For most industrial air filtration buyers, the H11, H12, and H13 filter grades are the three grades that come up on every quote, and the three grades are the three grades that decide the right HEPA class for the application. The three grades are defined by EN 1822:2019, the European standard for high-efficiency air filters, and the three grades cover the bulk of the industrial HEPA filter market from general pre-filtration (H11) through pharma secondary (H12) to cleanroom final (H13). The right way to choose between the three grades is not the headline efficiency number; the right way is the MPPS (Most Penetrating Particle Size) test, the pressure drop budget, the dust-holding capacity, and the destination-market emission target. Because the three grades are defined by the same standard but serve very different applications, the right grade is the grade that matches the application rather than the grade that maximises the headline number. This guide walks through the EN 1822 standard, the MPPS concept, the practical differences between H11, H12, and H13 on an ePTFE air filter membrane, the application match, and the common mistakes when specifying the three grades, drawing on the high-efficiency ePTFE filter membrane product line from CY-PTFE and the EN 1822 grade definitions that the line reaches.
Why H11, H12, and H13 Are the Three Grades Every Industrial Buyer Asks About
There is a structural reason the H11, H12, and H13 grades are the three grades that come up on every industrial air filtration quote. The three grades cover the bulk of the industrial HEPA filter market from general pre-filtration (H11) through pharma secondary (H12) to cleanroom final (H13), and the three grades are the three grades that the destination-market emission directive and the destination-market cleanroom standard both reference. The three grades are the three grades that the buyer’s spec sheet has to name, and the three grades are the three grades that the buyer’s compliance program has to defend. Because the three grades cover the bulk of the industrial HEPA market, the three grades are the three grades that the buyer’s spec sheet cannot avoid, and the three grades are the three grades that the buyer’s spec sheet has to get right.
There is a second reason the three grades come up on every quote. The three grades are the three grades that the ePTFE filter media can reach with the same manufacturing process. An ePTFE membrane manufacturer can reach H11, H12, and H13 on the same line, with the grade being set by the membrane’s pore size, pore size distribution, and open area rather than by a fundamental change to the membrane chemistry. The pore size, pore size distribution, and open area are the three parameters that the membrane manufacturer sets, and the three parameters are the three parameters that the buyer’s spec sheet has to name. For the broader context of how clean air sits inside the global energy and industrial agenda, the UN Sustainable Development Goal 7 — Affordable and Clean Energy framework is the right cross-industry reference for the energy and industrial efficiency side of the clean-air agenda.
There is a third reason the three grades come up on every quote. The three grades are the three grades that the buyer’s downstream customer understands. The downstream customer understands H11 as the pre-filtration grade, H12 as the secondary grade, and H13 as the cleanroom grade, and the downstream customer expects the buyer’s spec sheet to name the three grades. The downstream customer’s expectation is the right reason to write the three grades on the spec sheet rather than the underlying EN 1822 standard, and the downstream customer’s expectation is the right reason to defend the three-grade choice on the spec sheet. The three grades are the three grades that the buyer’s spec sheet has to name, and the three grades are the three grades that the buyer’s spec sheet has to defend.
What Is EN 1822 and Why Does It Use the H-Grade Naming?
EN 1822:2019 is the European standard for high-efficiency air filters (EPA, HEPA, and ULPA), and the H-grade naming is the naming the standard uses to classify filters by overall efficiency and by MPPS local efficiency. The standard defines five HEPA classes (H10, H11, H12, H13, H14) and three ULPA classes (U15, U16, U17), and the standard uses the H or U prefix to distinguish HEPA (H for High Efficiency) from ULPA (U for Ultra Low Penetration Air). The H-grade naming is the naming the European OEM and the European filter buyer both use, and the H-grade naming is the naming the destination-market emission directive references. Because the H-grade naming is the naming the destination-market emission directive references, the right way to write the spec sheet is to use the EN 1822 grade name, not the underlying ASHRAE or ISO equivalent.
