The component that decides what the room is
HEPA filtration for cleanrooms
Almost everything a cleanroom claims about itself comes down to one component you can point at: the filter in the ceiling. Get its grade, its seal and how much of the ceiling it covers right, and the room holds its class year after year. Get any one of the three wrong and no amount of air changes will rescue it.
- EN 1822
- H13 and H14
- ULPA U15 to U17
- ISO 14644
- ISO 16890
FIG. 01Filter efficiency against particle size. The dip is the most penetrating particle size, and it is not at 0.3 micron.
A HEPA filter does not catch particles down to 0.3 micron. Around 0.3 micron is roughly the hardest size for it to catch.
It performs better than its rating on everything larger, and better again on everything smaller. That single fact is the whole subject, and the rest of this page is what follows from it.
We walk through what the filter is, how the grades work, where the filter sits, how it is sealed and proved, and when it is changed. By the end, a filter datasheet will read differently.
- H13HEPA. At least 99.95 percent at MPPS, EN 1822
- H14HEPA. At least 99.995 percent at MPPS, EN 1822
- U15ULPA. At least 99.9995 percent at MPPS, EN 1822
What a HEPA filter is
A HEPA filter, short for High Efficiency Particulate Air filter, is a deep-pleated filter of fine glass-fibre media that removes airborne particles from a supply air stream. Under the European standard EN 1822, a filter earns the HEPA label only at grade H13 or grade H14.
H13 removes at least 99.95 percent of particles at its most penetrating particle size. H14 removes at least 99.995 percent.
Physically it is a shallow box. A frame of extruded aluminium, galvanised steel or stainless steel holds a continuous sheet of glass-fibre paper. The paper is folded into hundreds of pleats, separated by aluminium spacers or, in a mini-pleat design, by fine hot-melt beads.
The pleating is the point. It packs several square metres of media into a face the size of a ceiling tile. Air can then pass through slowly enough to be filtered while the room still gets the volume it needs. Slow air through a large area is the whole trick.
That is why a HEPA filter is wide and flat rather than small and fast. In a cleanroom, it is the last thing the air touches before it reaches your product. Everything else on this page, the grades, the seals, the testing, exists to protect what that one sheet of media does.
FIG. 02Why a HEPA filter is wide and flat. Folding the media multiplies the area the air passes through, so face velocity falls without the room losing volume.
The 0.3 micron misunderstanding
Read almost any filter listing and you will be told a HEPA filter removes particles down to 0.3 micron, as though 0.3 micron were a floor and anything smaller slipped through. It is the wrong way round. Believing it leads buyers to over-specify in one direction and worry about the wrong risk in the other.
What almost every listing says
Removes particles down to 0.3 micron
What the standard actually measures
Around 0.3 micron is where a HEPA filter is at its weakest
Above that size it does better. Below it, strange as that sounds, it does better again.
A filter is not a sieve with holes of a fixed size. It captures particles in several different ways, and the ways hand over to each other as particles get smaller.
Inertial impaction
Large, heavy particles cannot follow the air as it swerves around a fibre. They carry straight on and hit it.
Interception
Mid-size particles follow the airflow but pass close enough for their edge to touch a fibre and stick.
Diffusion
The very smallest particles stop behaving like tiny cannonballs. They jitter under Brownian motion and wander into fibres. The smaller they get, the more certainly they are caught.
FIG. 03The three capture mechanisms, drawn at the fibre. Each one owns a different part of the size range, and the MPPS band is where the handover between them leaves a gap.
Between those regimes sits a narrow band where nothing works well. For typical glass-fibre media it falls between roughly 0.1 and 0.3 micron. A particle there is too small to be thrown into a fibre and too large to jitter into one. That band is the most penetrating particle size, or MPPS, and it is the filter's worst case.
Micron. The most penetrating particle size, and the filter's worst case
| Particle size | Dominant capture mechanism | What the filter does |
|---|---|---|
| 1 micron and larger | Inertial impaction, plus straining | Near-total capture, far better than the rated figure |
| 0.5 micron | Interception, with some impaction | Very high, comfortably above the rating |
| Roughly 0.1 to 0.3 micronTHE MPPS BAND | None of them works well: this is the MPPS band | The weakest point, and the number the grade is based on |
| 0.05 micron | Diffusion begins to take over | Efficiency climbing again |
| 0.01 micron and smaller | Diffusion dominates | Near-total capture, better than the rated figure |
FIG. 04Capture regimes for typical glass-fibre HEPA media.
