Читать книгу Installation, starting and adjustment of ventilation and air conditioning systems A Guide - - Страница 14

Filters are divided into three classes according to their effectiveness. Class I filters trap dust particles of all sizes (the cleaning coefficient is not less than 0.99), Class II filters – particles of more than 1 micron (cleaning coefficient is more than 0.85), class III filters – particles of more than 10–50 microns (cleaning coefficient is not less than 0.60).