Buyer guide
HEPA and ULPA filters: EN 1822, ISO 29463 and integrity testing
Under EN 1822, EPA filters are classes E10 to E12, HEPA filters are H13 and H14, and ULPA filters are U15 to U17, graded by efficiency at the most penetrating particle size. ISO 29463 uses a different number scale for the same levels, and an installed filter is proved by a leak test of the filter and its seal, not by the class on the label.
By ZY Cleanroom · Updated · Sources at the end of the page
EN 1822 classes
Overall efficiency is the average over the whole filter. Local efficiency is the lowest allowed at any point, and it is set for H and U classes only. Values are percentages at the most penetrating particle size.
| EN 1822 class | Overall, at least | Local, at least | ISO 29463 class at the same overall efficiency |
|---|---|---|---|
| E10 | 85% | None set | Check ISO 29463-1:2024 |
| E11 | 95% | None set | ISO 15 E |
| E12 | 99.5% | None set | ISO 25 E |
| H13 | 99.95% | 99.75% | ISO 35 H |
| H14 | 99.995% | 99.975% | ISO 45 H |
| U15 | 99.9995% | 99.9975% | ISO 55 U |
| U16 | 99.99995% | 99.99975% | ISO 65 U |
| U17 | 99.999995% | 99.9999% | ISO 75 U |
Two ways to state efficiency
The most penetrating particle size depends on the media. ISO 29463-1 gives about 0.12 to 0.25 µm for micro-glass media.
US practice often quotes a different test. FDA's 2004 guidance says an intact HEPA filter retains at least 99.97% of particles larger than 0.3 µm. That is not the same test as H13 at 99.95%, so ask which test a quote uses.
ISO 29463 has more steps than EN 1822. ISO 40 H, at 99.99% overall, sits between H13 and H14. ISO 29463-1 was reissued as a third edition in August 2024. It added two E classes, so check the E rows above against that edition.
Integrity testing in place
FDA separates two tests. An efficiency test rates the filter. A leak test finds faults in the media, frame or seal after installation.
FDA's method challenges the filter upstream with a polydisperse aerosol such as PAO. A photometer probe scans the downstream face and frame about 1 to 2 inches away at 1 cubic foot per minute or more. One reading equal to 0.01% of the upstream challenge signals a significant leak.
ISO 14644-3:2019 covers the same ground in clause B.7. It sets out probe size, scan rate, acceptance criteria and upstream challenge, for both photometer and particle counter methods.
When to test
Test after installation, then on a schedule set by the rules that apply.
| Point | Requirement | Source |
|---|---|---|
| Qualification | Installed filter leakage and integrity test | Annex 1, para 4.25 |
| Requalification, Grade A and B | Final-filter integrity test, 6 months at most | Annex 1, para 4.32 |
| Requalification, Grade C and D | 12 months at most | Annex 1, para 4.32 |
| Pharmacy cleanroom suite | Leak test at the factory, after installation and at least every 6 months | USP <797>, section 5 |
What to specify when you buy
US drug law (21 CFR 211.42) calls for an air supply filtered through HEPA filters under positive pressure in aseptic processing areas, as quoted in FDA's 2004 guidance. Annex 1 defines a HEPA filter as one specified to a relevant international standard.
Name the standard and edition, and the class. Ask for a factory test report for each filter. Check that the housing allows aerosol injection upstream and a clear scan path downstream.
Plan a retest after any filter change. USP <797> repeats the smoke study and environmental monitoring after a HEPA unit is changed.
Who approves the room
Your regulator judges the facility, not the contractor. The contractor supplies filters, test reports and installation records to your specification. To have a room list reviewed, send it to ZY Cleanroom, a cleanroom design-and-build contractor with its own panel factory in Tianjin, China.
Questions
Common questions
Is H14 the same as HEPA?
In EN 1822, H13 and H14 are the HEPA classes. US usage quotes 99.97% at 0.3 µm, which is a different test.
What makes a filter ULPA?
EN 1822 classes U15 to U17: at least 99.9995% overall efficiency at U15, rising to 99.999995% at U17.
What leak reading fails a HEPA filter?
FDA's 2004 guidance treats one reading of 0.01% of the upstream challenge as a significant leak. Check the limit in your own specification.
Does a class label replace a leak test?
No. The class rates the filter. A leak test checks the filter, frame and seal as installed.
Can HEPA filters be cleaned or reused?
Treat a cleanroom HEPA filter as a replace-only part. Washing or vacuuming can damage the media, and we found no cleanroom standard that gives a method for it. Any filter that has been disturbed would need a new integrity test.
How often should you change a HEPA filter in a clean room?
The sources checked for this guide set no fixed interval. Change a filter when it fails a leak test, is damaged or wet, can no longer deliver the design airflow, or reaches the final resistance rated by its maker. Trend the pressure drop so that you can plan the change.
Related guides
- ISO 5 and ISO 6 cleanroom requirements
- Cleanroom monitoring systems: particles, pressure, temperature and humidity
- HEPA filter integrity and leak testing
- Cleanroom pressure alarm: how to find the cause
- Turnkey cleanroom contractor
- Room list builder
Sources
- CEN, EN 1822-1:2019, High efficiency air filters (EPA, HEPA and ULPA), Part 1: Classification, performance testing, marking (catalogue entry; checked 31 October 2026)
- MANN+HUMMEL, EN 1822 filter classes table (checked 31 October 2026)
- EMW, ISO 29463 filter table with EN 1822 comparison (filter manufacturer; checked 31 October 2026)
- ISO 29463-1:2024 preview on iTeh Standards (most penetrating particle size; checked 31 October 2026)
- ISO, ISO 29463-1:2024 catalogue entry (edition 3, August 2024; checked 31 October 2026)
- FDA, Guidance for Industry: Sterile Drug Products Produced by Aseptic Processing, Current Good Manufacturing Practice (September 2004, nonbinding; checked 31 October 2026)
- ISO 14644-3:2019, Cleanrooms and associated controlled environments, Part 3: Test methods (published August 2019; contents list checked 31 October 2026)
- EudraLex Volume 4, Annex 1: Manufacture of Sterile Medicinal Products (published 25 August 2022, applied from 25 August 2023; checked 31 October 2026)
- Washington State Department of Health, Pharmacy Self-Inspection Worksheet, 2026 USP 797 Sterile Compounding Addendum, DOH 690-296 (January 2026), which reproduces USP <797> text by section; checked 31 October 2026
Project enquiry
Send what you have
A room list, a floor plan or only the floor area is enough to start. After you submit, send drawings by email or WhatsApp.
We reply by email within one working day. We can sign an NDA before you send drawings.
WhatsApp +44 7962 561184 is our UK number for export enquiries. The factory is in Tianjin, China.
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