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5CSL0-06B Vacuum drying works
CAUTION
Outdoor unit
Pressure
gauge
Gas Pipe
Manifold valve
Lo Hi
Open Close
Vacuum pump
(0.5 ~ 1HP)
Liquid Pipe Pipe
Manifold gauge
Finishing the job
1. With a service valve wrench, turn the valve stem of liquid
side valve counter-clockwise to fully open the valve.
2. Turn the valve stem of gas side valve counter-clockwise
to fully open the valve.
3. Loose the charge hose connected to the gas side service
port slightly to release the pressure, then remove
the hose.
4. Replace the flare nut and fasten the flare nut securely
with an adjustable wrench. This process is very important
to prevent leakage from the system.
5. Replace the valve caps at both gas and liquid side service
valves and fasten them tight. This completes air
purging with a vacuum pump. The air conditioner is now
ready for test run.
2.7.3 Choosing a vacuum pump
The necessity for counter flow prevention
After the vacuum process of the refrigerant cycle, the inside
of the hose will be vacuumed after stopping the vacuum
pump, the oil of vacuumpump may flow back. Moreover, if
the vacuum pump stops during the operation for some rea-
Guideline for each installation process 313
son.
Gas Pipe
Manifold gauge
Therefore, in order to prevent the counter flow from the vacuum
pump, a check valve is reguired.
1) Vacuum pump performanceLiquid
Pipe
The 2 most important things for determining vacuum
pump performance are as follows:
(1) Exhaust velocity
(2) Degree of vacuum
(1) Exhaust velocity
Exhaust volume is usually expressed as l/min or m3 /hr. The
larger the number, the faster the vacuum is achieved.
Generally speaking, the faster the exhaust velocity, the larger
and heavier the vacuum pump itself is.
Commercially available vacuum pumps (exhaust velocity of
20 - 30 l/min) usually take an extremely long time to achieve
vacuum. (We recommend a vacuum pump of approx. 60 -
100 l/min.)
(2) Degree of vacuum
Ultimate vacuum varies largely according to use of the vacuum
pump. Vacuum pumps used for vacuum forming cannot
be used for vacuum drying. (A vacuum pump with a high
degree of vacuum is required.)
When selecting a vacuum, you should select one which is
capable of achieving 0.2 Torr of ultimate vacuum.
Degree of vacuum is expressed in Torr, micron, mmHg, and
Pascal (Pa). The units correlate as follows:
Unit
Standard
atmospheric
pressure
Perfect vacuum
Gauge Pressure kg/cm 2 0 -1.033
Absolute Pressure kg/cm 2 abs 1.033 0
Torr Torr 760 0
Micron Micron 760000 0
mmHg mmHg 0 760
Pa Pa 1013.33 0