RETA Breeze Jul-Aug 2025

UNDERSTANDING PLANT AIR BALANCE BASICS AND BASELINE PSYCHROMETRICS IN FOOD PROCESSING

T his feature provides generalized balance and psychrometrics in food processing plants, using a poultry plant as an example. It does not cover every scenario, possibility, or type of manufac turing plant that exists. The contents are generalized for the industry and both the materials and opinions in this paper are my own and do not in any way depict the operation or opinion of any of my previous, current, or future employers. Plant air balance and psychrometrics in food processing are two of the most misunderstood concepts by refrigeration operators and leadership, alike, extending beyond the basic refrigeration operation principles. Mastering both can improve plant air quality, quality control, reduce the potential for condensation and, in some cases, improve safety. If you have ever walked into a hospital or health clinic, it is very likely that as the doors opened you were met with a blast of cool air—indicating the building is positively pressurized (a higher pressure than outdoor air pressure). This is very different than air that is produced by an air explanations to help understand the baseline fundamentals of air

curtain positioned above a door. One of the biggest reasons for the positive pressure is to help keep bugs and bacteria from being able to freely enter the building. This also plays a big role in food processing to minimize the potential of contaminating food with anything the wind could pull into the building. As you move through the building or facility, you’ll probably notice that there are areas of varying pressures and airflow patterns. Some of this is by design. Like many other fluids, air will naturally move from one area of the plant to another by moving from a higher pressure to a lower pressure potential. The quantity of between the different areas of the plant. As the pressure difference rises, so does the rate of airflow. This feature will not discuss the mathematics behind the principle as we are focused on the basics. Mechanical ventilation helps us create the pressure difference necessary to establish desired ranges of pressure. In food plants, make up air comes from either a series of makeup air units (MAU) that have some form of heat (usually natural air that moves to the lower pressure depends on the pressure difference

By Victor Dearman CIRO, CRST

22 RETA.com