Abstract: A T-shaped valve for use in supporting a nebulizer cup in a ventilation circuit. The valve comprises an inner sheath and an outer sheath for supporting the inner sheath. Both the inner and outer sheaths have apertures which selectively align and misalign with one another. The inner sheath further includes an integral control knob which passes through an opening in the outer sheath. A displacement of the control knob shifts the inner sheath circumferentially relative to the outer sheath which, in turn, displaces the aperture in the inner sheath relative to the aperture in the outer sheath. When the aperture in the inner sheath is in communication with the aperture in the outer sheath, the circuit is open to permit fluid flow through the nebulizer cup and when the aperture in the inner sheath is not in communication with the aperture in the outer sheath, the circuit is closed to restrict fluid flow through the nebulizer cup and thus enable the removal of the nebulizer cup from the ventilation circuit.

Abstract: A screw rotor machine for compressing air or other working fluid comprises a housing including two intersecting bores axes which together define a working space. The pair of intermeshing rotors are rotatably mounted one in each bore. The rotors have helical lands and intervening grooves whereby rotation of the rotors in connecting engagement is effective to compress the working fluid (or to expand the fluid if the machine is used as an expander). A low pressure port and a high pressure port formed in the housing at opposite ends thereof permits inlet and outlet of the working fluid. The grooves of the rotors each have a primary flank and a secondary flank. The tips of the primary flanks of both the male and female rotors are formed by parabolic arcs which generate major portions of one of the flanks of the opposite rotors. A major portion of the secondary flank of the female rotor is also a parabolic arc.