Design and performance evaluation of the upgraded portable monitoring unit for air quality in animal housing

The Portable Monitoring Unit (PMU) was originally developed and used for measuring ammonia (NH3) and carbon dioxide (CO2) concentrations and emissions from poultry facilities. Its use entailed a substantial degree of manual setup and data processing, making field deployment of multiple PMUs a logistical challenge. The original commercial electro-chemical (EC) sensor for NH3 is no longer available. Thus, an effort to upgrade the PMU design was undertaken. A substantial redesign of the PMU system is reported in this paper, including the data acquisition and control system (DACS), and the circuit and tubing systems. A new NH3 EC sensor was selected by an evaluation of existing commercial sensors, followed by further tests to characterize its accuracy and limitations. The performance of the upgraded PMU (iPMU) was evaluated from field measurements taken in a commercial laying hen barn and subsequent laboratory reassessment. Results demonstrated the feasibility of iPMU, making multiple-point measurements for air quality in large-scale barns practical.