HEPA and ULPA Filters for ISO 5 Cleanrooms: Selection, Layout, and Testing

What Is an ISO 5 Cleanroom?

An ISO 5 cleanroom is a controlled environment as defined in ISO 14644‑1 where airborne particles are strictly limited. For example, for particles ≥0.5 µm, there is a maximum of 3,520 particles/m³ of floor area, and for all particles ≥0.3 µm, there is a maximum of 10,200 particles/m³.

ISO 5 cleanrooms are not just a matter of using high efficiency filters. A complete system has to be developed. The hepa filter efficiency iso 5 has to be combined with sufficient airflow, a proper room design and appropriate work practices.

Understanding the ISO 5 Cleanroom Classification

ISO 5 is not a filter rating but rather the performance criterion for a cleanroom. The end clean level will depend on filter efficiency and air flow design as well as on room design, human behavior, transfer of material and of operational procedures.

Which Industries Use ISO 5 Cleanrooms?

ISO 5 cleanrooms are used in a variety of industries and each of these require a different mix of filter quality, airflow and validation.

• Pharmaceutical & sterile manufacturing:H14 HEPA or ULPA filters, unidirectional air flow. These systems must be validated in accordance with GMP Annex 1.

• Medical devices: H13/H14 typically used in moderate airflow situations to protect sensitive products.

• Semiconductor & electronics: ULPA filters (U15 – U17) require high air-change rates (300+ ACH) and are strictly static controlled.

• Optics manufacturing: Low particle number required. ULPA filters for iso5 are often used in optics manufacturing and require special frame sealings.

• Biosafety laboratories – HEPA or ULPA filters  for iso 5 – work within negative pressure contaminated areas and are provided with bag‑in/bag‑out housings.

• Aerospace & precision assembly: HEPA filters in modular FFU’s to create clean areas of changing size and shape.

For example, in semiconductor fab clean rooms requiring ulpa filters to keep sub‑0.1 µm particles under control, H14 HEPA filters can be used in hospital operating rooms with unidirectional flow.

HEPA vs. ULPA Filters for ISO 5 Applications

A number of factors must be taken into account when choosing between HEPA filters and ULPA filters for an ISO 5 cleanroom. Deciding on the basis of efficiency numbers is not sufficient. Process risk, available HVAC capacity and possibilities for validation are more important.

The hepa filter efficiency iso 5 (H13/H14) is sufficient for most applications but very sensitive processes might even require ulpa filters for iso 5.

How HEPA Filters for ISO 5 Work

HEPA filters capture particles through four main mechanisms:

• Inertial impaction – larger particles collide with fibres.

• Interception – particles touch fibre surfaces while following airflow.

• Diffusion – sub‑micron particles are driven by Brownian motion to fibre surfaces.

• Electrostatic attraction – charged fibres are used to enhance capture in some filters.

How ULPA Filters for ISO 5 Work

ULPA (Ultra‑Low Penetration Air) filters use denser fibre matrices and smaller fibre diameters to capture particles down to 0.1–0.12 µm with efficiency ≥99.999%.

However, this higher performance brings trade‑offs:

• Higher initial resistance – typically 20–30% more than HEPA.

• Higher fan energy – due to increased pressure drop.

• Higher procurement cost – often 1.5–2× the price of HEPA.

• More demanding installation – tighter sealing and stricter field testing.

HEPA vs ULPA: Side‑by‑Side Comparison

The following comparison uses verified data from Deiiang™ product specifications. Efficiency values are based on MPPS (Most Penetrating Particle Size) testing per EN 1822 / ISO 29463.

How to Choose Between HEPA and ULPA?

Selecting the right filter for an ISO 5 cleanroom should follow a risk‑first logic rather than defaulting to the highest efficiency number.

For most ISO 5 applications, H14 HEPA filters provide the optimal balance of efficiency, cost, and energy consumption. Ulpa filters for iso 5 are reserved for specific high‑risk processes.

“A HEPA or ULPA filter can only perform as designed when the filter, housing, ceiling system, airflow pattern, and sealing details work as one system.”

How to Select HEPA and ULPA Filters for iso5

Selecting HEPA or ULPA filters for ISO 5 cleanrooms requires evaluating efficiency, dimensions, airflow, resistance, frame material, and sealing type.

