Filtration Efficiency Testing (ISO 16890 / HEPA)

Aerosol Science

We use calibrated CPC and OPC counters to measure upstream and downstream particle concentrations, then pair fractional efficiency curves with pressure-drop data.

Purpose & when to use

Filtration Efficiency Testing measures how effectively a filter or media removes particles across a defined size range. ARE Labs uses calibrated Condensation Particle Counters (CPC) and Optical Particle Counters (OPC) to quantify upstream and downstream concentrations. Methods align with ISO 16890 for general ventilation, EN 1822 for HEPA and ULPA media, and ASHRAE 52.2 for MERV-rated HVAC programs. ISO 17025 accreditation covers the full analytical workflow:

Media selection and supplier qualification for general ventilation filters — ISO 16890 size-resolved ePM10, ePM2.5, and ePM1 efficiency grades support performance claims and purchasing decisions.
HEPA and ULPA filter qualification for cleanrooms — EN 1822 and ISO 29463 penetration testing confirms H-class or U-class grade with documented MPPS sensitivity and leak detection.
HVAC filter MERV rating support under ASHRAE 52.2 — generates dust spot efficiency data for building systems engineers comparing products for commercial and residential air-handling applications.
Design change assessment for housings, seals, pleats, and cartridge frames — fractional efficiency and pressure-drop curves document performance before and after design iterations under ISO 16890 or EN 1822 framing.
System-level filtration testing for integrated air purifiers and in-duct devices — captures bypass and seal effects under ISO 16890 or ASHRAE 52.2 framing not visible in flat-sheet media tests.

Use filtration efficiency testing when the decision depends on particle removal performance, filter grade classification, or the trade-off between efficiency and pressure drop. Typical applications include media qualification, design verification, regulatory file support, and substantiation of indoor air quality claims.

Air-treatment and filtration device families

Filtration efficiency testing spans device categories wherever particle removal performance and pressure-drop trade-offs drive the product or compliance decision — from ISO 16890-classified HVAC modules to HEPA cleanroom filters and portable air purifiers.

HVAC filterDucted ventilation filter media
HEPA filterHigh-efficiency cleanroom filters
Air purifierPortable and whole-room units
Cabin air filterAutomotive and transport HVAC
Respirator mediaFilter media for respiratory protection

Instrumentation & measurement ranges

Platform selection depends on the filter class, target size band, and required sensitivity. We define the configuration during study planning and document it in the report.

0.01 – 1 µmoptical-condensation

Condensation Particle Counter (CPC)

Counts fine and ultrafine particles upstream and downstream — primary counter for HEPA and ULPA penetration measurements where sub-micron sensitivity is required.

0.3 – 10 µmoptical

Optical Particle Counter (OPC)

Size-resolved number concentration upstream and downstream — used for ISO 16890 fractional efficiency and ASHRAE 52.2 MERV-range measurements.

25 – 610 mmfilter-face

ISO/HEPA test fixtures and ducting

Leak-tight holders, gasketed adapters, and ducting sized to the filter or cartridge format — controls bypass and defines the upstream and downstream sampling geometry.

0 – 1000 Papressure-drop

Differential pressure sensors

Calibrated manometers and pressure transducers measuring pressure drop versus flow — reported alongside efficiency curves for performance trade-off analysis.

