Fibrous filters are the most common means used to separate liquid aerosol particles from an industrial gas stream. The pressure drop and penetration are the most important performance criteria of the filter. This study investigates the influence of an aerosol generation stop and go on the filter pressure drop and penetration. Experiments carried out using a HEPA glass fibre filter show that the pressure drop increases by up to 20% after an aerosol generation interruption. The pressure drop increase could be countered by performing a clean air permeation during the break period. If a permeation velocity higher than the filtration velocity is used, the pressure drop of the filter is noticeably reduced compared to what it would have been without an interruption. The same aerosol interruption did not have a clear influence on the filter penetration. The permeation technique could thus be considered to optimise liquid aerosol filter cleaning and/or regeneration
