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  2. Parts-per notation - Wikipedia

    en.wikipedia.org/wiki/Parts-per_notation

    At 1 ppm the solution is a very pale yellow. As the concentration increases the colour becomes a more vibrant yellow, then orange, with the final 10,000 ppm a deep red colour. In science and engineering , the parts-per notation is a set of pseudo-units to describe small values of miscellaneous dimensionless quantities , e.g. mole fraction or ...

  3. 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 ...

  4. Total dissolved solids - Wikipedia

    en.wikipedia.org/wiki/Total_dissolved_solids

    where TDS is expressed in mg/L and EC is the electrical conductivity in microsiemens per centimeter at 25 °C. The conversion factor k e varies between 0.55 and 0.8. [5] Some TDS meters use an electrical conductivity measurement to the ppm using the above formula. Regarding units, 1 ppm indicates 1 mg of dissolved solids per 1,000 g of water. [6]

  5. 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).

  6. Air pollutant concentrations - Wikipedia

    en.wikipedia.org/wiki/Air_pollutant_concentrations

    mg/m 3 = milligrams of pollutant per cubic meter of air at sea level atmospheric pressure and T: ppmv = air pollutant concentration, in parts per million by volume T = ambient temperature in K = 273. + °C 0.082057338 = Universal gas constant in L atm mol −1 K −1: M = molecular mass (or molecular weight) of the air pollutant

  7. Hard water - Wikipedia

    en.wikipedia.org/wiki/Hard_water

    1 mmol/L is equivalent to 100.09 mg/L CaCO 3 or 40.08 mg/L Ca 2+. A degree of General Hardness ( dGH or 'German degree' (°dH, deutsche Härte )) is defined as 10 mg/L CaO or 17.848 ppm. A Clark degree (°Clark) or English degree (°e or e) is defined as one grain (64.8 mg) of CaCO 3 per Imperial gallon (4.55 litres) of water, equivalent to 14. ...

  8. Useful conversions and formulas for air dispersion modeling

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

    As an example, given a concentration of 260 mg/m 3 at sea level, calculate the equivalent concentration at an altitude of 1,800 meters: C a = 260 × 0.9877 18 = 208 mg/m 3 at 1,800 meters altitude Standard conditions for gas volumes

  9. Solubility table - Wikipedia

    en.wikipedia.org/wiki/Solubility_table

    The tables below provides information on the variation of solubility of different substances (mostly inorganic compounds) in water with temperature, at one atmosphere pressure. Units of solubility are given in grams of substance per 100 millilitres of water (g/(100 mL)), unless shown otherwise.