EV Charging Stations
Filtration for Power Equipment
Cleanroom & Semiconductor
Ultra-High Cleanliness Filtration
Commercial HVAC
Central Air System Filtration
Data Centers
Precision Equipment Protection
Livestock & Farming
Farming Environment Purification
Spray Booths & Industrial Dust
Paint Mist & Dust Purification
Filtration for Power Equipment
Professional air filtration for EV charging devices, protecting against dust and sand ingress to ensure stable, reliable operation of charging piles and station infrastructure.
View Related Products →Ultra-High Cleanliness Filtration
Ultra-high efficiency filtration for semiconductor wafer fabs and precision electronics cleanrooms, capturing nano-scale particles to meet ISO Class 1–3 standards and maximize product yield.
View Related Products →Central Air System Filtration
High-efficiency filtration for commercial building HVAC systems, improving indoor air quality, reducing energy consumption, and extending equipment service life.
View Related Products →Precision Equipment Protection
Precision air filtration for data centers, shielding servers and critical hardware from dust contamination to keep cooling systems running efficiently and reliably.
View Related Products →Farming Environment Purification
Dedicated filtration systems for farms and livestock facilities — capturing dust, adsorbing ammonia, and inhibiting pathogen spread to improve animal health and overall productivity.
View Related Products →Paint Mist & Dust Purification
Designed for spray booths and grinding workshops, efficiently capturing paint mist, metal dust, and wood chips to meet emission standards while protecting finished surface quality.
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Pre-Filter (G1–G4)
First-Stage Large-Particle Capture
Medium-Efficiency Filter (F5–F9)
Precise PM2.5 Capture
HEPA High-Efficiency Filter
Sterile-Grade Purification
ULPA Ultra-High Efficiency Filter
Sub-Micron Particle Capture
First-Stage Large-Particle Capture
The first line of defense, capturing particles ≥5 μm such as dust, hair, and fibers to protect downstream filters and extend overall system service life.
View Related Products →Precise PM2.5 Capture
Captures fine particles of 1–5 μm including PM2.5, pollen, and mold spores, significantly improving indoor air quality for commercial HVAC and ventilation systems.
View Related Products →Sterile-Grade Purification
≥99.97% filtration efficiency for particles ≥0.3 μm, delivering sterile-grade clean air widely used in medical, pharmaceutical, and electronics manufacturing.
View Related Products →Sub-Micron Particle Capture
≥99.9995% efficiency for particles ≥0.12 μm, meeting the extreme cleanliness demands of semiconductor fabs, aerospace, and other ultra-precision applications.
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High-Temperature Resistant
Industrial-Grade Heat Tolerance
Washable & Reusable
Cut Costs, Reduce Waste
Activated Carbon
Odor & Harmful Gas Removal
Bag Filter
High Dust-Holding, Long Life
Panel / Pleated Filter
Compact Space-Saving Design
Low-Resistance Airflow
Energy-Saving Operation
Industrial-Grade Heat Tolerance
Built with specialized heat-resistant materials, operating stably up to 250°C for paint ovens, industrial dryers, and high-temperature process environments.
View Related Products →Cut Costs, Reduce Waste
Cleanable by water washing or air blowing, reusable multiple times to significantly reduce replacement frequency and O&M costs — an economical, eco-friendly choice.
View Related Products →Odor & Harmful Gas Removal
Leverages activated carbon's high adsorption capacity to eliminate odors, VOCs, and formaldehyde, ideal for newly renovated spaces and industrial exhaust treatment.
View Related Products →High Dust-Holding, Long Life
Bag-style construction delivers a larger filtration area, high dust-holding capacity, and extended service life — ideal for high-dust environments with reduced replacement frequency.
View Related Products →Compact Space-Saving Design
Compact form factor for easy installation and replacement; pleated structure maximizes filtration area within a small footprint for higher efficiency.
View Related Products →Energy-Saving Operation
Low-resistance design minimizes pressure drop while maintaining filtration performance, reducing fan energy consumption for cost-effective, eco-friendly operation.
