RJ150-30 / Operations and Maintenance Manual
Mobile Aircraft Air Conditioner
Trailer Mounted, Cool Mode Only
______________________________________________________________________________
SECTION 2 - 1
JANUARY 20, 2004
PAGE 22
A pump properly sized to the system should be used both to reducing
pumping time as well as preventing early pump failure. Table 3 provides
pump sizing-to-system requirements. Multiple vacuum pumps equaling the
single size required may be placed at various points on the system. Ensure all
valves are open to allow complete evacuation of the system.
The ideal vacuum pump should evacuate the system to at least 500 microns,
and must also be capable of holding that vacuum throughout the dehydration
process. It must pull that vacuum on the entire system and not simply at the
intake of the pump. This pump is able to remove moisture at an ambient
temperature of 80
°
F (26.6
°
C) or higher. Table 4 provides the boiling
temperature of water compared to the evacuation (vacuum pressure) of a
system. The higher the vacuum, the lower the boiling point, and results in
more complete system evacuation.
Table 3. Suggested High Vacuum Pump Size
System Size (Tons of Refrigerating Capacity)
Suggested High Vacuum Pump Size
Up to 7 tons
1.2 CFM
Up to 15 tons
2.2 CFM
Up to 32 tons
4.5 CFM
Up to 105 tons
15 CFM
