Process materials (gases and chemicals)

Which measure is commonly used to express trace moisture in high-purity gases?

  1. ApH
  2. BSpecific gravity
  3. CDew point (the temperature at which moisture begins to condense)
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Answer: C. Dew point (the temperature at which moisture begins to condense)

Moisture in gas is often expressed by the temperature at which it begins to condense on cooling (the dew point). The lower the dew point, the drier the gas; a dew point around −100 °C, for example, corresponds to ppb-level moisture. Moisture causes piping corrosion and degrades film quality.

  • A. pH measures the acidity or alkalinity of liquids.
  • B. Specific gravity is a density ratio, not a moisture measure.
  • C. Correct. Moisture is expressed by the dew point.
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