Series 7000 Rotary Air Compressors and Dry Vacuum Pumps


It is the use of the proper cooling method in your specific compressor application that will insure you of the greatest economy in initial cost and operating efficiency. That's why Yeomans has three basic rotary air and gas compressors: air- cooled, fan-cooled, and water-cooled.

The capacity of these units extends up to 300 c.f.m. and pressures up to 5O psi or for moderate vacuums up to 27" of mercury (or 95% of barometric pressure). Since they are of the positive displacement type, these units can­not be operated with a closed discharge. Air storage or cushion tanks are required only where automatic start-and-stop control is needed because the discharge from the units is pulsation-free.


The complete assembly of these units consists of a cyl­inder with inlet and discharge ports on opposite sides and a circular rotor that is mounted eccentrically in the cylinder so its surface runs close to one side of the cyl­inder wall. The rotor shaft is carried by anti-friction bearings in the two cylinder heads.

Radial slots are milled along the full length of the rotor to carry the composition vanes inserted in them. When operating, centrifugal force causes the vanes to follow the inside contour of the cylinder. Since the cylinder contour is not concentric with the rotor, the vanes are continuously being forced in and out. The cell space between the vanes is contracted with each revolution, trapping the gas and compressing it before discharging to the exhaust port. Vane action is wholly dependent upon centrifugal force. There are no springs and com­pensation for any wear of the vane is automatic.

Cooling of the fan-cooled machine is accomplished by forcing atmospheric air, which is taken in through the coupling end of the housing, over the fins on the com­pressor cylinder. In the larger machine, (Model No. 7108), a fan is mounted on each end. Lubrication of the smaller machines is by diaphragm operated force-feed lubricator (Model No. 545) and force-feed mechanical lubricator driven from the compressor shaft on all other sizes.

The air-cooled machine depends entirely upon the con­vection fins on the outer periphery of the compressor for cooling. Both fan-cooled and air-cooled machines oper­ate in similar fashion.


When pressures exceed the normal limitations of the air-cooled machine and in some continuous duty appli­cations, it is necessary to provide a separate water-cooling jacket to the cylinder head and cylinder of the compressor. When necessary, temperature-compensating equipment to maintain consistent temperature in the compressor is provided.

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