Pumps centrifugal Mixed flow

Whereas the total dynamic head developed by a centrifugal, mixed-flow, or axial-flow pump is uniquely determined for any given flow by the speed at whicdi it rotates, positive-displacement pumps and those which approach positive displacement will ideally produce whatever head is impressed upon them by the system restrictions to flow. Actually with slippage neglecTed, the maximum head attainable is determined by the power available in the drive and the strength of the pump parts. An automatic relief valve set to open at a safe pressure... 

BS 5316 Part 1 1976, (ISO 2548) Acceptance Tests for Centrifugal, Mixed Flow and Axial Pumps. 

Figure 3-56. Viscosity performance correction chart for centrifugal pumps. Note do not extrapolate. For centrifugal pumps only, not for axial or mixed flow. NPSH must be adequate. For Newtonian fluids only. For multistage pumps, use head per stage. (By permission. Hydraulic Institute Standards for Centrifugal, Rotary, and Reciprocating Pumps, 13th ed.. Hydraulic Institute, 1975.)...

Centrifugal pumps can also be classified by the design of the impeller. Centrifugal pumps may have radial-flow impellers, axial-flow impellers, and mixed-flow impellers (both radial-flow and axial-flow). 

Figure 3-66 gives the upper limits of specific speeds of single-suction mixed-flow and axial-flow centrifugal pumps handling clear water at 85°F at sea level [22]. 

The specific speed for centrifugal pumps (equation 5.2) usually lies between 400 and 10,000, depending on the type of impeller. Generally, pump impellers are classified as radial for specific speeds between 400 and 1000, mixed flow between 1500 and 7000, and... 

Rirbine Pumps The term turbine pump is applied to units with mixed-flow (part axial and part centrifugal) impellers. Such units are available in capacities from 20 mVh (100 gal/min) upward for heads up to about 30 m (100 ft) per stage. Turbine pumps are usually vertical. 

Figure 7.10. Some types of impellers for centrifugal pumps, (a) Open impeller, (b) Semiopen impeller, (c) Shrouded impeller, (d) Axial flow (propeller) type, (e) Combined axial and radial flow, open type, (f) Shrouded mixed-flow impeller, (g) Shrouded impeller (P) in a case with diffuser vanes (V). (h) Turbine impeller.

Pumps Centrifugal Vertical mixed flow Vertical axial flow Gear pumps Reciprocating pumps... 

Turbine pumps mix features of a simple propeller (axial flow) pump with a centrifugal pump and are often referred to as units with mixed flow. A simple turbine pump carries curved vanes on a central rotating spindle. Such pumps are often immersed in the liquid and find use in closed-loop circulation systems, in condenser circulating water, and in sumps and wells. Turbine pumps have noteworthy pumping capacity, and like positive displacements pumps are often used for heads up to about 100 ft/stage with capacities of up to several hundred gallons/minute. 

Compute the maximum pump capacity. For any centrifugal, mixed- or axial-flow pump, Ns =... 

In general, a centrifugal impeller can discharge its flow in three ways by directly throwing the flow radially into the side of the chamber circumscribing it, by conveying the flow forward by proper design of the impeller, and by a mix of forward and radial throw of the flow. The pump that uses the first impeller is called a radial-flow pump, the second, as mentioned previously, is called the axial-flow pump and the third pump that uses the third type of impeller is called a mixed-flow pump. The impeller in c is used for mixed-flow pumps. 

Characteristics of propeller (and mixed-flow) pumps vary considerably from those of radial flow centrifugal pumps. The head curve of a centrifugal pump is fairly flat, while that of the propeller pump rises sharply when its flow is restricted. A comparison of a centrifugal and a propeller pump rated for the same conditions is shown in Figure 25-4. 

Centrifugal pumps can be classified based on the manner in which fluid flows through the pump. The manner in which fluid flows through the pump is determined by the design of the pump casing and the impeller. The three types of flow through a centrifugal pump are radial flow, axial flow, and mixed flow. 

Fig. 2. Flow sheet of lecithin producing unit. Crude soybean oil is heated in the preheater, 1, to 80°C, mixed with 2% water in the proportion control unit, 2, and intensively agitated in 3. The mixture goes to a dweUing container, 4, and is then centrifuged after a residence time of 2—5 min. The degummed oil flows without further drying to the storage tanks. The lecithin sludge is dried in the thin-film evaporator, 6, at 100°C and 6 kPa (60 mbar) for 1—2 min and is discharged after cooling to 50—60°C in the cooler, 8. 9 and 10 are the condenser and vacuum pump, respectively.

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