Calculation pump head

Methods for the calculation of pressure drop through pipes and fittings are given in Section 5.4.2 and Volume 1, Chapter 3. It is important that a proper analysis is made of the system and the use of a calculation form (work sheet) to standardize pump-head calculations is recommended. A standard calculation form ensures that a systematic method of calculation is used, and provides a check list to ensure that all the usual factors have been considered. It is also a permanent record of the calculation. Example 5.8 has been set out to illustrate the use of a typical calculation form. The calculation should include a check on the net positive suction head (NPSH) available see section 5.4.3. 

THIS PROGRAM CALCULATES ALL PUMP HEAD CALCULATIONS REQUIRED TO WRITE A PUMP SPECIFICATION SUITABLE FOR A VENDOR INQUIRY OR PURCHASE ORDER. THE PROGRAM FURTHER CALCULATES THE CENTRIFUGAL PUMP EFFICIENCY AND PUMP HORSEPOWER USING AN EQUATION DEVELOPED BY BY C. BRANAN (The Process Engineer s Pocket Handbook, Gulf Publishing Company, Houston 1976.)... 

For the uninitiated reader, it is worthwhile performing a few exercises in pump head calculation and pump performance to develop a feel for what is going on in a pumping circuit. 

The suction head or lift for the pump (separate calculation from NPSHa) is ... 

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). 

Pump and treat hazardous waste management, 25 845 Pump-around streams, 13 223 Pump calculation worksheet, 21 56 Pump energy level, 14 695 Pump head, total developed, 21 57-58 Pumping, 14 658-659... 

Calculate the C value of the control valve, the pump head at design rate, the size of the motor required to drive the pump, the fraction that the valve is open at design, and the pressure drop over the valve at design rate. 

When the pump is being used for its primary purpose of introduction of modifier for extractions, the actual amount of modifier that is delivered is a function of four variables and these variables can be controlled. The variables include, the length and diameter of line between pump and inlet port to the column, the allowable pressure limit of the pump, the pump flow rate and the amount of material including air in the columns. The first factor can be accounted for by measuring the volume of the lines between the inlet port and the pump head. This volume can then be subtracted from the calculated amount delivered to the first extraction vessel filled in a series. The second and third variables are parameters that can be set on the pump. The fourth variable was rarely a problem, but can be controlled by placing a vacuum pump in position 3 or 4 to evacuate the column and the connected lines. 

In order to specify a pump to meet the required operating conditions it is necessary to calculate the forces opposing the pumping of this fluid, i.e. the pressure or head which makes pumping necessary. Calculations were performed for normal flow conditions and also for design conditions 20% above the normal. The pump specification is based on the larger design values. 

Pump Characteristic and System Head. The pump characteristic curve needs to be matched with the head loss through a piping system, which is known as the system head. The system head increases approximately in proportion to the square of the flow rate (Ap cc z/2). An example of a system head calculation is given in Section 3.10. 

Related Calculations. Use the similarity laws to extend or change the data obtained from centrifugal-pump characteristic curves. These laws are also useful in field calculations when the pump head, capacity, speed, or impeller diameter is changed. 

Chapter 5 considered pump types and their evaluation and selection. After selecting a pump type, the next step is to size the pump. This requires calculating the flow rate and the pressure rise across the pump or the pump head. The net positive suction head (NPSH), is also important, particularly for centrifugal pumps. NPSH is the difference between the total pressure and the vapor pressure of the fluid at the pump inlet. NPSH will be discussed later. 

The required pump head is calculated from Equation (5.141), with = Pn. ... 

If the maximum flow rate through the heat exchanger is 300 gpm when the CO signal is 0 percent of scale, calculate the Cy value of both control valves and the required pump head. What is the flow rate through valve 1 when the CO signal is 100 percent of scale ... 

It is wise to allow for pump head and efficiency deterioration, relative to its water performance, of a few per cent, based on the pump supplier s data and according to the slurry properties. Indeed, the suppliers of specialist slurry pumps will usually assist in the overall system design. It is also wise to allow a margin of 15-25 per cent of maximum calculated absorbed power when sizing the driver, to provide flexibility for operation at increased densities and pump speeds. 

The COAST computer program is used to calculate the reactor coolant flow coast down transient for any combination of active and inactive pumps and forward or reverse flow in the hot or cold legs. The equations of conservation of momentum are written for each of the flow paths of the COAST model assuming unsteady one-dimensional flow of an incompressible fluid. The equation of conservation of mass is written for the appropriate nodal points. Pressure losses due to friction, and geometric losses are assumed proportional to the flow velocity squared. Pump dynamics are modelled using a head-flow curve for a pump at fiill speed and using four-quadrant curves, which are parametric diagrams of pump head and torque on coordinates of speed versus flow, for a pump at other than full speed. 

For this purpose, commercially available calculation programs are frequently applied. Usually the results are one or more characteristic curves (pump head over volume flow) whereby different load conditions are taken into account. Furthermore the progression of the NPSHa-value can be calculated against the discharged volume flow. Here again the different modes of operation should be considered to determine the worst case . 

Pump suction or discharge pressure can be calculated by performing a hydraulic calculation on the pump sucti< i and discharge line re ctively. After pump suction and discharge pressures are known, required pump head can be calculated as follows. 

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