Below is a verified product data card from Deiiang™ to guide your selection.

Efficiency Grades and Test Standards

HEPA and ULPA filters for iso5are classified under EN 1822 and ISO 29463. Deiiang™ provides individual scan testing for every filter, with traceable serial numbers and test reports.

• H13: ≥99.95% @ 0.3 µm — general high‑efficiency applications

• H14: ≥99.995% @ 0.3 µm — hospitals, research labs, ISO 5 cleanrooms

• U15: ≥99.9995% @ 0.1–0.3 µm — semiconductor cleanrooms

• U16: ≥99.99995% — biotechnology, advanced pharmaceutical

For iso 5 cleanroom hepa filters, H14 is the most common grade, offering a good balance of efficiency and cost.

Dimensions, Airflow, and Initial Resistance

Deiiang™ offers both standard and custom sizes. The table below shows representative models:

Frame and Seal Options

Frame and seal selection directly impact installation integrity, leak tightness, and maintenance. Common options include:

• Aluminium frame – lightweight, corrosion‑resistant, standard choice.

• Galvanised steel – higher strength, suitable for large filters.

• Stainless steel – for corrosive or high‑humidity environments.

• Gel / liquid seal – provides the highest level of airtightness.

• Dry seal (gasket) – easier installation, suitable for less critical areas.

Cleanroom HEPA Filter Layout and Airflow Design

The filter layout of an ISO 5 cleanroom is equally as important to achieve the required cleanliness level as the number of filters. Uniform distribution, adequate coverage and a good integration with other components of the ceiling are equally important.

However, a poorly designed layout can create many problems, such as creating dead zones, allowing bypass leakage to occur and it may not achieve the desired hepa filter efficiency iso 5 even with the highest quality filters.

Common Filter Layout Approaches

• Full ceiling HEPA filter layout: The full ceiling of filters creates unidirectional airflow throughout the space. This layout is typical for pharmaceutical filling and for semiconductor lithography.

• FFU modular layout: The FFU’s can be set up in a grid to allow for maximum flexibility, such as adding or relocating filters in cleanrooms classified ISO 5-8.

• Local laminar flow / unidirectional zones: With local filters above workstations (FFUs), the areas immediately surrounding critical processes are kept at ISO 5 conditions while the remainder of the room is operated at higher classification levels, thus providing cost effective operation of very large cleanrooms.

Layout Is Not Just About Filter Count

A well‑designed layout must consider:

• Room area and ceiling height

• Equipment placement and heat sources

• Personnel traffic patterns

• Return air grille positions

• Maintenance access and filter replacement pathways

• Coordination with lights, sprinklers, and the ceiling grid

• Room pressure cascade requirements

Common Layout Mistakes

• Uneven filter distribution creating dead zones

• Return air paths blocked by equipment

• Bypass leakage around filter frames

• Conflict between filters and light fixtures / sprinklers

• Insufficient space for filter replacement

• Calculating total airflow without verifying airflow uniformity

For example, a 200 m² ISO 5 cleanroom with 48 filters (each rated 700 m³/h) must ensure that the total airflow (33,600 m³/h) is evenly distributed across the entire ceiling grid.

Cleanroom Sealing and Filter Installation

Sealing is where many ISO 5 cleanroom projects fail. A high‑efficiency filter is useless if air bypasses it through gaps in the frame, housing, or ceiling interface.

Even with iso 5 cleanroom hepa filters of H14 grade, bypass leakage can compromise the final particle count.

Why Sealing Matters as Much as Efficiency

• Filter media performance ≠ installed system performance

• Gaps between filter and housing create bypass leakage

• Uneven sealant application causes localised leakage

• Ceiling deformation reduces compression force over time

Common Cleanroom Sealing Materials

• Gel / liquid seal – highest integrity, used in critical applications

• Silicone – flexible, good temperature resistance

• Polyurethane (PU) – durable, commonly used in filter frames

• EPDM gasket – dry seal, easier installation

• Fire‑rated sealants – for penetration sealing

Cleanroom Fireproofing Materials and Filter System Integration

Fireproofing is not a filter property—it relates to cleanroom enclosure, duct penetrations, and ceiling systems. Key considerations:

• Fire‑rated wall and ceiling panels must maintain cleanroom integrity

• Penetration seals (pipes, cables) must be both fire‑rated and airtight

• Filter housing materials must be compatible with firestop systems

• Fireproofing cannot compromise cleanroom pressure differentials

→ Related guide: Cleanroom Fireproofing Materials: A Practical Guide for Walls, Ceilings, and Service Penetrations

“The weakest point in a cleanroom filtration system is often not the filter media—it is the installation interface around the filter.”

