• Switzer Instrument Limited

Humidity/Temperature Indicator

Switzer has developed a hand-held device for spot checking relative humidity and temperature named as Humiread. The display unit and the ergonomically designed probe with flexible cable provide freedom of measurement in a wide spectrum of applications such as air-conditioning, food processing industry, laboratories, clean rooms, computer rooms, archives, and film processing units. The 3&189;- digit LCD display indicates relative humidity in % of temperature in oC through a slide switch. While the basic probe allows climate sensing, a box sensor can be provided on request for the measurement of moisture in chips, fibres, grains and medical formulations. Switzer's humidity sensor HC-500 is a thin-film technology capacitance sensor. The active layers of the sensors are deposited onto a glass substrate. The sensitive polymer dielectric layer is spin coated onto a basic metallic electrode and covered by a top electrode which is permeable to humidity. The dielectric constant of the polymer varies with the amount of water absorbed corresponding to the relative humidity. The equilibrium with the humidity of the surrounding air thus established determines the capacitance of the sensor. The sensor is immune to common industrial pollutants like SO2, CO and NH3. It is also unaffected by high temperature and condensation. The sensor is easily cleanable with isoproponal using a soft brush exercising due care to avoid scratches. Switzer temperature sensor M-1000 is a molybdenum sensor which has excellent linearity and stable temperature coefficient. Protective coating of quartz and coloured polymer over the molybdenum layers achieve good long term stability. The instrument is available for the measurement of humidity range of 20-95% RH and 0-70oC temperature measurements. Designed with advanced electronics for high performance which offers an accuracy of &177;2% RH in the humidity range and &177;0.2oC in the temperature range. The case dimensions are 150 L x 80 W x 34 H mm and the weight is 400 g.