How are HEPA filters classified?

How does one classify HEPA filters?

There are three different classifications for the HEPA filter. The first axis is the efficiency rating, meaning that the letter and number classes such as H13, H14, E10, or U15 designate the HEPA filter rating determined through a specific test. The second axis is the test standard/method utilized to determine the classification such as EN 1822 or ISO 29463.

The third axis is based on the type of construction; that is the physical composition of the media, frame, sealant, and pleats of the filter which determines how it fits into the housing.

For example, a concrete specification that demonstrates how the three-axis classification works; for example, H14 / EN 1822 / separator-free box filter indicates that the product class is H14 — indicating the efficiency of HEPA filter classification — EN 1822 identifies the test standard, while the active product demonstrates the construction.

This article will discuss eACH classification in detail and provide comparison tables that engineers must utilize to classify a product and compare products. It will also provide guidance as to how to map the Deiiang product families onto the aforementioned classifications.

Executive Summary: The Three-Axis hepa Classification Framework

The HEPA filter classification is a better approach than merely providing a single classification rating system. The HEPA filter efficiency classification explains how it works and ultimately will assist you in choosing an appropriate filter.

The information concerning the measurement and reporting of each HEPA filter rating is contained within the test standard axis, while the form factor axis describes the construction and function of the filter in an air handling system. There is a single spot on all three axes for every HEPA filter manufactured and marketed.

Notably, the acronym "HEPA" is an umbrella term with several hepa filter grades. According to the EN 1822 HEPA classes and the wider family of HEPA filter standards [3], there are two commonly referenced grades that fall under the HEPA designation, namely the H13 HEPA filter and the H14 HEPA filter.

Across the hepa filter grades, the HEPA classification is bracketed by the EPA family (grades E10–E12) and the ULPA family (grades U15 through U17). The efficiency grade axis extends from E10 to U17, thereby covering the efficiency spectrum.

While both filtration systems may appear identical in physical aspects, they will yield dissimilar HEPA filter rating values for the same nominal HEPA filter grades, because of the application of different HEPA filter standards and regulations. EN 1822 protocol utilizes the most penetrating particle size (MPPS) challenge along with scan testing for each filter element.

The US MIL-STD-282 is a US test specification noted for the use of dioctyl phthalate aerosol at 0.3 microns; the test states that to meet the HEPA classification, the filter must operate at a minimum of 99.97% efficiency. ISO 29463 is an international standard that was developed as an adaptation of EN 1822.

Testing of the same physical filter by way of different protocols can yield varying results notwithstanding the performance being the same.

The form factor axis element of the HEPA filter classification describes why two filters that may be in the same HEPA filter class may exhibit different behavior in a practical situation. In particular, a flat panel H13 HEPA filter with a large surface area and large media capacity may accumulate more dust before replacement than a compact H14 HEPA filter cartridge of the same filtration family.

In such cases, a separator-free design may have lower pressure drop due to design elements.

Axis 1: The Efficiency Grade (Defining Performance Levels)

The HEPA filter efficiency axis consists of an applicable standard and a specific testing method used during classification. In this respect, the EN 1822 HEPA classes together with the ISO 29463 equivalent classifications are the primary references for cleanroom HEPA filters in Europe and Asia [3][5].

There are some exceptions where the naming conventions in the US and the ASHRAE 52.2 MERV classification system also appear in specifications, but these should not be confused with the EN 1822 HEPA filter standards.

Understanding EPA, HEPA, and ULPA Categories

The EN 1822 HEPA filter classification is divided into three families. The EPA (Efficient Particle Air) family includes E10, E11, E12 classifications. The HEPA (High Efficiency Particle Air) family includes classifications H13 to H14. The ULPA (Ultra Low Particle Air) family includes the range U15 to U17 [3]. Going from E10 through the EN 1822 HEPA classes to U17 shows the increase in the minimum HEPA filter efficiency at the MPPS.

In general, under the standard, H13 HEPA filter and H14 HEPA filter grades are the two most common grades utilised in pharmaceutical, hospital and semiconductor cleanrooms. The H13 HEPA filter normally achieves a minimum HEPA filter efficiency of 99.95% at MPPS, while the H14 HEPA filter reaches a minimum 99.995%.