EN 1822 classifies each HEPA class by two efficiency numbers, and the two efficiency numbers are the right numbers to read on the spec sheet. The first number is the overall efficiency (the fraction of particles captured across the entire filter media, weighted by the upstream particle size distribution), and the second number is the MPPS local efficiency (the fraction of particles captured at the most-penetrating particle size, typically around 0.3 micrometres for HEPA-grade ePTFE media). The H11 class reaches >= 95 percent overall and >= 85 percent local. The H12 class reaches >= 99.5 percent overall and >= 99.5 percent local. The H13 class reaches >= 99.95 percent overall and >= 99.95 percent local, the typical HEPA class. For the destination-market emission directive that the buyer’s spec sheet has to defend, the EPA mercury programme is the right North American reference, and the European industrial emission directive 2010/75/EU is the right European reference for the destination-side compliance that the H-grade choice has to satisfy.
| EN 1822 class | Overall efficiency | MPPS local efficiency | Typical US EPA equivalent | Typical application |
|---|---|---|---|---|
| H10 | >= 85 percent | n/a | EPA 9 to 10 | General pre-filtration (intake air) |
| H11 | >= 95 percent | >= 85 percent | EPA 10 to 12 | General industrial pre-filtration, metalworking, cement kiln preheater, asphalt primary stage |
| H12 | >= 99.5 percent | >= 99.5 percent | EPA 11 to 13 | Pharma secondary, food pre-HEPA, electronics pre-cleanroom, steel sinter plant baghouse |
| H13 | >= 99.95 percent | >= 99.95 percent | HEPA (typical) | Pharma final, hospital isolation, semiconductor cleanroom, nuclear adjacent |
| H14 | >= 99.995 percent | >= 99.995 percent | HEPA (high-end) | Pharma aseptic fill, semiconductor lithography |
| U15 | >= 99.9995 percent | >= 99.9995 percent | ULPA 15 | Pharma aseptic, BSL-3 lab |
| U16 | >= 99.99995 percent | >= 99.99995 percent | ULPA 16 | Semiconductor lithography, BSL-4 lab |
| U17 | >= 99.999995 percent | >= 99.999995 percent | ULPA 17 | Nuclear HEPA, semiconductor EUV |
The right way to read the table is to look at the MPPS local efficiency column, not the overall efficiency column. The MPPS local efficiency is the right metric to compare HEPA grades, because the MPPS local efficiency is the metric the destination-market emission directive references, and the MPPS local efficiency is the metric the cleanroom standard references. The overall efficiency is the right metric for the buyer’s spec sheet, and the MPPS local efficiency is the right metric for the buyer’s compliance program. The two efficiency numbers are the two numbers the buyer’s spec sheet has to defend, and the two efficiency numbers are the two numbers the buyer’s spec sheet has to publish.
How Does MPPS (Most Penetrating Particle Size) Change the Grade Comparison?
MPPS (Most Penetrating Particle Size) is the particle size at which a filter media is least efficient, and MPPS is the right metric to compare HEPA filter grades. The MPPS is the particle size at which the combination of diffusion, interception, and impaction is least effective, and the MPPS is the particle size at which the filter’s efficiency is the local minimum across the particle size distribution. For HEPA-grade ePTFE media, the MPPS is typically around 0.3 micrometres, and the MPPS is the right particle size to test the filter’s worst-case efficiency. Because the MPPS is the right metric to compare HEPA grades, the right way to compare H11, H12, and H13 is to compare the MPPS local efficiency, not the overall efficiency, and the right way to write the spec sheet is to publish the MPPS local efficiency alongside the overall efficiency.
The right way to read the MPPS concept is to start with the underlying physics. A filter media captures particles by three mechanisms: diffusion (dominant below 0.1 micrometres, the particles diffuse into the filter fibres), interception (dominant at 0.1 to 0.5 micrometres, the particles follow the airstream and are intercepted by the fibres), and impaction (dominant above 0.5 micrometres, the particles are too heavy to follow the airstream and impact the fibres by inertia). The minimum of the three mechanisms is the MPPS, and the minimum of the three mechanisms is typically around 0.3 micrometres for HEPA-grade ePTFE media. The MPPS is the right metric to test the filter, and the MPPS is the right metric to compare filter grades.
