Vesda Xtralis ISP-001 ICAM Filter Element FT Series Coarse - Black 20PPI (Pack of 10) Replacement filters elements for ASD / LASD aspiration detectors Coarse 20ppi. With normal use, the filter element will eventually become contaminated with dust particles, impeding airflow, and it is recommended that the filter element is changed every six months. The frequency of filter replacement depends on environmental conditions. For example, where the detector is placed in extreme environmental conditions, the filter should be changed every three months. Instructions 1. Remove the transparent cover using the corner stud key. 2. Lift out the foam filter element from the filter tube using tweezers or long nosed pliers. 3. Fit a new filter element. Ensure that the filter is not compressed during fitting and that it is positioned flush with the top of the filter tube. 4. Replace the transparent cover.