fine filter definition
fine filter means a filter that meets the relevant conditions described in Annex IX;
fine filter means a filter that meets the conditions for filter efficiency in the following test and calculation methods, to be declared by the filter supplier. Fine filters are tested at air flow of 0,944 m3/s and filter face 592 × 592 mm (installation frame 610 × 610 mm) (face velocity 2,7 m/s). After proper preparation, calibration and checking the airstream for uniformity, initial filter efficiency and pressure drop of the clean filter are measured. The filter is progressively loaded with appropriate dust up to a final filter pressure drop of 450 Pa. At first 30 g is loaded in the dust generator subsequently there must be at least 4 equidistant dust loading steps before reaching the final pressure. The dust is fed to the filter at a concentration of 70 mg/m3. Filter efficiency is measured with droplets in the size range 0,2 to 3 μm of a test aerosol (DEHS DiEthylHexylSebacate) at a rate of about 0,39 dm3/s (1,4 m3/h), Particles are counted 13 times, successively upstream and downstream of the filter at minimum 20 seconds with an optical particle counter (OPC). Incremental filter efficiency and pressure drop values are established. Average filter efficiency over the test for the various particle size classes is calculated. To qualify as a ‘fine filter’ the average efficiency for particle size 0,4 μm should be more than 80 % and the minimum efficiency should be more than 35 %. The minimum efficiency is the lowest efficiency among the discharged efficiency, initial efficiency and the lowest efficiency throughout the loading procedure of the test. The discharge efficiency test is largely identical to the average efficiency test above, except that the flat sheet of filter media sample is electrostatically discharged with isopropanol (IPA) before testing.
fine filter means a filter that meets the conditions for filter efficiency in the following test and calculation methods, to be declared by the filter