Which unit is used to express water conductivity in boiler water analysis data?

• A. Mhos
• B. Siemens
• C. Micromhos
• D. Micromhos per centimeter

Answer: (C)

Water conductivity is expressed in very small conductance units because boiler water conducts electricity only a little. The standard shorthand used in boiler water analysis is micromhos, which is the small-scale form of mho (the old name for the siemens unit). This makes the numbers practical and easy to compare on test sheets. While siemens is the modern SI unit of conductance, boiler-water data routinely uses micromhos to convey how conductive the water is, rather than giving a per-length value. Micromhos per centimeter would indicate conductivity per a specific path length, which isn’t how these boiler analyses typically report the data. So the micromhos unit best fits how this data is presented.