Hygroscopic properties of airborne particulates, weld fumes, and membrane filters, and weighing precision

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Other Title
  • 大気粉じん，溶接ヒューム，膜フィルターなどの吸湿特性とひょう量精度
  • タイキ フンジン ヨウセツ ヒューム マク フィルター ナド ノ キュウシツ

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Abstract

Hygroscopic properties of airborne particulates, weld fumes, and membrane filters, conditions for controlling their adsorbed moisture, and precise weighing were studied. A desiccator equipped with a miniature fan for agitating the atmosphere was used to control the adsorbed moisture of the samples. The humidity in the humidistat was adjusted with a sulfuric acid solution, and the temperature was controlled by dipping the lower part of the desiccator in water of a thermostat. The dried or moist materials described attained to equilibrium weights within about 12 h in an atmosphere of 20°C, 50% humidity. The moisture adsorption was similar to the BET type due to multilayer adsorption: The adsorbed moisture on the materials increased abruptly with increasing humidities over 70%, and variation of the moisture was small under lower humidities than 50%. Weld fumes were less hygroscopic than the airborne particulates. Standing these materials during more than 12 h in the atmosphere of (20±1)°C and (50±1)% humidity are recommended for their precise weighing. More than about 100 mg of the sample can be weighed within 1 % of relative precision. The membrane filters tested, and minor sample of the particulates or fume collected on a membrane filter can be weighed within 0.1 mg of precision by use of a counterpoise.

Journal

  • BUNSEKI KAGAKU

    BUNSEKI KAGAKU 30 (6), T55-T60, 1981

    The Japan Society for Analytical Chemistry

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