Thermo King 914970, Руководство пользователя, Страница: 118 / 186

Refrigeration Maintenance
118
Set Up and Test of Evacuation
Equipment
NOTE: See the previous two pages for the
following discussion.
1. Connect the evacuation system to a 110 Vac
power supply. Connect a gauge manifold and
refrigerant supply to the fitting above valve
V-4. Turn the micron gauge On.
2. Close valves V-1, V-3 and V-4. Valve V-2 is
open.
3. Turn the vacuum pump On.
4. Open valve V-1 at the pump. The micron
gauge needle will move to the left. (See
micron gauge scale diagram—previous page).
NOTE: If the vacuum pump is okay, and
there are no leaks between V-1 and V-3, the
micron gauge should show less than 500
microns. If not, locate and correct the
problem.
5. With the pump still operating, open valve V-3.
If the micron reading does not return to a level
of less than 500 microns, locate and correct
the problem before continuing.
6. With the vacuum pump still operating, open
valve V-4. The micron level will rise
momentarily. If the micron reading does not
return to a level of less than 500 microns,
locate and correct the problem before
continuing.
Figure 44: Leak
• Isolate the pump from the system by closing
the proper valve. Watch the movement of the
vacuum gauge needle. If the needle continues
to rise, this is an indication that a leak exists in
the unit or the connecting line. The leak must
then be located and eliminated.
Figure 45: Moisture
• Should the needle show a pressure rise but
finally level off to practically a constant mark,
this is an indication that the system is vacuum
tight but is still too wet, requiring additional
dehydration and pumping time.
7. Evacuate hoses to 100 microns or lowest
achievable level below 500 microns.
8. Once 100 microns is reached, close valve V-1
at the pump. Turn the vacuum pump Off.
9. Observe the micron gauge reading. The
vacuum rise should not exceed 1500 microns
in 5 minutes.
10. If the rise is above 1500 microns in 5 minutes,
check all hoses and connections for leaks.
Hoses with moisture present will require
additional evacuation time to achieve
satisfactory results.
NOTE: Dirty vacuum pump oil or a defective
vacuum pump will prevent a low micron
reading. Hoses and fittings can be isolated
individually to identify leaks.
Time
P
res
sur
e
Ri
se
Con
st
ant P
ressure
Rise
Leak
Time
P
res
su
re
R
ise
Pr
essure
Rise
Levels Off
Moisture