Ammonia generator for maintaining a set indoor gas concentration for poultry health research

An ammonia gas (NH3) generator was developed to maintain a desired concentration of ammonia gas in a controlled environmental chamber to study poultry physiological response to sustained elevated levels of ammonia gas. The goal was to maintain 50 parts per million (ppm) of ammonia gas in a 3.7 × 4.3 × 2.4m (12 × 14 × 8 ft) controlled environmental chamber. The chamber had a 1.5 m³/s (3,060 cfm) recirculation system that regulated indoor temperature and humidity levels and a 0.06 m³/s (130 cfm) exhaust fan that exchanged indoor air for fresh outdoor air. The ammonia generator was fabricated by coupling ultrasonic humidifiers with an Arduino-based control system. The reservoir chambers of the humidifiers were filled with 2% ammonia liquid. For the system tested, it was found that 7.6 liters (2 gallons) of 2% ammonia cleaning liquid could maintain the target gas level of 50 ppm in the chamber air for a duration of 30 hours before refilling was required. The control system was capable of maintaining an ammonia gas concentration within +/- 5% of the target using a metallic oxide MQ-137 ammonia gas sensor.