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  2. Grain per gallon - Wikipedia

    en.wikipedia.org/wiki/Grain_per_gallon

    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).

  3. Meyer's law - Wikipedia

    en.wikipedia.org/wiki/Meyer's_law

    Meyer's law is often used to relate hardness values based on the fact that if the weight is quartered, the diameter of the indenter is halved. For instance, the hardness values are the same for a test load of 3000 kgf with a 10 mm indenter and for a test load of 750 kgf with a 5 mm diameter indenter.

  4. List of equations in fluid mechanics - Wikipedia

    en.wikipedia.org/wiki/List_of_equations_in_fluid...

    Bernoulli's equation: p constant is the total pressure at a point on a streamline + ... List of equations in nuclear and particle physics; ... Springer. pp. 12 ...

  5. dGH - Wikipedia

    en.wikipedia.org/wiki/DGH

    In water testing hardness is often measured in parts per million (ppm), where one part per million is defined as one milligram of calcium carbonate (CaCO 3) per litre of water. Consequently, 1 dGH corresponds to 10 ppm CaO but 17.848 ppm CaCO 3 which has a molar mass of 100.09 g/mol.

  6. Hard water - Wikipedia

    en.wikipedia.org/wiki/Hard_water

    The total water hardness is the sum of the molar concentrations of Ca 2+ and Mg 2+, in mol/L or mmol/L units. Although water hardness usually measures only the total concentrations of calcium and magnesium (the two most prevalent divalent metal ions), iron, aluminium, and manganese are also present at

  7. Carbonate hardness - Wikipedia

    en.wikipedia.org/wiki/Carbonate_hardness

    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).

  8. Benedict–Webb–Rubin equation - Wikipedia

    en.wikipedia.org/wiki/Benedict–Webb–Rubin...

    The Benedict–Webb–Rubin equation (BWR), named after Manson Benedict, G. B. Webb, and L. C. Rubin, is an equation of state used in fluid dynamics.Working at the research laboratory of the M. W. Kellogg Company, the three researchers rearranged the Beattie–Bridgeman equation of state and increased the number of experimentally determined constants to eight.

  9. Lists of physics equations - Wikipedia

    en.wikipedia.org/wiki/Lists_of_physics_equations

    In physics, there are equations in every field to relate physical quantities to each other and perform calculations. Entire handbooks of equations can only summarize most of the full subject, else are highly specialized within a certain field. Physics is derived of formulae only.