The right way to read the MPPS on the buyer’s spec sheet is to look for the MPPS local efficiency, not the overall efficiency, and the right way to read the MPPS on the manufacturer’s test report is to look for the test method and the test aerosol. EN 1822 specifies the test aerosol (typically DEHS or equivalent oil aerosol, classified by a particle size distribution), the test airflow (typically 0.944 m/s face velocity for HEPA), and the test method (upstream and downstream particle counting). The test method is the right method to verify the manufacturer’s claim, and the test method is the right method to use on the buyer’s audit. For the filter test standards that the buyer’s spec sheet has to reference, the ASTM standards catalogue is the right North American reference for the test methods and the tolerance bands that the buyer’s audit has to respect.
The right way to apply the MPPS to the buyer’s spec sheet is to name the MPPS local efficiency, the test aerosol, the test airflow, and the test method. The four-field specification is the right way to defend the buyer’s grade choice, and the four-field specification is the right way to publish the grade choice on the buyer’s spec sheet. The four-field specification is the right specification to use when the buyer’s spec sheet has to defend the grade choice against the destination-market emission directive, and the four-field specification is the right specification to use when the buyer’s spec sheet has to defend the grade choice against the buyer’s own audit.
What Are the Practical Differences Between H11, H12, and H13 on an ePTFE Filter?
The practical differences between H11, H12, and H13 on an ePTFE filter media are the differences in pressure drop, dust-holding capacity, and lifetime. The three differences are the three differences that the buyer’s spec sheet has to name, and the three differences are the three differences that the buyer’s operating-cost model has to project. The three differences are the right differences to defend the grade choice, and the three differences are the right differences to publish on the buyer’s spec sheet. Because the three differences are the right differences to publish, the right way to read the grade comparison is to read the three differences together, not the headline efficiency number alone.
The pressure drop difference is the first difference. H11 ePTFE media typically runs 80 to 120 Pa initial pressure drop at rated airflow (typically 0.944 m/s face velocity for HEPA-grade testing), H12 ePTFE media typically runs 90 to 130 Pa, and H13 ePTFE media typically runs 100 to 150 Pa. The pressure drop difference is the right variable to add to the duct design, and the pressure drop difference is the right variable to set the fan energy consumption. The fan energy consumption is the right variable to set the operating cost, and the fan energy consumption is the right variable to defend the grade choice against the buyer’s operating cost model. For the broader industrial services and operations cost context that frames the filter’s lifetime operating cost, the BloombergNEF insights on industrial services is a useful practitioner reference for the operating-cost framework that the grade choice has to respect.
The dust-holding capacity difference is the second difference. H11 ePTFE media typically holds 200 to 300 g/m^2 of dust before the terminal pressure drop is reached (typically 250 to 350 Pa for HEPA-grade baghouse operation), H12 ePTFE media typically holds 250 to 350 g/m^2, and H13 ePTFE media typically holds 300 to 400 g/m^2. The dust-holding capacity is the right variable to set the filter change-out cadence, and the dust-holding capacity is the right variable to set the maintenance budget. The dust-holding capacity is the right variable to defend the grade choice against the buyer’s maintenance cost model, and the dust-holding capacity is the right variable to publish on the buyer’s spec sheet.
The lifetime difference is the third difference. An H11 ePTFE baghouse filter cartridge has a typical service life of 24 to 36 months on a cement kiln preheater and 36 to 48 months on an asphalt mixing primary stage. An H12 ePTFE baghouse filter cartridge has a typical service life of 18 to 30 months on a steel sinter plant. An H13 ePTFE HEPA filter cartridge has a typical service life of 12 to 24 months on a pharmaceutical final filtration line. The service life is the right variable to set the 5-year capital plan, and the service life is the right variable to defend the grade choice against the buyer’s capital plan model. The service life is the right variable to publish on the buyer’s spec sheet, and the service life is the right variable to use when the buyer’s spec sheet has to defend the grade choice against the buyer’s 5-year capital plan.
How Do You Choose Between H11, H12, and H13 for Your Application?
The right way to choose between H11, H12, and H13 for an application is to set the destination-market emission target first, the MPPS sensitivity second, the pressure drop budget third, and the dust-holding capacity fourth. The four thresholds are the four thresholds the buyer’s spec sheet has to satisfy, and the four thresholds are the four thresholds the buyer’s spec sheet has to publish. The right way to apply the four thresholds is to run the four thresholds against the buyer’s application, and the right way to set the four thresholds is to set the four thresholds on a per-application basis. Because the four thresholds are the right thresholds to publish, the right way to choose the grade is to apply the four thresholds on a per-application basis, and the right way to defend the grade choice is to publish the four thresholds on the spec sheet.
