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  2. Total dissolved solids - Wikipedia

    en.wikipedia.org/wiki/Total_dissolved_solids

    Total dissolved solids (TDS) is a measure of the dissolved combined content of all inorganic and organic substances present in a liquid in molecular, ionized, or micro-granular (colloidal sol) suspended form. TDS are often measured in parts per million (ppm). TDS in water can be measured using a digital meter. [1]

  3. Parts-per notation - Wikipedia

    en.wikipedia.org/wiki/Parts-per_notation

    In fractions like "2 nanometers per meter" (2 n m / m = 2 nano = 2×10 −9 = 2 ppb = 2 × 0.000 000 001), so the quotients are pure-number coefficients with positive values less than or equal to 1. When parts-per notations, including the percent symbol (%), are used in regular prose (as opposed to mathematical expressions), they are still pure ...

  4. Immediately dangerous to life or health - Wikipedia

    en.wikipedia.org/wiki/Immediately_dangerous_to...

    1000 ppm: 79243: 10102-44-0: 0930: Nitrogen dioxide: 37.6 mg/m 3: 20 ppm: 10102440: 7783-54-2: 1234: Nitrogen trifluoride: 2900 mg/m 3: 2000 ppm: 7783542: 55-63-0: 0186: Nitroglycerine: 75 mg/m 3-55630: 75-52-5: 0522: Nitromethane: 1875 mg/m 3: 750 ppm: 75525: 108-03-2: 1050: 1-Nitropropane: 3640 mg/m 3: 1000 ppm: 108032: 79-46-9: 0187: 2 ...

  5. 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.

  6. Abundance of elements in Earth's crust - Wikipedia

    en.wikipedia.org/wiki/Abundance_of_elements_in...

    The abundance of elements in Earth's crust is shown in tabulated form with the estimated crustal abundance for each chemical element shown as mg/kg, or parts per million (ppm) by mass (10,000 ppm = 1%).

  7. Useful conversions and formulas for air dispersion modeling

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

    Thus, a measured particulates concentration of 0.1 grain per dscf in a gas that has 8 volume % CO 2 is 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:

  8. Threshold limit value - Wikipedia

    en.wikipedia.org/wiki/Threshold_limit_value

    Its units are in parts per million (ppm) for gases and in milligrams per cubic meter (mg/m 3) for particulates such as dust, smoke and mist. The basic formula for converting between ppm and mg/m 3 for gases is ppm = (mg/m^3) * 24.45 / molecular weight. This formula is not applicable to airborne particles.

  9. Drinking water quality standards - Wikipedia

    en.wikipedia.org/wiki/Drinking_water_quality...

    A parametric value in this context is most commonly the concentration of a substance, e.g. 30 mg/L of iron. It may also be a count such as 500 E. coli per litre or a statistical value such as the average concentration of copper is 2 mg/L.