Air Tunnel to Enhance Reliability of Thermohygrometer Instrument Readings

摘要

An air tunnel has been designed that will control air velocity passing thermohygrometer temperature/humidity 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 m/sec, 0-100 ft/min). 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.