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Degrees of general hardness (dGH or °GH) is a unit of water hardness, specifically of general hardness. General hardness is a measure of the concentration of divalent metal ions such as calcium (Ca 2+) and magnesium (Mg 2+) per volume of water. Specifically, 1 dGH is defined as 10 milligrams (mg) of calcium oxide (CaO) per litre of
Recommendations have been made for the minimum and maximum levels of calcium (40–80 ppm) and magnesium (20–30 ppm) in drinking water, and a total hardness expressed as the sum of the calcium and magnesium concentrations of 2–4 mmol/L. [14] Other studies have shown weak correlations between cardiovascular health and water hardness.
A variety of hardness-testing methods are available, including the Vickers, Brinell, Rockwell, Meyer and Leeb tests. Although it is impossible in many cases to give an exact conversion, it is possible to give an approximate material-specific comparison table for steels.
The grain per gallon (gpg) is a unit of water hardness defined as 1 grain (64.8 milligrams) of calcium carbonate dissolved in 1 US gallon of water (3.785412 L). It translates into 1 part in about 58,000 parts of water or 17.1 parts per million (ppm). Also called Clark degree (in terms of an imperial gallon).
Vickers hardness test; Brinell scale This page was last edited on 16 November 2024, at 12:16 (UTC). Text is available under the Creative Commons ...
Hardness scales may also refer to: Methods of measuring the deposit formation by hard water. The scale of Pencil hardness This page was last edited on 11 ...
A week after cellphone users across the U.S. reported a flurry of racist text messages, members of the Hispanic and LGBTQ communities are now receiving text messages saying they have been selected ...
Carbonate hardness, is a measure of the water hardness caused by the presence of carbonate (CO 2− 3) and bicarbonate (HCO − 3) anions. Carbonate hardness is usually expressed either in degrees KH (from the German "Karbonathärte"), or in parts per million calcium carbonate ( ppm CaCO 3 or grams CaCO 3 per litre|mg/L).