The HEPA filter is a special type of mechanical filter made up of hundreds of thousands of intertwined plastic or fiberglass fibers. This creates a network that traps several particles suspended in the air. In the US, any particle that is larger or smaller than 0.3 μm in size must be removed by the filter with an efficiency of 99.97% in order to be certified as HEPA. The MERV classification table (minimum efficiency value) rates HEPA filters between 17 and 20 MERV, with 17 being the standard and any higher filter being even more effective at capturing airborne particles. HEPA filters were first used in the 1940s to prevent the spread of radioactive contaminants in the air during the Manhattan Project.
They are also used in biological safety cabinets (BSC) to protect both the product and the operator, and must be certified at the time of installation and at 6-month intervals thereafter. The cleaning class of the clean room can also affect the life of the filter, since “dirtier” environments place a heavier burden on them. Filter units for MicroSound fans include a HEPA filter with an efficiency of 99.99%, an ASHRAE pleated type prefilter at 30%, suspension points with a seismic clip, and a safety switch that deactivates the unit during maintenance. Manufacturers test each HEPA filter according to methodologies provided by the Institute of Environmental Science and Technology and the International Organization for Standardization.It is important to remember that HEPA filters must be inspected and certified every SIX MONTHS to ensure that they are in proper working condition. Companies may commit to replacing them every 3 years, although their maximum lifespan can reach up to 8 years.
As long as they are regularly evaluated and are considered effective, there is no need to replace them. Each time they are changed, repaired, or moved, they must also be recertified. In conclusion, it is essential to keep in mind that regular inspection and certification of HEPA filters is necessary for their proper functioning. The cleaning class of the clean room can also affect their lifespan, so it is important to take this into account when replacing them.
