This is similar to the conversion of 113 and 114 to 41, respectively, to facilitate use of these fractions in addition and subtraction. In order to make calculations for all the various hardness mineral compounds, the concentrations of the various ions must be expressed in equivalent units to permit direct addition and subtraction in analysis work. the minerals we are considering in these analyses are expressed in terms of hypothetical combinations in terms of grains per gallon or milligrams per liter as calcium carbonate (CaC0 3). An exception would be trace substances which are expressed in terms of milligrams per liter. This is done to avoid working with large figures in many instances. The point-of-use water conditioning industry generally expresses hardness in terms of grains per gallon. In the same way, 1 milligram, or 1/1,000 of a gram, in a liter of water which weighs 1,000 grams, is 1 milligram per liter or 1 part per million. For obviously, pounds and gallons are not similar units of measure. On the other hand, it would be incorrect to interpret 1 ppm to mean one pound in a million gallons of water without first converting the figures. Correctly, 1 ppm could be translated as one ounce in a million ounces of water, or one pound in a million pounds of water. One word of caution: the term parts per million means one part in a million parts. Milligrams per liter or parts per million To make a conversion from parts per million to grains per gallon, you simply divide the parts per million by 17.1 to convert to grains per gallon. gallon (gpg) equivalents per million (epm) and grains per imperial gallon (gpg imp). Why is this practice followed? Primarily for convenience in reporting concentrations of minerals-some of which are found in water in abundance and some of which are found in only scant, or even trace, amounts.Īctually there are four basic units of measure used in water analysis work: parts per million (ppm) or milligrams per liter (mg/1) grains per U.S. 1 shows that the iron is reported in parts per million while all the hardness minerals are listed in terms of grains per gallon. The type of model (manual, semi-automatic, or fully automatic) would be a matter of personal preference on the part of the buyer.Ī look at Water Analysis Example No. The capacity of a unit necessary for the installation would depend on the number of people in the household and to some extent on the number of water using appliances. Where possible, the toilets could also be bypassed, as the amount of iron in the water is not sufficient to produce any appreciable staining.
The outdoor sillcocks should be bypassed. The amount of iron, however, is negligible and would produce no staining of washables in the laundry.Ī sound solution for treating this water would be the installation of an ion exchange softener of proper capacity on both the hot and cold water lines. The sodium in the water (0.6gpg) accounts for the difference between total anions and the total hardness. While total hardness equals 15.8gpg, the total cations equal 16.4gpg. 1 shows that the water is very hard according to the Water Quality Association's hard water classifications. *All values are reported as CaC0 8 equivalent except pH and iron. Perhaps other sound solutions come to mind. Note the reasons given for these solutions. Examine each of these analyses carefully now.
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