Pre filter is the first stage filter to prevent dust particle to pass throughit. These filters are used for coarse filtration for removal of particles in range of 10 to 50 microns in the efficiency range of 80 – 95%. The output Air of pre filters is then passed to second stage i.e. fine filters and enhance the life of fine filter. Pre Filters are cleanable/ washable in nature to obtain longer life and having low pressure drop. These filters are very economical.