PUMPING SYSTEMS BASICS

Waste Water Pump Types

Effluent and De-watering (Sump pump) Sewage Pump (2” solids)

Non-Clog (2 ½” solids)Grinder Pump

AUTOMATIC PUMPS

Mechanical Switch

Tethered Ball Float SwitchDiaphragm 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 SIZINGTHREE 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.

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.

Calculating System Demand

Static Head( How High)

Static Head

Pump

Discharge Line

Discharge Point

Static Head = Elevation Change

Friction Head( HOW FAR)

Pump

Discharge Line

Discharge Point

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 SelectionMINIMUM FLOW VELOCITY: In order to keep solids

flowing in a horizontal pipe, a velocity of 2 ft. / sec. must be maintained.

Suspended Solids

Flow rates required to maintain 2 ft./sec:2” pipe = 21 gpm 3” pipe = 46 gpm 4”

pipe = 80 gpm

2 ft./sec flow

Pipe

Discharge Volume Exchange

Discharge LineSewer Main

Pump

To Find volume in Discharge line: Length of discharge ( ft.) X gal/ft. = Gal in Line

Liquid Volume in Pipe: 2” = .17 gal/ft.

3” = .36 gal/ft.

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

Discharge LineSewer Main

Pump

To Find volume in Discharge line:

Length of discharge ( ft.) X gal/ft. = Gal in Line

Liquid Volume in Pipe: 2” = .17 gal/ft.

3” = .36 gal/ft.

4” = .65 gal/ft.

There should be enough draw-down to change the volume in the discharge line every cycle.

Pump on

Pump offDraw down

Basin

Discharge Volume Exchange

Discharge LineSewer Main

Pump

To Find volume in Discharge line:

Length of discharge ( ft.) X gal/ft. = Gal in Line

Liquid Volume in Pipe: 2” = .17 gal/ft.

3” = .36 gal/ft.

4” = .65 gal/ft.

There should be enough draw-down to change the volume in the discharge line every cycle.

Pump on

Pump offDraw down

Basin

Basin Sizing CalculationsEXAMPLE: 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:

Pump

Floor level

Inlet pipe8”

18”

45” (Draw down)

Note: This would result in a complete change of volume and a run time of 3.5min

Invert

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

Water level

Potential confined air

Vent to atmosphere

Studor AAV

Liquid Inflow

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 Beiswengerchrisb@zoeller.com(317) 670-9764