Above the EN 1822 HEPA classes, ULPA filters must meet the ultra-low penetration efficiency for the range U15 to U17. Additionally, across all HEPA filter grades, it is important for purchasers to check whether the quoted value from a supplier is integral efficiency, local efficiency, or both values, because the EN 1822 standard distinguishes between different criteria of acceptance.

The table provided below lists the EN 1822 families along with their classification efficiency at MPPS values that are usually cited. The user is advised to check the validity of these figures by referring to the relevant standard edition and test reports pertaining to the product.

In closing, it is worth noting that Deiiang's catalogue states that it achieves H13 and H14 at 99.97–99.99% and 99.995–99.999% respectively. The given figures refer to the 0.3 µm particle size performance from the catalogue, specifying performance based on a defined particle size measurement.

These numbers should not be treated as classification values according to EN 1822 since they do not imply any information about the EN 1822 class in the system. In order to identify the classification evidence of each specific model, the EN 1822 test report would be required, and if necessary, the per-unit scan test result. Therefore, ensure that both reports are requested for the particular model you have ordered.

The Mapping to US/ASHRAE MERV Ratings

MERV Ratings for US HEPA filter standards differ from the EN 1822 standard for determining efficiency so no one-to-one conversion exists [8]. The MERV scale from ASHRAE 52.2 uses the particle-removal efficiency of a filter across selected particle sizes to establish the MERV rating from MERV 1 to MERV 20.

High-MERV ratings would fall into the part of the HVAC market generally referred to as HEPA and ULPA; however, the test aerosol used, the methods and criteria may be quite different from EN 1822 standards.

For instance, a filter designated as MERV 17 should not be automatically equated to a HEPA filter designated as H13 or H14, even though both sit at the top of the MERV and HEPA filter grades respectively.

Similarly, a US HEPA filter that meets the conventional 99.97% standard at 0.3 µm cannot therefore be treated as an H13 HEPA filter or an H14 HEPA filter under the EN 1822 designation. The proper process is to identify the specific test standard and method behind each HEPA filter rating before comparing efficiency levels.

If both classifications are referenced (i.e. if both EN 1822 and ASHRAE 52.2 are listed on the filter label), use them as separate classifications under different standards. Do not attempt to derive one from the other unless a specific crosswalk is cited.

Axis 2: The Testing Standard (Defining How Performance is Measured)

The second axis of the HEPA filter classification is the testing standard itself. This classification axis confuses many users because unless the filter label specifies the testing standard used, the information is typically not easily apparent. For example, the EN 1822 HEPA classes and the US test specification can yield significantly different results in terms of HEPA filter mean efficiencies when comparing physically identical filter media simply because each standard may employ a different testing method.

EN 1822 vs. US MIL-STD-282 and IEST-RP-CC001

EN 1822 uses the most penetrating particle size as the measure of classification. The most penetrating particle size is defined as the particle size or diameter at which the tested filter exhibits the least collection efficiency at that particle size, which is typically in the sub-micron range of particle diameters depending on the filter media and the airflow.

The standard mandates that each filter element must be tested individually using a scanning technique that inspects the entire filter surface for local efficiency [3]. The scanning method is used to find pinholes, seal leaks and filter media degradation that a single-point efficiency test would not be able to identify.

The most penetrating particle size is a classification condition, not a statement regarding the worst performance condition under which the filter will operate throughout its entire operating life. In-service performance is determined by factors such as aerosol composition, airflow, loading, and housing.

The MIL-STD-282 is a historic United States specification used in the HEPA filter classification; it determines the minimum efficiency requirement of 99.97% using DOP aerosols at 0.3 microns, which was historically selected as the particle size at which HEPA filter efficiency was thought to fall to its lowest point for fiberglass media.

It has since been discovered that the actual MPPS for any given HEPA medium is usually smaller than the stated figure. The DOP test remains the most commonly used factory inspection method under these HEPA filter standards for each specific unit produced.

IEST-RP-CC001 is the United States recommended practice for both HEPA and ULPA filter testing methods, which must be cited correctly with the appropriate edition number and the referred clause that is being addressed. Both IEST-RP-CC001 and MIL-STD-282 pertain to the same subject matter; however they do not always relate to each other as the two documents refer to different aspects of the same practices.

The comparison chart below illustrates the major standards that facility engineers use.