The destination-market emission target is the first threshold. The EU industrial emission directive 2010/75/EU sets PM2.5 limits that are typically met with H13 on the stack, and the US NESHAP sets PM limits that are typically met with H12 on the stack. The Asian markets vary; the right way to set the destination-market emission target is destination by destination, and the right way to write the spec sheet is to name the destination-market directive. The destination-market directive is the right threshold to publish on the buyer’s spec sheet, and the destination-market directive is the right threshold to defend the grade choice against the buyer’s compliance program.
The MPPS sensitivity is the second threshold. H11 is the right grade for processes where 5 percent particle penetration is acceptable, typically general industrial pre-filtration, metalworking, and cement kiln preheater. H12 is the right grade for processes where 0.5 percent penetration is acceptable, typically pharma secondary filtration, food processing pre-HEPA, electronics cleanroom pre-filter, and steel sinter plant baghouse. H13 is the right grade for processes where 0.05 percent penetration is required, typically pharmaceutical final filtration, hospital isolation room, semiconductor cleanroom, and nuclear adjacent. The MPPS sensitivity is the right threshold to publish on the buyer’s spec sheet, and the MPPS sensitivity is the right threshold to defend the grade choice against the buyer’s compliance program. For the maintenance-side reference on the baghouse filter, the cartridge change-out cadence, and the OEM service programme that the grade choice has to respect, the maintenance article published by Machinery Lubrication on belt-drive maintenance is a useful practitioner reference even though its primary subject is industrial belt drives rather than air filtration.
The pressure drop budget is the third threshold, and the dust-holding capacity is the fourth threshold. The right way to apply the pressure drop budget is to add the pressure drop to the duct design and to the fan energy consumption, and the right way to apply the dust-holding capacity is to set the filter change-out cadence and the maintenance budget. The two thresholds are the right thresholds to apply on a per-application basis, and the two thresholds are the right thresholds to publish on the buyer’s spec sheet. The two thresholds are the right thresholds to defend the grade choice against the buyer’s operating cost model, and the two thresholds are the right thresholds to use when the buyer’s spec sheet has to defend the grade choice against the buyer’s 5-year capital plan.
The right way to use the four thresholds is to apply the four thresholds on a per-application basis, and the right way to apply the four thresholds is to run the four thresholds against the buyer’s application. The right way to defend the grade choice is to publish the four thresholds on the spec sheet, and the right way to publish the four thresholds is to write the four thresholds into the buyer’s spec sheet. The right way to set the four thresholds is to set the four thresholds on a per-application basis, and the right way to refine the four thresholds is to update the four thresholds on a quarterly basis with the destination-market emission directive and the buyer’s operating cost model.
What Are the Most Common Mistakes When Specifying H11/H12/H13?
After enough HEPA-grade ePTFE filter shipments, the same five mistakes show up. They are not exotic. They are the predictable costs of treating the H-grade choice as a single-line efficiency number rather than as a four-threshold spec, and they show up most often on a new buyer that is scaling from a single HEPA-grade application to a multi-grade program for the first time.
- Specifying the overall efficiency without the MPPS local efficiency. The most common mistake is to write the overall efficiency on the spec sheet (>= 99.95 percent) without the MPPS local efficiency (>= 99.95 percent). The two efficiency numbers are the two numbers the destination-market emission directive references, and the spec sheet that publishes only the overall efficiency is a spec sheet that the destination-market compliance program cannot defend. The fix is to publish both numbers on the spec sheet, and the fix is to publish the test method and the test aerosol alongside the two numbers.
- Specifying the grade without the pressure drop budget. The second most common mistake is to specify the HEPA grade without the pressure drop budget. The pressure drop is the right variable to add to the duct design and to the fan energy consumption, and the spec sheet that publishes only the grade is a spec sheet that the buyer’s operating cost model cannot defend. The fix is to publish the initial pressure drop at the rated airflow on the spec sheet, and the fix is to publish the terminal pressure drop on the spec sheet.
