LG ATNH24GPLE2 User Manual page 66

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2. Guideline for each installation process
2.7 Vacuum drying works
2.7.1 What is Vacuum drying?
Vacuum drying is : The use of a vacuum pump to vaporize(gasify) the moisture (liquid) inside the pipe and expel it leaving
the pipes completely dry inside.
At 1 atm(760mmHg) the boiling point (evaporating temperature) of water is 100℃(212℉) but if a vacu-
um is created inside the pipes using a vacuum pump then the boiling point is rapidly reduced as the
degree of the vacuum is increased.
If the boiling point is reduced to a level below that of the ambient temperature then the moisture in the
pipes will evaporate.
Example
When outside temperature is 11.7℃(53.1℉) as shown
in the table on the right , the degree of vacuum must be
lowered below -750mmHg
The evacuation of air conditioner piping provides the fol-
lowing effects.
1. Vaccum drying
2. Removes air and nitrogen(used in air-tightness test)
from the inside of pipes.
Therefore , it is necessary to ensure that both purposes
have been achieved in the vacuum drying operation.
NOTE
Key point: Maintain a vacuum level of -755mmHg
30 _
Heat pump 60Hz/R410A
The degree
Boilng point of
of a vacuum
water(°C(°F))
mmHg
40 (104)
-705
30 (86)
-724
26.7(80.1)
-735
24.4(75.9)
-738
22.2(72)
-740
20.6(69.1)
-742
17.8(60)
-745
15.0(59)
-747
11.7(53.1)
-750
7.2(45.1)
-752
0(32)
-755
0
60
160
260
360
460
560
660
670
680
690
700
710
720
730 730 730
3.8MPa(551.1psi)
740
Required degree
755
of vaccum
Evaporation
point
mmHg
760
-20(-4) -10(14) 0(32) 10(50) 20(68) 30(86) 40(104) 50(122) 60(140) 70(158)
Temperature
Pressure
Pa psi Torr
7333 55
1.1
4800 36
0.7
3333 25
0.5
3066 22
0.4
2666 20
0.4
2400 18
0.3
2000 15
0.3
1733 13
0.3
1333 10
0.2
1066 8
0.2
667 5
0.1
760mmHg
700
600
500
400
300
200
100
90
70
60
50
40
30
20
10
5
Outside
temperature
range
0 mmHg
x
(°C(°F))