Why the Same Filter May Have Different Ratings

The same physical filter may receive two distinctly different HEPA filter rating values under the same HEPA filter classification, based on the particular testing standard used. The differences in standards are evident with the aerosol used, the size of the particle at which HEPA filter efficiency is measured, whether the test is done on the entire filter element or on a sample of the media, and the acceptance criteria set to determine if the filter is approved.

In cleanroom applications, the main practical concern is that a classification test at a factory facility and an installed leak scan measure two different procedures. The factory test confirms that the efficiency classification is established before shipment, and the leak scan confirms there are no leaks in the filter, its seal, and housing interface at the time of installation.

Additionally, both tests are important and neither can substitute for the other. The facility's qualification protocol establishes the leak test methodology and what required acceptance criteria apply. The cleanroom method outlined in iso 14644-3 includes cleanroom tests related to system verification; however, it does not ｒｅｐｌａｃｅ filter element classification per se [2].

Cleanroom air cleanliness is classified by means of the particle concentration (and does not assign an H13 or H14 class to the filter in question) according to iso 14644-1 [1].

Deiiang has conducted a per unit scan test on each combined H13 and H14 and DOP Integrated filter prior to shipment and has the documentation to support this fact. Moreover, for HEPA cleanroom filters, the DOP test port that is built into the DOP Integrated system allows for verification without removing the filter from its housing.

While this is not something that is required for every application, it is a common practice in the pharmaceutical and semiconductor field since production downtime is costly.

Axis 3: Form Factor and Construction (Defining Mechanical Integration)

The third axis refers to the mechanical aspects of the filter. The aspects of this axis determine how the filter will fit into the housing, how much media area will be available, how much pressure drop the filter will cause with a given airflow, and how long it is expected to last before it needs to be changed.

Even if two filters have the same efficiency rating, they can be located in different places on this axis and, as a result, you have a very different filter performance.

Matching Filter Design to Airflow Requirements

There are overlaps among construction features. For instance, box, flat panel and mini-pleat construction features are not mutually exclusive; they refer to different aspects of a filter's construction. A good methodology of discussing the construction of a filter is to separate each of those aspects into categories as described below:

• Geometry: box, V-bank, cylindrical/cartridge, and bag/pocket.
• Pleat type: standard pleat and mini-pleat.
• Separator style: separator or no separator.

For example, you would be able to describe one product as "box construction + mini-pleat + no separator." This classification is much more accurate than placing the product into one of six mutually exclusive categories. Another example would be the Deiiang filter; it is a box construction filter that has a mini-pleat design and no separator.

The following chart lists the main construction attributes and catalog data where available. All values are listed as Deiiang catalog values for the given models; they do not represent the universal values for other filter products using the same construction.

Table 2: Comparison of the six HEPA filter construction types.

High-volume replacement of usage-based applications: Condition-based replacement interval, rather than a calendar-based one, should be utilized. This replacement interval should be determined based on differential pressure limits at the site being managed, as well as integrity testing outcomes and recommendations offered by the manufacturer. No recommendation for the calendar-based replacement interval should be provided if it does not come from either facility or manufacturer sources.

Material Selection and Sealing Integrity

There is an optimal type of media pack, sealant, frame, and gasket that should be chosen to allow the filters to maintain their efficiency class. The use of high-efficiency media alone will not prevent leakage from happening. Leakage can occur at the interface of the media and the frame, the gasket, or in areas where the filter has broken media.

Using separation-free construction does not eliminate leakage paths from the media pack, requiring that the individual tests and installations are performed prior to installation.

When analyzing Deiiang's combined H13/H14 filter, ultrafine glass-fibre filter paper has been used with a separation-free design. EVA hot-melt thermoplastics act as spacers, while PU sealant is also used to provide steady operation.

The frame is made from ABS plastic, while diamond mesh covers the upstream sides; either EVA or neoprene gaskets are used to seal the unit, with the maximum temperature rating of 70°C and the highest relative humidity value of 80% for this filter. These specifications apply to the different product ranges of Deiiang, which cover several HEPA filter grades, but they are not general HEPA filter standards.

An engineering note on material selection is due. When ordering gaskets, ensure compatibility with the disinfectant and cleaning agents on site. Also check that the gasket will exert even pressure on the housing interface and that there is no risk of leakage due to uneven surfaces. Also check that the frame material, sealant and gasket are rated for the maximum operating temperature and humidity of the installation.

The compressor, gasket and frame materials are considered elements in the system. It is important to correctly order the gasket as much as it is to correctly identify the class of material.

