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  2. Grain per gallon - Wikipedia

    en.wikipedia.org/wiki/Grain_per_gallon

    Water chemists measure water impurities in parts per million (ppm). For understandability, hardness ordinarily is expressed in grains of hardness per gallon of water (gpg). The two systems can be converted mathematically.

  3. Useful conversions and formulas for air dispersion modeling

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

    Here are the conversion factors for those various expressions of wind speed: 1 m/s = 2.237 statute mile/h = 1.944 knots 1 knot = 1.151 statute mile/h = 0.514 m/s 1 statute mile/h = 0.869 knots = 0.447 m/s. Note: 1 statute mile = 5,280 feet = 1,609 meters

  4. 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 ...

  5. Air pollutant concentrations - Wikipedia

    en.wikipedia.org/wiki/Air_pollutant_concentrations

    where: 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

  6. 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]

  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. Per mille - Wikipedia

    en.wikipedia.org/wiki/Per_mille

    Download QR code; Print/export Download as PDF; Printable version; ... 1‱, 1 pcm and 1 ppm as fractions of the large block . Percentage point difference of 1 part ...

  9. Alkalinity - Wikipedia

    en.wikipedia.org/wiki/Alkalinity

    Alkalinity is typically reported as mg/L as CaCO 3. (The conjunction "as" is appropriate in this case because the alkalinity results from a mixture of ions but is reported "as if" all of this is due to CaCO 3.) This can be converted into milliequivalents per Liter (meq/L) by dividing by 50 (the approximate MW of CaCO 3 divided by 2).