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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.
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 14.254 ppm.
In a solution where only CO 2 affects the pH, carbonate hardness can be used to calculate the concentration of dissolved CO 2 in the solution with the formula CO 2 = 3 × KH × 10 (7-pH), where KH is degrees of carbonate hardness and CO 2 is given in ppm by weight. [citation needed]
Atmospheric pollutant concentrations expressed as mass per unit volume of atmospheric air (e.g., mg/m 3, μg/m 3, etc.) at sea level will decrease with increasing altitude because the atmospheric pressure decreases with increasing altitude.
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.
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
A sample point on the discharge line allows for the analyzer to determine the oil content of the ballast now and slop water in PPM. [2] The analyzer is self-maintaining by periodical cleansings with fresh water, and therefore requires a minimum of active maintenance from the crew. [2]
As a unit 1 dKH is the same as 1 °dH which is equal to approximately 0.1786 mmol/L or 10.02 milligrams (mg) of calcium carbonate per litre of water, i.e. 17.86 ppm.