HEPA Filter Grades Explained: H13 vs H14 — Which Do You Need?

Do I need H13 or H14? Both are HEPA, but there is a meaningful difference between them. If you are specifying filters for a cleanroom, hospital, or data centre, the grade you choose affects how many particles get through — and whether you pass your next compliance audit.

This guide explains the difference in plain language, covers when each grade is appropriate, and helps you make the right call for your facility.

How HEPA Filters Are Tested (EN1822)

HEPA filters are tested at the particle size they find hardest to catch. This is called the Most Penetrating Particle Size (MPPS) — typically between 0.1 and 0.3 micrometres. Particles larger than this get trapped by physical impact against the fibres. Particles smaller than this get trapped because they bounce around randomly and stick to the fibres. But at MPPS, neither mechanism works at full strength, so filtration efficiency is at its lowest.

The standard that defines all of this is EN1822 (current version EN1822:2019). When a filter passes at MPPS, you know it will perform even better against every other particle size.

The other important feature of EN1822 is individual unit testing. Every H13 and H14 filter is tested on its own and issued a serial-numbered certificate. You are not relying on a batch sample — you have proof that your specific filter meets the grade.

H13 vs H14 — What the Numbers Mean

In simple terms: H14 lets through ten times fewer particles than H13. Both are excellent filters, but that tenfold difference matters in high-stakes environments like pharmaceutical cleanrooms and operating theatres.

Grade	Overall Efficiency at MPPS	Maximum Local Penetration	Individual Testing
H13	≥ 99.95%	≤ 0.25%	Required
H14	≥ 99.995%	≤ 0.025%	Required

Overall efficiency is the average performance across the whole filter face.

Local penetration is the worst-case reading at any single point on the filter. This scan test catches pinholes, media defects, or seal failures that would let particles bypass an otherwise good filter.

When H13 Is the Right Choice

H13 is appropriate for applications where high-efficiency filtration is needed but the absolute highest grade is not mandated:

• Hospital general ventilation — critical care wards, oncology units, and bone marrow transplant areas typically specify H13 for supply air
• Data centre critical zones — ISO Class 8 environments can be achieved with H13 terminal filtration
• Pharmaceutical Grade C environments — where the process does not require Grade A cleanliness
• Electronics manufacturing — where particulate control matters but sterility is not required
• Research laboratories — BSL-2 exhaust filtration typically uses H13

When H14 Is Required

H14 is the minimum for the most demanding applications:

• Pharmaceutical Grade A cleanrooms — sterile manufacturing requires ISO Class 5 cleanliness, which means H14 terminal filtration
• Hospital operating theatres — infection control guidelines and accreditation standards require H14, particularly for orthopaedic implant surgery
• Sterile compounding pharmacies — hospital and commercial compounding facilities classified as ISO Class 5
• High-containment laboratory exhaust — exhaust air must pass through H14 before discharge to contain biological aerosols

The Individual Test Certificate

Every Airtech H14 HEPA filter supplied by Prebur comes with a serial-numbered EN1822 test certificate. The certificate records:

• Filter model and serial number — unique to the specific unit
• Overall efficiency at MPPS — measured against the H14 minimum of ≥99.995%
• Local penetration scan test results — confirming no point exceeds the ≤0.025% limit
• Test date and conditions — airflow rate and MPPS particle size
• EN1822 classification — standard version and grade

This certificate is the documentation your QA team or infection control officer needs. For pharmaceutical validation, it forms part of the Installation Qualification (IQ) package. For hospital HVAC records, it provides the evidence base for the service log.

Does South Africa Have Its Own HEPA Standard?

South Africa does not have a separate national HEPA filter standard. The applicable standard is EN1822, which is referenced by the regulatory frameworks that govern HEPA use in SA:

• SAHPRA aligns with EU GMP guidelines, which reference EN1822 H14 for pharmaceutical Grade A environments
• JCI accreditation for hospitals requires HEPA performance in operating theatres — South African engineers translate this to EN1822 H14
• SANS 10173 (ventilation for health facilities) requires defined cleanliness levels in critical areas, which engineers meet using EN1822 H13/H14

Practical takeaway: When specifying HEPA for a South African project, write “EN1822:2019 H14” (or H13 where appropriate) and require individual test certificates. This wording is unambiguous to contractors, accepted by SAHPRA auditors, and satisfies JCI and SANS requirements. Avoid specifying “HEPA” without a grade — the term on its own does not carry a defined efficiency threshold in South African regulation.

Practical Considerations

Physical size. The 610×610mm full-size format is standard for most South African AHU installations. The 305×610mm half-size fits AHU configurations where the full-size would require housing modification. Confirm your AHU terminal filter housing dimensions before ordering.

Storage. Store HEPA filters horizontally in their original packaging until installation. Vertical storage can stress the gasket. Avoid humid storage areas — moisture can damage the glass fibre media.

Installation. H14 filters must be installed with the gasket correctly compressed against the AHU housing face. Bypass air through a failed gasket seal defeats the purpose of an H14 filter entirely. Check gasket condition and face seal on installation, and replace any filter that shows damage or defects before fitting.

Local availability. Prebur holds Airtech H14 HEPA filters in full-size and half-size formats in stock in Pretoria, with EN1822 certificates included on delivery.

Summary

• H13 and H14 are both HEPA grades under EN1822, but H14 has tenfold lower penetration than H13
• H13 is appropriate for hospital general ventilation, data centre critical zones, and ISO Class 8 applications
• H14 is required for GMP Grade A pharmaceutical cleanrooms, hospital operating theatres, and sterile compounding
• Both grades require individual unit testing and serial-numbered EN1822 certificates

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Need help selecting the right filter? Call Nick Els on +27 74 159 1634 or request a quote.