2025 Nelsen Corporation Catalog - Catalog - Page 444
17 Water System Selection
Technical & Engineering
WATER SYSTEM SELECTION: In selecting the proper water
system for a given installation, facts about the water source as
well as the water requirements must be considered. Assuming
the water source is a well, the following information is needed:
1. Well size – (diameter)
2. Depth to pumping level
3. Well capacity (maximum pumping rate it will sustain)
4. Elevation and total length of piping
5. Amount of capacity required
6. Amount of pressure required
WELL SIZE: The inside diameter of the well must be known
since it may be the determining factor as to the type of pump
which can be used. Submersible pumps require well at least 4
inches in diameter. Packer type jet systems can be installed in
wells with diameters as small as two inches.
DEPTH-TO-PUMPING LEVEL: The depth to the water level at
maximum draw down determines the type of pump that must
be used. For depths of 25 feet or less, at or near sea level,
shallow well “suction lift” type pumps are adequate. Each
1000 feet of elevation above sea level reduces the shallow
well depth limit by one foot. For example, the maximum
practical suction lift in the Denver area, which is 5000 feet
above sea level, would be 25 minus 5, or 20 feet. For lifts
greater that the maximum suction limit, deep well type
pumps, which have a pumping mechanism in the well, are
required. The pumping level may be estimated from the well
drillers test log.
WELL CAPACITY: The maximum pumping rate the well will
sustain must be known to assure that the capacity of the
water system selected does not exceed that rate. As in the
case of pumping level, well capacity may be obtained from
the well drillers log.
ELEVATION AND TOTAL LENGTH OF PIPING: The elevation
the total length of piping are required to compute the
pressure drop in the system. This computation is made by
adding the elevation to the drop caused by pipe friction.
Pressure drop due to friction is calculated by using the
friction loss tables.
AMOUNT OF CAPACITY REQUIRED: In determining the
required capacity of a water system, it is important to provide
for the peak demand rather than for the average use rate.
A good rule of thumb to follow is to allow for one gallon per
minute of pump capacity for each household outlet. For farm
water systems, adequate water must not only be provided for
household purposes and animal drinking, but for cleaning and
fire protection as well. Average water consumption per day
for various animals is shown in Table 1. The pump selected
should have sufficient capacity to pump the entire daily
requirement in two hours. As an example, assume a farm with
20 milk cows, 100 hogs, 500 chickens, two milk houses and
eight household outlets. The daily water consumption of the
animals would be as follows:
17 - 24
Milk cows —
Hogs —
Chickens —
Total Daily Usage
20 x 35 = 700
100 x 4 = 400
500/100 x 6 = 30
1130
Pumping Capacity for 2 Hours (120 minutes)
Period
1130 ÷ 120 = 9.4 G.P.M.
Milk House Outlets = 2.0
Household Outlets = 8.0
19.4 G.P.M.
A 19 gallon per minute pump will provide sufficient water for
the farm needs, including fire protection. The Well Capacity
should be compared to the Pump Capacity to make sure the
well can sustain a pumping rate of 19 gallons per minute. If it
will not, an extra large pressure tank, or a two-pump system
with storage tank will be required.
Average Water Consumption For Home/Farm Use
A. Home Use
For overall daily consumption, checks of families of
various sizes in different parts of the country indicate 100
gallons per day per person is a very good average.
Outlet
Shower
Bathtub
Lavatory
Toilet - Flush
Kitchen Sink
Laundry Tub
Washer - Automatic
Dishwasher
Water Softener
Garden Hose 1/2"
Garden Hose 3/4"
Sprinkler - Lawn
Total Gallons
Per Usage
25-60
35
1-2
3-7
30-50
10-20
up to 150
Flow Rate
(gpm)
5
5
4
4
5
7
5
2
7
3
6
3-7
B. Farm Use
Horse, Mule, Steer
Dry Cow
Milking Cow
Hog
Sheep
Chickens/100
Turkeys/100
Fire
Gallons Per Day
12
15
35
4
2
6
20
20-60 gpm
(Based upon a study of over 20 sources by the Water Source and Use Subcommittee of the
Water Systems Council. Values given are average. They do not include the extremes.)
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