Evacuation And Dehydration; Evacuation Of The Complete System - Carrier VECTOR 6500 Operation & Service Manual

CAUTION
Only a refrigerant cylinder containing
R404A should be connected to this refriger-
ation unit in order to pressurize the system.
However, dry nitrogen may be used to in-
crease pressure. Any other gas or vapor will
contaminate the system and require addi-
tional removal and evacuation.
CAUTION
Do not vapor charge R404A. Only liquid
charging through the liquid line service
valve is acceptable.
3. Pressurize the compressor to 5 to 10 psig (0.3 to 0.7
bar) by opening the suction service valve for a few
seconds, then closing (frontseating) it again.
WARNING
Do not use a nitrogen cylinder without a
pressure regulator. Cylinder pressure is
approximately 2350 psig (159.9 bar). Do not
use oxygen in or near a refrigerant system
as an explosion
Figure 8−30.)
4. Connect a cylinder of dry nitrogen. Use the nitrogen to
increase the compressor pressure to 20 to 150 psig
(1.4 to 10.2 bar) to detect the leak. The larger the leak
the less pressure is required. The smaller the leak,
the greater pressure required
5 The recommended procedure for finding leaks from a
compressor is with an electronic leak detector.
Checking joints with soapsuds is satisfactory only for
locating large leaks, or pinpointing small leaks once a
general area has been located.
6 Once leak checking is complete, remove the refriger-
ant/nitrogen vapor from the compressor.
7 If no leaks are found the compressor is ready for
evacuation. (Skip to Step 10)
8 If any leaks are found they must be repaired before
proceeding.
9 Repeat steps 4 thru 9 as necessary.
10 Disconnect the nitrogen cylinder. Evacuate the
compressor after all leaks are repaired. (Refer to Sec-
tion 8.6.4.)

8.6.4 Evacuation And Dehydration

Moisture is detrimental to refrigerant systems. The
presence of moisture in a refrigeration system can have
many undesirable effects such as: copper plating, acid
sludge formation, "freeze-up" of the expansion valves,
and formation of acids, resulting in metal corrosion.
Proper evacuation of the system will remove any
moisture from inside the system.
may occur. (See
1. Essential tools to properly evacuate any
system include a good vacuum pump
(5 cfm/8m#H volume displacement, Carrier
Transicold part number 07-00176-11) and a
good vacuum
thermocouple
(micrometer). (Carrier Transicold part
number 07-00414-00)
2. The use of a compound gauge is not
recommended for use in determining when
the evacuation process is completed
because of its inherent inaccuracy.
3. Standard
recommended for evacuation purposes.
Evacuation hoses are recommended for
this procedure.
a. Evacuation of the Complete System
1. Evacuate only after pressure leak check. (Refer to
Section 8.6.3.)
2. If possible keep the temperature of the major com-
ponents (condenser, evaporator, compressor and re-
ceiver) above 60_F (15.6_C) to speed evaporation of
moisture. If the temperature is lower than 60_F
(15.6_C), ice might form before moisture removal is
complete. Heat lamps, heat guns or alternate
sources of heat may be used to raise system temper-
ature.
3. The recommended method to evacuate the system is
to connect three evacuation hoses with vacuum
pump and vacuum indicator (see Figure 8−18).
4. Ensure that the microprocessor MessageCenter dis-
plays "RECOVER/LEAK CHK/EVAC MODE" during
the evacuation and dehydration procedures. (Refer
to Section 5.2.3.) If the microprocessor switches to
charge mode during the process, switch it back to the
"RECOVER/LEAK CHK/EVAC MODE".
5. Backseat (turn counter-clockwise) the liquid line ser-
vice valve, suction service and discharge service
valves.
6. With the unit service valves closed (back seated) and
the vacuum pump and vacuum indicator valves open,
start the pump and draw a deep vacuum. Shut off the
pump and check to see if the vacuum holds. This
operation is to test the evacuation setup for leaks. Re-
pair if necessary.
7. Midseat the refrigerant system service valves. En-
sure that the MessageCenter displays "RECOVER/
LEAK CHK/EVAC MODE".
8. Start the vacuum pump. Evacuate unit until the vac-
uum indicator indicates 2000 microns. Close the va-
cuum pump valve and shut off the pump. Wait a few
minutes to ensure the vacuum holds.
9. Break the vacuum with dry nitrogen through the dis-
charge service valve. Raise system pressure to
approximately 2 psig (0.1 bar). Ensure that the micro-
processor does not switch to the charge mode. If this
8−19
NOTES
indicator such as
vacuum gauge
service hoses are
62-11389
a
not