Pump selection

Presence of Solids When a pump is required to pump a hquid containing suspended solids, there are unique requirements which must be considered. Adequate clear-liquid hydraiilic performance and the use of carefully selected materials of construction may not be all that is required for satisfacdoiy pump selection. Dimensions of all internal passages are critical. Pockets and dead spots, areas where solids can accumulate, must be avoided. Close internal clearances are undesirable because of abrasion. Flushing connections for continuous or intermittent use should be provided. 

Pump Selection One of the parameters that is extremely useful in selecting a pump for a particular apphcatiou is specific speed N,. Specific speea of a pump can be evaluated based on its design speed, flow, and head. 

A Statistical Analysis of Nuclear Power Plant (Pump and Valve) Failure Rale Variability me Preliminary Results Nuclear All IPRDS data base records for the pumps and valves selected for analysis The set of valves and pumps selected for analysis from the IPRDS data base 104. 

Pumps, compressors, turbines, drivers, and auxiliary machinery should be designed to provide reliable, rugged performance. Pump selection and performance depend on the capacity required and tlie nature of Uie fluids involved. Remotely controlled power switches and shutoff valves are necessary to control fluid flow during an emergency. The inlets for air compressors should be strategically located to prevent the intake of hazardous materials. 

Compressors and Expanders Selection and Application for the Process Industry, Heinz P. Bloch, Joseph A. Cameron, Frank M. Danowski, Jr., Ralph James, Jr., Judson S. Swearingen, and Marilyn E. Weightman Metering Pumps Selection and Application, James P. Poynton Hydrocarbons from Methanol, Clarence D. Chang Form Flotation Theory and Applications, Ann N. Clarke and David J. Wilson... 

In general, the final pump selection and performance details are recommended by the manufacturers to meet the conditions specified by the process design engineer. It is important that the designer of the process system be completely familiar with the action of each pump offered for a service in order that such items as control instruments and valves may be properly evaluated in the full knowledge of the system. 

The pump selected for this application (water boiling at 0.98 psia) must have a required NPSH less than 4.7 ft, preferably about 3 to 3.5 ft. This is a difficult condition. If possible the vessel should be elevated to make more head (S) available, which wll raise the available NPSH. 

Now the pump selected reads NPSHr on its pump performance curve of 12 feet for cold water ser dce. 

Assume that a boiler feed water is being pumped at 180 °F. Read the chart in Figure 3-46 and the water vapor pressure curve, and follow over to read NPSH reduction = 0.45 feet. A pump selected for the sertice requires 6 feet cold water service NPSHr ... 

Determine proper pump selection and specifications when pumping oil with SpGr of 0.9 and viscosity of 25 cen-tipoise at the pumping temperature, if the pump must deliver 125 GPM at 86 feet total head (calculated using the viscous liquid). 

The pump specified identifies the design data, key portions of the construction materials and driver data as required informadon for the pump manufacturer. If the pump is to be inquiried to several manufacturers this is all that is necessary. The individual manufacturers will identity their particular pump selection and details of construction materials and driver data. From this informadon a pump can be selected with performance, materials of construction, and driver requirements specified. 

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

Neerken, R. E, Pump Selection for the Chemical Process Industries, Chem. Engineering, Feb. 18, 1974, p. 104. 

Wilkins, C., NPSH and Pump Selection Two Practical Examples, Healing, Piping and Air Conditioning, October 1988. 

Significant Features in Reciprocating Pump Arrangements, 215 Performance, 217 Discharge Flow Patterns, 218 Horsepower, 218 Pump Selection, 221. 

To place the process of pump selection in the plant decision tree it is necessary to follow the iterative way a complete plant evolves. 

Davidson, J. (ed.). Process Pump Selection-A Systems Approach, I. Mech. E., London (1986). 

In applications where the liquid is used directly by one or more system components, the contribution of these components to the total system head may be difficult to calculate. In some cases, the vendor s manual or the original design documentation will provide this information. If these data are not available, then the friction losses and back pressure need to be measured or an over-capacity pump selected for service based on a conservative estimate. 

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