HP 5973 - To Check the Diffusion Pump Fluid

110
4 Maintaining the MSD
To check the diffusion pump fluid
To check the diffusion pump fluid
Materials needed: Screwdriver, TORX T-15 (8710-1622)
1 Remove the upper and lower MSD covers (page 50).
2 Check the diffusion pump fluid level.
The diffusion pump fluid level can be seen through the window below the fan at
the front of the MSD. The diffusion pump fluid level should be between the top
and bottom of one of the
FULL ranges. There are two sets of marks. Use the HOT
marks if the diffusion pump is on and is at its normal operating temperature. Use
the
COLD marks if the pump is off and has had time to cool. If the fluid level is
below the bottom of the appropriate range, replace the diffusion pump fluid. Do
not just add fluid.
The pump fluid should be clear or almost clear. Dark or cloudy pump fluid indi-
cates an air leak or excessive heat. If the pump fluid appears dark or cloudy,
replace it. Then, check for an air leak.
The diffusion pump fluid does not need to be replaced at regular intervals. A low
pump fluid level or dark or cloudy pump fluid are the only reasons to replace the
diffusion pump fluid.
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