The High Efficiency Particulate Air (HEPA) mini-pleat filters that we supply are at least 99.99% efficient in removing particles 0.3 micron and larger (Grade H13 meeting ISO 6 clean room class). HEPA filters utilise spun-hooked glass fibre rolled into a paper-like material. This material is pleated to increase the fibre surface area and bonded, or potted, into a frame. Hot melt is used to hold the pleats far enough apart to allow air to flow between them. Ultra Low Penetration Air (ULPA) filters are at least 99.9995% efficient in removing particles 0.12 micron and larger (Grade U15 meeting ISO 4 & 5 clean room classes). Like HEPA filters, ULPA filters are made of spun-hooked glass fibre rolled into a paper-like material.
How long will a HEPA filter last?
A HEPA filter can last three to five years or more in a standard cleanroom environment. The life of the HEPA also depends on ambient conditions, the pressure drop across the clean room and maintenance of the pre-filters. Since airflow capacity decreases and static pressure increases over time, HEPA filters actually become more efficient as the filter loads. The filter should be changed once it has reached its capacity. For example, if a HEPA unit is set to 0.45 m/sec outlet velocity but is only achieving 0.35 m/sec, then the HEPA filter should be changed. Some manufacturing industries insist on changing filters every two years regardless of their condition.