Rapid Sand Filter : A relatively small filtering unit containing sand. The liquid movement through the sand bed is fairly rapid. The filter bed usually has to be cleaned often, by backwashing. (SSWID)
The Mudblogger (Oilfield, Energy and Related Photographs), Oil Field Glossary, TX, USA 2014. http://mudblogger.com/oilfield-glossary/, (Oil - Amer) {777}
