When purchasing air filters for food processing plants, the first questions often asked are, “What MERV rating do we need?” or “Do we need to use HEPA filters?” However, filter efficiency is only one part of air contamination control. If an outdoor air intake is located too close to an exhaust outlet, there are gaps between the filter and its frame, airflow direction in a clean area is inappropriate, or clogged filters continue to be used, even a filter with a higher efficiency rating may fail to deliver the expected results.

In June 2025, Taiwan’s Ministry of Health and Welfare amended and promulgated the Regulations on Good Hygiene Practice for Food (GHP), continuing to emphasize risk management, environmental hygiene, process control, and recordkeeping as key areas of food industry management. Relevant GHP guidance from the Taiwan Food and Drug Administration (TFDA) also indicates that ventilation openings should be kept clean, and areas with different cleanliness requirements should be effectively separated and managed.

Therefore, air filtration planning in food processing plants should begin with the entire airflow path rather than focusing solely on the specifications of a single filter.

What Grade of Air Filter Does a Food Processing Plant Need?

There is no single filter grade suitable for every food processing plant. The appropriate filtration level should be determined through a risk assessment based on factors such as whether food is exposed, whether the process takes place before or after heating, the cleanliness requirements of the area, outdoor air pollution, product characteristics, airflow volume, and equipment capacity.

Raw material warehouses, general processing areas, cooling areas, and ready-to-eat food packaging areas present different levels of risk. When products are exposed to the environment again after sterilization or heating, the impact of airborne contamination on finished products generally warrants greater attention. In such cases, it is important to evaluate not only filter efficiency but also the source of supply air, airflow patterns between areas, and the movement of personnel and materials.

The U.S. FDA’s inspection guidelines for dairy plants identify several areas for evaluating air systems, including the quality and source of intake air, whether recirculated air is filtered, the distance between exhaust and intake openings, and whether filters are tightly installed to prevent air from bypassing around the filter frame. These principles can also provide useful planning references for other food processing facilities, although actual requirements should still be determined based on the product and applicable regulations.

Five Issues That Are Easier to Overlook Than Filter Efficiency

1. Is the Outdoor Air Intake Drawing in Contaminants?

If an outdoor air intake is located close to an exhaust outlet, loading and unloading area, roadway, cooking fumes, dust, or a waste storage area, the HVAC system may continuously bring contaminants into the facility. Increasing filter efficiency can reduce some particulate matter, but it cannot replace proper intake location and cannot guarantee the removal of all gaseous contaminants.

During site inspections, the locations of air intakes and exhaust outlets, prevailing wind direction, surrounding sources of contamination, and the potential entry of rainwater or pests should be documented.

2. Does Airflow Move from Cleaner Areas to Less-Clean Areas?

Food processing plants often divide different areas according to the requirements of raw material handling, processing, cooling, and packaging. Airflow direction should be designed according to contamination risks to prevent large amounts of air from less-clean areas from entering areas where products are exposed.

Whether positive pressure, negative pressure, or independent HVAC systems are required should be determined through a process hazard analysis. “All food processing areas should be positively pressurized” should not be treated as a universal rule. For example, processes that generate dust, steam, heat, or odors may require additional exhaust and pressure-control measures.

3. Is There Air Leakage Between the Filter and the Frame?

Air preferentially flows through areas with lower resistance. If the filter is undersized, the gasket is damaged, the retaining frame is not properly secured, or the mounting slot is deformed, unfiltered air may pass through gaps around the filter.

FDA food plant inspection materials specifically emphasize that filters should fit tightly into or be sealed within their frames to prevent air bypass. Therefore, when purchasing filters, the actual dimensions, flange configuration, installation direction, and gasket requirements should be provided. Nominal dimensions alone are not sufficient.

4. How Much Airflow Remains After the Filter Becomes Loaded?

As dust accumulates on a filter, its pressure drop gradually increases. If the fan cannot maintain the design airflow rate, the supply airflow and pressure relationship in the clean area may change. Even if the filter’s particle-capture efficiency has not decreased, the overall contamination-control performance may still be affected.

It is recommended to record the initial pressure drop and airflow after installing a new filter and then track changes under comparable equipment operating conditions. Filter replacement decisions should consider the manufacturer’s recommended final pressure drop, actual airflow, room pressure, and process risks.

