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Refrigeration Maintenance
185
Factors Affecting the Speed of System Evacuation
The time needed to evacuate a system can vary. Some factors that can influence evacuation time are listed
below.
•
System size
•
Amount of moisture contained in the system
•
Ambient temperature
•
Internal restrictions within the system
•
External restrictions between the system and the vacuum pump
Hose size, both diameter and length, affect evacuation times. Laboratory tests show that the evacuation
time can be significantly reduced by larger diameter hoses and shorter hoses. For example, it takes eight
times as long to pull a given vacuum through a 6 mm (1/4 inch) diameter hose as it does through a 12 mm
(1/2 inch) diameter hose. It takes twice as long to pull a vacuum through a 2 meter (6 foot) long hose as it
does through a 1 meter (3 foot) long hose.
Heat Saves Time
The application of heat to the system is a useful and practical time saver. Increasing the temperature of the
compressor oil and refrigerant will speed up the vaporization of any water present in the system.
Heat lamps, electric heaters, or fans can be applied to the compressor crankcase and other parts of the
system to increase the temperature of the refrigerant and compressor oil.
1.
Close the vacuum valve and watch the movement of vacuum gauge needle. If needle shows a pressure rise
but finally levels off to a constant pressure, the system still contains too much moisture. Dehydration and
additional evacuation time are required.
2.
Time
3.
Pressure (Vacuum)
4.
Atmospheric Pressure
Figure 161: Pressure Rise Levels Off After Evacuation Indicates Moisture in System
WARNING: Never use a torch or other concentrated heat source to heat the compressor or
other refrigeration system component.
AXA0192
Summary of Contents for 098203
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Page 3: ...MAGNUM TK 60275 4 MM Rev 3 08 15 Copyright 2012 Ingersoll Rand EMEIA Printed in Ireland...
Page 193: ...Refrigeration Maintenance 191 Figure 163 Filter Drier...
Page 200: ...Refrigeration Maintenance 198 Figure 169 Receiver Tank Figure 170 Water Cooled Condenser Tank...
Page 257: ...255 Schematic Diagram RELEASED 19 Sep 2013...
Page 258: ...256 Wiring Diagram Page 1 of 2 RELEASED 19 Sep 2013...
Page 259: ...257 Wiring Diagram Page 2 of 2 RELEASED 19 Sep 2013...
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