Abstract: The invention is an improvement in a pneumatic regulating valve of the type having a main flow path and a bleed passage. In the improvement, the bleed passage is in parallel with the main flow path and regulates a downward-trending pressure at the outlet port to prevent such pressure from diminishing or from rapidly diminishing. The valve also includes a check valve in series with the bleed passage for regulating an upward-trending pressure at the outlet port. Using a constant bleed orifice to substantially pressure-balance the check valve and a small-area protrusion on the check valve to reduce contact area, the check valve exhibits very low hysteresis.

Abstract: An improvement in a control valve having a body, a body interior portion and plural exterior ports in communication with the interior portion. The improvement includes a plurality of dovetail-like body slots "isolated" or spaced from other slots. Each slot intersects an aperture in fluid communication with the body interior portion. A complementarily shaped, friction-retained slide-by plate is in each slot and at least one plate includes a port in fluid communication with the slot aperture. Each plate slides for removal without disturbing any other plate. A plate may be a blind closure plate, a ported plate tapped with any of several thread sizes or a "back-to-back" interface plate for supportively mounting valve bodies in tandem. A control valve system including a slotted valve body and an assortment of plates of various types provides substantially "universal" porting between the body and another valve body and/or one or more separate control components.

Abstract: A 90 degree swivel coupling formed of a general purpose and heat-stabilized injection molding grade 6/6 type plastic resin includes a socket member and a stem member in telescoped relation. The socket member includes an outer skirt connected by spaced flexing arms to a connecting body portion. The skirt and opposed stem have a close complementing and mating bearing projection and recess establishing a swivel coupling. The bearing walls are inclined at an angle of 15 degrees. The skirt portion is slightly expandable outwardly. In the unstressed state, the bearing wall has a maximum diameter slightly less than that of the recess to establish a pressurized fit. The stem includes a cam having an inclined wall corresponding to the bearing projection with a maximum diameter slightly greater than the bearing wall of the skirt bearing and the same angle. The cam has a maximum smaller diameter than mating recesses in the flexing arms to allow the pressure bearing engagement.