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Piping weight must not be supported by the valve housings or other portions of the reagent head, as the
resulting stresses can cause leaks. If appropriate, provide for thermal expansion and contraction so
that no excess force or moments are applied to the pump.
If piping assembly, use a sealing compound chemically compatible with the process material.
Users of sealing tape are cautioned to ensure that the pipe thread ends are not taped. Both new and
existing piping should be cleaned, preferably by flushing with a clean liquid (compatible with process
material) and blown out with air, prior to connection to the pump. Flow issues at pump startup are often
related to the check valves being fouled with piping and process debris.
5.3 Suction Pressure Requirements
Although PulsaPro metering pumps have suction lift capability, all pump installations should have
minimum lift for optimum performance. A flooded suction (i.e., suction pressure higher than
atmospheric pressure) is preferable whenever possible. The pump should be located as close as
possible to the suction side reservoir or other source.
Piping should be sized to allow for best possible NPIP conditions.
IT IS NOT RECOMMENDED TO INSTALL A PUMP EQUIPPED WITH A PULSALARM LEAK
DETECTION IN A SUCTION LIFT SYSTEM
If suction lift is required, the net positive inlet pressure required (NPIPR) is 5 PSI (.35 BAR). If this
requirement is not met the process liquid may cavitate inside the pump, degrading metering accuracy.
To maintain prime on a suction installation, a foot valve is required. In addition, suction pressure must
be maintained at a minimum absolute value of 7 PSI (.48 BAR) to ensure proper hydraulic system and
proper pump operation.
IT IS CRITICAL THAT PULSAPRO PUMPS HAVE FREE FLOWING AND UNOBSTRUCTED
SUCTION CONDITIONS AT ALL TIMES. CLOSED VALVES, CLOGGED STRAINERS,
OBSTRUCTED PIPING, ETC. ARE TO BE AVOIDED. SUCTION RESTRICTIONS CAN PLACE
STRESS ON THE DIAPHRAGM THAT MAY RESULT IN PREMATURE FAILURE.
Refer to Appendix II for procedures for the calculation of suction pressure.
5.4 Discharge Pressure Requirements
PulsaPro Metering Pumps are designed for continuous service at the rated discharge pressure. If
system suction pressure exceeds system discharge pressure, flow would be generated in addition
to that caused by the pump, resulting in a reduction in accuracy and loss of control over the
metering process. To prevent this condition, commonly referred to as “flow-through”, discharge
pressure must exceed suction pressure by at least 20 PSI (1.37 BAR). The installation of a back-
pressure valve can achieve this is necessary to achieve the differential pressure.
Discharge systems should be protected from excessive pressures by utilizing a pressure relief or
pressure limiting valve in the piping system. Operation of the pump at pressure above its rated
maximum (found on nameplate) may result in damage to the pump components and/or unsafe
system conditions.
Refer to Appendix II for procedures for the calculation of discharge pressure.
