ABSOLUTES EPA HEPA E ULPA
Absolute filters are used where complete control of submicrometric particles is required. Based on efficiency, the absolute filters are classified into EPA, HEPA, and ULPA. The best known field of application for these devices is their use as absolute filters for operating theaters and clean rooms
How an absolute filter works
In absolute filters, the filter medium is made of glass microfiber paper, pleated and arranged along the geometry of the filter so as to create a large filtering surface capable of handling a more or less intense flow of air.
For high flow rates, the HEPA or ULPA filter with a multi V geometry is usually used, so as to increase the filtering surface without increasing the overall size of the filter.
The frame of the absolute filter can be made of galvanized sheet, stainless steel, plastic, aluminum or wood
Efficiency and operating range of absolute air filters
The efficiencies of this type of air filters for absolute filtration are classified according to the European standard EN 1822-1: 2009 and range from 85% of the EPA E10 class, to 99.995% for maximum HEPA H14 class, up to 99.9995% of ULPA class U15 and 99.999995% of ULPA U17 filters. The efficiency is measured according to the MPPS method
The figure that varies greatly depending on the geometry and materials of the filter is the recommended final pressure drop and the maximum pressure drop. The recommended final pressure drop is a parameter that for our filters varies from 250 Pa to 450 Pa and corresponds to normal operation at steady state.
The maximum pressure drop for our absolute filters is 600 Pa and corresponds to the limit operating condition at which it is necessary to replace the filter itself.
Absolute filters are used in operating theaters and clean rooms