Abstract: Method and apparatus for achieving a high degree of vacuum pumping in an enclosure utilizing a single-stage pump. A vacuum pumping unit is coupled to a plurality of interconnected enclosures through a series of valves. When evacuation of a selected enclosure is desired, the valves are opened sequentially for a brief duration such that the enclosures are alternatively evacuated to the atmosphere and to other partially evacuated enclosures.

Abstract: The invention comprises a novel oil distributing arrangement, employing a valve which has a plurality of responses, for use in a gas compressing system or the like. The valve has a plurality of ports for admitting oil thereinto from an oil pump via a cooler, and for discharging oil therefrom, to a gas compressor (or some such similar oil-using end item) or for by-passing oil directly back to the oil pump (or a pump-serving oil reservoir), or for by-passing the cooler, etc. A translating valving element opens and closes communication between different oil admittance and oil discharge ports in the valve, in response to discrete ranges of valve-operating fluid pressures addressed to the valving element, to effect the cited by-passing functions, and to maintain a fairly uniform pump output pressure level.

Abstract: The invention comprises a subsystem or assembly which lends itself to retro-fitting to a machine to controllingly supply oil to the machine. In the embodiment shown by way of example, the invention supplies injection oil and lubricating oil to an oil-injected and oil-lubricated gas compressor, and includes a pressure-responsive metering device for regulating the relative quantities of injection and lubricating oil supplied pursuant to the operating condition of the compressor. Particularly the invention comprises the use of a small, inexpensive oil pump, to supply substantially only lubrication for the compressor on start-up, and by-passes the pump, when substantially "on line" (i.e., with the compressor discharge pressure elevated), and then supplies less of the oil for lubrication purposes and more for injection (for compressor sealing and cooling).

Abstract: The invention, in an embodiment shown, employs a piston-controlled metering valve to attenuate oil-pressure biasing of a thrust piston as discharge pressure in the gas compressor diminishes, and to increase the biasing as the discharge pressure increases. Discharge pressure of the compressor is impressed on one surface of the valve piston, and compressor oil pressure is addressed to the opposite surface of the piston from the oil pressure line. A shunt line communicates with a valve-metered orifice to bypass oil flow therethrough, from the oil pressure line, upon the compressor discharge diminishing, and the orifice becomes constricted--to impede an oil bypass--upon the compressor discharge increasing. The degree of oil bypassing or shunting from the oil pressure line results in a modulation of the oil line pressure which, in turn, is addressed to the thrust piston.

Abstract: In the embodiment depicted, the system comprises a gas compressing arrangement of first and second rotary compressing stages with an intercooler and an aftercooler for condensing and removing moisture from the compressed gas product. In order to cool the gas compressor, generally, and the second-stage rotor shafts in particular, the cooled, de-moisturized, compressed-gas product is used. Thus, the second-stage rotor shafts are axially bored or hollowed, and a tube is supported within the bore. The tube is through-connected with the outlet of the aftercooler to admit the cooled, compressed gas product into the bore, and, in turn, the compressed gas product is discharged from the bore. Accordingly, the cooled, compressed gas product is cycled through the bore, constantly to cool the shafts all the while that the compressor is running, or under load.

Abstract: The unloading means comprise unloading ports, and valving therefor, for step-control unloading of a gas compressor. In a first embodiment, the unloading means are provided in side walls of a rotary, positive displacement, gas compressor, and in an alternate embodiment the unloading means are disposed within end walls (of a rotary, positive displacement, gas compressor), and comprehends means for step-control of a plural-stage machine.

Abstract: The unloading means comprise unloading ports, and valving therefor, for step-control unloading of a gas compressor. In a first embodiment, the unloading means are provided in side walls of a rotary, positive displacement, gas compressor, and in an alternate embodiment the unloading means are disposed within end walls (of a rotary, positive displacement, gas compressor), and comprehends means for step-control of a plural-stage machine.