![]() Centrifugal Pump Sizing, Selection and Design Practices by Scribd_del in Types > Presentations, selection, and sizing. To size a pump, you must define: • The flow rate of liquid the pump is required to deliver • The total differential head the pump must generate to deliver the required flow rate This is the case for all types of pumps: centrifugal or positive displacement. Other key considerations for pump sizing are the net positive suction head available (NPSHa) and the power required to drive the pump. Pump System Diagram Flow Rate Usually, the flow rate of liquid a pump needs to deliver is determined by the process in which the pump is installed. New bin file sonicview 8000 hd ihub breakout. This ultimately is defined by the mass and energy balance of the process. For instance the required flow rate of a pump feeding oil into a refinery distillation column will be determined by how much product the column is required to produce. Another example is the flow rate of a cooling water pump circulating water through a heat exchanger is defined by the amount of heat transfer required. Essentially, the total differential head is made up of 2 components. The first is the static head across the pump and the second is the frictional head loss through the suction and discharge piping systems. Total differential head = static head difference + frictional head losses Static Head Difference The static head difference across the pump is the difference in head between the discharge static head and the suction static head. Static head difference = discharge static head – suction static head Discharge Static Head The discharge static head is sum of the gas pressure at the surface of the liquid in the discharge vessel (expressed as head rather than pressure) and the difference in elevation between the outlet of the discharge pipe, and the centre line of the pump. Discharge static head = Discharge vessel gas pressure head + elevation of discharge pipe outlet – elevation of pump centre line The discharge pipe outlet may be above the surface of the liquid in the discharge vessel or it may be submerged as shown in these 3 diagrams. Discharge Pipe Enters The Bottom Of The Vessel Suction Static Head The suction static head is sum of the gas pressure at the surface of the liquid in the suction vessel (expressed as head rather than pressure) and the difference in elevation between the surface of the liquid in the suction vessel and the centre line of the pump. Suction static head = Suction vessel gas pressure head + elevation of suction vessel liquid surface – elevation of pump centre line Note: gas pressure can be converted to head using: Gas head = gas pressure ÷ (liquid density x acceleration due to gravity).
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