Suction Head - Lorentz PSk2-7 Manuel D'installation Et De Fonctionnement

WARNING – Inlet and outlet pipes must be
mounted to the pump housing free of
tension.
CAUTION – Make sure that the suction
pipe is sealed with no leaks, otherwise the
pump will not prime or will prime
insufficiently.
CAUTION – The pumps are shipped with
plastic covers on the pump inlet and
outlet. Remove them before connecting
the pipes to the pump.
Check valve – A check valve at the inlet pipe is needed
to assure that the pump and its suction pipeline remains
completely water filled during the time the pump is switched
OFF. Always install a check valve with one inch (1") larger
diameter than the suction pipe in order to avoid too much
suction pressure drop. For example if the suction pipe size is
3", then a 4" check valve should be installed.
Pump Installation

9.3.4 Suction Head

The maximum suction head is limited by the local air pres-
sure, the water temperature of the medium, the pipe losses
and the NPSH value of the pump.
CAUTION – If the suction pressure in the
pump is lower than the vapor pressure of
the fluid, cavitation will occur. Cavitation
creates noise and will damage the pump.
Damage due to cavitation is not subject to
warranty. To avoid cavitation, the pressure
of the fluid must be maintained above its
vapor pressure at all points as it passes
through the pump.
The maximum suction head (H) must be calculated in
advance. Please refer to COMPASS and the corresponding
LORENTZ knowledge base article for NPSH calculation.
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