That settles the two questions this page gets asked most. Will a HEPA stop something smaller than 0.3 micron, such as a virus-sized particle or a semiconductor-relevant nanoparticle? Yes, and more reliably than it stops 0.3 micron itself. Should you jump to ULPA because your contaminant is small? Not for that reason alone. Small is the easy end.
Carry this forward
Hold onto that idea through the rest of the page. It reframes what every number below is really telling you.
HEPA and ULPA grades under EN 1822
- EPA
- E10 to E12. Not individually scanned
- HEPA
- H13, H14. Scanned, certificate per filter
- ULPA
- U15 to U17. Scanned, certificate per filter
Filter grades are not marketing labels. EN 1822 sorts high-efficiency filters into three families by how much gets through at MPPS. The families are EPA, HEPA and ULPA, and the table below shows the grades inside each.
Each step up takes another slice out of what passes. Each step also costs more fan energy to push air through. That makes the grade a real operating decision rather than a free upgrade.
Two efficiency figures matter, and datasheets often quote only the first. Overall efficiency is measured across the whole filter face. Local efficiency is the worst reading found anywhere on that face while the filter is scanned point by point. The scan is what catches a pinhole in one pleat that an averaged figure would hide.
HEPA and ULPA grades carry both figures. EPA grades are not individually scanned at all. That difference matters more than it looks, and the table shows why.
| Grade | Family | Overall efficiency at MPPS | Local (scanned) efficiency | Where it is normally used |
|---|---|---|---|---|
| E10 to E12 | EPA | 85 to 99.5 percent | Not required | Secondary filtration and protection of the HEPA behind it, never as the final filter of a classified room |
| H13 | HEPA | At least 99.95 percent | At least 99.75 percent | ISO Class 7 and ISO Class 8 space, general GMP areas, pass boxes, air showers |
| H14 | HEPA | At least 99.995 percent | At least 99.975 percent | ISO Class 5 to 7, laminar airflow units, biosafety cabinets, aseptic areas |
| U15 | ULPA | At least 99.9995 percent | At least 99.9975 percent | ISO Class 5 and cleaner, semiconductor and micro-electronics work |
| U16 | ULPA | At least 99.99995 percent | At least 99.99975 percent | Ultra-clean tool environments |
| U17 | ULPA | At least 99.999995 percent | At least 99.9999 percent | The most demanding process environments |
FIG. 05Source: EN 1822, high-efficiency air filters. Efficiencies are stated at the filter's own MPPS.
One thing to watch when a quotation lands. E11 and E12 filters are often sold as HEPA-type or near-HEPA, and they are neither. They sit a whole family below H13, and no one scans them individually. Nothing certifies that the particular filter you receive is leak-free.
Ask for this before it goes in the ceiling
A genuine HEPA arrives with an individual test certificate carrying its own serial number and measured efficiency. Ask for it before the filter goes into the ceiling, not after. Reading a datasheet with this in hand is simple: find the grade, find both efficiency figures, and check the certificate belongs to the filter in the box.
Rated at its own worst case
A filter rated H14 is rated at its own worst case.
At 0.5 micron it is better than its printed figure, and at 0.01 micron it is better again. A worst-case rating cannot flatter itself, which is exactly why the standard uses it.
- Better than the printed figure
- 0.5 micron
- Where the grade is measured
- MPPS
- Better again
- 0.01 micron
Why “99.97 percent at 0.3 micron” is not the same as “H14”
Two different numbers turn up on filter datasheets in this market, and they are routinely treated as interchangeable. One says H14 to EN 1822. The other says 99.97 percent at 0.3 micron. They come from different test methods at different particle sizes. Comparing them directly will lead you to the wrong filter.
The older convention
The older figure comes from the American convention. The filter is challenged with an aerosol at a fixed 0.3 micron and read on a photometer, which gives one overall number at one size. The classic test aerosol is DOP, di-octyl phthalate, now widely replaced in practice by the safer PAO, poly-alpha-olefin.
