Free Water Knockout (FWKO) 1 : A vertical or horizontal vessel into which oil or emulsion is run in order to allow the water that is not emulsified with the oil (free water) to drop out. (SSWID)
The Mudblogger (Oilfield, Energy and Related Photographs), Oil Field Glossary, TX, USA 2014. http://mudblogger.com/oilfield-glossary/, (Oil - Amer) {777}