Methods of expressing hardness of water
The hardness of water is expressed by the amount of calcium present in water. In this method, chlorides, sulphates and bi-carbonates of calcium and magnesium and also carbonates of magnesium are not takes into consideration
Hardness is expressed by—
PPM: The number of grains of calcium carbonates which is present in one million grains of water is called PPM. 1 grains of calcium carbonate present in 1 million grains water. PPM can be related to degrees.
The relation is i.e. PPM=Degrees/0.07
English Degree: The no of grains of substance per one U.S gallon of water is called English Degree.
1 grain=1/7000 pound
1 US gallon of water= 8.33 pound
German Degree: Parts per hundred thousand (PP/100000)= Number of parts of substance per 100000 parts of water is called German degree.
French Degree: Grain per imperial gallon= Number of grains of substance per 1 British imperial gallon of water is called French degree.
1 grain=1/7000 pound.
1 imperial gallon of water= 10 pound.
Conversion table of different methods:
|
German Degree |
PPM (CaCO3) |
English Degree |
French Degree |
|
|
German Degree |
1 |
17.80 |
1.25 |
1.78 |
|
PPM (CaCO3) |
0.056 |
1 |
0.07 |
0.1 |
|
English Degree |
0.798 |
14.30 |
1 |
1.43 |
|
French Degree |
0.56 |
10 |
0.702 |
1 |