SDRLF DUPLEX LARGE FLOE RATE RETURN LINE FILTER SERIES 1.INTRIDUCTION SDRLF series filter is composed of two single bowl filters and a 2-position 6-way directional valve,it is simple in construction and easy to use,There is a by-pass valve and a contamination indicator in it,for protecting the hydraulic system safety. The feature of this filter allows continous operation even during element is changed for which is clogged by contaminants,After opening the balance valve and then turn the directional valve,the other filter begins to work,the clogged element should be changed in time. This series filter is widly used in the hydraulic system of heavy duty mining and metallergical machines.