6.6 Coalescing bed-type oily water separators It is advisable to fit a high capacity basket strainer with a 20 mesh screen between the oily water pump and the separator to prevent dirt and debris from fouling the underside of the coalescing bed With a suitable strainer the bed will operate almost indefinitely without servicing and does not normally require cleaning by back flushing or renewal but without adequate filtration the bed is liable to become partiall blocked resulting in a fall-off of effluent quality and a significant rise in back-pressure. In the event of this occurring the bed should be backwashed6.6 Coalescing bed-type oily water separators • It is advisable to fit a high capacity basket strainer with a 20 mesh screen between the oily water pump and the separator to prevent dirt and debris from fouling the underside of the coalescing bed. • With a suitable strainer the bed will operate almost indefinitely without servicing and does not normally require cleaning by back flushing or renewal but without adequate filtration the bed is liable to become partially blocked resulting in a fall-off of effluent quality and a significant rise in back-pressure. In the event of this occurring the bed should be backwashed