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water hardness
Water hardness
Hard water is a term used to describe water containing calcium, magnesium, strontium, iron, manganese, etc. Since the amount of strontium, iron, and manganese in water is very low, calcium and magnesium cations are the main factors responsible for causing water hardness.
Hard water is one of the factors that affect the formation of deposits in facilities.
Water hardness is expressed in units such as milligrams of ions per liter, milliequivalents per gram per liter, or equivalents of calcium carbonate dissolved in water. These units are interchangeable. For ease of calculation, the concentration of all salts is first calculated in milliequivalents per gram per liter, and then, given that the equivalent gram of calcium carbonate is 50, the resulting numbers are multiplied by a factor of 50 to express the concentration of salts in terms of equivalents of calcium carbonate. For example, if the hardness of a sample is 150 mg/L of calcium carbonate, its value in milliequivalents per gram per liter is 3, and in milligrams per liter of calcium, it is 60.
Types of Water Hardness
Total Hardness (T.H)
The total calcium and magnesium salts present in water are called total hardness and consist of two parts:
a) Total calcium hardness: Indicates the amount of calcium ions in water.
b) Total magnesium hardness: Includes all magnesium dissolved in water.
Permanent Hardness
Includes all calcium and magnesium salts except bicarbonates. For example, it includes sulfates, chlorides, and nitrates of calcium and magnesium dissolved in water. Permanent hardness is not removed by boiling.
Temporary Hardness
Calcium and magnesium bicarbonate dissolved in water is called temporary hardness. Calcium and magnesium bicarbonate in water decompose upon boiling according to the following reaction and form a precipitate.
Ca(HCO3)2 → CaCO3↓ + CO2 + H2O
Mg(HCO3)2 → MgCO3↓ + CO2 + H2O
Total hardness = temporary hardness + permanent hardness
Pseudo hardness
In measuring the total hardness of concentrated solutions by the standard titration method, the value obtained is greater than the actual value of the hardness-producing ions. The difference between these two values is called pseudo hardness.
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Corrosion comparison: Mitreh Cold scale remover solution (MDA0102) vs. hydrochloric acid
1404/08/24What is the Langelier Index? A Complete Guide to Predicting Water Sedimentation and Corrosion
1404/08/21Measuring Carbonate and Bicarbonate in Water: A Complete Guide to Alkalinity Control
1404/08/19Warning signs that indicate the need for chemical cleaning of the heat exchanger
1404/08/17
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