Page 107 - QRedition5.0 062021

Quality Requirements Edition 5.0 European Enamel Association

8.5.2 Requirements set on water to be used in the enamelling shop Units of water hardness of different countries and their conversion factors
(mval/kg = 28 mg CaO or 50 mg CaCO per 1000 ml water):
3
Generally

In general water is not considered to be an enamel raw material, although it is used with Germany:
about 30% in the enamel slip. The other consumer of water in the enamelling shop is the 1 GH = German degree of hardness = 10 mg CaO per 100 ml water
0
0
0
pre-treatment line. Requirements upon the quality of water as requested by these two 1 GH = 1.78 FH = 1.25 BH = 17.8 ppm = 0.357 mval/kg
0
users are quite different.

France:
Water for the pre-treatment 1 FH = French degree of hardness = 10 mg CaCO per 1000 ml water
0
3
The particular pre-treatment steps are finishing with a rinse. Task of the rinse is to wash-off 1 FH = 0.56 GH = 0.7 BH = 10 ppm = 0.2 mval/kg
0
0
0
emulsified and saponified greases, oils and salts. No chemical reaction must take place be-

tween the products arising from the various working processes and the rinsing water. The Great Britain:

0
to be used water must be extensively free of alkaline earths. The percentage of alkaline 1 BH = British degree of hardness = 1 grain CaCO
3 per gallon = 14.3 mg
earths in the water is expressed in degree of water hardness which can be inquired from CaCO per 1000 ml water
3
the water supplier. In order to achieve the highest possible production assurance, the use 1 BH = 0.8 GH = 1.43 FH = 14.3 ppm = 0.286 mval/kg
0
0
0
of at least cation-desalinated water is recommended.

USA:

Water for the preparation of the enamel slip ppm = 1 part per million = 1 mg CaCO per 1000 ml water
3
On earth, water is the most widespread solvent. The purer a water, the more eager it is to 1 ppm = 0.056 GH = 0.1 FH = 0.07 BH = 0.02 mval/kg
0
0
0
assimilate ions. With the preparation of enamel slips this dissolving behaviour is undesired

because it is looked upon equivalent to the leaching process of enamels. A too high alkali Regulations for the analysis of water
content in the water of the slip normally influences the setting characteristics of the clay in a

negative way. The properties of the slip become uncontrollable because of the longer lasting Determination of the pH-value
dissolving process. The use of harder waters for milling is proven. Thereby, additions of clay The pH-value indicates the acidic or alkaline character of the water. It is measured on an
and setting agents can be reduced. In order to have always the same level of calcium in the electrometric basis with potentiometers. For the calibration of the testing instruments, test
milling water, one adjusts by adding calcium silicate hydrate to about 350 GH, which is the solutions are available.
degree of saturation.

Determination of the conductivity
The conductivity is measured on an electrometric basis with potentiometers.
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