Mapping Deiiang's Engineering Solutions to Classification

The three axes of the HEPA filter classification are useful only when they are applied to distinct products. Here, we consider three product families from Deiiang — the Combined High Efficiency Filter, the DOP Integrated Filter, and the Super High Efficiency Baffle-Free Filter — to illustrate the application of the HEPA filter classification to the three axes. All values provided in this section are from the relevant catalogue for those products.

There are no general values for other HEPA filter grades or products from other manufacturers.

The primary comparison table below serves as a comparison of the three axes side by side.

Table 1: The three classification axes of HEPA filters.

The second table maps the three Deiiang product families onto the rating framework.

Table 3: Deiiang product families mapped onto the three classification axes.

Combined High-Efficiency Filters (H13/H14)

The Combined High-Efficiency Filter from Deiiang is the most common terminal filtration product in air conditioning and high air flow volume purification systems. It uses H13 or H14 rating from EN 1822 classification based on its separator-free construction. This filter is designed for terminal use primarily in ceilings and housings used in air systems.

The catalog efficiency values are 99.97–99.99% for the H13 unit at 0.3 µm and 99.995–99.999% for the H14 unit at the same size. These are catalog values at the specified size, and are independent catalog data that do not by themselves indicate the class as per the standard EN 1822.

Clients have to verify the report of testing for a particular model, rather than depending upon the 0.3 µm figure alone. Where the qualification protocol of a facility requires it, clients must also get the per-unit testing report for a specific unit.

The technical data sheet for the Combined High Efficiency Filter is stated below. The data is taken from the catalog of Deiiang, corresponding to mentioned ratings of airflow of specified models.

Dust holding capacity is around 1,200 g for the 2,500 m³/h unit. The maximum operating temperature is 70 degrees Celsius and the maximum relative humidity is 80 percent. The catalogue indicates that each filter has been tested on an individual basis prior to shipment; it is necessary to confirm the specific documentation regarding a filter purchased — classification report, per-unit scan result, or catalogue specification — with Deiiang for that particular model.

DOP Integrated Filters for Compact Cleanrooms

The DOP Integrated Filter has been designed for cleanrooms with a low civil construction height. Its frame is constructed in a manner that provides a built-in inlet air duct of either 250, 300, or 350 mm in diameter. It includes a valve for regulating airflow and a port for conducting a DOP test, both of which will be secured on the outlet side with a rubber cap.

PEF insulation foam is utilized as the exterior. The media consists of ultra-fine glass fiber paper sealed with a two-part PU sealant in either an aluminum or hot-dip galvanized structure with an EVA hot melt separator.

According to the catalogue, the efficiencies for both models are as follows: the Combined family performed at 99.97 percent to 99.99 percent for the H13 and 99.995 percent to 99.999 percent for H14 at the 0.3-micron size.

Catalog size and performance information:

The built-in test port allows DOP scan confirmation at the installation site without having to remove the filter from its housing. This is a design feature that impacts maintenance but does not change the filter classification.

Super High-Efficiency (U15-U17) for Critical Environments

The Super High Efficiency Baffle-Free Filter provides ultra-clean filter media for semiconductor fabs, super-LSI production, and ultra-clean laboratories. It utilizes US HV ultrafine glass-fibre paper along with a thermoplastic spacer and an anodized outer frame and plastic diamond mesh. The catalog classification is specified at a 0.12 µm particle size.

The performance specifications for the catalogue at 0.12 µm are below:

The specific efficiency at 0.12 µm does not guarantee the classification under EN 1822 which is based on the results of the MPPS test procedure. Buyers should acquire the certified EN 1822 ratings of each model including MPPS testing and efficiency data prior to using these products as classified under EN 1822. In the absence of verified testing records only catalogue designations of efficiency can be used and not a classification under U15/U16/U17.

Due to not being full replacements for a cleanroom HEPA filter in a cleanroom intended generally, the products should not be used unless there are specifications in specific systems indicating the necessity of products.

Addressing Common Industry Confusion

The majority of procurement mistakes related to HEPA filter classification stem from mixing all three axes of classification. Labels may provide information as to the class of filter, form factor, or marketing terminology, leading the buyer to make assumptions based on the missing data. The two biggest problems in this situation are the misuse of "True HEPA" terminology and confusion over what each HEPA filter rating actually measures.

