Deep dive into the world of HEPA air filters and why they define industry standards

Filtration is a physical, biological or chemical operation that separates solid matter – and sometimes fluids – from a mixture with a filter medium that has a complex structure through which only certain elements of the air (or fluid) can pass.

There is a vast collection of different types of filter to cater for a host of applications from the nuclear industry to pharmaceuticals and semiconductor manufacturers. However, perhaps because of this variety, there is also a great deal of confusion among many people surrounding the definition of different types of filters available to clean air. 

That makes these filters perfect for critical applications such as semiconductor, pharmaceutical, and food or beverage manufacture and especially medical facilities. HEPA filter is a type of mechanical air filter; it works by forcing air through a fine mesh that traps harmful particles. HEPA filters are not a recent innovation. Developed for the Federal Government in the early 1950's their original design intent was to capture contaminants associated with the manufacture of the atomic bomb.

They were called Absolute filters at that time as the goal was to have absolute efficiency, capturing any and all particles from the air. After World War II, the rights to the Absolute filter became the property of a company that is now known as Camfil.

For some time, into the 1960s the HEPA filter had no commercial viability. Then came transistors and semiconductor industry.

Our modern world would look very different in terms of technology had it not been for the HEPA filter because it would have been impossible to develop the sensitive electronics found in modern appliances without the clean rooms needed to manufacture them.

But clean room technology does not end with micro-electronics. Other sectors have subsequently benefited from HEPA filters for clean rooms including pharmaceutical manufacture.

HEPA filters are also used in nuclear containment, some food and beverage production, and even to protect workers where they may be exposed to hazardous materials such as asbestos.

The filters are typically installed in a ceiling of a room that is commonly referred to as a clean room. Some rooms have cleanliness levels that only allow less than 1 particle per cubic foot of air. The common atmospheric air sample has tens of thousands of particles. Pharmaceuticals commonly use HEPA filters in the 99.97% at 0.3 micron to 99.99% efficiency. Their demands are not as stringent as the semiconductor industry, but they still employ clean room technology to protect the integrity of their products. 

As filter manufacturing technology has improved, and the cleanliness requirements of product manufacturers has also increased, filter manufacturers have developed HEPA filters that have extraordinary efficiencies even to the level of 99.99995 at 0.12 micron. Imagine this level of efficiency, yet air can move through the filter. 

HEPA filters now come in many different configurations, yet all still have the requirement of efficiency testing and certification to meet the definition. They are even manufactured for high temperature applications, up to 2000 degrees Fahrenheit or 1093 degrees Celsius.