Evacuation Of The System - Mitsubishi Electric City Multi PUHY-P200YNW-A Installation Manual

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, continue evacuation for at least one hour.
③ Stop the vacuum pump and leave it for an hour.
④ Verify that the vacuum has not increased by more than 130 Pa.
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. 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 from both service ports, using a vacuum pump.
② Pressurize the system with dry nitrogen gas up to 0 Pa from the discharge service port.
③ Evacuate the system to 200 Pa from the suction service port, using a vacuum pump.
④ Pressurize the system with dry nitrogen gas up to 0 Pa 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, 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.
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HI
LO
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・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) within five minutes of operation.
KJ79F137H01
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Ⓔ
Ⓕ
Ⓞ
Ⓖ
Ⓘ
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GB-35
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Gauge manifold
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Low pressure knob
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High pressure knob
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Service valve
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Liquid piping
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Gas piping
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Service port
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Three-way joint
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Valve (vacuum pump)
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Valve (for charging refrigerant)
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Refrigerant tank
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Scale
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Vacuum pump
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To indoor unit
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Outdoor unit