Technical Guides

Before You Install HEPA Filters: A Pre-Installation Checklist

2020-11-05 · Updated 2026-09-27

How well HEPA terminals are installed decides whether a cleanroom reaches its class. What to check on the specification, the room, the system, the delivered filters and the finished installation.

Key points

Check size and efficiency against the cleanroom design before anything is installed.
Clean the room, ceiling void and air system, then run the system for at least 12 hours and clean again.
Inspect every filter on arrival: media, sealant, frame, dimensions, burrs and rust, and its certificate.
Match filter resistance on each supply face, and scan-test terminal filters after installation.

Why installation decides performance

A HEPA filter only performs as well as it is installed. A damaged corner, a poorly sealed flange or dust left in the duct can keep a cleanroom from reaching its class even with the right filters. Every step below has caused failures on real projects.

1. Confirm the specification

Check that the dimensions and efficiency of the filters or terminal units match the cleanroom design and the customer's application standard before installation starts.

2. Prepare the ceiling and the openings

Seal the joints between the terminal flanges and the ceiling panels with gaskets; treat every crack or gap.
Do not install any unit whose filter or coating is damaged.
Connect terminals firmly to the ductwork; cover open duct ends with plastic film and tape until connection.

3. Clean first, then run the system

Clean the delivered products and the entire cleanroom. Clean any dust out of the clean-air system, the ceiling void and interstitial spaces until they meet the cleanliness requirement. Then run the air system continuously for at least 12 hours and clean again before the HEPA filters go in.

4. Transport and handling

Transport and store filters in the orientation marked by the manufacturer. Handle them gently and avoid vibration and impact — the media is fragile.

5. Inspect every filter on arrival

Media, sealant and frame are undamaged.
Side lengths, diagonals and thickness are within tolerance.
Metal frames have no burrs or rust.
Each filter has its certificate, and its technical data meets the design.

6. Match resistance, then scan

For unidirectional-flow rooms, allocate filters by their measured resistance so that on the same outlet or supply face the rated resistance of each filter differs from the average by less than 5% — this keeps the airflow uniform.

Terminal HEPA filters used to filter aerosols in ISO 5 or cleaner rooms, or where the project requires it, must each be leak-scanned on site after installation and pass.