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Installation
Si39-303
32
General Information
Choosing a
Vacuum Pump
General
Refrigerant piping content volume of the VRVII R410A 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
The 2 most import 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/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.)
(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, nnHg, and Pascal (Pa). The units correlate as follows:
Unit
Standard atmospheric pressure
Perfect vacuum
Gauge Pressure
kg/cm2
0
–1.033
Absolute Pressure
kg/cm2 abs
1.033
0
Torr
Torr
760
0
Micron
Micron
760000
0
∗
mmHg
mmHg
0
760
Pa
hPa
1013.33
0
Vacuum pump adapter
Reverse flow preventive
vacuum adapter
Vacuum pump with
check valve
Degree of vacuum must be within the range expressed by
0 Torr
0 Pa
760 mmHg
Perfect vacuum
5 Torr
667 Pa
755 mmHg
Vacuum target value
760 Torr
1013.33 hPa
0 mmHg
Standard atmospheric pressure
(V0992)
Содержание VRV II Series
Страница 6: ...Si39 303 iv Table of Contents...
Страница 31: ...Si39 303 Installation General Information 25 Flaring Procedure...
Страница 124: ...Appendix Si39 303 118 General Information 3P114237A...
Страница 130: ...Appendix Si39 303 124 General Information BHFP22M135 Refer P 120 for Table 7 8 and 9 After connection piping...
Страница 140: ...Appendix Si39 303 134 General Information 7 10 Piping System Diagrams 7 10 1 Outdoor Unit RXYQ5MY1B...
Страница 141: ...Si39 303 Appendix General Information 135 RXYQ8MY1B RXYQ10MY1B RXYQ12MY1B 4D040338A...
Страница 142: ...Appendix Si39 303 136 General Information RXYQ14MY1B RXYQ16MY1B 4D040339A...
Страница 144: ...Appendix Si39 303 138 General Information 7 11 Wiring Diagrams 7 11 1 Outdoor Unit RXYQ5MY1B...
Страница 145: ...Si39 303 Appendix General Information 139 RXYQ8MY1B RXYQ10MY1B RXYQ12MY1B 3D038582...
Страница 146: ...Appendix Si39 303 140 General Information RXYQ14MY1B RXYQ16MY1B 3D038058...
Страница 147: ...Si39 303 Appendix General Information 141 7 11 2 Field Wiring RXYQ5 16MY1B 3D040746...
Страница 148: ...Appendix Si39 303 142 General Information RXYQ18 32MY1B 3D040747...
Страница 149: ...Si39 303 Appendix General Information 143 RXYQ34 48MY1B 3D040748...
Страница 158: ...Appendix Si39 303 152 General Information...
Страница 180: ...Refrigerant Piping Si39 303 174 Installation Manual...
Страница 226: ...Troubleshooting Si39 303 220 Operation Manual...