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2.5 Piping Before and After the Pump
Sizing the correct upstream and downstream piping including valves and
fittings is very involved and depends on the experience of the application
engineer.
Processtec
of common sanitary valves and pipe fittings at various sizes and port
arrangements. The program requires the input of a valid apparent viscosity
value. Please consult
your piping arrangement.
2.5.1 Upstream Piping
The upstream piping of the pump requires the utmost attention. The NPSH available from the system
(NPSHa) needs to be higher (higher absolute pressure) than the NPSH required (NPSHr) by the pump
(lower absolute pressure).
The NPSHa must be less than the NPSHr or cavitation occurs. The pumped media creates vaporized bubble
that immediately collapse & damage both the product & the pump.
ViscoTwin
The
has excellent suction capabilities and will maintain it throughout its life cycle if operated
ViscoTwin
per design. Since
the product from arriving at the pump suction nozzle at the desired flowrate must be removed. If the
pump is sped up faster than the product can enter the pump, the pump cavitates, and will damage the
pumped media, and the pump itself.
Typical installation errors that create cavitation:
• Product has a higher apparent viscosity than anticipated. Typically, colder product results in a higher
apparent viscosity.
• The upstream pipe is undersized in diameter as well as the associated valves, fittings, elbows, and
tees.
• Too many restricting devices in the suction line like valves, tees, elbows, or other pipe restrictions.
• The suction pipe is too long.
• Particulates in the product are caught in valves, restricting the flow
PROCESSTEC INC. 2022
developed a sizing program that accounts for kV values
engineering if you need support to verify
Processtec
pumps can be used with very viscous media, any flow restrictions preventing
2. INSTALLATION
Page 27
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