PRIVATE WATER SYSTEMS - Pumping Installation - Storage - Amount

Storage Amount

In considering the amount of water to be stored two important considerations are: 1) the rate of water yield from the source, and 2) is a reserve for fire fighting purposes desired.

If the water source provides plenty of water to meet the peak demand, then not much storage will be required. Either pressure-cell or a pressure tank installation may be used, and the pump will be able to take care of extra demands.

If the well or spring has a limited yield, intermediate storage is required.

Pressure-Cell

Pressure Cell One pressure-cell will be needed for each 10 gpm of pump capacity. This means that if a 300 gal-per-hour pump is in use, its pumping capacity is 5 gpm and only one pressure cell is needed. For pressure greater than 50 psi, figure on only 2 gallons of storage per cell. For a large capacity pump. instead of installing several small cells, a cell having a 12 gallon capacity may be installed.

Pressure Tank

For pressure-tank installations, the size of the tank is increased in proportion to the pumping capacity. The size is also increased with higher tank pressures (above 20-40 psi range)

PRESSURE TANK SELECTION CHART
 
Pressure-switch Settings
pounds per square inch
Pump Capacity
gal per min
20-40 30-50 40-6050-70 60-80 70-100
 
Pressure-tank Sizes
gallons
44282120120120120
882120180220315315
12120180220315315315
15144220315525525525
18180315315525525525
2422031552552510001000
32315525525100010001000

Higher

The amount of water a pressure tank delivers between the top pressure (when pump stops) and the lower pressure (when pump starts) becomes less as the pressure is raised. Therefore a larger tank is needed.

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