Pumps, centrifugal selection

Figure 5.6. Centrifugal pump selection guide. Single-stage >1750 rpm, multi-stage 1750 rpm...

I.J. Karassik and R. Carter, Centrifugal Pump Selection Operation and Maintenance, F.W. Dodge Corp., New York, i960. 

SIMILARITY OR AFFINITY LAWS IN CENTRIFUGAL-PUMP SELECTION 6.31... 

SPECIFIC-SPEED CONSIDERATIONS IN CENTRIFUGAL-PUMP SELECTION... 

Horowitz— Affinity Laws and Specific Speed Can Simplify Centrifugal Pump Selection, Power, November 1964. 

From the definition of specific speed (eqs. 9 and 10), it follows that reciprocating pumps operate at high pressures and low flow rates. Conversely, centrifugal pumps are appHed at lower pressures and higher flow rates. Many rotary pumps are selected for viscous Hquids having pressures equal to or less than, and capacities lower than, centrifugal pumps. However, these limits are relative and a gray area exists as some pump types cross boundaries into the domain of other types. 

Reaction in a Centrifugal Pump In the reaction between acetic acid and gaseous ketene to make acetic anhydride, the pressure must be kept low (0.2 atm) to prevent polymerization of ketene. A packed tower with low pressure drop could be used but the required volume is very large because of the low pressure. Spes (Chem. Ing. Tech., 38, 963-966 [1966]) selected a centrifugal pump reactor where... 

Fiqiially, the pump will generate less flow as the discharge head or pressure requirements are increased. Obviously, both flow and head should be known before selecting a centrifugal pump. 

The system of Figure 2-27 consists of 125 feet of unknown size schedule 40 steel pipe on the discharge side of a centrifugal pump. The flow rate is 500 gallons per minute at 7o°F. Although the tank is located above the pump, note that this elevation difference does not enter into the pipe size-friction drop calculations. How ever it will become a part of selection of the pump for the serrice (see Chapter 3). For quick estimate follow these steps ... 

For general service the average centrifugal pump should lift about 15 feet of water on its suction side. However, since each process situation is different, it is not sufficient to assume that a particular pump wll perform the needed suction lift. Actually, certain styles or models of a manufacturer s pumps are often specially adapted to high lift conditions. On the other hand it is unnecessary to select a high lift pump when pressure head or flooded suction conditions prevail. Proper evaluation of suction lift conditions cannot be over emphasized. 

Suction and discharge heads are determined the same as for centrifugal pumps. Total head and capacity are used in selecting the proper rotary pump from a manufacturer s data or curves. Since viscosity is quite important in the... 

Reciprocating pump selection follows the fundamentals of centrifugal pumps ... 

Olmstead, P. J., Selecting Centrifugal Pumps, Heating and Ventilating, Feb.. 1946. 

Bloch, H, P., Flow to Select a Centrifugal Pump Vendor, Hydro. Proc., June 1978,... 

There are important calculations that are needed to properly evaluate and select the appropriate centrifugal pump [20]. 

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