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Table 5B — HFC-134a Pressure — Temperature (C)
TEMPERATURE (C)
PRESSURE (kPa)
-18.0
44.8
-16.7
51.9
-15.6
59.3
-14.4
66.6
-13.3
74.4
-12.2
82.5
-11.1
90.8
-10.0
99.4
-8.9
108.0
-7.8
118.0
-6.7
127.0
-5.6
137.0
-4.4
147.0
-3.3
158.0
-2.2
169.0
-1.1
180.0
0.0
192.0
1.1
204.0
2.2
216.0
3.3
229.0
4.4
242.0
5.0
248.0
5.6
255.0
6.1
261.0
6.7
269.0
7.2
276.0
7.8
284.0
8.3
290.0
8.9
298.0
9.4
305.0
10.0
314.0
11.1
329.0
12.2
345.0
13.3
362.0
14.4
379.0
15.6
396.0
16.7
414.0
17.8
433.0
18.9
451.0
20.0
471.0
21.1
491.0
22.2
511.0
23.3
532.0
24.4
554.0
25.6
576.0
26.7
598.0
27.8
621.0
28.9
645.0
30.0
669.0
31.1
694.0
32.2
720.0
33.3
746.0
34.4
773.0
35.6
800.0
36.7
828.0
37.8
857.0
38.9
886.0
40.0
916.0
41.1
946.0
42.2
978.0
43.3
1010.0
44.4
1042.0
45.6
1076.0
46.7
1110.0
47.8
1145.0
48.9
1180.0
50.0
1217.0
51.1
1254.0
52.2
1292.0
53.3
1330.0
54.4
1370.0
55.6
1410.0
56.7
1451.0
57.8
1493.0
58.9
1536.0
60.0
1580.0
Machine Dehydration —
Dehydration is recom-
mended if the machine has been open for a considerable pe-
riod of time, if the machine is known to contain moisture, or
if there has been a complete loss of machine holding charge
or refrigerant pressure.
Do not start or megohm test the compressor motor or
oil pump motor, even for a rotation check, if the ma-
chine is under dehydration vacuum. Insulation break-
down and severe damage may result.
Dehydration is readily accomplished at room tempera-
tures. Use of a cold trap (Fig. 29) may substantially reduce
the time required to complete the dehydration. The higher
the room temperature, the faster dehydration takes place. At
low room temperatures, a very deep vacuum is required for
boiling off any moisture. If low ambient temperatures are
involved, contact a qualified service representative for the
dehydration techniques required.
Perform dehydration as follows:
1. Connect a high capacity vacuum pump (5 cfm
[.002 m
3
/s] or larger is recommended) to the refrigerant
charging valve (Fig. 7 and 8). Tubing from the pump to
the machine should be as short and as large a diameter as
possible to provide least resistance to gas flow.
2. Use an absolute pressure manometer or a wet bulb vacuum
indicator to measure the vacuum. Open the shutoff valve
to the vacuum indicator only when taking a reading. Leave
the valve open for 3 minutes to allow the indicator vacuum
to equalize with the machine vacuum.
3. Open all isolation valves (if present), if the entire ma-
chine is to be dehydrated.
4. With the machine ambient temperature at 60 F (15.6 C)
or higher, operate the vacuum pump until the manometer
reads 29.8 in. Hg vac, ref 30 in. bar. (0.1 psia)
(–100.61 kPa) or a vacuum indicator reads 35 F (1.7 C).
Operate the pump an additional 2 hours.
Do not apply greater vacuum than 29.82 in. Hg vac
(757.4 mm Hg) or go below 33 F (.56 C) on the wet bulb
vacuum indicator. At this temperature/pressure, isolated
pockets of moisture can turn into ice. The slow rate of
evaporation (sublimination) of ice at these low temperatures/
pressures greatly increases dehydration time.
5. Valve off the vacuum pump, stop the pump, and record
the instrument reading.
6. After a 2-hour wait, take another instrument reading. If
the reading has not changed, dehydration is complete. If
the reading indicates vacuum loss, repeat Steps 4 and 5.
7. If the reading continues to change after several attempts,
perform a leak test up to the maximum 180 psig
(1241 kPa) pressure. Locate and repair the leak, and re-
peat dehydration.
Fig. 29 — Dehydration Cold Trap
51
Содержание 17
Страница 13: ...Fig 6 Open Drive 17 Series Lubrication Cycle 13 ...
Страница 15: ...Fig 7 17EX Controls and Sensor Locations 15 ...
Страница 16: ...Fig 7 17EX Controls and Sensor Locations cont 16 ...
Страница 17: ...Fig 7 17EX Controls and Sensor Locations cont 17 ...
Страница 19: ...Fig 8 19EX Controls and Sensor Locations cont 19 ...
Страница 23: ...Fig 16 17 19EX LID Menu Structure 23 ...
Страница 24: ...Fig 17 17 19EX Service Menu Structure 24 ...
Страница 50: ...Fig 28 17 19EX Leak Test Procedures 50 ...