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The History and Facts of HEPA Filters: From Gas Masks to Modern Air Purification
HEPA filter history begins with a problem that had nothing to do with air quality: the need to stop radioactive particles from leaving a laboratory. Everything that followed — the name, the test methods, the class letters used in specifications today — comes from that single requirement. Reading HEPA filter history in order also explains why the same filter is rated 99.97% at 0.3 µm in one country and H13 at MPPS in another.
The starting point: gas masks and the limits of early media
The first high-efficiency media were developed for respirators, and they solved a different problem from the one HEPA filter history is usually told as.
The distinction matters because it explains the design philosophy that followed. A respirator filter could be judged by whether it protected the wearer. A containment filter had to be judged by a number that could be verified before installation, because the consequence of failure was contamination of an entire facility.
The 1940s: containment drives the design
The Manhattan Project's requirement for containing radioactive aerosols produced the first filters of the type now classified as HEPA. The essential design features were established then and have barely changed: a deep pleated media pack, a rigid frame, and a seal that prevents bypass around the media rather than through it.
| Design feature | Why it was introduced | Still current |
|---|---|---|
| Deep pleated media | Large surface area within a manageable frame depth, so face velocity stays low | Yes — the basis of every HEPA format |
| Rigid frame | Maintains media geometry under pressure and handling | Yes |
| Gasket or gel seal | Prevents unfiltered air bypassing the media pack | Yes — and still the most common field failure |
| Efficiency stated at a particle size | Made performance verifiable and reproducible | Yes — now stated at MPPS in EN 1822 and ISO 29463 |
That fourth row is the pivot. Earlier filters were described qualitatively; from this point on, a filter claim was a test result at a stated particle size. That is the pivotal shift in HEPA filter history.
From "absolute filter" to HEPA
The filters were initially described as absolute filters, a term that survives in some markets and in some legacy specifications. The name HEPA — high efficiency particulate air — came later, as the technology moved from classified programmes into industrial and then commercial use.
The lesson from this part of HEPA filter history is still relevant in procurement: a name is not a specification. "Absolute" and "HEPA" both describe an intent, and only a test standard with a stated particle size makes it verifiable. That distinction runs through the rest of HEPA filter history.
The test methods that came with the class
Efficiency classes only mean something alongside a test method, and the methods in HEPA filter history have changed more than the filters have.
Two changes in that list shaped the later course of HEPA filter history. The first is the move from batch sampling to scan testing, which turned HEPA performance into a per-unit claim. The second is the adoption of MPPS as the reference point, which replaced the earlier convention of rating at a fixed particle size.
Why the numbers differ: 0.3 µm and MPPS
This is the point in HEPA filter history where most confusion originates.
| Convention | Basis | Typical statement | Where it is used |
|---|---|---|---|
| US convention | Efficiency at 0.3 µm | 99.97% minimum | Legacy US specifications and many supplier datasheets |
| EN 1822 / ISO 29463 | Efficiency at MPPS, plus local penetration | H13 ≥99.95%, H14 ≥99.995% at MPPS | European and international cleanroom specifications |
The two are close in practice because 0.3 µm sits near the MPPS of typical glass-fibre HEPA media, but they are not the same claim. One names a fixed particle size; the other names the worst-case particle size for the media, which may be anywhere between 0.1 and 0.3 µm. That is why a HEPA filter can legitimately be quoted as 99.97% under one standard and H13 under another, and why the two figures cannot simply be converted. A specification that names both the value and the standard removes the ambiguity.
What HEPA filter history explains about today's hardware
Three features of current products are direct consequences of the history rather than independent design choices.
| Current feature | Historical origin |
|---|---|
| Scan testing as standard practice | Containment applications could not tolerate a leak anywhere on the filter face |
| The attention paid to sealing and gaskets | Bypass, not media efficiency, was recognised early as the dominant failure mode |
| Multiple frame formats for one class | Installations moved from laboratories into plant rooms and equipment cabinets with fixed dimensions |
The second row is worth carrying into any installation. HEPA filter history is largely a story about containment, and every generation of that story has found the same weak point — the seal, the frame joint, the installation tolerance. A filter that passes its class test and leaks at the frame has not solved the original problem.
