Grundfos NK Montage- Und Betriebsanleitung Seite 28

6.8 Bearing monitoring
6.8.1 Vibration level
Bearing brackets with automatic grease lubricators or constant-
level oiler are prepared for vibration measurement by means of
the shock pulse method (SPM). The vibration level gives an
indication of the condition of bearings.
Fig. 23 Bearing bracket with SPM measuring points
6.8.2 Temperature
Bearing brackets with automatic grease lubricators or constant-
level oiler have tappings for Pt100 sensors for monitoring the
temperature of the bearings.
These sensors can be factory-fitted, but can also be retrofitted.
A Grundfos sensor is available.
1/4" tapping for
Pt100 sensor
Fig. 24 Pt100 sensors fitted in bearing bracket
6.9 Pressure monitoring
To ensure continuous monitoring of operation, it is recommended
to install a pressure gauge (on the discharge side) and a mano-
vacuum gauge (on the suction side). The pressure gauge taps
should only be opened for test purposes. The measuring range of
the gauges should be 20 % above the maximum pump discharge
pressure.
When measuring with pressure gauges on the pump flanges, it
should be noted that a pressure gauge does not register dynamic
pressure (velocity pressure). On most NK pumps, the diameters
of the suction and discharge flanges are different which results in
different flow velocities at the two flanges. Consequently, the
pressure gauge on the discharge flange will not show the
pressure stated in the technical documentation, but a value which
may be up to 1.5 bar (approx. 15 metres) lower.
To check the motor load, it is recommended to connect an
ammeter.
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