Pumps, centrifugal diaphragm

Most often, the sludge is pumped to a collection tank before going on to final disposal. Advancing-cavity pumps and diaphragm pumps operated by air or electricity are in common use, and in larger units, centrifugal slurry pumps are the norm. 

As the flow rate and quantity of liquor are the most important controllable variables in developing design data, a feed pump suitable for accurate and continuous flow is required. Depending on the size of the pilot column system, the use of peristaltic, diaphragm, piston-type or centrifugal pumps are recommended. The feed pump should be used in combination with a volumetric or gravimetric flow control... 

There are trade-offs for magnetic drive and canned pumps versus centrifugal pumps with double-mechanical seals. The former have no seals to leak, but need active interlocks to prevent high temperature for temperature sensitive materials. Similarly, diaphragm pumps, that have... 

PPDS works on the principle of metering pumps and employs diaphragm, bellows, centrifugal, or vacuum-pressure-dispense pumps. These systems may be used for slurries including shear-sensitive slurries and cause minimal recirculation during slurry usage and replenishment. 

FIGURE 18.15 Test setup for CMP slurry handling and filter characterization. Experiments can be performed emplo5hng an air operated diaphragm (AOD) pump or a magnetically levitated centrifugal (MLC) pump. 

Figures 8.15 A and B Figure A illustrates the diaphragm pump and B the centrifugal pump.

Diaphragm pumps. These offer very gentle handling of slurries and are inexpensive and mobile. However, the pulsating flow can cause feeding and distribution problems in some types of filtration systems, e.g., conventional basket centrifuges. They can also interfere with process instrumentation e.g., flowmeters and loadcells. 

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