Dust generator for maintaining a set indoor airborne dust concentration for poultry health research

A dust generator was developed to disperse and maintain a desired concentration of airborne dust in a controlled environmental chamber to study poultry physiological response to sustained elevated levels of particulate matter. The goal was to maintain an indicated PM10 concentration of 50 µg/m³ of airborne dust in a 3.7 × 4.3 × 2.4m (12 × 14 × 8 ft) controlled environmental chamber. The chamber had a 1.5 m³/s (3,200 cfm) filtered recirculation system that regulated indoor temperature levels and a 0.06 m³/s (130 cfm) exhaust fan that exchanged indoor air for fresh outdoor air. Dry powdered red oak wood dust that passed through an 80 mesh screen cloth was used for the experiment. Challenges included dust being trapped by the recirculation filter and the exhaust fan which removed airborne dust from the environmental chamber. The dust generator metered dust from a rectangular feed hopper with a flat bottom belt to a 0.02 m³/s (46 cfm) centrifugal blower. A vibratory motor attached to the hopper ran only when the belt was operated to prevent bridging of powdered materials and provide an even material feed rate. A Plantower PMS5003 laser particle counter was used to measure the concentration of airborne dust and provided feedback to an Arduino-based control system that operated the dust generator. The dust generator was operated using a duty cycle of one second on for every five seconds off to allow time for dispersed dust to mix with chamber air and reach the laser particle counter. The control system maintained an airborne PM10 dust concentration of 52.72 ± 4.68 µg/m³ in the controlled environment chamber for a duration of 24 hours using red oak wood dust.