5. Is There Condensation or Dust Accumulation Around the Cooling Coil and Filter Section?

Food processing plants often operate in environments with high humidity, cooling, and temperature differences. If condensation, poor drainage, or dust accumulation occurs inside an air-handling unit, it may create contamination points that are difficult to clean. FDA guidance for dairy plants also highlights the need to monitor condensation and temperature and humidity conditions that may support microbial growth.

A filter itself is not a dehumidification device. The cooling coil, drain pan, drainage pipes, insulation, and interior surfaces of the air-handling unit must also be properly managed and maintained to prevent moisture from reaching products or food-contact surfaces.

Where Should Medium-Efficiency Aluminum Separator Filters Be Used?

Hencolin’s medium-efficiency aluminum separator filters use fiberglass filter media and corrugated aluminum separators. The official product information lists MERV 11–14 options, with galvanized steel, aluminum, or wood frames available, as well as single-flange, double-flange, and box-style configurations.

Food processing is listed by the manufacturer as one of the applicable industries. Depending on the HVAC system design, these box-style filters can be used as medium-efficiency or downstream particulate filters in food processing HVAC systems, or as prefilters to protect higher-efficiency filters. The actual installation position should still be determined based on the degree of product exposure, upstream prefiltration, required airflow, and the fan’s available static pressure.

The product information lists a recommended final pressure drop of 350 Pa and provides initial pressure-drop data for different sizes, efficiency levels, and airflow rates. When comparing products, the corresponding data should be evaluated at the actual design airflow of the system rather than comparing only the lowest stated pressure-drop value.

Food Processing Plant Air Filter RFQ Checklist

Before requesting a quotation, it is recommended to prepare the following information:

• Type of food product and whether the product is directly exposed in the area.
• Whether the process is before or after heating or sterilization.
• Type of air-handling unit, filter-section location, and airflow direction.
• Actual filter width, height, depth, and flange configuration.
• Design airflow, face velocity, and available fan static pressure.
• Current filter efficiency, initial pressure drop, and current pressure drop.
• Temperature, humidity, dust, oil mist, and other contamination conditions.
• Any specific requirements such as moisture resistance, frame material, or fire resistance.
• Daily operating hours, current replacement interval, and annual filter consumption.
• Photos of the filter frame, gasket, mounting slot, and retaining mechanism.

Hencolin can provide filter options with different frame materials, efficiency levels, and configurations according to site dimensions. It is recommended to provide equipment nameplate information, the current filter label, photos of the mounting slot, and pressure-drop data together so that compatibility with the existing air-handling unit can be confirmed, rather than determining the specification based solely on the industry type.

FAQ

Does a Food Processing Plant Always Need HEPA Filters?

Not necessarily. The appropriate filtration level should be determined based on product exposure, process risks, cleanliness requirements, and applicable regulations. Before increasing filter efficiency, it is also important to confirm that the fan can maintain the required airflow.

Can a Medium-Efficiency Filter Be Used as the Final Filter in a Food Processing Plant?

It can be appropriate for certain applications, but this must be confirmed based on the process hazard analysis and site-specific requirements. Hencolin’s product information lists medium-efficiency aluminum separator filters as products that can be used for final filtration in food processing applications; this does not mean that the same configuration is appropriate for every food processing operation.

Why Might a Filter Need to Be Replaced Even When It Does Not Look Dirty?

Visual appearance does not fully indicate pressure resistance or contamination status. Pressure drop, actual airflow, condensation, odors, filter-media damage, and process-environment monitoring results should also be considered.

Can a Filter That Is a Few Millimeters Different in Size Be Used With Gasket Material to Make Up the Difference?

It is not recommended to fill gaps with temporary materials. An improperly sized filter can cause air bypass. The actual mounting slot, gasket, and retaining method should be confirmed before purchasing the appropriate filter size.

Can Food Processing Plant Filters Be Washed and Reused?

This depends on the design of the product. Fiberglass or disposable filter media that are not designed to be washable should not be washed with water or blown out for reuse, as this may damage the filter media and cause contaminants to become re-entrained into the air.