Pumps/pumping internal gear

Exiernal Gear Pump Internal Gear Pump Three-Lobe Pump Discharge... 

TWo-Teeth Difference. In this type of pump an abutment on one side plate is used to fill the clearance between the external and internal gear. This construction reduces leakage but involves the use of an overhung internal gear. Such a gear arrangement limits the application of these pumps to small and moderate-volume capacity pumps. 

FIGURE 4.5 Various types of pump impellers, continued (a) lobe type (b) internal gear type (c) vane type (d) impeller with stationary guiding diffuser vanes (e) impeller with volute discharge and (f) external gear type impeller. 

Gear pumps (a) spur-gear pump (i) internal-gear pump. 

Figure 13.6 Gear pump versions (a) external gear pump (b) clearance situation (c) internal gear pump (d) trochoidal pump E inlet A outlet channel S clearance channels source Institute of Process Machinery and Systems Engineering, University of Erlangen-Nuremberg, Germany).

The piston is driven in and out of a solvent chamber by an eccentric cam or gear. On the forward stroke, the inlet check valve closes, the outlet valve opens, and mobile phase is pumped to the column on the return stroke the outlet valve closes and the chamber is refilled. Unlike syringe pumps, reciprocating pumps have an unlimited capacity, and their internal volume can be made very small, from 10-100 p. The flow rate can be varied by changing the length of stroke of the piston or the speed of the motor. Access to the valves and seals is usually fairly straightforward. 

Some questions will require the identification of various mechanical tools or devices. Some of the types of mechanical devices that may appear on the exam— and covered in this chapter—include hand tools, gears, pulleys, levers, fasteners, springs, valves, gauges, and pumps. In addition to individual mechanical devices, the exam may test your knowledge of various systems, or combinations of mechanical devices. A common example of a mechanical system is the internal combustion engine of an automobile. 

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