How HEPA and ULPA Filters Are Tested

Testing ensures that HEPA and ULPA filters for ISO 5 cleanrooms perform as specified—both at the factory and after installation.

For ulpa filters for iso 5, testing is even more critical due to the higher risk of leakage at ultra‑high efficiencies.

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Factory Production Testing

Deiiang™ performs the following factory tests on every filter:

• Individual scan testing – each filter is scanned for leaks

• Airflow and resistance measurement – verifies rated performance

• Appearance and dimension check

• Packaging inspection – prevents damage during transit

• Test report and traceability number – issued with all units.

On‑Site Integrity Testing

On‑site integrity testing (PAO/DOP method) verifies the installed system:

• Check filter installation and sealing

• Introduce test aerosol (PAO/DOP)

• Scan with photometer or particle counter

• Identify leak points

• Repair seals or ｒｅｐｌａｃｅ filter

• Document and certify results

What Field Testing Must Verify

Field testing is not just about measuring filter efficiency—it must also verify:

• Filter perimeter sealing

• Frame and housing joints

• Filter media surface (scanning)

• Installation orientation (airflow direction)

• Filter identification and location mapping

• Environmental conditions during testing

For example, a typical leak test scans the filter face at a speed of 5 cm/s and identifies any penetration ≥0.01% of the upstream concentration.

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Deiiang Case Study: ISO 5 Cleanroom Filtration Project

This case study demonstrates how Deiiang™ delivered a turnkey ISO 5 cleanroom filtration solution for a global lithium‑ion battery R&D facility.

Project Overview

Customer Requirements

• Cleanliness stability – critical for solid‑state electrolyte research

• Limited installation space – ceiling plenum height < 250 mm

• Zero bypass leakage – strict leak test requirement

• Custom dimensions – standard filters did not fit the ceiling grid.

• Fire and seal requirements – this research needed fire‑rated materials and gel seal etc.

Project Challenges

• Ceiling module dimensions did not match standard filter sizes

• 48 filters in a 200 m² area – dense FFU array required careful coordination

• Complex return air path with equipment obstructions

• Strict pressure drop limit – ≤200 Pa to meet energy budget

• International shipping – robust packaging needed to prevent media damage

Deiiang Solution

• Custom‑sized filters – adjusted dimensions to fit the existing ceiling grid

• Optimised pleat spacing – increased filter area while maintaining ≤200 Pa resistance

• Gel seal frame – ensured zero bypass leakage

• Pre‑assigned location numbering – simplified installation and tracing

• 100% factory scan testing – each filter with individual test report

• On‑site installation guidance – Deiiang™ technician supervised sealing and torquing

• Assisted PAO integrity testing – achieved 100% pass rate on first attempt

Results

• Particle count: Number of 0.3 µm particles <200/m³ (ISO 5: <3,520/m³)).

• Integrity test: 100% pass rate – zero leaks detected

• Air recovery time: 42 sec (iso 14644-3: ≤90 sec)

• Energy savings: 41% reduction in HVAC energy consumption

• Particle interference: reduced by 99.8%

• Customer outcome: The project was accepted and the client has placed an order for Phase 2.

This project confirms that proper selection of iso 5 cleanroom hepa filters combined with meticulous sealing and testing yields reliable results.

A Typical Buyer Scenario

Cleanroom Filtration Glossary

Frequently Asked Questions

Request a Cleanroom Filter Recommendation

References

• ISO 14644-1:2015 — Cleanrooms and associated controlled environments, Part 1: Classification of air cleanliness

• EN 1822-1:2019 — High efficiency air filters (EPA, HEPA and ULPA), Part 1: Classification

• ISO 29463-1:2017 — High‑efficiency filters and filter media for removing particles in air

• Deiiang™ product specification data — HEPA filter without partition, H14 (2025)

• Deiiang™ cleanroom case study — ISO 5 electronics R&D facility