Psychrometers
The Q Corporation Psychrometer is built according to the ASHRAE 41.1 specification for reading wet bulb temperatures using RTDs, T/Cs, thermisters, or temperature elements (TE). Per the specification, air is drawn through an air chamber at approximately 1000 ft/min as it passes over two TEs. The TEs measure the 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 devices 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 the air speed over the wet bulb.
Capillary tubes can also be installed to enhance the continuous wetting of the wet bulb wick by wetting from above as well as from below.