The HEPA filters Filtrotecnica Italiana are divided into 5 categories:

Medium and high efficiency filters DELTA CELL
Delta Cell 60 – 80 – 95 medium and high efficiency filters have been designed to be used in all filtration systems requiring air cleaning to a high degree. The compact design and strong construction enable “DELTA CELL” to operate in ventilation, air conditioning, and painting plant. Filters are made of a “FIRE RETARDANT” particle board or galvanized steel frame holding the filter pack made of fine glass fibre paper wound on corrugated aluminium spacers. The insertion of special synthetic sealant assures the perfect tightness of the system. The filter with galvanized steel frame is also available with single or double header flange, protection screen on both sides and “dual layer” paper for heavy operating conditions as air intake for compressors, gas turbines, engines, etc. “DELTA CELL” filter efficiencies according to UNI EN 779 dust spot test are 60-65% (F6), 80-85% (F7), 95% (F9).
The dust spot test with atmospheric dust will be replaced with the new test method EN 779-2002 based on a polydispersed aerosol DEHS (or equivalent) and an optical particle counter (OPC) connected to a computer and able to measure particle sizes from 0.2 to 3 µm. The new filtration classes are referred to particles of 0.4 µm that give values equivalent to the dust spot method (EN 779).

Absolute filters HEPA and BIO HEPA
Hepa and Bio Hepa absolute filters assure high cleaning degree and sterility of the air conditioning and ventilating plant where the pureness of the air is of crucial importance. Filters consist of a “FIRE RETARDANT”particle board or galvanized steel frame holding the filter pack made of ultrafine glass fibre paper wound on corrugated aluminium spacers. The insertion of special synthetic sealant assures the perfect tightness of the system. The absolute filters are supplied as standard with a flat profile neoprene gasket on air outlet side (on both sides as an option).

Due to their highest collecting efficiency these filters are particularly used in the following field:
– Nuclear power station
– Electronics industries
– Operating theatres
– Sterilization rooms and boxes
– Photografic industries
– Clean rooms and clean workbenches
– Chemical and pharmaceutical industries
– Food industries
– Animal experimental stations
– Sterile bacteriological laboratories

The BIO HEPA and HEPA filters are tested according to European Standard EN 1822 for particle size at which the lowest efficiency occurs (MPPS) normally between 0.12 and 0.25 µm. BIO HEPA (H 11) filters are type tested to verify they are free from leaks. HEPA (H 13 – 14) filters are individually tested to verify they are free from leaks by scan test. With an automatic particle counting method it is possible to define the degree of extraction or penetration as a local value and integral value, leak-tightness can also be assessed by paraffin oil mist test (OIL THREAD TEST) as per EN 1822 – 4 Annex A. Please remember that the method previously used was the DOP test according to U.S. MIL – STD 282 that erroneusly considered the particle of 0.3 µm the most critical.

High temperature absolute HEPA filters
This particular range of absolute filters has been designed for critical application where high temperatures occur (that standard filters cannot stand), especially in the pharmaceutical and nuclear industries. They can work at temperatures of 250/300° C. Initial/final pressure drop: 250/600 Pa. Filtration efficiency is not less than 99.95% (H 13) according to EN 1822. The filters consist of a stainless steel AISI 304 frame which encloses the filter pack made of a special glass micro-fibre paper wrapped on aluminium spacers sealed by special black silicon resin and extruded red silicon gasket.

POLYDIHEDRAL absolute filters
The polydihedral are absolute filters realized with the media folded into closely spaced pleats and assembling the filter packs in a “V” shape into wood or galv steel frames. The perfect tightness is guaranteed by a special synthetic sealant. Due to the particular profile the efficiency is individually tested according to EN 1822 – 4 Annex A. (OIL THREAD TEST). These filters, mainly used in non laminar applications, thanks to high flow rates and large effective filtration areas, represent great achievements in air handling units and in filter housings.

Minipleat filter panels LAM
Minipleat filter panels with extruded aluminium profile frame, 66 mm thick, used for terminal applications in laminar flow ceiling and clean work benches to match particle concentrations in order to ensure and maintain the degree of cleanliness required by Federal Standard 209 E or ISO 14644 – 1. The integral efficiencies to EN 1822 at MPPS are: 99.995% (class H 14) and 99.9995% (class U 15). The solution with wood frame (78 mm thick) is suitable for less severe applications. Integral efficiencies to EN 1822 at MPPS are 99.95% (H 13). The filters are individually scan tested in the factory according to EN 1822 by automatic particle counting method to detect local efficiency values and, by computer arithmetical mean, the integral value. The efficiency is based on particle size MPPS (0.12÷0.25 µm).