A cementing head is provided for introduction and separation of fluids in a well. The cementing head comprises a plug container having upper and lower fluid inlets oriented tangent to the bore of the plug container. The upper inlet is located below the upper end of the plug so that a compact manifold can be used therewith. The compact manifold includes first and second discharge tees which may be connected by a one-piece coupling such that rotation of the coupling in one direction causes the discharge tees to seal against a spacer therebetween and rotation in a second direction causes the discharge tees to move apart from one another. A coupling for quick coupling of the plug container to a casing collar is also provided. The coupling apparatus comprises a locking clamp having pivotally connected arcuate clamp portions. Each arcuate clamp portion engages a lower end of a casing collar. A threaded adjustment is provided for increasing an initial compression of a seal against the upper end of the casing collar.