Selection and Application
GORMAN-RUPP PUMPS
SELECTION & APPLICATION
OF SELF-PRIMING CENTRIFUGAL PUMPS
PUMP SELECTION
To assist with the selection of self-priming pumps, we have created the following hypothetical example. We believe the problem and its solution to be typical of a job
that might confront engineers and users.
We shall assume there is a requirement for a wastewater collection system that will require a lift station to pump the wastewater to a pretreatment collection system.
The following data were acquired by actual accurate measurements.
SYSTEM REQUIREMENTS
Flow: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200 gpm (12.6 lps)
Solids:. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3″ (76 mm)
Configuration: . . . . . . . . . . . . . Duplex, one pump for standby
Site Elevation: . . . . . . . . . . 5280′ (1609.3 m) above sea level
SYSTEM CONDITIONS
Static Suction Lift
15′ (4.6 m) vertical distance from low liquid level to center line of pump suction.
Suction Pipe
17′ (5.2 m), 4″ (100 mm) C.I. pipe. Measured from end of suction pipe to pump suction.
90° L.R. elbow and 45° elbow equivalent to 11.5′ (3.5 m) of 4″ (100 mm) C.I. pipe (for friction loss calculation).
Static Discharge Head
7.5′ (2.3 m) vertical distance from center line of pump suction to invert of discharge outlet.
Discharge Pipe
500′ (152.4 m), 4″ (100 mm) C.I. pipe. Measured from pump discharge outlet.
90° L.R. discharge elbow, check valve and gate valve equivalent to 49.8′ (15.2 m) of 4″ (100 mm) C.I. pipe (for friction loss calculation).
Priming Lift
10′ (3.0 m) measured from high liquid level to center line of pump suction.
The accumulation of the preceding data now permits calculating the Total Dynamic Suction Lift (TDSL), Total Discharge Head (TDH), and Net Positive Suction Head (NPSH)
using the worksheets on the following pages.
