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Daikin RXYQ5PY1 Service Manual Page 46

Daikin r-410a heat pump 50hz/60hz cooling only 50hz.
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Choosing a
Vacuum Pump
Refrigerant piping content volume of the VRV III R-410A Series is larger than the VRV Inverter
Series, and consequently takes more time for vacuum drying. If you have time to spare, you
may use the same vacuum pump, but if you want to save time, you will have to use a pump with
higher exhaust velocity (exhaust volume).
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, and the vacuum pump oil may flow back. Moreover, if the vacuum
pump stops during the operation by some reason, the same thing happens.
In such cases, different oil mixes in the HFC system refrigerant apparatus cycle, and becomes
the cause of a refrigerant circuit trouble. Therefore, in order to prevent the counter flow from the
vacuum pump, a check valve is needed.
Vacuum pump with check valve or vacuum pump adapter
1. Vacuum pump performance
(1) Exhaust velocity
Vacuum pump with
check valve
The 2 most import things for determining vacuum pump performance are as follows:
(1) Exhaust velocity
(2) Degree of vacuum
Exhaust volume is usually expressed as l/min or m³/h. The larger the number, the faster
vacuum id 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.)
Vacuum pump adapter
Reverse flow preventive
vacuum adapter
General Information


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