Rotary gear pumps

Figure 3-65B. Typical rotary gear pump. (By permission. Viking Pump, Inc., Unit of Idex Corporation.)...

Fig. 10.13. Venturi tube (1 feed, 2 metering pump, 3 nozzle, 4 rotary gear pump, 5 pump, 6 heat exchanger, 7 funnel, 8 sample valve, 9 valve).

External rotary gear pumps are particularly suitable for moderate-to-very high-kinematic viscosity liquids in the range of 100 to 500,000 centistokes for flow capacities to at least 1,500 gpm (0.252 mVs) and heads to at least 3,000 ft (914.4 m). They are moderately priced, but usually more expensive than radial centrifugal pumps. They cannot be used with liquids containing particles and do not give as smooth a flow rate as do radial centrifugal pumps. 

FIGURE 18.8 Venturi tube (1, feed 2, metering pump 3, nozzle 4, rotary gear pump 5, pump 6, heat exchanger 7, funnel 8, sample valve 9, valve). 

In 1840 a hydrauHc power network, which involved large reciprocating pumps that were driven by steam engines, suppHed fluid power to London. However, concurrent technology in steam (qv) turbines and the electric generators outmoded such networks until hydrauHc systems were improved with the use of rotary pumps and oil. The rotary piston pump marked the transition from use of water to oil as the hydrauHc fluid (4). The use of vacuum-distilled, refined mineral oils were instmmental in the success of rotary axial piston pumps and motors such as the Waterbury variable speed gear... 

Positive Pumps. Positive pumps employed by the food industry have a rotating cavity between two lobes, two gears that rotate in opposite directions, or a crescent or stationary cavity and a rotor. Rotary positive pumps operate at relatively low speed. Fluid enters the cavity by gravity flow or from a centrifugal pump. The positive pump also may use a reciprocating cavity, and may be a plunger or piston pump. These pumps are not truly positive with respect to displacement, but are used for metering product flow. 

Rota.ry Lobe Pumps. Rotary lobe pumps are similar to gear pumps in principle. These pumps have an added advantage of noncontacting metal parts by use of external gears, which reduces the wear, but adds complexity. Low wear and improved shear characteristics make these pumps apphcable to the food industry, where cleanliness and absence of contamination are required. These pumps produce a strong pulsing flow that must be addressed. 

Other positive displacement pumps, such as rotary, gear, and diaphragm pumps, normally require PR valve protection for both the pump and downstream equipment. PR valves for all positive displacement pumps should have a capacity at least equal to the pump capacity. 

Positive-displacement rotary pumps The gear pump and the lobe pump... 

One of the most common rotary pumps is the external gear pump illustrated in Figure 4.11. The fixed casing contains two meshing gears of equal size. The driving gear is coupled to the drive shaft which transmits... 

A family of table-top microreaction systems named mikroSyn is provided by MiKroglas Chemtech (Figure 4.26) [77]. The basic system has a size of 700 mm x 70 mm x 330 mm and a weight of 30 kg. It can be equipped with two rotary pumps, one gear pump, valves and pressure and temperature sensors. The reactor itself is interchangeable with all reactor modules provided by Mikroglas Chemtec. 

Rotary positive-displacement pumps with no valve action gear pumps, lobe pumps, screw pumps, eccentric-cam pumps, metering pumps... 

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