Equalizing Feature (Ef) 1 : An SSSV mechanism which permits the well pressure to bypass the SSSV closing element to aid in opening the valve. (RP 14B, Spec 14A)
The Mudblogger (Oilfield, Energy and Related Photographs), Oil Field Glossary, TX, USA 2014. http://mudblogger.com/oilfield-glossary/, (Oil - Amer) {777}