Abstract: A desiccant tower receives air at its air inlet and concentrates the oxygen in this air in order to provide a gas at its gas outlet which has a concentration of oxygen exceeding the concentration of oxygen normally found in air. A bypass conduit is coupled to the desiccant tower so as to syphon off gas from the desiccant tower at a point where the gas within the desiccant tower has a concentration of oxygen which is less than the concentration of oxygen in the gas at the gas outlet of the desiccant tower. The gases at the gas outlet of the desiccant tank and in the conduit are mixed so as to produce an output gas mixture having a desired concentration of oxygen. The desired concentration of oxygen is less than a desiccant tower can ordinarily provide but greater than the concentration of oxygen normally found in air.

Abstract: A globe valve having a main body, a bonnet, and a stem is provided with a mechanism that prevents the bonnet from being inadvertently backed off the main body. The mechanism includes a lock held to the body so that the lock is incapable of rotating as the stem is rotated, and means for releasably engaging the bonnet to the lock. For example, the lock can have a plurality of teeth that engage corresponding teeth on the bonnet. A locking ring can be used to hold the stem in the bonnet.

Abstract: A low noise level valve for controlling high pressure fluid flow between an inlet and an outlet. The valve comprises a poppet movable along a given line with respect to a complementarily formed valve seat. The area between the poppet and valve seat comprises a series of spaced undulations which extend along a continuous curve of approximately 90.degree.. The undulations are disposed substantially parallel to the direction of poppet movement adjacent to the inlet and are substantially transverse adjacent to the outlet. The undulations define a plurality of orifices which are opened progressively from the outlet toward the inlet. The orifices act as pressure drops and also cause turbulence as fluid flows around the undulations, thereby holding the fluid flow below undesirable speed and noise levels. A balancing chamber may be provided to counter-balance the poppet movement. Sealing means may be provided by an undercut lip formed on a sealing member adjacent to the inlet.

Abstract: A low pressure dew and frost point indicator of the type having a vortex tube which directs a cold air stream against the back of a viewing mirror for observation of the initial formation of frost. The mirror has means for simple and automatic centering with respect to the cold air stream of the vortex tube for maximum temperature transfer. The mirror engages no heat conducting elements and has means for improved cold temperature transfer. A venturi nozzle passes the warm air output of the vortex tube around the cold air output for adjustment to provide optimum cold air generation by reduction of the vortex tube outlet pressure. A temperature control valve controls the temperature in the sample chamber by mixing the warm and cold air outputs of the vortex tube.