EN 1822
EN 1822 does something harder. It first finds the MPPS for that specific media and measures efficiency there with a particle counter. It then scans the whole filter face for local leaks and issues a per-filter certificate. Because MPPS usually sits below 0.3 micron, the EN 1822 figure is taken at the tougher point on the curve.
| Compared on | EN 1822, the MPPS method | The older 0.3 micron convention |
|---|---|---|
| Particle size tested | The filter's own most penetrating particle size, determined by test | A fixed 0.3 micron challenge |
| Test aerosol | DEHS or PAO, counted particle by particle | DOP or PAO, read on a photometer |
| Leak scanning | Every filter individually scanned, local efficiency recorded | Overall figure only, scanning is a separate practice |
| What you are handed | A grade (H13, H14, U15 to U17) and a serial-numbered certificate | A percentage at one particle size |
| Practical reading | Worst case, so the filter is better everywhere else | A good number taken at a size the filter already handles well |
FIG. 06Both methods are in current use on datasheets sold into India. They are not interchangeable.
For a specification the instruction is short. State the EN 1822 grade you require, then ask for the individual test certificate and the scan record. Treat 99.97 percent at 0.3 micron as the start of a conversation rather than a grade.
The difference is not academic. A tender written in one convention and priced in the other can land the wrong filter entirely. If the tender you are holding uses the older language, translate it onto an EN 1822 grade before anyone prices it.
When in doubt, ask the supplier which method produced the number on the datasheet. A good one will tell you without hesitation, and the answer tells you plenty.
The curve, and the trough the whole industry gets wrong
Everything on this page so far lives on one chart. The capture mechanisms are its two limbs, the EN 1822 grades are the horizontal bands, and the two rival test methods are two different points on it. Read the trough and the rest follows.
- Efficiency of an H14 medium
- EN 1822 grade threshold
- Arriving particle
FIG. 07Efficiency of a typical H14 medium against particle size, with the EN 1822 grade thresholds on the same axes. The curve bottoms out in the MPPS band, and 0.3 micron sits on the way back up.
- The dip
- The curve does not fall as particles get smaller. It falls to a minimum in the MPPS band and climbs again on both sides.
- Where the grade is read
- EN 1822 measures at the bottom of that dip. An H14 medium meets 99.995 percent there, and beats it everywhere else on the axis.
- Where 0.3 micron sits
- To the right of the trough, already on the rising limb. A single reading taken there is taken at a size the filter already handles well.
Terminal HEPA, fan filter unit or AHU-mounted: where the filter goes
The same H14 filter behaves differently depending on where in the air system you put it. That choice drives cost, maintenance access and how quickly a room recovers after a disturbance. There are three normal answers, and most facilities use more than one of them.
FIG. 08The same H14 filter in three positions in one air system. Everything downstream of the filter is unfiltered air, which is why a classified room filters at the ceiling.
- 1
Terminal HEPA housing
A terminal HEPA housing puts the filter in the ceiling of the room itself, fed by ducted air from a central air-handling unit. It carries a volume damper, an aerosol injection port and a test port built in.
- 2
Fan filter unit
A fan filter unit, or FFU, carries its own fan and filter in one ceiling module. It draws from a pressurised plenum above and pushes straight down into the room.
- 3
AHU-mounted or in-duct
AHU-mounted or in-duct filtration puts the high-efficiency stage back at the air handler, upstream of the ductwork. Each arrangement places the filter at a different point between the air handler and your product, and the table compares them.
The working rule for a classified room is to filter terminally, at the ceiling. That way no duct, plenum or length of insulation sits between the filter and your process. AHU-mounted stages then do what they are good at: protecting the terminal filters and conditioning the air.
| Compared on | Terminal HEPA housing | Fan filter unit (FFU) | AHU-mounted and in-duct |
|---|---|---|---|
| Where the filter is | In the room's ceiling, at the boundary | In the room's ceiling, fan included | Back at the air-handling unit |
| Air source | Ducted from a central AHU | A common plenum above the ceiling | The AHU itself |
| Strength | The last thing air touches is the filter, so nothing downstream can contaminate it, and it is easy to scan from the room | Airflow is set unit by unit, so a ceiling can be zoned and re-zoned. Well suited to large open ISO Class 5 to 6 areas | One place to service, lower ceiling cost, good for recirculation and for exhaust duty |
| Watch out for | Needs ducted balancing and a damper per outlet | More motors to maintain, and fan noise and heat land in the ceiling | Every metre of duct downstream is unfiltered, so it should not be the only high-efficiency stage for classified space |
| Typical use | GMP pharma rooms, ISO Class 7 and 8, most classified space | Semiconductor, electronics and photovoltaic ceilings, ISO Class 5 and 6 | Pre-filtration and fine filtration, containment exhaust, recirculation air |
FIG. 09Most facilities run more than one of these arrangements. The choice is made room by room, not building by building.
