Displacement pumps

Since changes in pump speed affect volumetric output, some pumps are rated by their displacement. Pump displacement is the amount of fluid the pump can deliver per cycle or complete rotation. Since most pumps use a rotary drive, displacement is usually expressed in terms of cubic inches per revolution. 

For example with 5 percent gas entrainment at 15 in Hg (381 mmHg) vacuum, the liquid displacement will be 90Y2 percent of the pump displacement neglecting slip or with 10 percent dissolved gas liquid displacement will be 90Y2 percent of pump displacement, and with 5 percent entrained gas combined with 10 percent dissolved gas, the liquid displacement will be 83 Y, percent of pump displacement. 

To use the pump-down factor, apply this relation t = VF/d, where t is pump-down time, min Vis system volume, ft3 F is pump-down factor for the pump dis pump displacement, ft3/min. 

If this backing pump is to be used for pumping down the system, compute the pump-down time as shown in the previous example. Should the pump-down time be excessive, increase the pump displacement until a suitable pump-down time is obtained. 

Feed sludge Flow Venturi with diapragm sensors Magnetic Doppler Pump displacement... 

Rotary Pumps. Rotary pumps are characterized by a rotary movement types include screw, lobe, vane, and gear. Figures 5-16 and 5-17 illustrate rotary-type pumps. Rotary pumps displace liquid with gears, vanes, screws, or other rotating elements. The common thread between these two groups is the positive displacement action of the device. Centrifugal pumps are often mistakenly... 

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