be pressured to more than 551.1 psi. Pressures greater than 551.1 psi may damage the piping system and cause unit
malfunction.
2. Check for pressure drop. If there is no drop in pressure, the test is successful. If the pressure drops, there is a leak in the piping system.
If, however, there was a change in the ambient temperature between when pressure was initialized and when pressure drop is checked,
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Compensation Value: Temperature at Pressure Initialization – Temperature at Pressure Check × 1.45
Figure 55: Leak Test Time Diagram.
REFRIGERANT PIPING PREPARATION
Leak Test