"True HEPA" vs. "HEPA-Type" Marketing Terms

"True HEPA" is a phrase used for marketing purposes and is not a HEPA filter rating and is not defined in a technical sense; it may be used in some instances to distinguish products that truly meet the requirements of a specific HEPA filter standard from those labeled "HEPA-type" and/or "HEPA-like," which may not meet the necessary standard. Neither of these phrases serves as a substitute for compliance with a specific standard, given class, or study report.

Upon hearing the use of any such label in the context of a supplier, please request the following information. Whether each of these items constitutes a mandatory request is dependent on project specifications, facility qualification protocols, and all applicable regulations.

• The exact model number for the filter in question.
• The standard used to classify the filter (EN 1822, ISO 29463, IEST-RP-CC001, etc.).
• The applicable class (for example, "H13 filter" or "H14 filter" in relation to EN 1822).
• The measured HEPA filter efficiency and size of the particles or MPPS used for classification.
• The specification of the evidence related to the model classification.
• If applicable, any individual scan test results per unit.
• The identity of the laboratory where testing was conducted.

A factory classification report is different from a per-unit scan result. The classification report gives information about how well the product family meets the standard while the per-unit scan result verifies that the filter was tested and found to be acceptable. If traceability is needed for compliance purposes, the person should get both the classification report and the per-unit scan result.

Efficiency vs. Capacity (Class vs. Type)

Class and type refer to two different aspects of the HEPA filter classification. Class, such as an H13 HEPA filter or an H14 HEPA filter grade, makes reference to the HEPA filter efficiency according to the applicable standard. Type indicates the physical construction of the filter. Therefore, a filter can be H14 type with small media area or H13 type with large media area.

In the first case, the H14 filter may be high efficiency, but perhaps will not need to be replaced after longer use hours as compared to the H13 type.

Therefore, because different classes of filters will behave differently depending on the structure and characteristics of the filter, it is not useful to simply pick a filter based upon its class. In reality, the engineer needs to consider the media area, airflow rated capacity, and dust-holding capacity which dictates how the filter will perform in practice.

Selection Criteria for Facility Engineers and Contractors

The international standards set for testing mean that the compliance expectations differ based on the geographical region and various regulations to comply with government standards. The international organization is satisfactory according to the different variations that may occur in the environment, airflow through the equipment, and access for maintenance purposes. A systematic decision will help sequentialize these decisions.

Evaluating Pressure Drop and Energy Costs

The initial resistance will determine the pressure that the fan will generate when the filter is under testing conditions. An increase in resistance signifies an increase in the energy costs of the fan unless oversized or the use of variable speed fans. Throughout the time of the machines, the difference in the amount of pressure drop from one type of filter to another will be noted.

Deiiang previously stated the fine filter range H13/H14 that include initial pressure resistance less than or equal to 200 Pa for the H13 filter and less than or equal to 220 Pa for the H14 filter at standard airflow conditions (rated airflow). For example, the 4-pleat filter will have 20.04 m² of media, which will result in 2,500 m³/h of media area. All the necessary calculations concerning airflow must take into consideration only catalogue numbers.

It must be remembered that the level of pressure drop cannot be treated as the common property of all the variations. Moreover, the pressure drop can change and depends on various characteristics and conditions, which take place in the surroundings. In cases where any project claims energy and efficiency savings, the following aspects are documented and available: baseline, measurement method, and results.

Ensuring Compliance and Installation Integrity

Compliance does not only refer to the filter element. It should also involve the sealing mechanism between the filter and housing and the proof that confirms that the filter element and installation meet the required standards.

Here is a realistic guide to help any engineer working in facility design:

For instance, prior to using the 2,500 m³/h rated Deiiang Combined H14 filter that has a media area of 20.04 m² and initial resistance of ≤220 Pa, an engineer has to assess if the housing fits the filter dimensions of 592 × 592 × 292 mm, confirm that the gasket design corresponds with the housing interface, check the fan's ability to supply 2,500 m³/h of airflow at the used final resistance of 400–600 Pa, and confirm if the project's qualification protocol agrees with the classification report and per-unit scan result.

The catalog specifications outline the product description while the standard project acceptance report specifies requirements that must be met by a facility.

Here is a practical checklist for specifiers:

Installation integrity will qualify safe installation based on the leak scan, which uses aerosol, using methods laid out in the standard prescriptive documents [2][3].

