If the pump that you wish to model in PIPE-FLO is not available in one of the electronic pump catalogs, then the next best thing is to manually enter the pump curve data.  This article will describe how to extract the appropriate data points from a pump manufacturer’s paper curve and enter them into the Pump dialog box in PIPE-FLO.

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 from.  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 represent iso-efficiency curves for the pump’s efficiency.  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 includes the following:  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.  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.

Now, to enter this data into PIPE-FLO, you want to open the pump dialog box, and click the Enter Curve  button from the Pump tab, or the Edit Curve  button from the Curve tab.  This opens the Pump Data dialog box, where you next want to click the Advanced  button.  The dialog box should look like the one in Figure 2.


Figure 2:  Pump Data Dialog Box - blank

Now we can begin entering our data from the manufacturer’s paper curve.  First, we will add the “Additional Data”.  This data is not required, however, having a minimum and maximum speed allows you to use the “Variable speed pump” setting or to vary the speed of the pump manually.  And having a minimum and maximum diameter allows you to vary the impeller diameter up and down between these upper and lower limits.  Since the pump curve does not have information about motor efficiency, we can leave in the default value of 95%.

Manufacturer	Pumps-R-Us
Size	6x8x11
Maximum speed	1200 rpm
Minimum speed	300 rpm
Maximum diameter	11 in
Minimum diameter	7.25 in
Motor Efficiency	95 %

Next, we can enter the pump’s test speed and impeller diameter along with the flow and head units.

Speed	1180 rpm
Diameter	10 in
Flow units	US gpm
Head units	ft

Last, but not least, enter the flow, head, efficiency and NPSHr data from the manufacturer’s performance curve.  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.

Note:  When extrapolating data, your best resource for complete accuracy is going to be the manufacturer.

Flow (US gpm)	Head (ft)	Efficiency (%)	NPSHr (ft)
0	49.5	0	7.2
200	45.6	30	7.2
400	42.5	60	7.4
600	39.2	76	9.1
800	35.5	83.5	12
900	32.9	85	13
1000	30.1	84	15
1200	23.5	77	20
1400	15.8	59	26
1500	12	50	29

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 necessarily do not want to enter efficiency data.  This prevents PIPE-FLO from performing those viscosity corrections a second time.

The pump data dialog box should now look like Figure 3.


Figure 3:  Pump Data Dialog Box - filled

After you have finished entering the data, you can now set the pump to fixed speed or variable speed operation.  You can graph the pump as shown below in Figure 4.  Since we can only enter data points for one impeller diameter, the graph won't display iso-efficiency, iso-horsepower, or iso-NPSHr curves.  Instead, these are converted to line curves as shown.  The minimum and maximum curves are generated using the Pump Affinity Rules.  Inside this graph window, you can vary the speed or the impeller diameter of the pump.  Now you can operate this pump in your model just as you would operate a pump selected from an electronic catalog.  The manually entered pump is a fully functional pump as long as all the data has been specified.


Figure 4:  Manually Entered Pump Graph Window