System Evacuation - Williamson-Thermoflo 9SRA-HE Installation & Service Manual

SYSTEM EVACUATION

Condensing unit liquid and suction valves are closed to contain the charge within the unit. The unit is shipped with the valve
stems closed and caps installed. Do not open the valves until the system is evacuated.
1. Connect the vacuum pump with 250-micron capability to the services valves.
2. Evacuate the system to 250 microns or less using suction and liquid service valves. Using both valves is necessary for some
compressors create a mechanical seal separating the sides of the system.
3. Close pump valve and hold vacuum for 10 minutes. Typically pressure will rise during this period
• If the pressure rises to 1000 microns or less and remains steady the system is considered leak-free; proceed to startup.
• If the pressure rises above 1000 microns but holds steady below 2000 microns, moisture and/or noncondensibles may
be present or the system may have a small leak. Return to step 2: If the same result is encountered, check for leaks as
previously indicated and repair as necessary then repeat evacuation.
• If pressure rises above 2000 microns, a leak is present. Check for a leaks as previously indicated and repair as
necessary then repeat evacuation.
Caution:
Refrigerant must not be discharged into the atmosphere.
After connecting the piping, check the joints for leakage with a gas leak detector.
Manifold valve
Low pressure side valve
Charging hose
A
B
High pressure side valve
Charging hose
Vacuum pump
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