Research on pressure difference characteristics of entire process of flight transport in biological safety isolation chambers for transporting infectious patients

In response to the practical needs of long-distance flight for biological safety isolation, a container-type biological safety isolation chamber has been constructed through layout design and ventilation control system design. Equipped with pressure and pressure difference monitoring instruments with real-time recording capabilities, the changes in cabin atmospheric pressure and the pressure difference between the inside and outside of the isolation chamber during the three stages of takeoff, cruise, and descent of the aircraft are measured. The results show that the pressure difference between adjacent functional areas throughout the entire flight stage is greater than 15 Pa, and the absolute value of the pressure difference between the ward and the cabin is greater than 40 Pa, forming an orderly pressure gradient to ensure that the airflow moves from the clean area to the contaminated area. The cabin pressure fluctuates significantly mainly during the takeoff and descent stages, while the changes during the cruise stage are not significant. The pressure difference absolute value changes in each functional area of the isolation chamber are basically consistent with the pressure change pattern of the aircraft cabin, and the reasons for the pressure difference fluctuations in each functional area are mainly due to the changes in the internal air temperature and pressure of the aircraft. Considering the convenience and reliability of design and operational control, it is recommended to use a ductless distributed fan ventilation system as the ventilation control system for the isolation chamber. It is also recommended to use a pressure difference redundancy control method to facilitate simple and reliable pressure difference and pressure gradient control.