7
System Evacuation
Safe Refrigerant Handling
1. Connect the vacuum pump, high vacuum manifold
set with high vacuum hoses, thermocouple vacuum
gauge and charging cylinder as shown. Begin with
all valves fully closed.
2. If service dill valves are used for evacuation, use a
core remover to lift the valve core. It provides
greater efficiency.
3. Confirm proper pump and gauge operation. Open
the shutoff valve which leads to the high vacuum
gauge manifold. Start the pump. When the com-
pound gauge (low side) reading drops approximately
29 inches of vacuum, open the valve to the thermo-
couple vacuum gauge and evacuate until the gauge
reads 250 microns or less.
4. Close the valve to the thermocouple vacuum gauge.
This avoids potential gauge damage from “pegging
the meter”.
5. Open the high and low side valves on the gauge
manifold. Keeping the valve on the charging cylinder
closed, open the valve on the gauge manifold that
leads to the cylinder.
6. Evacuate the system to about 29 inches Hg as mea-
sured by the compound (low side) gauge.
7. Open the valve to the thermocouple vacuum gauge.
Evacuate until the gauge reads 250 microns or less.
8. Close the valve to the vacuum pump. Wait five min-
utes, then check the pressure on the thermocouple
vacuum gauge:
a. If the pressure is not more than 1500 microns, the
system is leak-free and properly evacuated. Pro-
ceed to Step 9.
b. If the pressure rises, but holds at about 5000 mi-
crons, moisture and noncondensibles are still
present. Open the valve to the vacuum pump, and
go back to Step 7.
c. If the pressure rises above 5000 microns, a leak is
present. Refer to the previous section “Leak Test-
ing”.
9. Close the valve to the thermocouple vacuum gauge.
Close the valve to the vacuum pump. Shut off the
pump.
A. LOW SIDE VALVE
B. HIGH SIDE VALVE
C. VACUUM PUMP
D. THERMOCOUPLE GAUGE
E. MANIFOLD GAUGE
F. CHARGING CYLINDER
C
A
B
E
D
HIGH VACUUM PUMP
LARGE DIAMETER
BRAIDED VACUUM
HOSES
TO
RELATED
GAUGE
PORTS OF
COND. UNIT
HIGH VACUUM
MANIFOLD
LOW SIDE
GAUGE
HIGH SIDE
GAUGE
DIAL-A-CHARGE
CHARGING CYLINDER
THERMOCOUPLE
VACUUM
GAUGE
F
Figure 3