The facts most often stated incorrectly
Five claims to check before repeating them
- HEPA filters do not remove gases or odours — they are particulate filters, and gas-phase control needs an adsorptive stage.
- HEPA efficiency is defined at MPPS, not at an arbitrary particle size, in EN 1822 and ISO 29463.
- A HEPA class is a minimum threshold, not a measured value — two H14 filters can differ in pressure drop and life.
- Local penetration is part of the class definition, which is why scan testing exists.
- HEPA filters cannot be washed and reused without losing their class, unlike coarse washable media.
These five points cover most of what is misattributed to HEPA filter history. The technology has been stable for decades; the standardisation around it is what has changed, and that is where specifications should be anchored.
Where a project needs the class today, the choice is mostly about frame depth and sealing method rather than about efficiency: the mini-pleated HEPA filter and the V-bank HEPA filter deliver the same class in different footprints, and the liquid tank HEPA filter is used where the seal itself must hold the class. The efficiency basis behind those classes is set out in air filter classification, and the measured parameters behind them in air filter performance.
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Related Products
These products cover the filtration stages discussed above; see each product page for full specifications.
ProductDeep Pleated HEPA FilterThe classic deep pleated construction, essentially unchanged since the original containment filtersView product details →ProductMini-Pleated HEPA FilterCompact HEPA format for terminal units and equipment cabinets where frame depth is fixedView product details →ProductV-Bank HEPA FilterLater format that delivers the same class within a smaller frame for high airflow systemsView product details →
ProductLiquid Tank HEPA FilterGel-sealed construction for installations where the seal itself must hold the classView product details →Frequently Asked Questions
The questions our engineering team receives most often on this topic.
When was the HEPA filter invented?
The filters now classified as HEPA were developed in the 1940s for the Manhattan Project, where airborne radioactive particles had to be contained rather than merely reduced. The essential design — deep pleated media in a rigid frame with a positive seal — dates from that period and has changed very little. The name HEPA came later, as the technology moved from classified programmes into industrial and commercial use.
Why were HEPA filters originally called absolute filters?
Because the term described an assertion rather than a tested class. Early filters were described as absolute to convey that nothing passed them, which was a manufacturing claim rather than a measurable definition. As the filters spread beyond their original applications, specifications needed a definition that could be tested and disputed, which led to efficiency stated at a defined particle size and to the HEPA name.
Why do some HEPA filters say 99.97% and others H13?
They follow different conventions. The US convention rates efficiency at 0.3 µm, typically as a 99.97% minimum. EN 1822 and ISO 29463 rate at the most penetrating particle size, which for typical glass-fibre media falls between 0.1 and 0.3 µm, and define H13 at 99.95% and H14 at 99.995%. The figures are close in practice and are not convertible, because one names a fixed particle size and the other the worst case for the media.
What is the DOP test and is it still used?
The DOP test uses a generated aerosol to challenge the filter and measures the downstream concentration, which is the basis of high-efficiency filter testing. Dioctyl phthalate was the original challenge aerosol and the name persists in specifications. For health and safety reasons it has largely been replaced by poly-alpha-olefin, or PAO, with the test principle unchanged. Modern standards add scan testing, which checks local penetration across the filter face rather than relying on an average.
Do HEPA filters remove odours or gases?
No. HEPA filters are particulate filters, and the class is defined by particle capture efficiency at MPPS. Gases, odours and VOCs are molecular and pass through the media, so gas-phase control requires a separate adsorptive stage using activated carbon or a catalyst. Systems that need both typically stack a gas-phase stage after the particulate stages, and the two are specified and replaced on different criteria.