Test method options

Method	Strengths	Tradeoff	Aligned with
General ventilation fractional efficiency (ISO 16890 aligned)	Size-resolved ePM10, ePM2.5, and ePM1 efficiency grades widely accepted for ventilation filter classification and procurement programs. Supports media comparison, supplier qualification, and design-change documentation under ISO 16890 classification framing.	Requires controlled polydisperse test aerosol and defined volumetric flow setpoints — setup overhead increases for non-standard filter formats or face velocities.	ISO 16890
HEPA and ULPA penetration testing (EN 1822 aligned)	Targets H- and U-class high-efficiency media at MPPS — generates penetration data supporting EN 1822 grade classification for cleanroom and critical-environment filters. Leak scanning and local penetration mapping confirm seal and media integrity across the full filter face.	More demanding sealing, upstream uniformity, and acceptance criteria than ventilation methods — fixture preparation and leak verification extend setup time.	EN 1822
HVAC filter MERV rating support (ASHRAE 52.2 aligned)	MERV-rated reporting format widely used for HVAC product specifications and building-systems engineering comparisons under ASHRAE 52.2 framing. Supports efficiency measurement across the composite filter area with documented flow conditions — outputs feed product data sheets and procurement programs.	Reporting format differs from international ventilation standards — a separate campaign is needed when both MERV and ePM grades are required.	ASHRAE 52.2
System-level filtration study (fit for purpose)	Tests filters in housings or integrated products — captures bypass, seal effects, and frame losses that flat-sheet tests cannot measure. Configurable challenge particle size and flow range to match device operating conditions and intended use environment.	Requires fixture design or product housing adaptation to match the specific product geometry — adds engineering setup time before testing begins.	—

Setup configurations

The test configuration is matched to the filter format, target method, and relevant regulatory or product framework. It combines a defined aerosol size distribution, stable flow, and leak-managed fixtures with the practical geometry of the filter or test article. During study planning, we define the following parameters:

Device interfaces

Gasketed filter holders, flanged duct adapters, or custom frames sized to the filter format — geometry selected to eliminate bypass and match the intended installation condition.

Flow & actuation profiles

Fixed volumetric flow setpoint or a flow curve stepped across the filter's operating range — face velocity documented and verified pre- and post-test.

Sample numbers

Duplicate or triplicate filter samples per condition with blank runs — replicate plan sized to expected variability across media batches and filter classes.

Environmental controls

Temperature and relative humidity characterized and logged throughout the test — conditioning steps added when the method or filter class requires pre-test equilibration.

Calibration & verification

Upstream aerosol concentration and OPC/CPC count verified at start and end of each test set — line-loss corrections applied when sampling distances are non-negligible.

Methods anchored to the standards that matter

Filtration efficiency studies operate within a documented quality system built around the measurement and compliance requirements for air filtration. Together, the four anchors below define the measurement, documentation, and reporting requirements carried through to the §7 outputs.

ISO 17025AccreditedTesting-laboratory competence — documented methods, calibration traceability, and uncertainty contributors.
ISO 16890AlignedSize-resolved fractional efficiency and ePM classification for general ventilation air filters.
EN 1822AlignedHEPA and ULPA filter testing — MPPS penetration, leak scanning, and H/U grade classification.
ASHRAE 52.2AlignedMERV rating and dust spot efficiency for HVAC filters in commercial and residential systems.

Key data outputs & reporting

A filtration efficiency study produces fractional efficiency and penetration curves, pressure-drop data, and the underlying replicate statistics. The standard report presents primary metrics, QA / QC controls, and uncertainty contributors in formats suited to product files, procurement decisions, or regulatory packages. For extended studies that compare media lots or examine design variables, we also provide the relevant comparison tables and figures.

Primary outputs

Fractional efficiency and penetration versus particle size (number-based, per test method), reported at each size channel with mean, SD, and CV across replicates.
Pressure drop versus volumetric flow — steady-state curves and optional pressure-drop stability data where loading concepts apply.
Derived grade or rating summary (ePM10 / ePM2.5 / ePM1 for ISO 16890; H or U class for EN 1822; MERV for ASHRAE 52.2) with supporting efficiency values.
Uncertainty contributors including counter calibration, flow control accuracy, line-loss corrections, and pressure sensor performance.

Deliverables

#	Format	Contents
01	PDF report	Methods, controls, replicate statistics, efficiency curves, and uncertainty contributors.
02	CSV / XLSX datasets	Per-size-channel efficiency and pressure-drop tables across all conditions and replicates.
03	Figures	Efficiency versus particle size and pressure-drop versus flow plots for technical files or presentations.

