20
Maintenance
7.2
Changing the operating fluid
The changing interval for the operating fluid depends on the pump applications,
but should be carried out once a year.
Switch off pump.
Unscrew operating fluid drain screw 172a and drain operating fluid.
Fill the specimen in a test tube or some similar vessel and test by holding
against the light.
The level of deterioration of operating fluid P3 can be read off the colour scale
in accordance with DIN 51578; request the supplementary sheet PK 0219 BN or
download it from the Internet.
Where discolouration is dark yellow to red brown (equivalent to 4 ... 5 on the sca-
le) change operating fluid.
Fig. 13: Draining the operating fluid
NOTE
Depending on the applications, Pfeiffer Vacuum recommends determining the
exact service life of the operating fluid during the first year of operation.
The replacement interval may vary from the guide value specified by Pfeiffer Vacuum
depending on the thermal and chemical loads, and the accumulation of suspended par-
ticles and condensation in the operating fluid.
WARNING
Hot operating fluid!
Danger of burns when draining due to contact with skin.
Wear suitable protective clothing.
Use a suitable collecting vessel.
172a
