Pump Handbook

Horizontal Self-Priming End Suction (Cont.)

---

B - Suction Piping Design the suction piping to reduce the possibility of cavitation problems. Generally, the suction piping should be one or more pipe sizes larger than the pump's suction connection. Keep the suction piping as short as possible. Keep the suction piping as straight as possible. Keep a minimum of 5 to 10 pipe diameters of straight run in the piping prior to the pump inlet. Avoid high points in the suction piping. Go around objects instead of over them. Reducers used in the suction piping should be eccentric with the flat side to the top. Strainers should be used to prevent foreign objects from entering the pump. The strainer should be sized based on minimum pressure drop and not on line size. Valves in the suction line should be sized for minimum pressure drop, and never used as throttling valves. Always provide a gauge connection between the suction valve and the pump connection. The gauge connection should be located as near the pump suction connection as possible. Insure that the suction piping connection to the source reservoir is sufficiently submerged or baffled to prevent vortices or drawing in air. Don't be mistaken in believing that a flooded suction will always provide sufficient NPSHa. Calculate the losses in the suction line to insure you have sufficient NPSH available. Support the piping independently of the pump. (A pump is a very expensive pipe support.) Use expansion loops or flexible connectors in systems where thermal expansion of the piping will occur. C - Discharge Piping Support the piping independently of the pump. The piping should line up naturally with the pump connection and not need to be forced into position. Provide a discharge valve for isolation of the pump should maintenance be required. Provide a discharge check valve located between the pump discharge connection and the discharge isolation valve. Provide a pressure gauge or gauge connection on the discharge as close to the pump discharge connection as possible and before any valves. D - Alignment There are three times at installation and commissioning that alignment should be checked; At installation, before start-up and after operation has stabilized, or hot alignment. There are several methods for shaft alignment, most of which are satisfactory. The quickest and most accurate is probably laser alignment. Whichever method of alignment you use, follow the manufacturer's recommendations for the proper alignment tolerances to extend the pump, bearing and seal life. Properly aligning a pump unit will extend its serviceable life several fold.

Back To Top