In real facilities the arrangements mix. A pharma suite may run terminal housings fed by one air handler while an electronics ballroom next door runs an FFU ceiling. How the pieces fit together with air-change rates and the pressure cascade is set out on the cleanroom HVAC page.
Where a filter sits inside equipment rather than a ceiling, as in a laminar airflow unit or a biosafety cabinet, the same grade logic applies inside the machine. The range is on the cleanroom equipment page.
Gel seal or gasket: how the filter meets its housing
A perfect filter in a leaking frame is a leaking ceiling. Air takes the easiest route it can find, and a hairline gap around a filter edge is easier than several square metres of glass-fibre media. The seal is part of the specification, not an installation detail to settle on site.
Two sealing systems dominate, and the right one depends on how clean the room behind the filter has to be. The seal is chosen with the filter grade, not after it. The cleaner the room, the less forgiveness there is for a marginal edge.
Gasket seal
A strip of closed-cell neoprene or EPDM bonded to the filter frame and clamped against the housing. It is simple, proven and less expensive. But it depends on even clamping pressure against a flat surface, and the material slowly takes a permanent set. So it is re-checked at every filter change.
Gel seal
The filter frame carries a channel of viscoelastic gel, and a knife edge on the housing sits down into it. The gel flows around the blade and forms a continuous, self-healing seal. It forgives small irregularities in the ceiling grid and survives repeated removal and refitting.
Where each belongs
Gel seal is the standard choice for EU-GMP Grade A and Grade B areas, ISO Class 5 work and any ULPA installation. A gasket seal remains reasonable in ISO Class 8 support space, where the consequence of a marginal leak is lower.
Containment exhaust
Sometimes the filter's job is to hold something in rather than keep something out, as on BSL laboratory or potent-compound exhaust. Here the housing changes. A bag-in, bag-out safe-change housing lets a loaded filter be removed inside a sealed bag, so nobody is exposed to what it has collected.
How filtration sets the ISO class: grade, coverage and air changes
- 01Grade. The filter's own efficiency at MPPS
- 02Coverage. How much of the ceiling is filter face
- 03Air changes. How often the room's air is replaced
The question that arrives most often is simple: which HEPA grade does an ISO Class 7 room need? The honest answer is that grade is one of three levers, and usually not the decisive one. How much of the ceiling is filter and how many times an hour the air is replaced do most of the work.
ISO Class 8
5 to 15
percent ceiling coverage
H13 or H14
ISO Class 7
15 to 25
percent ceiling coverage
H14
ISO Class 6
25 to 40
percent ceiling coverage
H14
ISO Class 5
60 to 100
percent ceiling coverage
H14 or U15
FIG. 10Ceiling plans at four classes, drawn to the same room. The filled tiles are filter face. Coverage, not grade, is what changes most between them.
A room with the finest filter money can buy, covering five percent of its ceiling, will not hold ISO Class 5. Cleanliness comes from dilution and sweeping as much as from filtration.
Every hour a cleanroom generates particles from people, process and movement. The air system has to remove them faster than they appear. More filter area in the ceiling means more clean air delivered, and a shorter recovery time after a door opens or a gowned operator walks through.
That is why coverage climbs steeply as the class tightens, until at ISO Class 5 the ceiling is effectively one continuous filter face delivering unidirectional air.
