of the chamber respectively and are flow conduits through which drilling mud flows into and from the chamber the inlets are preferably 4 inch diameter fittings so that normal flow of mud is received referring to both fig2 and to fig3 which is a tope view of the flow chamber 50 it can be seen that the chamber is split along the major axis and hinged along the outer perimeter of both the inner and outer cylinders 54 and 52 respectively a hinge strap 72 and pin 73 is used to pivot the halves of the inner cylinder 54 and a strap 70 and pin 71 is used to pivot the halves of the outer cylinder 52 it should be understood that other hinge arrangements can be used with equal effectiveness the hinge assemblies allow the flow chamber 50 to be opened and closes in a 34 clam shell 34 fashion and easily fitted and removed around the drill string 12 and kelly 22 the chamber 50 is held closed with clamps 64 opposite the hinges and is further secured the drill string with chamber slips 80 attention is now drawn to fig4 which shows the continuous flow cylinder positioned on the drill string kelly joint 26 assume for purposes of discussion that a joint of pipe is being added to the drill string 12 the drill string is lifted and held with tapered slips 81 such that the kelly upper pipe joint is far enough above the rotary table 24 so that the flow chamber 50 can be clamped around the joint 26 the chamber 50.