PID air pressure controller in a positive pressure screening cabinet (PPS-Cabinet) for healthcare operator screening of SARS-CoV-2 infection

Abstract

This paper presents the implementation of a PID pressure controller for a Positive Pressure Screening Cabinet (PPS Cabinet), designed to reduce the risk of COVID-19 transmission to healthcare personnel. The PPS Cabinet was designed, constructed, and tested to optimize internal pressure by adjusting the proportional (Kp), integral (Ki), and derivative (Kd) gains of the PID controller. In the experimental setup, the cabinet has a total volume of 2.88 m³. A PID controller integrated with a Programmable Logic Controller (PLC) receives a 0–10 V analog signal from a pressure transducer and is programmed using a standard PID algorithm. The Kp, Ki, and Kd values were determined using the Ziegler-Nichols tuning method. Testing scenarios included opening and closing the cabinet door, both with and without an airlock chamber. Results indicate that the PID controller effectively regulates cabinet pressure, with optimal tuning values identified as Kp = 0.6, Ki = 0.4, and Kd = 0.4. While the PPS Cabinet without an airlock is deemed suitable for practical use, door opening causes a pressure drop below 0 Pa, posing a significant risk to healthcare workers. However, incorporating an airlock chamber maintains pressure above 0 Pa, thereby enhancing safety and reducing the likelihood of COVID-19 transmission to operators.