Psychrometer—WB/DB Assembly

The Q Corporation Pychrometer is built according to ASHRAE 41.1 specification for reading wet bulb temperatures using RTDs, T/Cs, thermisters, or thermometer temperature elements (TE). Per specification air is drawn through an air chamber at approximately 1000 ft/min it passes over two TEs. The TEs measure dry bulb and wet bulb temperature of the air. All other moist air properties can be calculated using the temperature’ values from the two thermometers.  The wet-bulb TE is wetted by a cotton wick that draws distilled water from a lower water reservoir through capillary action.  This process enables the wet-bulb to remain wetted for continuous measurement.


  • Several options are available for enhancing accuracy when testing.
  • There are ports for chilled mirror, pitot tube and capillary tube access.  These devises are not necessary for the Psychrometer to work properly, but can be used to enhance certain features.
  • The chilled mirror sensor can be used as an alternate indicator of moist air properties.
  • Pitot tubes can be installed to verify air speed over wet bulb.
  • Capillary tube can also be installed to enhance the continuous wetting of the wet bulb wick by wetting from above as well as below.

Operation & Set Up

The Q Corp Psychrometer is designed for use within an array of airflow systems in which detailed thermal tests are being conducted.  Testing environments involving airflow measurement require that the focal air stream in contact with the unit under test (UUT), also pass through a flow metering device.  Therefore, any air which is sampled before entering the meter device must be returned to the air stream, as an unknown amount of air being removed from the system may skew results.   If air is sampled downstream of airflow meter (i.e., after the airflow across the test product has been measured), return ducting is not necessary.