PUMPING SYSTEMS BASICS
Waste Water Pump Types
Effluent and De-watering (Sump pump)
Grinder Pump
Sewage Pump (2” solids)
Non-Clog (2 ½” solids)
AUTOMATIC PUMPS
Mechanical Switch
Tethered Ball Float Switch
Diaphragm Switch
NON-AUTOMATIC PUMPS
Wide Angle Switches
PIGGY BACK FLOAT SWITCH
DOUBLE PIGGY BACK SWITCH
Control Switch
SIMPLEX SYSTEM
Simplex Control Panel
DUPLEX SYSTEM
Duplex Control Panel
BASINS
Polyethylene Basin
Fiberglass Basin
PUMP SIZING
THREE BASIC QUESTIONS FOR SIZING:
1. HOW MUCH ( Demand)
2. HOW HIGH ( Static Head)
3. HOW FAR ( Friction Head)
Calculating System Demand
( HOW MUCH)
POPULATION METHOD:
Formula: ((NP x 100 gal/day/person x 4 )/24hrs/day )/60 min/hr. = GPM
NP = population served.
Number 4 is the peak flow factor
Examples: 80 people in a sub-division.
((80 x 100 x 4)/24)/60 = 23 GPM.
Calculating System Demand
FIXTURE COUNT METHOD:
Each fixture in a building is given a “ unit weight”.
The total “unit weight” of all the fixture in the
building is referenced on a conversion graph and a gallons per
minute flow is determined.
Static Head
Discharge Line
( How High)
Discharge Point
Static Head = Elevation Change
Static Head
Pump
Friction Head
Discharge Point
( HOW FAR)
Discharge Line
Pump
Friction head is determined by adding the total length
of the discharge line (including fittings) then referencing a
friction loss chart . Using the system demand flow and the
size of the discharge pipe, the total head loss can be found.
TOTAL DYNAMIC HEAD = Static Head + Friction Head
Discharge Pipe Selection
MINIMUM FLOW VELOCITY: In order to keep solids
flowing in a horizontal pipe, a velocity of 2 ft. / sec. must be
maintained.
Pipe
Suspended Solids
2 ft./sec
flow
Flow rates required to maintain 2 ft./sec:
2” pipe = 21 gpm 3” pipe = 46 gpm 4” pipe = 80 gpm
Discharge Volume Exchange
To Find volume in Discharge line: Length of discharge ( ft.) X gal/ft. = Gal in Line
Discharge Line
Liquid Volume in Pipe:
Sewer Main
2” = .17 gal/ft.
3” = .36 gal/ft.
Pump
4” = .65 gal/ft.
Pump and System Curves
System Curve
Combined Pump and System
Curves
Basin Sizing
& Selection
1. Physical
Dimensions :
Will it Fit ?
Discharge Volume Exchange
Liquid Volume in Pipe: 2” = .17 gal/ft.
3” = .36 gal/ft.
To Find volume in Discharge line:
Length of discharge ( ft.) X gal/ft. = Gal in Line
4” = .65 gal/ft.
Basin
Discharge Line
Sewer Main
Pump on
Pump
Pump off
Draw down
There should be enough draw-down to change the
volume in the discharge line every cycle.
Discharge Volume Exchange
Liquid Volume in Pipe: 2” = .17 gal/ft.
3” = .36 gal/ft.
To Find volume in Discharge line:
Length of discharge ( ft.) X gal/ft. = Gal in Line
4” = .65 gal/ft.
Basin
Discharge Line
Sewer Main
Pump on
Pump
Pump off
Draw down
There should be enough draw-down to change the
volume in the discharge line every cycle.
Basin Sizing Calculations
EXAMPLE: Commercial building with 50 gpm flow rate. Pump selected has a flow rate of 60
gpm. The pump height is 18” and the invert is 8”. The discharge line is 3” in diameter and
150 ft long.
Step 1. Invert Distance - 8”
Step 2. Pump Height - 18”
Step 3. Draw down ( largest of the following )
a. Max starts – (( 50 gpm x 60 min )/ 6) x .4 = 200 gal/cycle
200 gal / 4.4 gal per inch = 45”
b. Volume in discharge - .36 gal / ft x 150ft = 54 gal
54 gal / 4.4 gal per inch = 12”
c. Pump run time : (60 gpm x 1 Min) / 4.4 gal per inch= 14
The total of all three critical dimensions is 71” The closest basin depth is 72”. Thus the
suggested basin is 36 x 72. If this depth is too great for the application, then a wider basin
can be used. This would result in a shallower basin.
Calculating Depth
• 36” diameter basin:
Floor level
8”
Inlet pipe
45”
Pump
18”
Invert
(Draw down)
Note: This would result in a
complete change of volume and
a run time of 3.5min
Residential Reality
The preceding examples work well for commercial applications and for those
residential applications serving the whole house. The reality is that most
residential sewage applications serve just one, seldom used bathroom. In these
applications the usage is so small that the pump protecting guidelines do not have
the same importance. In these applications, a 2” solids pump and an 18 x 30 poly
basin work very well.
Related Topics
VENTS AND AIR ADMITTANCE VALVES
Vent to atmosphere
Potential confined
air
Liquid Inflow
Studor AAV
Water
level
Incoming liquid displaces air,
which is released through the
vent. AAV’s prevent this release,
causing the system to “air lock”.
Questions
• For Additional Information:
Chris Beiswenger
chrisb@zoeller.com
(317) 670-9764