HEPA fitlers or HIGH EFFICIENCY PARTICULATE AIR filters are made of 100% glass microfibre. These filters remove 0.3micron and larger particles at a minimum efficiency of 99.97%. First Air coming out of a HEPA filter is Class 100. HEPA filters are used in applications where a Dust free and Sterile Environment is required. These filters have a high pressure drop of the order of 250Pa, so high static pressure blowers are required for overcoming the pressure drop. We are looking for inqueries from South India & Overseas Countries.
As HEPA filters remove sub-micron particles and as the HEPA filter media is delicate, these can get damaged even while storing. To ensure that the HEPA filters installed in the equipment/AHU are not damaged, there are certain tests that have to be done. These tests are Air velocity checking, HEPA filter Pressure drop test & HEPA filter Integrity Test (DOP Test)
HEPA filter Integrity test procedure: the filter is challenged with known aerosolized particles of 0.3micron and larger (DOP, POA etc)on the upstream side and checked downstream using a Photometer Probe. If there is a leak in the filter, the particles are sensed by the scanner of the Photometer and displayed as leak on the LED screen. If the leak is more that 0.03%, the filter is supposed to have failed.
While procuring HEPA filters it should be insisted that the supplier has a HEPA filter testing facility and ensure that the filter is tested onsite after installation.
As more than 95% of the HEPA filter media used in India is imported and expensive, to prevent frequent replacements, always a pre-filter has to used before HEPA to filter the coarse particles.
These are designed based on air quantity. Two types of HEPA filters are available, one is Aluminium Separator type and the other is the State-of-the-art Minipleat type. Minipleat HEPA filter is more sleek than the Separator type HEPA.
In Clean Rooms HEPA filters are installed in the Air Handling Unit or in the specially designed Terminal Plenum. Apart from Clean Rooms HEPA filters are used in Lab Equipment employing Air filtration such as Laminar Flow Workstations, Biological Safety Cabinets, Air Showers, Positive Pressure Modules etc.