- Specifying the grade without the dust-holding capacity. The third most common mistake is to specify the HEPA grade without the dust-holding capacity. The dust-holding capacity is the right variable to set the filter change-out cadence, and the spec sheet that publishes only the grade is a spec sheet that the buyer’s maintenance budget cannot defend. The fix is to publish the dust-holding capacity at the terminal pressure drop on the spec sheet, and the fix is to publish the expected filter change-out cadence on the spec sheet.
- Confusing the EN 1822 grade with the ASHRAE or ISO equivalent. The fourth most common mistake is to write the ASHRAE 52.2 MERV rating on the spec sheet instead of the EN 1822 HEPA grade, and the spec sheet that publishes the ASHRAE rating is a spec sheet that the destination-market European compliance program cannot defend. The fix is to write the EN 1822 grade on the spec sheet, and the fix is to write the ASHRAE or ISO equivalent on the spec sheet as a secondary reference, not as the primary reference.
- Skipping the test method on the spec sheet. The fifth most common mistake is to skip the test method on the spec sheet, and the test method is the right method to use on the buyer’s audit. The fix is to publish the test method on the spec sheet, and the fix is to publish the test aerosol, the test airflow, and the test method on the spec sheet. For the air-quality and cleanroom-side reference on the HEPA filter’s role in indoor air quality and the baghouse filter’s role in industrial air quality, the Compressed Air Challenge programme is the right practitioner reference for North American facility operators.
None of these mistakes are unique to ePTFE filter media. They are the standard HEPA-grade spec mistakes dressed up in EN 1822 grade names, and the fix is the same four-threshold specification, applied on a per-application basis, with the four thresholds published on the buyer’s spec sheet. The right way to think about the four-threshold specification is that the four-threshold specification is the buyer’s HEPA-grade spec sheet, and the right way to refine the four-threshold specification is to update the four thresholds on a quarterly basis with the destination-market emission directive and the buyer’s operating cost model.
Frequently Asked Questions
What is the difference between H11, H12, and H13 ePTFE filter grades?
EN 1822:2019 defines the three grades by overall efficiency and MPPS local efficiency. H11 reaches >= 95 percent overall and >= 85 percent MPPS local. H12 reaches >= 99.5 percent overall and >= 99.5 percent MPPS local. H13 reaches >= 99.95 percent overall and >= 99.95 percent MPPS local, the typical HEPA class. The right way to compare the three grades is on the MPPS local efficiency, not the overall efficiency alone.
What is MPPS (Most Penetrating Particle Size) on an ePTFE filter?
MPPS is the particle size at which a filter media is least efficient. For HEPA-grade ePTFE media, MPPS is typically around 0.3 micrometres. The MPPS is the right metric to compare HEPA filter grades, because the MPPS is the local minimum of the filter’s efficiency across the particle size distribution, and the MPPS is the metric the destination-market emission directive references.
What is the right HEPA grade for a pharmaceutical final filtration line?
H13. H13 is the right grade for processes where 0.05 percent particle penetration is required, which is the typical requirement for pharmaceutical final filtration, hospital isolation room, semiconductor cleanroom, and nuclear-adjacent applications. For aseptic fill or semiconductor lithography, the right grade moves up to H14, U15, U16, or U17 depending on the cleanroom class.
What is the pressure drop difference between H11, H12, and H13 ePTFE filter media?
H11 ePTFE media typically runs 80 to 120 Pa initial pressure drop at rated airflow. H12 ePTFE media typically runs 90 to 130 Pa. H13 ePTFE media typically runs 100 to 150 Pa. The pressure drop difference is the right variable to add to the duct design and to the fan energy consumption, and the spec sheet that publishes only the grade without the pressure drop is a spec sheet that the buyer’s operating cost model cannot defend.
What is the dust-holding capacity of H11, H12, and H13 ePTFE filter media?
H11 ePTFE media typically holds 200 to 300 g/m^2 of dust before the terminal pressure drop is reached. H12 ePTFE media typically holds 250 to 350 g/m^2. H13 ePTFE media typically holds 300 to 400 g/m^2. The dust-holding capacity is the right variable to set the filter change-out cadence, and the dust-holding capacity is the right variable to set the maintenance budget.
Post time: Oct-14-2026