masosine SPS 100, User Manual

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12 Connection to the piping
Before connection, clean the piping and remove foreign bodies such as welding
residues.
Fit elastic intermediate members (compensators) between pump and fixed piping
on the suction and pressure sides, to stop pump vibrations being transmitted to
the piping system.
Avoid forces and torques acting from the piping on the pump connections (e.g.
distortion, expansion due to temperatures etc.).
The piping on the pressure side of the pump should run upwards from the pump,
so that residual liquid can flow back into the pump when pumping stops, and total
dry running is avoided. Fluid left in the pump facilitates suction when pumping re-
starts.
The user must ensure that a pressure rise above the pressure agreed in the
purchase order and listed in the technical data sheet is not possible.
MasoSine pumps normally run with such a low resonant frequency that no damage
results. However, particularly when running with inverters, certain frequencies can
cause inter-ference vibrations which must be avoided. It is important during
commissioning to ascertain whether such vibrations exist and to define them, so
that the inverter can be programmed to avoid these frequencies. Similarly,
interference from cavitation or rigid lines must be avoided. See "Cavitation" below.
12.1 Cavitation
Cavitation is a problem in certain devices where fluid interacts with a moving surface. It can occasionally
occur in sinusoidal pumps.
Where a surface moves through a fluid, low pressure areas are formed on the surface. The faster the
surface moves, the lower the pressure around it can become. If the static pressure of the liquid falls
below its vapour pressure, vapour bubbles form on the pressure side. These implode, causing very high,
short-term pressure peaks up to several thousand bar. These pressure peaks can cause material erosion
and are noisy.
To identify cavitation
If the pump is very noisy and vibrates vigorously, along with the pipe system attached to the pump,
cavitation is likely to be the cause.
To avoid or remove cavitation
Increasing the inlet pressure on the suction side, installing a larger diameter or shorter inlet pipe or
slowing the pump may solve the problem. Make sure that the pump is not starved of duty fluid at all
times.
Cavitation can destroy the pump. The operator must ensure that the pump can
work free of cavitation.
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