Recovery is the quiet part of the specification. A room is judged not only on how clean it sits, but on how fast it comes back after people and process disturb it.
| ISO 14644-1 class | Typical HEPA ceiling coverage | Airflow pattern and rate | Filter grade usually specified |
|---|---|---|---|
| ISO Class 5EU-GMP GRADE A | Roughly 60 to 100 percent | Unidirectional, about 0.36 to 0.54 m/s across the zone | H14, or U15 where the process demands it |
| ISO Class 6 | Roughly 25 to 40 percent | Non-unidirectional, high turnover | H14 |
| ISO Class 7GRADE B AT REST, C IN OPERATION | Roughly 15 to 25 percent | Non-unidirectional, roughly 40 to 60 ACPH | H14 |
| ISO Class 8GRADE C TO D | Roughly 5 to 15 percent | Non-unidirectional, roughly 20 ACPH | H13 or H14 |
FIG. 11Directional figures for a typical Indian pharmaceutical or electronics facility, not a specification.
Read the table as directional rather than prescriptive. The real numbers come out of the room's heat load, its occupancy, the process inside it and the recovery time the qualification protocol demands. If you keep one rule from this section, keep this one: buy coverage and air first, grade second.
The particle limits for each class, and how they line up against the EU-GMP grades at rest and in operation, are on the ISO classification of cleanrooms page. The way air-change rates and the pressure cascade are engineered around them is on the cleanroom HVAC page.
A ceiling that is effectively one continuous filter face is a vertical laminar airflow problem as much as a filtration one.
- Grade standard
- EN 1822
- The two HEPA grades
- H13 and H14
- The ULPA grades
- U15 to U17
- Room classification
- ISO 14644
- Pre-filter and fine-filter grades
- ISO 16890
In-place integrity testing: proving the filter after it is installed
A filter that passed every test at the factory can still leak once it is in your ceiling. A knock in transit, a frame fractionally out of true, an over-tightened clamp, a ceiling grid that is not quite flat. Any of these opens a path around a filter that is itself perfectly sound.
So the test that decides whether a room can be released is the one done in place, after installation, with the air system running. This is the test that turns a built ceiling into a working cleanroom.
FIG. 12The in-place scan. The probe travels the whole downstream face and the full perimeter of the seal, in overlapping strokes, because a leak at the frame reads exactly like a leak in the media.
- 01
Introduce the challenge
A test aerosol, today usually PAO rather than the older DOP, is introduced into the duct upstream and allowed to reach a uniform, known concentration.
- 02
Scan the face and the seal
A probe is then passed slowly across the entire downstream face and around the seal and frame. A photometer or particle counter reads what comes through. The probe is held about 25 mm from the surface and moved at roughly 5 cm per second, in overlapping strokes.
- 03
Judge against the criterion
Anything above the acceptance criterion is a leak. For an H14 installation the criterion is commonly 0.01 percent penetration of the upstream concentration.
- 04
Repair or replace, then re-scan
A found leak is located precisely, repaired within the limits the filter standard permits and re-scanned, or the filter is replaced.
Integrity testing is not a one-off. It is performed at installation as part of qualification, after any filter change, and at defined intervals through the life of the facility. EU-GMP Annex 1 expects filters serving Grade A and Grade B areas to be integrity tested at least every six months. Lower grades follow a risk-based interval.
The methods sit in ISO 14644-3, alongside airflow velocity, pressure differential, recovery and particle-count testing. Together these tests turn a built room into a qualified one.
The record runs through four stages: design, installation, operational and performance qualification. On paperwork the first two appear as DQ and IQ. The last two appear as OQ and PQ. The full scope is on the cleanroom validation and qualification page.
Pre-filters, differential pressure and when a HEPA is actually changed
A terminal HEPA is expensive, slow to change and disruptive to re-qualify. It should never be the filter doing the dirty work. That job belongs to the cheap filters in front of it. The single biggest thing that shortens a HEPA's life is a neglected pre-filter regime upstream.
In a normal cleanroom the air passes through a train of three stages. A coarse pre-filter at the air-handling unit catches insects, fibres and visible dust, and is cleaned or swapped often. A fine filter then removes the fine fraction that would otherwise load the HEPA. Only after both does the air reach the terminal HEPA in the room.
Fine filters are classified under ISO 16890 as ePM1 or ePM2.5 grades, in place of the older EN 779 G and F designations. Each stage carries a differential-pressure gauge, because pressure drop, not the calendar, tells you the state of a filter.
- Clean resistanceA clean terminal HEPA typically presents somewhere around 100 to 250 Pa of resistance, depending on its face velocity and media area. As it loads, resistance climbs, the fan works harder and delivered air volume falls.
