Procedure
It is not possible to specify a precise switch-off threshold as the power input depends on the process
and motor as well as other parameters, such as rotation speed and pressure differential.
► Pfeiffer Vacuum recommends that you determine the comparison value for the max. permissible
power input in the first operating year.
► Measure the power input of the motor at least
1x daily
during operation.
6.6 Vibration monitoring
WARNING
Risk of injury due to the bearing bursting after overheating
During longer operation with defective bearings, there is a risk of explosion due to hot surfaces if
there is a potentially explosive atmosphere.
► Perform a vibration measurement at the defined measuring points at the prescribed time inter-
vals.
► Switch the roots pump off if process-independent trend changes of characteristic variables occur.
Boundary conditions of the vibration measurement
The boundary conditions of the vibration measurement (including operating conditions,
measurement parameters etc.) and the vibration measurement equipment (incl. vibration
sensors) must meet the requirements of guidelines VDI 3836 and VDI 3832 and standards
DIN ISO 10816-1 and DIN ISO 10816-3.
●
VDI 3836
: Measurement and evaluation of mechanical vibrations of screw compres-
sors and roots blowers
●
VDI 3832
: Measurement of structure-borne sound of rolling element bearings in ma-
chines and plant for evaluation of condition
●
DIN ISO 10816-1
: Mechanical vibrations – Evaluation of machine vibration by meas-
urements on non-rotating parts – Part 1
●
DIN ISO 10816-3
: Mechanical vibrations – Evaluation of machine vibration by meas-
urements on non-rotating parts – Part 3
The evaluation of the pump, motor and bearing condition must take place based on trend changes in
characteristic variables, compared with a defined reference value from the start-up phase and through-
out the service life of the roots pump. Due to the different set-up and process conditions, Pfeiffer Vac-
uum cannot specify any binding, generally-applicable limit values. The alarm, warning and limit values
for the vibration measurement, as specified in the guidelines and standards are not to be used as evalu-
ation criteria.
1
2
3
Fig. 12:
Position of the vibration sensors
1 Position of vibration sensor 1 (pump housing on fixed bearing
side)
3
Position of vibration sensor 3
(motor connection flange)
2 Position of vibration sensor 2 (pump housing on floating bear-
ing side)
Installing the vibration sensors
You must install the vibration sensors using the designated M8 threads at the designated positions:
Operation
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