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Water Hardness

Water Softeners
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Pipes filled with scale not only reduce water flow, but ultimately must be replaced. Fortunately, these problems may be reduced or eliminated with the installation of a water softener in the cold water line where it enters the home. This equipment uses "ion exchange" to remove the hardness minerals and certain other contaminants from the water. The equipment contains a bed of permanent softening material in the form of small granules or beads which are initially charged with sodium ions. As the hard water passes through the bed, the calcium and magnesium which cause water hardness are attracted to the softening material and held. At the same time, a chemically equivalent amount of sodium is released into the water.

This ion exchange process, as chemists call it, occurs literally billions of times during the softening process. Eventually so much hardness accumulates that the initial supply of sodium is depleted, and the bed of softening material is considered "exhausted." Water passing through a softener in this condition would retain much of its hardness, and recharging or regeneration is necessary.

To prepare the softener for further service, brine (a strong solution of common salt) is flushed through the bed. This drives out the accumulated hardness and replaces it with sodium. After the hardness and excess brine are rinsed down a drain with fresh water, the renewed softening material is once again ready to remove hardness from water.

In using this method, it should be noted that the flow rate required for fixtures or outlets which are likely to impose continuous demands during periods of heavy use of the listed fixtures, such as hose connections, air conditioning units, etc., should be estimated separately and added to the demand for fixtures used intermittently, in order to estimate total demand.

Further, the curves in this section are not intended to estimate rare peak flow requirements, but to cover normal flow variations. However, occasional leakage of hardness into the treated water due to unusual high flow requirements will not present major difficulties in the normal installation.

Fixture or GroupType of Supply ControlWeight in Fixture Units
Water ClosetFlush Valve6
Water ClosetFlush Tank3
LavatoryFaucet1
BathtubFaucet2
Shower HeadMixing Valve2
Bathroom GroupFlush Valve for Closet8
Separate ShowerMixing Valve2
Kitchen SinkFaucet2
Laundry Trays (1-3)Faucet3
Combination FixtureFaucet3

For example. let us assume a home with 11/2 baths, a kitchen sink, and conventional facilities. From the table, we would find:
Bathroom Group6 Fixture Units
Water Closets (Flush Tank)3 Fixture Units
Lavatory1 Fixture Units
Kitchen Sink2 Fixture Units
Laundry Tray3 Fixture Units
TOTAL15 Fixture Units

From the graph, we then can see that 15 Fixture Units indicate a peak flow rate of about 8.2 gallons per minute (gpm). Therefore, a water softener should be selected which has a rated service flow of at least 8.5 gpm, to insure adequate flow and fully softened water at all times.

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