Case Study: Pharmaceutical cleanroom iso 6 Upgrade

The case study presented here is an unqualified project report using particulars provided in the project documentation. There is no complete documentation of data nor measurements of particles or energy consumption provided.

Project Challenges and Site Requirements

The project being described here was a cleanroom for pharmaceutical packaging that is to achieve a class 1000 or ISO 6 standard of cleanliness. However, class 1000 refers to a historical designation for cleanliness which does not automatically mean it is interchangeable with ISO 6 unless particular information about the size of particles and measuring conditions has been confirmed.

The internal goal of this project is provided in the form of ISO 6. In this instance, the site has to overcome a great deal of particle load due to surrounding processes and also has to deal with limited ceiling height above the cleanroom and follow strict limits on the pressure drop.

The Deiiang Engineering Solution

Deiiang Engineering has provided the installation of low-height H14 HEPA filter units, dimensions 592 × 592 × 292 mm, with a capacity of 2,500 m³/h and a filter area of 20.04 m² rated at an initial resistance of ≤220 Pa.

In addition to the above, silicone-free sealing gaskets were employed for maintaining compatibility with the decontamination agent in the facility and added F7 pre-filters in front of the HEPA filter. Each H13 HEPA filter and H14 HEPA filter unit underwent DOP scan testing prior to shipment. In this case, the design was done to meet the desired height, pressure drop, and particle loading simultaneously.

These configurations cannot be reported as measured results but rather as a design justification.

Results and Performance Metrics

The project showed that particle counts moved from ISO 7 baseline levels to stable ISO 6 levels. The accompanying documentation is supposed to include detailed reports to confirm this finding such as pre- and post-installation particle count reports, locations and test conditions available for sampling along with details on particle sizes and test results regarding each installation.

Measurement data regarding the energy consumed by fans is also required with documented results in the beginning until records become available. Until that point, the result should be classified as project-reported rather than verified.

There are no claims made by this article concerning energy savings. The amount of energy that will be impacted by filter choice will rely on various parameters including the amount of air, fan efficiency, systems being utilized, running time and filters already being utilized. Initial catalogue resistance can help determine pressure on the fan at startup but it shall not automatically lead to energy savings for the current user.

The Role of Pre-filtration in Extending HEPA Lifecycle

Pre-filtering has been instrumental in increasing the performance of cleanroom HEPA filters, because the pre-filter takes part of the particle load before it reaches the HEPA filter. However, this result can differ based on the number of ambient particles per unit of volume of air, maintenance procedures utilized, total airflow, and efficiency of the pre-filter.

Strategies for Multi-Stage Filtration

Deiiang manufactures F5–F9 bag filters, which upon testing have been cataloged by their well-established outdated EN 779 standards [7]. Their catalog efficiency ratings with respect to 0.5 µm efficiency are as follows: F5 = 45%, F6 = 65%, F7 = 85%, F8 = 90%, and F9 = 95%. Due to changes in consulting standards EN 779 has become obsolete in a majority of regions in favor of ISO 16890 standards. Further guidance on how to maintain specs needs to be confirmed per project basis.

A good example of a protective stage for cleanroom HEPA filters is the 592 × 592 × 381 mm six bag filter which can generate a capacity of 2,050 m³/h while providing a filter area of 3.18 m². Its initial resistance at the F5 is less than 50 Pa while for the F8 filters it stands below 100 Pa and final resistance is between 250–400 Pa.

The glass fiber model has a heat tolerance of 150°C while the synthetic one can handle temperatures of 80°C. Under the relevant HEPA filter standards these function as pre-filters only, not as final HEPA stages.

The pre-filter still requires HEPA filter classification, although it decreases the HEPA filter loading. Even with the pre-filter in place, cleanroom HEPA filters must still pass their classification requirements and prove that they meet the necessary technical requirements.

The most common cleanroom use consists of multi-stage filtration. This is when the pre-filter is used first, then either the HEPA or ULPA filter, and lastly the final air supply using a terminal filter or ffu.

Conclusion and Technical Consultation

Recap of the Classification Axes

This table is intended as a guide only. The right filter for any given installation is the one whose coordinates on all three axes match the project's cleanliness requirements.

