Casella CEL Airborne particulate monitoring system - Manual (Page 15)

HB3256-03 Page 13
Combined Temperature &
Relative Humidity
Description
This combination %rh and temperature sensor is mounted within a single radiation screen. Both
transducers are unaffected by condensation and are resilient to airborne pollution. The
hygrometer is of the capacitative type, is largely free from drift and offers high repeatability over
large ranges of humidity for long periods. The temperature sensor is based upon a platinum
resistance element to BS1904, DIN 43760, and incorporates linearisation electronics within the
sensor. The output of the temperature sensor is used to compensate the hygrometer for
temperature effects. This ensures that the combination sensor achieves the maximum
performance for this type of device.
Specifications
Hygrometer
Sensor type
Capacitive
Measuring range 0 - 100%rh
Calibrated accuracy †2% between 30 and 80%
Hysteresis †1%
Time constant 10% to 90% rh <10 seconds
Operating temperature -25°C to +80°C
Temperature
Sensor type
Platinum resistance MO 1000RTD thin film
Measuring range -40°C to +60°C
Calibrated accuracy †0.3°C @0°C, †0.55°C @50°C
Operating temperature -40°C to +60°C
General
Part no.
120738B-02
Supply voltage 8 to 24 volts d.c.
Current consumption Typically 10mA at 12 volts
Output calibration Temperature = 0 to 1 volt for -40°C to +60°C
Humidity = 0 to 1 volt for 0 to 100%rh