HEPA vs ULPA Filters: What’s the Difference and How to Choose
HEPA vs ULPA Filters: What’s the Difference and How to Choose
Choosing the right cleanroom air filter is one of the most important decisions in facility design. Install the wrong grade and you either pay too much for performance you do not need, or — far worse — fail the cleanliness requirements of your application.
Two terms dominate the conversation: HEPA and ULPA. They sound similar, and both are high-efficiency filters, but they are engineered for different jobs. Here is what actually separates them, and how to pick the right one for your cleanroom.
What is a HEPA filter?
HEPA stands for High Efficiency Particulate Air. Under the European standard EN 1822, HEPA filters are rated H13 and H14:
- H13: minimum efficiency of 99.95% at MPPS (Most Penetrating Particle Size)
- H14: minimum efficiency of 99.995% at MPPS
HEPA filters are the workhorse of controlled environments. They remove dust, bacteria, mould spores and fine particles down to around 0.3 microns, which covers the vast majority of contaminants found in pharmaceutical, food and general industrial cleanrooms.
What is an ULPA filter?
ULPA stands for Ultra Low Penetration Air. ULPA filters sit above HEPA in the EN 1822 classification:
- U15: minimum efficiency of 99.9995%
- U16: minimum efficiency of 99.99995%
- U17: minimum efficiency of 99.999995%
Because they capture particles down to 0.1 microns or smaller, ULPA filters are reserved for environments where even trace contamination is unacceptable.
Key differences at a glance
- Efficiency: ULPA removes roughly 100 times more particles than a standard H13 HEPA filter at MPPS.
- Particle size: HEPA is rated around 0.3 microns; ULPA extends protection to 0.1 microns and below.
- Airflow resistance: ULPA media is denser, so initial pressure drop is higher — typically 1.5 to 2 times that of HEPA at the same airflow.
- Energy cost: the higher resistance of ULPA means fans must work harder, increasing energy consumption and operating cost.
- Service life: under identical pre-filtration, ULPA filters tend to load faster and require more frequent replacement.
- Price: ULPA is significantly more expensive per unit and per replacement cycle.
Which one does your cleanroom need?
Choose HEPA (H13/H14) when:
- Your application is pharmaceutical manufacturing, labs, food processing or general cleanroom production (ISO Class 5–8).
- You need a proven balance of efficiency, airflow and running cost.
- You operate fume hoods, biological safety cabinets or HVAC supply systems.
Choose ULPA (U15–U17) when:
- Your process demands ISO Class 3–4 conditions or better.
- You work in semiconductor, microelectronics or precision optics manufacturing.
- Your product is sensitive to sub-0.1 micron particles, such as advanced display or battery production lines.
A common mistake is specifying ULPA “just to be safe”. In most cleanrooms this adds cost and energy use without improving the outcome — the correct HEPA grade, properly sealed and maintained, already meets the standard. Match the filter to the ISO class you actually need.
Other factors that matter just as much
- Filter media: glass fibre (borosilicate) is the industry standard; PTFE membranes suit aggressive chemical environments.
- Frame material: galvanized steel for standard use, stainless steel or aluminium for humid or corrosive conditions.
- Temperature rating: standard filters handle up to about 80°C; high-temperature HEPA filters are available up to 350°C for spraying plants and coating lines.
- Sealing method: gel seal or gasket seal — gel seal offers lower bypass for critical applications.
- Test reports: always ask for MPPS efficiency test reports and leak test certificates with every batch.
Why choose Onecleans
Onecleans is a CNAS-certified cleanroom filter manufacturer with two production bases, 12 fully automated production lines and an annual capacity of 60 million filters. We manufacture HEPA and ULPA filters in a wide range of sizes, efficiencies and frame options, including custom dimensions to fit existing housings. Every filter can be supplied with complete test documentation, and our engineers will help you select the right grade — not the most expensive one.
Need help choosing between HEPA and ULPA?