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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. Hardnesses of the elements (data page) - Wikipedia

    en.wikipedia.org/wiki/Hardnesses_of_the_elements...

    number symbol name Mohs hardness [1] Vickers hardness (MPa) [1] Brinell hardness (MPa) [1] Brinell hardness ... 1.2: 26.5–44.7: 82: Pb: lead: 1.5: 38–50:

  4. Grain (unit) - Wikipedia

    en.wikipedia.org/wiki/Grain_(unit)

    [14] [15] Otherwise, water hardness is measured in the dimensionless unit of parts per million (ppm), numerically equivalent to concentration measured in milligrams per litre. [14] [15] One grain per U.S. gallon is approximately 17.1 ppm. [14] [note 1] Soft water contains 1–4 gpg of calcium carbonate equivalents, while hard water contains 11 ...

  5. Useful conversions and formulas for air dispersion modeling

    en.wikipedia.org/wiki/Useful_conversions_and...

    0.1 × ( 12 ÷ 8 ) = 0.15 grain per dscf when corrected to a gas having a specified reference CO 2 content of 12 volume %. Notes: Although ppmv and grains per dscf have been used in the above examples, concentrations such as ppbv (i.e., parts per billion by volume), volume percent, grams per dscm and many others may also be used.

  6. Hard water - Wikipedia

    en.wikipedia.org/wiki/Hard_water

    Parts per million (ppm) is usually defined as 1 mg/L CaCO 3 (the definition used below). [20] It is equivalent to mg/L without chemical compound specified, and to American degree . Grain per gallon (gpg) is defined as 1 grain (64.8 mg) of calcium carbonate per U.S. gallon (3.79 litres), or 17.118 ppm.

  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. Total dissolved solids - Wikipedia

    en.wikipedia.org/wiki/Total_dissolved_solids

    Conductivity based TDS meter in a cup of water. The two principal methods of measuring total dissolved solids are gravimetric analysis and conductivity. [4] Gravimetric methods are the most accurate and involve evaporating the liquid solvent and measuring the mass of residues left.

  9. Rockwell hardness test - Wikipedia

    en.wikipedia.org/wiki/Rockwell_hardness_test

    The Rockwell hardness test can be conducted on different types of hardness testers. [12] Benchtop hardness testers can be found either in a digital or analog model. Digital models utilize a digital display whereas the analog models display results on a dial on the machine. Other testers are portable. [citation needed]