Leak Detection; Evacuation; Recharging Liquid Refrigerant; Characteristics Of R-410A - Danfoss BW10 020-090 Installation, Operation And Maintenance Instructions

14.5 - Leak detection

Never use oxygen or dry air, as this would cause a risk of fire
or explosion.
• Carry out a leak detection test on the whole system using
the following methods: pressure test using dehydrated
nitrogen or a mixture of nitrogen and refrigerant used for
the system, helium leak test.
• Connect the compressor to the system by opening the
valves.
• The duration of the test must be sufficient to guaran-tee
the absence of very small leaks in the circuit.
• Use specific tools, designed for leak detection.
• The low-pressure side test pressure must not exceed
pressure Ps indicated on the compressor and unit name
plates.
• If there is a leak, repair it and carry out the leak detec-tion
test again.

14.6 - Evacuation

To evacuate the system, observe the following recommen-
dations:
Connect the vacuum pump to the high (HP) and low-pressure
(LP) side for evacuation of the complete circuit.
All units are equipped with valves with 3/8" SAE connec-tions
on the suction, discharge and liquid lines, permitting the
connection of large-diameter flexible pipes limiting the
pressure drops for the evacuation.
1. The vacuum level achieved must be 0.67 mbar (500 µm
Hg).
2. Wait 30 minutes.
3. If the pressure increases rapidly, the system ist not leak-
tight. Localise and repair the leaks.
Restart the evacuation procedure and repeat steps 1, 2 etc.
4. If the pressure increeases slowly, this indicates that
moisture is present inside the system. Break the vacuum
with nitrogen and restart the evacuation procedure (steps
1, 2 etc.).
5. Repeat the evacuation procedure (steps 1, 2); a vacuum
level of 0.67 mbar (500 µm Hg) must be achieved and
maintained for four hours.
This vacuum level must be measured at one of the system
connections and not at the vacuum pump pressure gauge.
ATTENTION: Do not use a megohmmeter and do not place
any stress on the compressor motor when the system has been
evacuated. There is a risk of internal short circuits between the
motor windings.
Do not use additives for leak detection. Do not use CFCs/
HCFCs as tracer fluids for leak detection.

14.7 - Recharging liquid refrigerant

CAUTION: The units are charged with liquid R-410A
refrigerant.
With high-pressure R-410A refrigerant the unit operating pressure
is above 4000 kPa (40 bar), the pressure at 35°C air temperature
is 50% higher than for R-22. Special equipment must be used
when working on the refrigerant circuit (pressure gauge, charge
transfer, etc.).
All checks must be pressure tests, and the appropriate
pressure/temperature ratio table must be used to determine the
corresponding saturated temperatures (saturated bubble point
curve or saturated dew point curve).
Leak detection is especially important for units charged with
refrigerant R-410A. Depending on whether the leak occurs in
the liquid or in the vapour phase, the proportion of the
different components in the remaining liquid is not the same.
NOTE: Regularly carry out leak checks and immediately
repair any leak found.

14.8 - Characteristics of R-410A

Saturated temperatures (°C) based on the relative pressure (in kPa)
Saturated Relative
temperature, °C pressure, kPa
-20 297
-19 312
-18 328
-17 345
-16 361
-15 379
-14 397
-13 415
-12 434
-11 453
-10 473
-9 493
-8 514
-7 535
-6 557
-5 579
-4 602
-3 626
-2 650
-1 674
0 700
1 726
2 752
3 779
4 807
5 835
6 864
7 894
8 924
9 956
10 987
11 1020
12 1053
13 1087
14 1121
15 1156
16 1192
17 1229
18 1267
19 1305
20 1344
21 1384
22 1425
23 1467
24 1509
Saturated Relative
temperature, °C pressure, kPa
25 1552
26 1596
27 1641
28 1687
29 1734
30 1781
31 1830
32 1880
33 1930
34 1981
35 2034
36 2087
37 2142
38 2197
39 2253
40 2311
41 2369
42 2429
43 2490
44 2551
45 2614
46 2678
47 2744
48 2810
49 2878
50 2947
51 3017
52 3088
53 3161
54 3234
55 3310
56 3386
57 3464
58 3543
59 3624
60 3706
61 3789
62 3874
63 3961
64 4049
65 4138
66 4229
67 4322
68 4416
69 4512
70 4610
37