- Change triggerThe filter is changed when its differential pressure reaches roughly twice the clean value, or the manufacturer's stated final resistance. It also goes when airflow can no longer hold the air-change rate the class requires, or when it fails an in-place scan that cannot be repaired.
- Service lifeWith a well-maintained train in front of it, a terminal HEPA in a pharmaceutical cleanroom commonly runs three to five years. Without one, it can be finished in a fraction of that. The economics are straightforward: change the cheap filters often so the expensive one lasts.
- Indian ambient loadAmbient particulate loading around most industrial estates is high. Monsoon humidity puts moisture through the intake for months at a time, and construction dust travels a long way. All of it lands on the pre-filter stage.
FIG. 13The three-stage filter train, with a differential-pressure gauge across every stage. Air marches left to right. The terminal HEPA only ever sees what the two stages in front of it let past.
A disciplined monthly pre-filter routine, checked against the gauges rather than the diary, is the cheapest protection a terminal HEPA will ever get. None of this needs a specialist on site every day. It needs the gauges read, the readings logged and the swap done when the numbers say so.
- Micron. The MPPS band, where a HEPA is weakest
- 0.1 to 0.3
- Grade normally specified for ISO Class 5 to 7
- H14
- Months. Maximum integrity-test interval for Grade A and BEU-GMP Annex 1
- 6
- Years. Typical terminal HEPA life behind a maintained train
- 3 to 5
What HEPA filtration does not do
Knowing what a technology cannot do is as useful as knowing what it can. A HEPA filter is a particle device, and only a particle device. Gases, vapours and odours pass straight through it as if it were not there.
Solvent vapour, ammonia, ozone, formaldehyde and volatile organics are molecules, orders of magnitude smaller than the particles the media is built to capture. No HEPA grade changes that. The plain test is memorable: if you can smell it, a HEPA will not remove it.
Where those contaminants matter, the answer is a different medium in series with the HEPA, not a better HEPA. Activated carbon and impregnated chemisorbent media adsorb gases and vapours. In semiconductor and photovoltaic facilities they are specified explicitly against airborne molecular contamination, the acid, base, condensable and dopant fractions that damage a wafer surface long before a particle would.
Where the chemistry is handled by an operator rather than filtered from a room, containment at source is the right control. That is what a fume hood does.
There is a second limit worth stating plainly. A HEPA retains micro-organisms. It does not kill them. A loaded filter on a containment exhaust is holding live material. That is why safe-change housings exist, and why biosafety cabinets are decontaminated before their filters are touched.
It removes
- Airborne particles
- Viable particles carried on skin flakes and droplets
- Fibres, dust and process debris
- Virus-sized particles, caught by diffusion
It does not remove
- Solvent vapour and volatile organics
- Ammonia, ozone and formaldehyde
- Odours of any kind
- Micro-organisms already on the media, which it retains rather than kills
FIG. 14Two media in series. Particles are held at the HEPA. Gas molecules pass it untouched and are adsorbed at the activated carbon behind it, which is why raising the HEPA grade buys nothing against a vapour.
The lesson for a specification is short. Match the medium to the contaminant, and let the HEPA do the one job it is built for: particles.
Particles: HEPA. Gases and vapours: activated carbon or chemisorbent media, in series.
How Fabtech delivers HEPA filtration
Fabtech specifies, supplies, installs, integrates and validates HEPA and ULPA filtration as part of the cleanroom it belongs to. The grade set in the design is then the grade that gets scanned and released on site. One team owns the filter decision from the first design meeting to the final scan.
The laminar airflow units and biosafety cabinets that carry H14 filters inside them are engineered and built in-house. The filter, the housing and the airflow around it are designed as one thing, not assembled from three assumptions.
ULPA grades U15 and above are specified where the process calls for them. Equipment-level AMC covering filter condition and replacement is available afterwards.
Behind that sits Fabtech Cleanrooms. The company has designed, built and validated more than 2,000 controlled environments across every industry that needs controlled air in India since 2004, holding ISO 9001 for quality management. Its cleanrooms are built to withstand inspection under EU-GMP and US-FDA expectations. They stand just as ready under WHO-GMP and cGMP.
- 01
Specify
The grade against your target ISO class and process risk.
