Bearing
Bearing damage frequency
Okta 500 ATEX
Fixed bearing
Cage rotation frequency
(0.41 × n
1)
) Hz
Rollover frequency of an irregularity on the outer ring
(5.36 × n) Hz
Rollover frequency of an irregularity on the inner ring
(7.64 × n) Hz
Rolling element rotation frequency
(2.66 × n) Hz
Rollover frequency of an irregularity on both rolling tracks
(5.32 × n) Hz
Loose bearing
Cage rotation frequency
(0.42 × n) Hz
Rollover frequency of an irregularity on the outer ring
(4.99 × n) Hz
Rollover frequency of an irregularity on the inner ring
(7.01 × n) Hz
Rolling element rotation frequency
(2.88 × n) Hz
Rollover frequency of an irregularity on both rolling tracks
(5.75 × n) Hz
Harmonic (integral numbers of multiples) of these frequencies can also be of relevance for the diag-
nosis.
Tbl. 12:
Characteristic bearing damage frequencies of the roots pump
Frequency
Okta 500 ATEX
Rotation frequency
(n) Hz
Output frequency
(4 × n) Hz
Tooth engagement frequency
(43 × n) Hz
Harmonic (integer multiples) of these frequencies can be relevant for diagnosis
Tbl. 13:
Characteristic frequencies of the roots pump
Optional method for the overall roots pump
► The characteristic frequencies of the roots pump can also be evaluated using the frequency-selec-
tive method (narrow band method).
– The evaluation is not relevant for the ignition protection concept.
6.6.3 Monitoring the motor condition
Condition monitoring of the motor takes place in accordance with the standards DIN ISO 10816-1 and
DIN ISO 10816-3. Information provided in these standards includes the measuring and evaluation of all
types of electric motors. The frequency range incorporates the significant mechanical vibration stimula-
tions of the motor.
Frequency range of the motor
10 Hz – 1000 Hz
Tbl. 14:
Evaluated frequency range of the motor
1. Evaluate the vibrations in a relevant frequency range using the broadband method.
2. Determine and evaluate the broadband root-mean-square-value for the vibration speed (v
eff
) with-
in the relevant frequency range.
6.7 Switching off and venting the vacuum pump
WARNING
Risk of crushing on rotating parts when reaching into the open flange
The pistons continue to run in the vacuum after switching off the motor, and can trap fingers and
hands within their reach.
► Wait until the vacuum pump comes to a complete standstill.
► Secure the vacuum pump against re-start.
1)
n: Rotation speed in Hz
Operation
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