Liquid ring pumps Rotary piston pump

Figure 6-110. Typical performance curves for steam jet ejectors, liquid ring pumps, and rotary piston oil-sealed pumps. By permission, Ryans, J. L. and Roper, D. L. [24],...

Vacuum capacities and operating ranges, table, 344, 355 Ejectors, 344, 357 Integrated systems, 344 Liquid ring pumps, 344 Rotary lobe blowers, 344 Rotary piston pumps, 344 Rotary vane pumps, 344 Vacuum equipment, 343 Applications diagram, 352 ASME Code, 344 Pumps, 382 Steam jets, 357 Vacuum flow,... 

The most used mechanical vacuum pumps or compressors are reciprocating, liquid-ring, rotary-vane, rotary blower, rotary piston, and diaphragm. 

Combination ejector/liquid-ring systems and mechanical systems that use rotary blowers backed with other mechanical pump types are versatile and energy efficient. Thermal efficiencies of combination pumping systems are shown in Figure 23-12. Ejector/liquid-ring systems offer the highest reliability and are versatile for both wet and dry loads over a wide range. Rotary-blower/ rotary-piston systems are the most efficient and have been extensively applied. 

But the liquid ting pump has (1) multiple vanes (fins) vs. a single one (often) for the rotary vane pump (2) no vanes which contact the perimeter of the cavity as it s essential for aU to do so in a rotary vane pump (3) a point of entry for the vapor within the rotor and not at the circumference of the casing as is typical of other vacuum pumps and (4) a "pool" of liquid which acts a "collector" to remove vapor from the work chamher and also as a piston to compress the vapor not a good descriptive diagram of a liquid ring vacuum pump is shown in Figure 2.9. 

Positive displacement pumps diaphragm vacuum pumps, liquid ring vacuum pumps, rotary vane and rotary piston vacuum pumps as well as Roots vacuum pumps (dry compressing claw and screw pumps are not yet mentioned here but also belong to this group of pumps). 

It is to be taken into account that with the employment of rotary piston vacuum pumps, the temperature of the fluid fed to the liquid ring compressor is higher than with the other combinations. In addition, this heat is to be dissipated by the ring liquid, so that the temperature of the liquid ring will be higher and with it the suction capacity will be lower. 

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