| 摘要 |
<p>Relative Humidity or Water Activity Apparatus Anthony Nelson Sharpe, 230 Christian St. Almonte, Ontario K0A lA0, Canada An apparatus for measuring relative humidity or the water activity level in a food sample, within defined limits, gives a reading within seconds. The apparatus comprises a rough or porous display surface to which is applied a pattern of graded indicator substances, each of which deliquesces at a known relative humidity. Said indicator substances are applied in such quantity that they are invisible or nearly so when dry, but become severally or wholly visible again on exposure to a moist atmosphere, according to the relative humidity of the atmosphere in relation to the range of relative humidities covered by said deliquescent indicators. If said indicators are applied in the form of the decimal fractions corresponding to their relative humidity values the apparatus provides a digital readout of relative humidity, directly and without electronics. In a modification the display surface is of glass treated with dichlorodimethylsilane after the indicators have been applied. In another the display surface is a thin porous polymer film. In further modifications the display is enclosed in a shallow dish which may be applied to the surface of a food, or in a spearlike container which may be plunged inside a food. In a final modification the deliquescent indicators are mixed with a dye which diffuses into a removable porous layer to provide a permanent record of the humidity or water activity.</p> |
