Drill String Float : A check valve in the drill string that will allow fluid to be pumped into the well but will prevent flow from the well through the drill pipe. (RP 53)
The Mudblogger (Oilfield, Energy and Related Photographs), Oil Field Glossary, TX, USA 2014. http://mudblogger.com/oilfield-glossary/, (Oil - Amer) {777}