Extended deliverables · multi-arm comparability · stability · predicate studies

Media comparison pack — Side-by-side efficiency overlays and statistical framing for multiple media lots or candidate suppliers.
Design-change delta report — Before/after efficiency and pressure-drop comparison for housing, seal, or pleat design iterations.

QA / QC & data integrity

The QA / QC plan is matched to the study method and covers the challenge aerosol, particle counters, and flow measurement system. We run verifications before and after each test set. Under our ISO 17025 quality system, we maintain calibration traceability from counter characterization through the final efficiency result. Background and leak checks are standard for every campaign.

Counter zero-check and background runs before each test set — confirms sampling-line background is within acceptance limits before challenge aerosol is introduced.

Aerosol generator stability verification — upstream concentration logged and confirmed stable before downstream sampling begins for each replicate.

Leak checks on filter holders and fixtures before each test article — pressure-hold or smoke-pencil check to confirm bypass is below acceptance threshold.

Flow calibration and pre/post verification with calibrated flowmeter — face velocity documented at setup and confirmed after each condition block.

Chain of custody records for all test articles — labeled, photographed, and tracked from receipt through test and reporting.

Why ARE Labs

ARE Labs connects technical topics to practical study design, method selection, controlled aerosol work, and reportable evidence without turning technical pages into sales pages.

Reviewed byJamie Balarashti (25 yrs - cascade & inhalation methods) - Weston Schaper (7 yrs - real-time sizing & nanoparticle work)

17025Accredited testing

900+Studies Performed

17+Years in operation

300+Clients supported

Common questions

These answers cover the questions HVAC engineers, air purifier developers, cleanroom operators, and filter media suppliers most often raise when planning a filtration efficiency study. Topics include method selection, compatible filter formats, pressure-drop measurement, sample counts, and deliverables. They are starting points. Contact us if your filter format, flow range, or regulatory framework differs from what is shown here, since most studies require at least one application-specific configuration choice.

Q.What is the difference between ISO 16890 and ASHRAE 52.2 efficiency testing?

A.ISO 16890 reports size-resolved efficiency and classifies filters as ePM10, ePM2.5, or ePM1. ASHRAE 52.2 produces MERV ratings using different test details and reporting conventions. We select the method for the target market: ISO 16890 for international or European programs and ASHRAE 52.2 for US HVAC specifications.

Q.Can you test a filter inside my product housing rather than as a flat sheet?

A.Yes. Testing the complete system captures bypass and seal effects that flat-sheet testing can miss. We design or adapt the fixture to match the product geometry so the result reflects performance in the tested configuration.

Q.Do you measure pressure drop alongside efficiency?

A.Yes. We measure pressure drop with calibrated sensors and report it against flow alongside the efficiency curve. These measurements are typically evaluated together to support product performance claims or examine the trade-off between filtration efficiency and energy use.

Q.What particle size range can you measure for HEPA filter testing?

A.CPC-based counting measures fine and ultrafine particles down to approximately 0.01 µm. This range includes the most penetrating particle size (MPPS) region relevant to HEPA and ULPA classification under EN 1822.

Q.How many filter samples are recommended for a qualification campaign?

A.We typically test duplicate or triplicate samples for each condition and run controls to confirm aerosol stability and system background. The final replicate plan reflects the expected variability across the media batch and the decision threshold for qualification.

Q.What do I receive at the end of the study?

A.Deliverables include a PDF report covering methods, controls, replicate statistics, and uncertainty contributors; CSV / XLSX datasets with efficiency by size channel and pressure-drop tables; and efficiency and pressure-drop figures for technical files or regulatory packages.

Standards & guidance

ARE Labs conducts filtration efficiency studies in alignment with the regulatory and consensus standards governing air filter performance, HEPA and ULPA classification, and HVAC filter ratings. When a method falls within our third-party ISO 17025 accreditation, we identify it as accredited. When a standard is followed outside that accredited scope, we describe the method as aligned or conformant, where applicable. The cards below list the standards most relevant to filtration efficiency programs.

QA & Regulatory - Accredited

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