MCAC-VTSM-2011-09
Installation
Refrigerant Piping Installation
99
3.3.2.1.1. Ordinary vacuum drying
1) Firstly, connect the pressure gauge to the infusing mouth of gas pipe and liquid pipe, keep vacuum
pump running for above 2 hours, and it is quality that vacuum degree of vacuum pump is below
-755mmHg.
2) If the vacuum degree of vacuum pump could not be below -755mmHg after 2 hours of drying, system
will continue drying for one hour.
3) If the vacuum degree of vacuum pump could not be below -755mmHg after 3 hours of drying, please
check the system leakage source.
4) Vacuum placement test: when the vacuum degree reaches -755mmH, keep rest for 1 hour. If the
indicator of vacuum gauge does not go up, it is qualified. If going up, it indicates that there is moisture
and leak source.
5) Vacuum drying shall be conduct from liquid pipe and gas pipe simultaneously. There are a lot of
functional parts like valves, which could shut down the gas flow midway.
3.3.2.1.2. Special vacuum drying
This kind of vacuum drying method shall be adopted when:
1) Finding moisture during flushing refrigerant pipe.
2) Conducting construction on rainy day, because rain water might penetrated into pipeline.
3) Construction period is long, and rain water might penetrated into pipeline.
4) Rain water might penetrate into pipeline during construction.
Procedures of special vacuum drying are as follows:
a. The first vacuum drying 2 hours.
b. The second vacuum damage, filling nitrogen to 0.5Kgf/cm
2
.
Because nitrogen is dry gas, vacuum damage could achieve the effect of vacuum drying, but this
method could not achieve drying thoroughly when there is too much moisture. Therefore, special
attention shall be drawn to prevent the entering of water and the formation of condensate water.
c. The second vacuum drying 1 hour.
It is qualified when vacuum degree is under -755mmHg; if the vacuum degree is still above -755mmHg
within 2 hours drying, please repeat the
procedures of ―vacuum damage---vacuum drying‖.
d. Vacuum placement test: when the vacuum degree reaches -755mmH, keep rest for 1 hour. If the
indicator of vacuum gauge does not go up, it is qualified. If going up, it indicates that there is moisture
and leak source.
3.4. Recharged of Refrigerant
3.4.1 Operation procedure for recharging refrigerant
3.4.1.1. Operation procedure
Calculate the required refrigerant volume by
the length of liquid pipe → recharging refrigerant.
※
The refrigerant volume from factory does not include the recharged amount of the pipeline extending.
3.4.1.2. Detailed steps for recharging refrigerant
1. Make sure vacuum drying is qualified before recharging refrigerant.
2. Calculate the required refrigerant volume by the dia. and the length of liquid pipe.
3. Use electronic scale or fluid infusion apparatus to weight the recharged refrigerant volume.
4. Use soft pipe to connect refrigerant cylinder, pressure gauge, and examine valve of outdoor unit. And
recharge with liquid mode. Before recharging, eliminate the air in
the soft pipe and pressure gauge’s pipe.
5. After finishing the recharging, by the gas leak detector or soap water, to detect whether there is
refrigerant leakage in expansion part of indoor and outdoor units.
6. Write the recharged refrigerant volume in the indicating plate of outdoor unit.
