Measuring Instruments; Condensation Cover - Grundfos NB Installation And Operating Instructions Manual

Rubber bellows expansion joint without limiting rods
We always recommend that you use expansion joints
with limiting rods for flanges larger than DN 100 in
order to reduce the effects of the expansion or
contraction forces on the pipes.
Follow the supplier's instructions and pass them on to
advisers or pipe installers.
You must anchor the pipes in such a way that they do
not stress the expansion joints and the pump.
The figure below shows an example of a metal
bellows expansion joint with limiting rods.
Metal bellows expansion joint with limiting rods
Due to the risk of rupture of the rubber bellows, we
recommend that you use metal bellows expansion
joints at temperatures above 100 °C combined with
high pressure.

5.8 Measuring instruments

5.8.1 Pressure gauge and mano-vacuum gauge
To ensure continuous monitoring of the operation, we
recommend that you install a pressure gauge on the
outlet side and a mano-vacuum gauge on the inlet
side. The pressure gauge tappings must only be
opened for test purposes. The measuring range of
the gauges must be 20 % above the maximum pump
pressure.
When measuring with pressure gauge on the pump
flanges, note that a pressure gauge does not register
dynamic pressure.
On all pumps, the diameters of the inlet and outlet
flanges are different which results in different flow
velocities at the two flanges. Consequently, the
pressure gauge on the outlet flange will not show the
pressure stated in the technical documentation, but a
value which may be up to 1.5 bar or approximately 15
m of head lower.
5.8.2 Ammeter
We recommend connecting an ammeter to check the
motor load.

5.9 Condensation cover

When installing the pumps outdoors, provide the
motor with a suitable cover to avoid condensation.
When mounting the condensation cover on top of the
motor, make sure to leave enough space for the air to
cool the motor.
Motors with condensation cover
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