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When measuring emissions of gases, particulate, and odor from animal buildings, the ventilation data are equally important as the concentration data, because emission rate of a pollutant is the product of its concentration and the ventilation rate. However, effectively measuring and monitoring building ventilation remains a technical challenge, especially in barns with numerous fans. Although several measurement and monitoring techniques have been used in livestock barn studies, they are either relatively expensive or unreliable.

A new technique was introduced for continuously monitoring exhaust fan operation in real-time by detecting the vibration of its housing or frame member. A low-cost vibration sensor, a 2- coductor cable, a signal filter, and a digital input channel are used for each fan. A laboratory test was conducted to evaluate the technical viability of using the sensor in continuous vibration conditions. A 4-month field test in layer barns was conducted to test the accuracy and life of three vibration sensors, which were installed on the fan housings and cones. The fan operation data was logged by a computer every minute. Coupled with simultaneous building static pressure measurement, the continuous ventilation rate can be calculated by using the fan airflow vs. pressure performance curve.

The advantages of this technique include low cost (only about 1% to 10% of the cost of other tested techniques), simplicity, no interference by wind and dust, and the capability of directly monitoring individual fans to avoid false signals caused by fan failure, fan management changes or other problems. This paper describes the technique and presents the test results.