- 02
Supply
Terminal housings, fan filter units, gel or gasket seals to match the grade.
- 03
Install
Set into the ceiling grid, balanced, damper by damper.
- 04
Integrate
Filtration, ceiling coverage and air-change rate designed as one system.
- 05
Validate
In-place integrity testing and particle counts, into the qualification dossier.
Capability record
HEPA-filtered, ISO 14644 classified
Fabtech has delivered HEPA-filtered, ISO 14644 classified cleanrooms for pharmaceutical, research and electronics clients across India.
- Ajanta PharmaAurangabad. Pharmaceutical.
- DesanoPharmaceutical.
- BARCResearch.
- BoschNashik. Electronics.
- PGICH NoidaBSL containment.
- ASMC ShahjahanpurBSL containment.
Filter grades, coverage and per-project scope are available on request.See the work on turnkey cleanroom solutions
Frequently asked questions
The one thing to carry
Every answer here comes back to the same fact. A filter is graded at MPPS, its own worst case, and 0.3 micron sits on the way back up from it.
A HEPA filter, or High Efficiency Particulate Air filter, is a deep-pleated filter of fine glass-fibre media that removes airborne particles from supply air. Under EN 1822 it qualifies as HEPA at grade H13 or H14. In a cleanroom it is the last filter before the product.
No, the common phrasing has it backwards. Around 0.3 micron is the hardest size for a HEPA filter to catch, not the smallest. Larger particles are caught by impaction and interception, smaller ones by diffusion, so the filter performs better on both sides of that band than within it.
MPPS is the most penetrating particle size, the size at which a given filter medium performs worst. For typical glass-fibre HEPA media it falls between roughly 0.1 and 0.3 micron. EN 1822 measures efficiency at the MPPS, so a filter's published grade is its worst case, not a flattering figure.
Both are HEPA grades under EN 1822. H13 removes at least 99.95 percent of particles at the most penetrating particle size, H14 at least 99.995 percent, so roughly ten times less passes through. H13 suits ISO Class 7 and 8. H14 serves ISO Class 5 to 7 and aseptic areas.
ULPA stands for Ultra Low Penetration Air. Under EN 1822 ULPA runs from U15, at least 99.9995 percent at the most penetrating particle size, up to U17. It suits ISO Class 5 and cleaner work in semiconductor and micro-electronics, chosen on process need rather than as a general upgrade.
No. They come from different test methods at different particle sizes. The 0.3 micron figure is one overall reading at a fixed size, from the older American convention. EN 1822 measures at the most penetrating particle size and scans every filter for leaks. Specify the grade and request the certificate.
An ISO Class 7 room normally carries H14 terminal filters, but grade alone does not deliver the class. Ceiling coverage near 15 to 25 percent and 40 to 60 air changes per hour do most of the work. The final numbers come from heat load, occupancy and recovery time.
A gasket seal is a neoprene or EPDM strip clamped between frame and housing, simple but dependent on even pressure. A gel seal sets a knife edge into a channel of gel, giving a self-healing seal. Gel is standard for Grade A and B areas and ISO Class 5 work.
On condition rather than on a calendar. A terminal HEPA is replaced when its differential pressure reaches roughly twice the clean value, when airflow can no longer hold the required air-change rate, or when it fails an integrity scan. With good pre-filters it commonly runs three to five years.
It is an in-place leak test of the installed filter, housing and seal. A PAO or DOP aerosol is fed in upstream, and a probe scans the downstream face for any penetration. It runs at qualification, after filter changes, and at least every six months for Grade A and B.
They remove particles, including virus-sized particles, which diffusion catches efficiently. They do not remove gases, vapours or odours. Activated carbon or chemisorbent media handle those. A HEPA also retains micro-organisms rather than killing them, so containment exhaust filters are changed through safe-change housings.
Yes. Fabtech specifies, supplies, installs, integrates and validates HEPA and ULPA filtration as part of the cleanroom and its air system, from terminal housings to fan filter units. The laminar airflow units and biosafety cabinets built in its own facility carry the same filtration, proved at qualification.
Send us the class you have to hold
Send us the class you have to hold, the floor plan and the process running inside it. Our engineers will come back with the filter grade, the ceiling coverage, the air-change rate and the qualification plan that will get you there.