Midea MDV-252(8)W/D2DN1(B)

MCAC-VTSM-2015-09 R410A All DC Inverter V4+S Series 60Hz
Installation 115
No.
Phase (phase-in pressurization)
Criteria
1
Phase 1: large leakage after over three minutes of pressurization with 42.6PSI(3.0kgf/cm
2
).
No pressure drop
after modification
2
Phase 2: major leakage after over three minutes of pressurization with 213.3PSI(15.
0kgf/cm
2
).
3
Phase 3: small leakage after over 24 hours of pressurization with R410A:
568.8PSI(40.0kgf/cm
2
).
10.2.2 Pressure observation
1. System pressure should be maintained for 24 hours. When pressure change is related to temperature
change according to below calculation, it means there are on leakage. If pressure falls, identify and address
the leakage source.
2. Modification method
When ambient temperature difference is ±1.8°F(1°C), the pressure difference shall be ±1.4PSI(0.1kgf/cm
2
).
Modification formula: Real value = pressure of pressurization + (temperature of pressurization – temperature
during observation)x1.4PSI(0.1kgf/cm
2
)
A pressure drop can be identified by comparing the modification value with pressurization value.
3. General method for identifying the source of a leak
Detection process involves three general steps.
1) Audio detection for identifying large leaks.
2) Touch detection -----place hand at the joint to feel the leakage
3) Soap water detection is used to identify small leaks. Escaping gas will create bubbles at the leak point after
soapy water is applied..
4) Detection by use of halogen leak detector
Use a halogen leak detector when finding the source of difficult to detect leakages..
a. Keep nitrogen at 42.6PSI(3.0kgf/cm
2
).
b. Supplement refrigerant to 71.1PSI(5.0kgf/cm
2
).
c. Use halogen leak detector, methane leak detector and electric leak detector for detection.
d. If the leak source cannot be found, continuously pressurize to 568.8PSI(40.0kgf/cm
2
) (R410A) and then
serach again.
4. Caution
1) The air tightness test is conducted by pressurized nitrogen (R410A system: 568.8PSI(40.0kgf/cm
2
)).
2) Oxygen, flammable gas and toxic gas shall not be used to conduct air tightness test.
3) Before pressure reading, let the system rest for several minutes till pressure is stable.
4) After test is complete, reduce system pressure to 71.1~113.7PSI(5~8kgf/cm
2
) and then conduct
pressure-keeping and storage.
5) If pipeline is too long, conduct phase-in detection.
Outdoor unit
Indoor unit
Nitrogen
Nitrogen
Liquid pipe
Gas pipe
Liquid side of
shut-off valve
Gas side of float valve
Pressure meter connector