Abstract: A system for mixing a liquid solution or suspension includes a collapsible container having an interior surface bounding a compartment, the compartment being adapted to hold a liquid solution or suspension. A mixer is enclosed within the compartment of the container. A shaft has a first end connected to the mixer within the compartment of the container and a second end disposed outside of the compartment, the shaft being selectively movable relative to the container. A gas pathway extends from a portion of the shaft disposed outside of the container to a portion of the shaft or mixer disposed within the compartment of the container, the gas pathway extending through at least a portion of the shaft.

Abstract: A poppet valve has a threaded end of its stem. A coiled valve spring is provided with a valve spring retainer having a central bore for the valve stem, a circular groove for the spring, and a first ball bearing race on the opposite face from the spring groove. A valve retainer has a threaded bore and a second ball bearing race. A set of ball bearings is disposed in the spring retainer race, the valve stem is inserted through the spring and spring retainer, and the valve retainer is threaded onto the valve stem engaging the ball bearings by the second race. The ball bearing assembly thus permits the valve to rotate with respect to the spring and spring retainer during operation. A lock nut is used to lock the assembly.