The ten most important features you can specify in a single
stage centrifugal pump design
Here they are in no particular order:
1. A low L3/D4
- The lower numbers will allow you to operate off the pump "BEP"
without excessive flexing of the shaft.
- A double volute design is a good alternative to the low
2. A centerline design
- This feature prevents excessive strain on the volute casing
caused by thermal expansion or contraction.
3. A "C" frame adapter to ease alignment
- A very logical way to get proper pump/ driver alignment that
compensates for thermal expansion.
4. An oversize jacketed stuffing box
- Mechanical seals need lots of radial room to prevent the
rotating portion of the seal from coming into contact with the
stuffing box inside diameter.
5. Semi-open and open Impeller adjustments made from the wet end
of the pump
- Adjusting the impeller clearance from the power end moves the
mechanical seal setting. Pumps that adjust the impeller from the
wet end are not common, but they are available.
6. Large bearing oil capacity with easy to read bearing oil level
- Oil has a very low specific heat and poor thermal
conductivity. You should have at least a two-liter capacity.
7. A sealed up bearing case
- You will need positive face seals to prevent the ingress of
moisture. When the bearing case is sealed the bearing case
pressure will build up to about fifteen pounds (one atmosphere)
between cold and operating temperature. Be careful because this
pressure can blow out some seal designs that have not been
positively retained on the shaft and in the bearing housing
8. Instrumentation to check the condition of the pump and
- How else can you tell when the impeller needs adjusting, or if
you are using too many amps for the application?
9. The correct impeller for the application
- The impeller's specific
speed number will help you determine if you have the correct
- The Duplex metals seem to be the preferred materials for
modern pump impellers. They offer the ideal combination of low
wear and chemical resistance.
10. A pump that matches the system
curve you supplied with your "request to quote."
- Without a system curve supplied by the consumer, the pump
manufacturer has little to no chance of supplying the correct size
pump and driver. If you do not know how, learn how to make a
system curve and always supply one when you ask for a centrifugal
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