PYD Electrobombas CX Serie Manual De Instalación Y Mantenimiento página 14

OPERATING AND MAINTENANCE MANUAL
SERIE CX
3)Pump material:
Material selection should be based on the liquid (SUS304 OR SUS316).
4) Mimimum inlet pressure-NPSH
Calculation of the inlet pressure "H" is recommended when:
- The liquid temperature is high. ∞ The fl ow is signifi cantly higher than the rated fl ow.
- Water is drawn from depths.
- Water is drawn through long pipes.
Inlet conditions are poor. o avoid cavitation, make sure that there is a minimum pressure on the
suction side of the pump.
The maximum suction lift "H" in metres head can be calculated as follows:
H=Pb*10.2-NPSH-Hf-Hv-Hs
Pb=Barometric pressure in bar. (Barometric pressure can be set to 1 bar). in closed systems, Pb
indicates the system pressure in bar.
NPSH=Net positive suction Head in metres head. (To be read from the NPSH curve at
the highest fl ow the pump will be deivering).
Hf=Friction loss in suction pipe(unit:m).(At the highest fl ow the pump will be delivering.)
Hv=Vapour pressure (unit:m).
Hs=safty margin=minimum 0.5 metres head.
If the"H" calculted is positive,the pump can operate at a suction lift of maximum "H" metres head.
If the "H" calculted is negative, an inlet pressure of minimum "H" metres head is required.
Fig. 1. Mimimum inlet pressure-NPSH
14
www.proindecsa.com / [email protected]