If the pump that you wish to model in PIPE-FLO is not available in one of the electronic pump catalogs, then the pump performance data can be easily entered in PIPE-FLO 12 or Flow of Fluids 12.
Manual Data Entry:
You can enter the pump performance data by selecting either the sizing pump or centrifugal pump device and right clicking the mouse. A context menu, like the one shown below, will appear.
Next, select "Enter Pump Data" and the Enter Pump Data dialog box will appear. In this dialog box you enter the flow rate and head data for the pump. You have the option of also entering the efficiency and Net Positive Suction Head required (NPSHr) based on the flow rates.
Most pump manufacturers will have performance curves available for their pumps. These might be paper curves from a catalog or even electronic .pdf files. Whatever the format, it’s important to have a representative performance curve to glean data points. Figure 1 depicts a paper curve from a manufacturer which has all of the relevant information needed.
Figure 1: Manufacturer's Performance Curve
Several of the key parameters in this curve have been colorized to set them apart a little better. The black curves moving from left to right and downward are the performance curves for flow versus head. Flow rate is scaled on the x-axis while total head is scaled on the y-axis. The green curves are iso-efficiency curves for the pump, blue curves represent iso-horsepower or brake horsepower, and the pink curves represent iso-NPSHr or Net Positive Suction Head Required.
Some of the other information that you can gather from this performance curve: The size of the pump is 6x8x11. This means there is a 6 inch discharge with an 8 inch suction, and a maximum impeller diameter of 11 inches. The minimum impeller diameter is 7.25 inches. The test speed of the pump is 1180 rpm, which means that the synchronous speed is likely 1200 rpm. Some manufacturers allow you to speed the pump up past the synchronous speed, but to be conservative, we will assume that the maximum speed is the synch speed. The only parameter that we are missing that we would like to have is the minimum speed for variable frequency drive operation. For this, we can just take a typical value of 50% of the synchronous speed, so we will assume the minimum speed is 600 rpm.
The next step is to pick points off the impeller curve for entry into PIPE-FLO The available data to enter is flow rate, head, efficiency and NPSHr. So for the example in Figure 1, let’s say we want to enter data points for a 10 inch impeller diameter curve You want to make sure that you mark the shut off head, the run out flow rate, and the best efficiency point (BEP). We’ve marked points on this curve in red at those important landmark points, plus regular 200 gpm increments. Below is same pump curve with a yellow marker showing how to determine the Head value based on flow rate.
This pump data can be tabulated into the following chart.
Another possible way to choose points would be to mark off the points where the iso-efficiency lines intersect the impeller curve. This way, you wouldn't have to interpolate the efficiency values. Just remember, the more points you can select and specify, the better the PIPE-FLO curve will be. Also, if there are any slope changes, inflection points or other anomalies in the manufacturer’s curve, then you will want to make sure to get a good sampling of points on and around those anomalies.
We can try to get a minimum of 5 data points, and be as precise as you can as these data points will determine how much total head will be generated by the pump. Use a straight edge if necessary. For efficiency data points which are below or beyond the last available iso-efficiency curve, try to interpolate or extrapolate your values. For efficiency data points which are in an area beyond the highest iso-efficiency curve, just enter the same value as the highest iso-efficiency curve. Do not assume the efficiency continues to increase unless it’s expressly indicated. For NPSHr data points below the lowest iso-NPSHr curve, just enter the same value as the lowest iso-NPSHr curve. For NPSHr data points above the highest iso-NPSHr curve, try to extrapolate your values.
Important note: Efficiency and NPSHr data points are not a requirement. However, efficiency is a requirement if the program is to be able to make viscosity corrections due to viscous fluids If you are entering pump curve data points which have already been corrected for viscosity, then you do not want to enter efficiency data. This prevents PIPE-FLO from performing those viscosity corrections a second time.
With the data extracted from the manufactures curve, it can be entered into PIPE-FLO by following Knowledge Base "Entering Manual or Electronic Catalog Pump Curves into PIPE-FLO 12".