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An Air Tunnel to Enhance Reliability of Thermohygrometer Instrument Readings.
ARMY RESEARCH INST OF ENVIRONMENTAL MEDICINE NATICK MA
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An air tunnel has been designed that will control air velocity passing thermohygrometer temperaturehumidity air probes thereby improving accuracy and reliability of readings. The air tunnel produces a constant air velocity passing a sensing probe to create stable, accurate measurements in areas where air movement is classified as low to stagnant 0-50 msec, 0-100 ftmin. Measurements of temperature and relative humidity using a thermohygrometer may very significantly depending on how data are being collected static, swinging or air tunnel probe. Static probe is unreliable because the measuring circuit has an electrical current that heats the sensor causing readings to be above ambient in relative humidity. Erratic readings produced by swinging the probe in order to cancel the heating effects are attributable to user techniques and variable air velocities. Responsiveness, accuracy, and reproducibility of measurements are consistently improved by using the air tunnel.
APPROVED FOR PUBLIC RELEASE