Pulsafeeder PulsaPro 900 EN - Manual (Page 55)

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Appendix I – Piping Calculations
Suction Head Requirements
All reciprocating metering pumps require a net positive suction head (NPSH
R
). Refer to Table
1 for the (NPSH
R
) required for
PulsaPro
Series pump models. The NPSH
R
is defined as the
pressure required above the absolute vapor pressure of the process fluid at the pumping
temperature. This pressure is required at the suction port of the pump throughout the entire
pump stroking cycle in order to prevent cavitation of the process fluid within the reagent head.
The NPSH
R
is one of the requirements necessary to assure metering accuracy.
NPSH
R
English (psi) 3
Metric (bar) 0.35
Table 1. NPSH
R
values
The net positive suction head available (NPSH
A
) must be greater than the NPSH
R
. The NPSH
A
of any given system is calculated as follows for comparison to the NPSH
R
as shown in Table 1.
Equation 1 – For fluid viscosity below 50 centipoise.
Equation 2 – For fluid viscosity above 50 centipoise.
The variables used in Equations 1 through 5 must be in the units shown in Table 2 for the
constants listed below to be used correctly.