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9-8. Evacuation of the system
Do not purge the air using refrigerant. Use a vacuum pump to evacuate the system.
- Residual gas in the refrigerant lines will cause bursting of the pipes or an explosion.
Use a vacuum pump with a check valve.
- If the vacuum pump oil flows back into the refrigerant lines, the refrigerant oil may deteriorate
and the compressor may malfunction.
<Evacuation procedures>
① Evacuate the system from both service ports, using a vacuum pump with the service valves closed.
② After the vacuum reaches 650 Pa (0.0943 psi/5 Torr), continue evacuation for at least one hour. When the
outdoor temperature drops below 1ºC (or when the saturation pressure drops below 656 Pa (0.0951 psi/5 Torr)),
continue evacuation for another 1 hour after the vacuum degree has reached the saturated vapor pressure of
the water (ice) at the outdoor temperature. When performing evacuation at a low outdoor temperature, use a
vacuum gauge appropriate for the temperature range.
Degree of vacuum (reference)
Outdoor temperature
Degree of vacuum
* The degrees of vacuum shown above are obtained based on the saturated vapor pressure of ice.
* In a system using water heat exchangers, circulate water to prevent the water from freezing during evacuation.
③ Stop the vacuum pump and leave it for an hour.
④ Verify that the vacuum has not increased by more than 130 Pa (0.01886 psi/1 Torr).
⑤ If the vacuum has increased by more than 130 Pa, water infiltration is suspected. Pressurize the system with dry
nitrogen gas up to 0.05 MPa (7.25 psi/375 Torr). Repeat ① though ⑤ until the vacuum is increased by 130 Pa
or below. If the results persist, then perform the "Triple Evacuation" below.
<Triple Evacuation>
① Evacuate the system to 533 Pa (0.07729 psi/4 Torr) from both service ports, using a vacuum pump.
② Pressurize the system with dry nitrogen gas up to 0 Pa (0 psi/0 Torr) from the discharge service port.
③ Evacuate the system to 200 Pa (0.029 psi/1.5 Torr) from the suction service port, using a vacuum pump.
④ Pressurize the system with dry nitrogen gas up to 0 Pa (0 psi/0 Torr) from the discharge service port.
⑤ Evacuate the system from both service ports, using a vacuum pump.
⑥ After the vacuum reaches 66.7 Pa (0.09672 psi/5 Torr), stop the vacuum pump and leave it for an hour. A
vacuum of 66.7 Pa must be maintained for at least one hour.
⑦ Verify that the vacuum has not increased for at least 30 minutes.
Ⓝ
Ⓝ
Ⓐ
LO
HI
Ⓑ
・Use a scale that can measure down to 0.1 kg (0.1 oz).
・Recommended vacuum gauge: ROBINAIR 14830A Thermistor Vacuum Gauge or Micron Gauge
・Do not use a gauge manifold to measure the vacuum pressure.
・Use a vacuum pump capable of attaining a vacuum of 65 Pa (abs) (0.00943 psi/0.5 Torr) within five minutes of
operation.
WT09973X01
-20ºC (-4ºF)
-15ºC (5ºF)
0.77 Torr (103 Pa)
1.24 Torr (165 Pa)
Ⓓ
Ⓔ
Ⓕ
Ⓞ
Ⓖ
Ⓒ
Ⓘ
Ⓗ
Ⓚ
Ⓙ
Ⓛ
-10ºC (14ºF)
-5ºC (23ºF)
1.95 Torr (260 Pa)
3.01 Torr (402 Pa)
Gauge manifold
Ⓐ
Low pressure knob
Ⓑ
Ⓒ
High pressure knob
Ⓓ
Service valve
Ⓔ
Low-pressure pipe
High-pressure pipe
Ⓕ
Service port
Ⓖ
Ⓗ
Three-way joint
Ⓘ
Valve (vacuum pump)
Ⓙ
Valve (for charging refrigerant)
Ⓜ
Ⓚ
Refrigerant tank
Scale
Ⓛ
Vacuum pump
Ⓜ
Ⓝ
To indoor unit
Ⓞ
Outdoor unit
36
0ºC (32ºF)
4.58 Torr (611 Pa)
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