ULPA or HEPA Filters? What to choose?

ULPA or HEPA Filters? What to choose?

All controlled environments with a centralized heating and ventilation systems are vulnerable to the accumulation of dust, grime, mites, pollen, mould, spores, and airborne contaminants that undermine indoor air quality levels. Maintaining superior indoor air quality levels is paramount in sterile manufacturing sites like pharmaceutical, electronics, semiconductor, medical devices, and aerospace facilities to protect the integrity of the products and components and avoid costly defects.?

To achieve a controlled environment with a higher degree of contamination control, the building HVAC system must incorporate design elements with specialised particulate air filters that can trap suspended matter (invisible to human eyes) between 0.12-0.3 microns in diameter and purge the area of any potential sources of contamination

So, what are these highly configured filters?

When designing a HVAC system for a sterile manufacturing facility, the choice of filters depends on the intended nature of operations and the corresponding ISO 14644-1 cleanliness classifications desired to suit the work performed inside such a facility. The choice typically is between : High-Efficiency Particulate Air Filters (HEPA) and Ultra Low Particulate Air Filters (ULPA). These two variants of highly efficient filtration are usually applied to trap microparticulate contaminants.?

Differences between ULPA & HEPA Filters

Although HEPA and ULPA filters are widely used in industrial air filtration systems and share some common characteristics, they are distinctly different in certain technical aspects and intended applications.?

HEPA Filters

Frequently used in cleanroom facilities, HEPA filters are one of the more popular and thoroughly configured filtration technologies widely adopted across many industrial HVAC applications. The robust engineering of HEPA filters protects personnel, environment, products and processes from pathogens, dust, and moulds in hospitals, aseptic manufacturing facilities, and other hazardous environments. They are economically more viable and offer a longer useful life in contrast to a ULPA filter.?

ULPA Filters

In comparison to HEPA filters, ULPA filters capture much smaller particulate matter that potentially escapes from HEPA filter media. While HEPA filters capture upto 99.97% of contaminants, eliminating particulate subjects with 0.3 microns or larger diameters, ULPA filters are 99.999% successful in doing the same, capturing much smaller particles of 0.12 micros diameter or above.

Let’s compare the several attributes of both HEPA and ULPA filters,?

The Major Differences:

• Restricted Airflow:?

The ULPA filter is more constrictive than a HEPA filter, which is the chief cause why you can't just replace it with one. In fact, airflow is the main factor that distinguishes HEPA and ULPA filters. ULPA filters are made with a much denser filter medium that significantly reduces the air passing through it by nearly 20-50% of a comparable HEPA filter of the same dimensions. Also, Air Changes Per Hour (ACPH), a crucial measure of the amount of air volume replaced with fresh, filtered air, would be impacted by a higher pressure drop (owing to more resistance) to an unacceptable low level, leading to poorer indoor air quality in the room.

• Shorter Life:

ULPA filters are also more expensive due to their shorter lifespan (5-8 years on average) instead of about 10 years for HEPA filters used in similar circumstances. Additionally, pre-filters are frequently used upstream to safeguard the finer filters. Hence, an additional pre-filtration may be required to preserve and protect the ULPA filter thereby increasing the initial cost of installation.?

• Higher expense:

ULPA filters cost about 35% more than HEPA filters because they have higher-density media and are more challenging to manufacture. In addition, the running costs of a HVAC system with ULPA filters is significantly higher.?

A larger filter surface area to compensate for the more constrictive flow and a more powerful blower is critical to design a ULPA system to address the same ACH as a HEPA system, increasing the size and cost of the entire filtration system.

The final verdict: Which one to choose?

The selection of either a ULPA or HEPA filter entirely depends on your design considerations, nature of intended work, level of protection needed, and any applicable regulations to operate sterile manufacturing facilities. A HEPA filter is ideal, practical and economically viable if your facility requires a filtration system to eliminate airborne dust and pathogens of 0.3 microns or above. Typically, a majority of industrial applications and regulations are concerned with particulate matter which can be sufficiently handled by a HEPA or a series of HEPA filters in conjunction with other pre and intermediate filters.?