Ten pump features

The ten most important features you can specify in a single stage centrifugal pump design T017_1

Here they are in no particular order:

1. A low L3/D4 shaft design

  • 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 L3/D4 design

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 problems

  • 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 indication

  • 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 driver

  • 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 impeller shape.
  • 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 pump quote.