an apparatus , system , and method are disclosed for differential pressure measurement across a fluid conduit flow area change . the apparatus may include a particulate filter , a differential pressure sensor , and a fluid conduit size change downstream of the particulate filter . the apparatus may include a tube configured to place the downstream differential pressure sensor port in fluid contact with a uniform flow region of the fluid conduit downstream of the particulate filter . an apparatus is thereby provided to measure differential pressure across a fluid conduit flow area change such that the differential pressure measurement is minimally affected by the change in flow characteristics induced by the change in cross - sectional flow area .