Description

PUMPCALC is a Centrifugal Pump Analysis program. It can be used to predict the performance of one or more centrifugal pumps in series or parallel configurations. Several options are available for calculations based on input data from pump manufacturer’s curves as follows:

• Single pump performance - Impeller size and speed changes
• Multiple Pump Performance - Series and Parallel Configuration
• Viscosity Corrected Pump Performance - Hydraulic Institute method
• Pump Head Curve versus Pipe System Head Curve -Operating point
• Screen and Printer Graphic Plots

The main data needed for running PUMPCALC is the pump curve data file. This consists of sets of values of Flow rate (or capacity), Head and Efficiency for a particular pump, for a specific impeller size and speed. Normally, you will need to get this information from a pump catalog. The number of sets of Flow, Head and Efficiency values are limited to between 3 sets of points (minimum) and 15 sets of points (maximum).The data points taken off of a manufacturer's pump curve must cover the entire range of flow rate permissible for the specific pump.Extrapolation can be made but may result in inaccurate results. Pump data files are saved under a name such as PUMP123.PMP and can be opened up within PUMPCALC for editing data and plotting curves.

Using Affinity Laws, the performance of a centrifugal pump at different impeller diameters, speeds and stages can be calculated from the manufacturer's pump curve data.

The speed or diameter required to meet a specific design condition can also be calculated. Performance of pumps in series and parallel can be predicted.

For high viscosity liquids, the water performance curve is used in conjunction with the built-in Hydraulic Institute charts to estimate the viscosity corrected pump performance. The resultant performance curves may be plotted on the screen as well as on the connected printer.

The viscous performance calculated requires the use of the best efficiency point (BEP) from the water curve. This is defined as the point on the water performance curve with the maximum efficiency. The flow rate, head and efficiency at this point on the curve is used as the starting point for viscosity corrected performance calculations. The Best Efficiency Point values may be specified in the appropriate fields or you may have PUMPCALC calculate the BEP by interpolation. After entering all data, click on the Calculate button to start calculations. Based on the Hydraulic Institute Charts, the water performance curve will be corrected for the given liquid viscosity and both water and viscous performance results will shown side by side in spreadsheets.

Once the viscous performance is calculated, additional points on the viscous curve can be determined by interpolation. If the water performance and the corresponding viscous performance are desired at a particular flow rate, enter these values in the Water Capacity and Viscous Capacity fields and click on the Calculate button. The performance on both curves at the specified flow rate will be calculated and displayed on the spreadsheets, in a highlighted color. Similarly, additional data points on both curves can be calculated. Note that extrapolating beyond the limits of the performance curve, though feasible may be inaccurate. Due to the nature of the Spline Interpolation method used, extrapolation may, in some cases yield incorrect results. However interpolation is generally quite accurate. The calculated viscous performance curve is saved in a data file. This curve information may then be used with Single Pump performance option to determine other performance characteristics using affinity laws.

Clicking on the Plot button, opens another dialog box to choose the type of plot. The calculated water performance and viscous performance curves may be plotted on the screen as well as on the connected printer.

For a given pipeline diameter, length and elevations, the system head curves can be generated for different liquid properties and the point of intersection of the pump curve and the pipeline system curve can be determined. Screen graphics of the combined pump performance is also generated.

The input data for the pump curve consists of selected capacity (flow rate), head, and efficiency points from the manufacturer's catalog. This pump curve information is created and stored as a data file. For calculating the pipe system head curves, the pipeline data (distance, elevation, diameter, wall thickness) are input and stored as a data file. The liquid specific gravity, viscosity, pipe absolute roughness, pump suction pressure, pipe delivery pressure and the maximum allowable pipe pressure are also input. The system head curve may also be input by the user. This option allows you to enter the Flow rate versus System head data for plotting against the pump performance data. If the System Head curve data is input, PUMPCALC ignores the pipe data and uses the system head curve data, without calculating the pressure drops.

When used with the given pipeline data, in the absence of system head curve information, pipeline pressures are calculated for various flow rates to generate the System Head curve. Hydraulic calculations are performed based on the chosen pressure drop formula, such as Colebrook-White, Moody, Hazen-Williams, MIT or Miller equation for isothermal conditions of flow. The output consists of the pump operating flow rate, discharge pressure, efficiency and horsepower at the operating point. Screen graphics of the combined pump curve and system head curve are also generated.

The output consists of the pump operating flow rate, discharge pressure, efficiency and horsepower at the operating flow as shown on the next page. Additionally, the combined pump performance data and the individual pump flow rates and pressures are also output.