Partnering with Deiiang for Your Cleanroom

Deiiang specializes in the manufacture of cleanrooms and air filtration process systems, with industries that span all three efficiency grades of the HEPA filter classification. With a combined product line that covers the H13 HEPA filter and H14 HEPA filter grades, we are able to provide both box and mini-pleat designs without separators.

The specifications for our DOP integrated filter are also designed with both H13 and H14 grades in mind, while maintaining a compact footprint to cover areas with limited ceiling heights. The Super High-Efficiency Baffle-Free Filter covers the ULPA class range. Its catalogue rating values are found to be at 0.12 µm. The preceding filters of F5–F9 also function to protect the HEPA stage.

The Deiiang engineering team and the product designer Jason.peng collaborate with the facility teams, HVAC contractors and cleanroom integrators during selection of filters. The data in this article for the products is sourced from Deiiang catalogue. The report of the pharmaceutical cleanroom is a project report, and it should not be considered as a performance guarantee.

Engineers are required to provide drawings, the rated airflow, the plenum dimensions available, requirements regarding the class requirements and standards, the pressure drop that must be allowed, the requirements pertaining to the gaskets and the test documentation requirements for the project specific review. The team provides the guidance for classification, construction and pre-filtration strategy; the actual site needs and compliance requirements must be considered while selecting the final system.

Frequently Asked Questions

What does HEPA mean?

HEPA in the simplest terms represents high-efficiency particulate air. This means that the filters that qualify under HEPA standards are able to trap a large number of airborne particles, meeting certain performance standards and so on.

How are HEPA filters classified?

Classification depends on the applicable standard and measured performance, including particle collection efficiency and, in some standards, the most penetrating particle size. The EPA classes E10–E12 and ULPA classes U15–U17 are also included in the standard.

What are the EN 1822 HEPA classes?

EN 1822 classifies filters as H13 or H14 within the HEPA category. The standard also includes EPA classes E10–E12 and ULPA classes U15–U17.

What is the difference between H13 and H14 filters?

Filter performance data should be confirmed under EN 1822 for comparison purposes. H13 is classified as 99.97–99.99% while H14 is classified as 99.995–99.999% at 0.3 µm according to the Deiiang catalogues; these figures are catalog data and do not supplant model-specific EN 1822 classification reports.

Is a U.S. HEPA rating the same as an EN 1822 class?

Not necessarily. Given the different classification criteria and test methods used, U.S. HEPA ratings should not be interpreted as interchangeable with EN 1822 classifications.

How should facility engineers select a HEPA filter?

Facility engineers should match filter classes with system cleanliness and airflow requirements, then confirm dimensions, drop pressure, sealing, compatibility, and certification/test documentation.

References

• [1] iso 14644-1:2015 — Cleanrooms and associated controlled environments — Part 1: Classification of air cleanliness by particle concentration. International Organization for Standardization. Classifies air cleanliness according to particle concentration; does not assign H13 or H14 class to all filters.
• [2] iso 14644-3:2019 — Cleanrooms and associated controlled environments — Part 3: Test methods. International Organization for Standardization. Provides cleanroom test methods including necessary testing for installed systems; does not ｒｅｐｌａｃｅ filter classification.
• [3] EN 1822-1:2019 — High efficiency air filters (EPA, HEPA and ULPA) — Part 1: Classification, performance testing, marking. European Committee for Standardization.
• [4] EN 1822-4 and EN 1822-5 — Test methods for filter elements and media. European Committee for Standardization.
• [5] ISO 29463-1 — High efficiency filters and filter media for removing particles in air — Part 1: Classification, performance, testing, and marking. International Organization for Standardization.
• [6] IEST-RP-CC001 — HEPA and ULPA filters. Institute of Environmental Sciences and Technology. Verify current edition and title and tie statements to the clause.
• [7] EN 779:2012 — Particulate air filters for general ventilation — Determination of the filtration performance. European Committee for Standardization. Legacy classification that has been surpassed in many markets by ISO 16890.
• [8] ASHRAE Standard 52.2 — Method of Testing General Ventilation Air-Cleaning Devices for Removal Efficiency by Particle Size. ASHRAE.
• [9] US MIL-STD-282 — Method of Test for Filter Units, Protective Clothing, Gas-Mask Components, and Related Products. Historical test specification of the US.
• [10] Deiiang Combined High-Efficiency Filter catalogue, DOP Integrated Filter catalogue, and Super High-Efficiency Baffle-Free Filter catalogue, product data.