I have a filter that meets the beta ratio and dust holding capacity requirements but has a low life in terms of reaching terminal pressure drop. Perhaps the filter is capturing lot of small sized particles!. How do i capture this aspect thro testing?. what type of test can throw light on this?

Send it to a Oil Analysis Laboratory for microscopic analysis. For type of particles, they can run an element analysis of the particles (ICP/RDE) by mixing the particles with 0-oil (oil with no additives). Also make them take some digital images.