How to select HEPA type for aseptic filling area?

The aseptic filling area has a characteristic: it is not a uniform clean space, and the risk levels of various locations inside are different.

Filling ports, stopper hoppers, and open containers are locations where products are directly exposed and are the core of pollution control; particle control requirements in personnel operating areas and peripheral equipment are relatively loose. If the selection is based on 'use the same set of configurations for the entire area', it will easily leave shortcomings in key locations, and may also lead to overinvestment in non-critical areas.

Identify key workstations first

The first step in model selection is not to check the standards, but to open the process plan and mark the exposed positions of the product.

Below the filling needle, above the container opening, and the rubber stopper conveying path, these are the areas that need to be covered by local air supply. The exposure time of each location, the operation method, and whether there is any obstruction by surrounding equipment will all affect the air supply plan.

After the key workstations are determined, let’s look at how the airflow is organized. A common practice for aseptic filling is to cover the exposed area with localized unidirectional flow, allowing clean air to blow vertically through the product from above and carry away particles. This local air supply unit is usually composed of EFU equipment-side fan filter unit or high-efficiency air supply outlet provides power, with internal matching HEPA/ULPA air filter。

The range, height, and surface wind speed of local air supply should be determined according to the size and operating actions of the exposed area. The movement range of the filling needle, container conveying path, and personnel arm activity area must be included in the coverage calculation.

The air supply volume is calculated based on the local area, not the entire room.

The air supply design of the aseptic filling area is usually a combination of 'background clean room + local reinforcement'.

The background area is controlled by the factory air conditioning system or The FFU fan filter unit provides basic cleanliness, and key workstations are protected by local air supply units. The air volume of local air supply should be calculated separately: the coverage area multiplied by the target surface wind speed, plus the margin for air flow attenuation.

The higher the face wind speed, the better. Too high will cause turbulence in the operating area, which will affect the stability of the air flow and may also cause particles around the filling equipment to be rolled up. Design values ​​are usually determined based on process verification requirements and cannot be determined based on experience.

Sealing and leak detection should be clearly thought out in the design stage

Filter replacement in aseptic filling areas often involves re-validation of the production environment, resulting in high downtime costs. Therefore, the sealing method and leak detection accessibility must be confirmed during model selection.

If the end interface adopts a liquid tank sealing structure, the matching dimensions of the knife edge and the tank body must be checked clearly at the drawing stage. For specific methods, please refer to the relevant interface instructions. If the gasket compression method is used, confirm whether the compression parts are evenly distributed and whether the four corners can be pressed in place.

More importantly: after the filter element is installed, can the leak detection probe be able to reach around? Some air supply vents have diffusers or flow-equalizing structures. After installation, the frame is blocked and must be disassembled and assembled for on-site leak detection, which will affect the schedule of each maintenance. It is better to reserve leak detection channels during the design stage than to discover problems after installation.

The replacement process should be included in the verification plan

The replacement of the filter in the aseptic filling area does not end after the replacement.

After replacement, installation leak detection, wind speed measurement, and restoration verification as required by project quality documents are required. These steps should be clarified in the selection stage: who is responsible for leak detection, what method to determine, which items to retest, and what conditions can be met to resume production.

Plan the replacement and verification process in advance so that the filter model, number, installation location and inspection records can be matched one by one. When an abnormality occurs later, the specific product and location can be quickly located, rather than a general inspection of the entire area.

About Aili Industrial’s pharmaceutical cleanliness packages

Provided by Aili Industrial HEPA/ULPA air filters and clean air supply equipment, product lines cover FFU fan filter unit、EFU equipment end fan filter unit and high-efficiency air supply inlet, etc., can provide size and structure supporting information according to the requirements of the project process documents.

For the aseptic filling area, it is recommended to provide the process plan, key workstation locations, local air supply range and verification requirements to facilitate the judgment of filter grade, sealing method and interface configuration of the air supply unit. Specific selection, testing methods and acceptance conditions should be subject to the applicable specifications and quality documents of the project.