DT722 User’s Manual
16
97332 Issue 2, January 2018
APPENDIX D
Practical recommendations for specifi c types of hygrometer
Relative humidity capacitive sensor
•
Care should be taken to avoid mechanical shock (impact) or thermal shock (sudden
temperature changes). Sensors should be protected from steam or water sprays, and from
direct sunlight.
•
Where a sensor is at risk of exposure to dust, droplets, or the occasional knock during
handling, the appropriate guard or filters for the sensor head should be used.
•
Any temptation to breathe on the sensor, or to wave it over cups of tea, etc. should be
resisted. Filters and saturation guarding may protect the sensor, but these actions carry a
risk of damage by condensation or other contamination.
•
Protective filters can slow the response time of sensors. This can be avoided by removing
any filter, but the benefit must be weighed against the risk of damage to the sensor.
•
Sensors should not normally be submerged in liquids. In the case of a resistive (electrolytic)
sensor, water or other liquids would certainly damage the sensor beyond repair.
•
Salt solutions are especially commonly used for calibration of electrical sensors, and should
be provided with traceability directly or via a calibrated hygrometer. Protection of sensors
from direct contact with salt or solution is most important as contamination would destroy
or seriously impair the sensing element.
