DOB Back Ferrule

BI-Lok Series D Dual Ferrule Tube Fittings are composed of four precision machined component parts: fitting body, front ferrule, back ferrule, and nut. 

BI-Lok Tube Fittings are shipped fully assembled and individually bagged. Once the tubing has been fully inserted into the fitting, a leak tight seal is achieved through the simple action of tightening the nut against the fitting body. 

The tightening of the nut provides the axial thrust required to engage the captively held ferrules against the outside diameter of the tubing. 

The staged swaging action of the ferrules, with minimal torque transfer to the tubing during make-up, provides the key to BI-Lok’s high integrity sealing capability and exceptional service life.