An Instrument for Determining the Total Water Content in Air when Extinguishing Fires

摘要

An instrument suitable for measuring the total water content both as small liquid droplets and as vapour in the air, in water mist total flooding extinguishing tests, is presented. The instrument consists of a heater and a Vaisala humidity meter. The Vaisala humidity meter is capable of measuring relative humidity at temperatures up to 180℃. The instrument has a measuring range of 0-600 g/m~3, a sample rate of 1 L/min, a time constant of 5-10 s and an accuracy of ± 40 g/m~3. Accurate results are obtained when used outside the direct spray from a nozzle. If the instrument is placed in the spray the total water content can be either over-or underdetermined, depending on which part of the instrument faces the spray.