Pentair Pentek Series Electronic Manual page 104

SECTION 14: Appendix
The answer to four basic questions will help select the
proper pump.
1. What is the size of the well? The inside diameter of
the well must be known so that the proper size pump
and drop pipe can be determined.
2. What is the submergence? The vertical distance
in feet from the pump to the water level while the
pump is operating (see Figure 12-1). If the pump is
installed away from the well and is on higher ground,
this elevation must also be included. This must not be
confused with the standing water level.
3. What should the average discharge pressure be?
Usual average discharge pressure is 50 lbs. – half way
between the 40 lbs. to 60 lbs. switch setting of most
water systems. More pressure is needed when the
tank is installed away from the pump and at a higher
level, or when house or yard fixtures are above the
pump and tank, and a larger pump must be used.
4. What capacity is required? The discharge capacity
of the pump in gallons per minute that is needed
for satisfactory service. The pump should have
enough capacity so that it can deliver the total water
requirement in 2 hours of continuous operation. See
Table 12-1 for average water requirements.
Installation Terminology
Standing or Static Water Level – distance from top of
well to natural water level when pump is not operating.
Drawdown Distance – distance water level drops while
pump is operating.
Drawdown or Pumping Water Level – standing water
level plus drawdown.
Submergence – distance submersible pump intake
screen is installed below drawdown level.
Elevation – vertical distance between top of well and
service inlet.
Pump Setting – distance from top of well to pump
inlet screen.
Service Pressure – pressure required (in PSI) at
service inlet.
Friction Loss – loss of pressure due to friction of water
flowing through pipe and fittings.
Head – discharge head (in feet) delivered when pump is
operating at desired capacity.
Horizontal Pipe Run – horizontal distance between
service inlet and well.
"Top of Well" also means "Pitless Adapter Level" or
well exit.
"Service Inlet" also means "Storage Tank Inlet".
Selecting a Pump
TIP: PSI can be converted to equivalent feet of head by
multiplying by 2.31.
i.e. 60 psi = 138.6 feet of head
To choose a motor for your submersible pump you first
must know:
• Flow required in Gallons per Minute
• Total head (Pumping level, friction losses
and service pressure required)
Friction loss must be calculated, and depends upon total
length, diameter and type of pipe plus additions for each
fitting (valves, elbows...) in the line.
Refer to the product catalog for friction loss charts.
Table 12-1: Average Water Requirements
Av erage Water Requirements For
General Service Around The Home
And Farm
Each person per day, for all purposes . . . . . . . 50 gal.
Each horse, dry cow or beef animal . . . . . . . . . 12 gal.
Each milking cow . . . . . . . . . . . . . . . . . . . . . . . . 35 gal.
Each hog per day . . . . . . . . . . . . . . . . . . . . . . . . . 4 gal.
Each sheep per day . . . . . . . . . . . . . . . . . . . . . . . 2 gal.
Each 100 chickens per day . . . . . . . . . . . . . . . . . 4 gal.
Av erage Amount Of Water Required By
Various Home And Yard Fixtures
Drinking fountain, continuously
flowing . . . . . . . . . . . . . . . . 50 to 100 gal. per day
Each shower bath. . . . . . . . . . . . . . . . . . . Up to 60 gal.
To fill bathtub . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 gal.
To flush toilet . . . . . . . . . . . . . . . . . . . . . . . . .2.5-6 gal.
To fill lavatory . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 gal.
To sprinkle 1/4" of water on each
1000 square feet of lawn . . . . . . . . . . . . . . . 160 gal.
Dishwashing machine, per load . . . . . . . . . . . . . 3 gal.
Automatic washer, per load . . . . . . . . . . Up to 50 gal.
Regeneration of domestic water softener 50-100 gal.
Av erage Flow Rate Requirements By
Various Fixtures
(gpm equals gal. per minute, gph equals gal. per hour)
Fixture New (at 60 PSI)
Shower 2.5 gpm
Bathtub 3 gpm
Toilet 1.6 gpm
Lavatory 2.5 gpm
Kitchen sink 2.2 gpm
1/2" hose and nozzle . . . . . . . . . . . . . . . . . . . . 200 gph
3/4" hose and nozzle . . . . . . . . . . . . . . . . . . . . 300 gph
Lawn sprinkler . . . . . . . . . . . . . . . . . . . . . . . . . 120 gph
Older Style
4 to 6 gpm
4 to 8 gpm
4 to 5 gpm
1 to 3 gpm
2 to 3 gpm
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