While we understand there are many nuances to airflow design and unique considerations based on the type of facility, layout of the facility and what is being produced in it, some of the common considerations that apply to most facilities include:
- Air Distribution
Temperature and Humidity
With proper air distribution and pressurization, temperature and humidity control become much easier to achieve. Different processes have different temperature and humidity needs. They also introduce heat and moisture at different rates which need to be removed to maintain the desired environmental conditions. These factors along with weather conditions for the location of the facility are taken into account in sizing the HVAC equipment that will serve the production areas. In the past, it was less common for production areas to be air-conditioned, but a combination of process needs and better environmental conditions for the personnel has led to more facilities providing air-conditioning.
As previously mentioned, pressurization requires outside air which is often not in the temperature and humidity range desired indoors. Therefore, the outside air may need to be heated, cooled and/or dehumidified. In rarer cases, humidity may need to be added. Outside air intakes should be located as far away from sources of contaminates as possible, but this often means they are on the roof where they can be subject to more extreme heat and at times humidity as well.
Most commercial HVAC units are not designed to handle the amount of outside air needed to maintain the pressurization in air-conditioned food production facilities. That is why it is important to determine the airflow and outside air needs first, and then select the equipment that is capable of control temperature and humidity in all weather conditions anticipated at that location. This may require multiple selections and often requires equipment with the ability to vary capacity over a wide range to handle the different load conditions the facility will experience.
Condensation and moisture control are critical in most food production facilities given the potential for the growth and spread of bacteria that can result from standing water. Keeping the space dew point temperature several degrees below the anticipated coldest surface temperature in the space keeps condensation from forming. The space dew point is a function of the moisture introduced into the space. Outside air is the most common source of moisture, but some processes and cleaning procedures will generate moisture as well. It is the combination of the outside air and return air from the space that will determine the amount of heat and moisture that needs to be removed by the HVAC units to achieve the desired ambient and dew point temperature. Surfaces that are anticipated to be cold as part of the process are typically insulated, but depending on the type and thickness of the insulation, they may still be cooler than the room, so if the dew point is not controlled, they will often be subject to condensation. In some cases, high volumes of heated air can be used to dry out spaces after they have been washed down to reduce the dwell time of any residual standing water.
Did you miss Part 3? Read it now. Use the links below to explore the entire air flow design series.
Would you like to discuss all of the airflow design considerations now? Contact our expert, Frank Mangin at firstname.lastname@example.org.