What is a HEPA Filter? H10-H14 Classification under EN 1822-1:2009 and Real-World Applications

The moment "medical-grade air filtration" or "GMP cleanroom" comes up, the first keyword that appears is HEPA Filter. This filter grade is mission-critical in pharma plants, hospitals, semiconductor fabs, and food production — and these days it has even spread to home air purifiers as PM2.5 pollution grows more serious. This article explains what HEPA is, how it works, and how to pick the right grade for your needs.

1. Defining the HEPA Filter

HEPA stands for High Efficiency Particulate Air filter — a high-efficiency air filter meeting the HEPA standard. The standard requires the filter to retain at least:

• 99.95% of particles ≥ 0.3 µm per the European standard (EN 1822), or
• 99.97% of particles ≥ 0.3 µm per the US standard (DOE/IEST).

The 0.3 µm figure is no accident — it is the MPPS (Most Penetrating Particle Size), the hardest particle size to capture. Larger particles are easier to block by impaction and inertia; smaller particles are captured by Brownian diffusion. HEPA efficiency is measured at exactly this "weak spot", so actual efficiency at other sizes is usually higher than the published figure.

2. Operating principle: 3 particle-capture mechanisms

The HEPA core is a mesh of millions of glass (or synthetic non-woven) fibres 0.5-2 µm in diameter, randomly arranged. The gaps between fibres are typically larger than 0.3 µm, yet the filter still captures smaller particles thanks to three combined mechanisms:

• Diffusion — Very small particles (<0.1 µm) are struck by gas molecules and zigzag in Brownian motion, increasing the chance of hitting a fibre. Most effective at slow flow.
• Impaction — Large particles with high inertia cannot change direction with the airflow when they meet a fibre — they hit it head-on and stick. Effectiveness rises with higher velocity and smaller fibre spacing.
• Interception — Particles travel along the airflow, brush past a fibre, and are caught by direct contact.

Thanks to this, HEPA captures pollen, fungal spores, bacteria, particle-bound viruses, smoke, pet dander, and especially fine PM2.5 dust — a major cause of severe respiratory and cardiovascular disease.

3. HEPA classification per European standard EN 1822-1:2009

EN 1822-1:2009 is the most widely used standard in Vietnam and internationally. HEPA filters split into 5 grades:

Grade	Overall efficiency (%/MPPS)	Local efficiency (%/MPPS)	Overall penetration (%)	Local penetration (%)
H10	≥ 85	–	15	–
H11	≥ 95	–	5	–
H12	≥ 99.5	–	0.5	–
H13	≥ 99.95	99.75	0.05	0.25
H14	≥ 99.995	99.975	0.005	0.025

Note: under EN 1822-1:2009, only H13 and above can properly be called "HEPA"; H10-H12 are actually EPA (Efficient Particulate Air filters). On the Vietnamese market, however, all five grades are commonly lumped together as HEPA — check the exact code when ordering to avoid a grade mismatch.

4. Picking HEPA by cleanroom class

The required HEPA grade depends directly on the cleanroom requirement:

• Class 100,000 cleanroom (GMP Grade D) → use HEPA H13. Suitable for secondary packaging, storage areas, and some food processing.
• Class 10,000 cleanroom (GMP Grade C) → use HEPA H14. The common choice for pharmaceutical compounding and moderate-requirement electronics assembly.
• Class 1,000 or tighter (GMP A & B) → combine HEPA H14 + ULPA U15-U17 at the final supply point (terminal HEPA box or FFU).

Over-specification wastes money and adds pressure drop; under-specification fails GMP / ISO 14644. A proper step of computing dust load and ACH should precede every selection.

5. Real-world applications of HEPA Filters

HEPA shows up in many environments:

• Pharma plants and vaccine production — supply air for compounding and sterile vial filling, ensuring GMP-WHO compliance.
• Semiconductor, hard-drive, display, and camera manufacturing — controlling dust that would defect microchips.
• Hospitals — operating rooms, negative-pressure isolation rooms, tissue-culture rooms, ICUs.
• Food production & packaging — especially infant formula, functional foods, premium confectionery.
• Transport — commercial aircraft, some premium cars.
• Homes & offices — HEPA air purifiers protect against PM2.5, pollen, pet dander, and tobacco smoke.

6. Common HEPA form factors on the market

Depending on the mounting position, HEPA is built in several forms:

• HEPA Box (terminal HEPA) — mounted at the cleanroom ceiling with duct connections.
• HEPA Panel — used inside AHUs, FFUs, and air purifiers.
• HEPA Mini-pleat / V-bank — pleated for greater surface area and lower ΔP, increasingly replacing traditional aluminium-separator HEPAs.
• HEPA for 575×1175 FFUs — the standard module size for electronics and pharma cleanrooms.

The frame can be aluminium, powder-coated steel, or 304 stainless steel depending on environment (wet/decontamination environments use stainless).

7. Operation & maintenance notes

• Always install Pre + Medium Filters upstream — protects HEPA from coarse dust, extending life by 3-5×.
• Check differential pressure regularly — when ΔP across the HEPA exceeds 2× its initial value, it is time to replace.
• DOP / PAO testing — GMP cleanrooms require periodic leak tests (every 6-12 months).
• Do not reuse — HEPA is single-use, never wash or back-blow.

Conclusion

HEPA Filters are the "heart" of most high-end air-filtration systems — from GMP pharma cleanrooms and semiconductor fabs to home air purifiers in our PM2.5 era. Understanding EN 1822-1:2009 properly, picking the right H13-H14 grade, and pairing it with Pre + Medium upstream are the most effective ways to balance air quality with operating cost.

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About Green Filter

Green Filter is a Vietnamese brand specialising in HEPA Filters (H10-H14), ULPA, Medium, Pre Filters, FFUs, Cartridges and cleanroom accessories for pharma, electronics, food, and hospital plants nationwide. We offer free filter-grade consulting, FFU sizing from drawings, and long-term warranty.

📞 Contact Green Filter to find the right HEPA grade for your project: [insert hotline / email / website]

See also: ULPA Filter: how is U15/U16/U17 different from HEPA? · How to choose HEPA/ULPA by cleanroom class · GMP cleanrooms for pharma plants.