ULPA vs HEPA Filter: What’s the Difference & Which Do You Need?

When sourcing commercial/industrial air filtration solutions for end-filtration of various ventilation systems, you may frequently face a critical decision: pick a HEPA filter or a ULPA filter? Both are high-efficiency air filtration units to capture contamination particles from airflows, but their performance characteristics, costs, and ideal use cases differ significantly.

Following this guide, let’s explore their technical differences in detail, to point you in the right direction and ensure your facility meets local regulatory cleanliness standards.

 What is a HEPA Filter?

HEPA Filter stands for the High-Efficiency Particulate Air Filter. Defined under standards such as EN 1822 (Europe) and IEST-RP-CC001 (U.S.), a true HEPA filter captures at least 99.97% of airborne particles sized 0.3 μm (300 nm).

HEPA filters are classified into sub-grades:

* MPPS: Most Penetrating Particle Size

** The commonly cited “99.97% at 0.3 μm” corresponds to the U.S. DOE standard. European classifications (H13/H14) are slightly more stringent. 

Key HEPA Characteristics

• MPPS: ~3 μm
• ISO Cleanliness Grade: ISO Class 5 – ISO Class 8
• Pressure drop: 100- 220 Pa (typical at rated airflow)
• Media: Micro fiberglass or synthetic non-woven
• Cost: Moderate- widely manufactured, good supply chain availability
• Lifespan: 2- 5 years depending on environment and pre-filter deployment

What is a ULPA Filter?

ULPA Filter stands for Ultra-Low Penetration Air Filter. ULPA filters represent the highest tier of particulate filtration, capturing > 99.999% of particles as small as 0.12 μm (120 nm).

Key ULPA Characteristics

• MPPS: ~12 μm
• ISO Cleanliness Grade: ISO Class 1 – ISO Class 4
• Pressure drop: 150- 400+ Pa
• Media: Ultra-fine fiberglass, denser packing
• Cost: 2- 4× higher than comparable HEPA filters
• Lifespan: Shorter- higher loading rate due to finer media; often 1 – 3 years

ULPA vs HEPA: Head-to-Head Comparison

▶The Differences That Actually Matters

• Efficiency & Particle Size

Smaller isn’t automatically better. The MPPS (Most Penetrating Particle Size) represents the specific particle size at which a filter exhibits its lowest efficiency, making it the hardest size to capture. For HEPA, this is approx. 0.3 μm; and for ULPA, approx. 0.12 μm.

While ULPA filters can be engineered to capture smaller particles, they are not always the preferred choice. A high-grade HEPA (H14) can fully cover your process that generates contaminants primarily across the 0.3 – 1.0 μm.

• Pressure Drop & Energy Cost

ULPA filters create 2 – 3 times more airflow resistance than HEPA filters. That means your blower must work harder to push the same volume of air thru dense media, and the result shows up on your electricity bill every month.

Across a filter’s life, this extra energy can cost more than the filter itself. For a facility running hundreds of units, it’s a real line item. Rule of thumb: ULPA filter energy cost ≈ 2 – 4× HEPA energy cost per unit airflow.

• Media Technology 

HEPA and ULPA filters are primarily made of a same material for their filter media, micro-fine glass fibers. The key difference lies in the microstructure of the fibers and the resulting physical properties.

HEPA filter fibers typically have a diameter of 0.5 – 2 micrometers, whereas ULPA filters, designed to capture even smaller particles, generally have fibers with diameters ranging from 0.1 to 1 micrometer, and some even feature nanoscale fibers.

In certain applications with special requirements (such as environments with highly corrosive chemicals, semiconductor fabs requiring resistance to hydrofluoric acid, and cleanrooms requiring ultra-low resistance), PTFE film composite filter media are used.

• Pre-Filtration Dependency

ULPA filters are highly sensitive to loading. Without robust pre-filtration (typically ASHRAE MERV 8 – 13 or EU G4 – F9 pre-filters), ULPA media will clog rapidly, drastically shortening lifespan. HEPA filters are more tolerant of moderate pre-filtration.

Which Filter Does Your Industry Need?

The table below outlines some typical applications and the industrial air filter selection matrix for your reference:

▶How to Choose: A Decision Framework

Make your right decision based on the following five questions:

• What ISO Class does your cleanroom require?

Class 6 – 8 → HEPA H13/H14 is sufficient

Class 1 – 4 → ULPA is likely required

Class 5 → HEPA H14 (Pharma/GMP) or ULPA (Semiconductor)

• What is the smallest critical particle size in your process?

≥ 0.3 μm → HEPA

< 0.3 μm → ULPA

• What is your energy budget?

Tight energy budget → HEPA (lower OPEX)

Process justifies cost → ULPA

• Is your facility already equipped with adequate pre-filtration?

No → Start with HEPA

Yes → Either option viable

• What do regulatory standards mandate?

If your standard (FDA GMP, EU GMP Annex 1, ISO 14644) specifies HEPA, don’t over-specify to ULPA unless your process demands it

Procurement Tip: For a facility with 100 filter units, switching from HEPA to ULPA can add $15,000 – $40,000/year in combined energy and replacement costs. Always calculate TCO, not just unit price.

People Also Ask (FAQ)

Can a ULPA filter replace a HEPA filter?

Technically yes. ULPA filters exhibit superior filtration efficiency compared to HEPA filters, based solely on performance metrics. However, ULPA series requires higher-capacity blowers, stronger pre-filtration, and more frequent replacement.

So, if you want to upgrade your HEPA-rated system to ULPA, a prior professional engineering review is required to prevent airflow problems and premature filter failure.

What is the Most Penetrating Particle Size (MPPS)?

MPPS is the particle size at which a filter is least efficient — the “weakest point” of your air filter. HEPA MPPS is ~ 0.3 μm; ULPA MPPS is ~ 0.12 μm. Efficiency ratings are always measured at the MPPS.

How often should I replace my air filters?

A standard HEPA filter typically lasts 2 – 5 years, while a ULPA filter features shorter lifespan of commonly 1 – 3 years. However, replacement is best determined by monitoring pressure drop (ΔP) — when the dP increases to 2× the initial value, it’s time to replace.

Do ULPA filters remove gases or odors?

No. Both HEPA and ULPA filters are 100% physical particulate filters and lack adsorption capacity. For gas-phase contaminants (VOCs, chemical fumes), you need activated carbon or chemical adsorption media in addition to particulate filtration.

What certifications should I look for when sourcing?

Look for filters tested to EN 1822 (European) or IEST-RP-CC001 (U.S.). For pharmaceutical applications, ensure compliance with EU GMP Annex 1 and ISO 14644-3. Request factory scan test certificates for each batch.

Conclusion

Choosing between HEPA and ULPA filters is not a question of “better vs worse” — it’s a question of right-sizing filtration to your application requirements. Filson manufactures and supplies EN 1822-tested HEPA and ULPA filters for cleanroom operators worldwide, with batch certifications and standard or custom dimensions. Contact us via sales@filsonfilters.com or +(86) 157-3695-8886 for a quote, a technical consult, or a free filter-sizing review of your facility.