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  2. NTU method - Wikipedia

    en.wikipedia.org/wiki/NTU_Method

    The number of transfer units (NTU) method is used to calculate the rate of heat transfer in heat exchangers (especially parallel flow, counter current, and cross-flow exchangers) when there is insufficient information to calculate the log mean temperature difference (LMTD). Alternatively, this method is useful for determining the expected heat ...

  3. Turbidity - Wikipedia

    en.wikipedia.org/wiki/Turbidity

    Turbidity is the cloudiness or haziness of a fluid caused by large numbers of individual particles that are generally invisible to the naked eye, similar to smoke in air.The measurement of turbidity is a key test of both water clarity and water quality.

  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. Nephelometer - Wikipedia

    en.wikipedia.org/wiki/Nephelometer

    Parts Per Million of standard substance, such as PPM/DE (Kieselguhr) "Trübungseinheit/Formazin" (TE/F) a German standard, now replaced by the FNU unit. diatomaceous earth ("ppm SiO 2") an older standard, now obsolete; A more popular term for this instrument in water quality testing is a turbidimeter.

  6. Hard water - Wikipedia

    en.wikipedia.org/wiki/Hard_water

    The different conversion factors arise from the fact that equivalent masses of calcium oxide and calcium carbonates differ and that different mass and volume units are used. The units are as follows: Parts per million (ppm) is usually defined as 1 mg/L CaCO 3 (the definition used below). [20]

  7. Talk:Parts-per notation - Wikipedia

    en.wikipedia.org/wiki/Talk:Parts-per_notation

    The examples don't seem to be too accurate. A drop is usually defined as 0.05 ml, which then gives;. 1 drop in 50 ml = 1‰, 50ml is a very small cup 1 drop in 50 l = 1ppm 50 l is about 11 gallons, not 40 1 drop in 50 cubic metres = 1 ppb 1 drop = 1ppt, a 50 m swimming pool is 50*25*2 = 2,500 m^3 1 drop in 50,000,000 cubic metres = 1ppq, 50,000,000 m^3 is equivalent to a lake covering a square ...

  8. List of conversion factors - Wikipedia

    en.wikipedia.org/wiki/List_of_conversion_factors

    Definition Relation to SI units barrel of oil equivalent: boe ≈ 5.8 × 10 6 BTU 59 °F: ≈ 6.12 × 10 9 J: British thermal unit (ISO) BTU ISO: ≡ 1.0545 × 10 3 J = 1.0545 × 10 3 J: British thermal unit (International Table) BTU IT = 1.055 055 852 62 × 10 3 J: British thermal unit (mean) BTU mean: ≈ 1.055 87 × 10 3 J: British thermal ...

  9. Useful conversions and formulas for air dispersion modeling

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

    There are other definitions of standard gas conditions used in the USA besides 60 °F and 1 atmosphere. That being understood: 1 Nm 3 of any gas (measured at 0 °C and 1 atmosphere of absolute pressure) equals 37.326 scf of that gas (measured at 60 °F and 1 atmosphere of absolute pressure).