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Performing a Cost Analysis in PUMP-FLO

The following instructions will walk you through a typical Cost Analysis on our web-based selection engine at www.pump-flo.com using our sample catalog, Olympia Pumps.

To begin, go to: http://www.pump-flo.com/pumpselection/storefront.aspx?DirName=olypumps

Next, choose the Olympia Pumps Demonstration Catalog. Run a design point search using 400 gpm and 250 feet of head. Make sure the Generate SRC box is checked to allow the program to automatically generate a 2nd Order System Resistance Curve using the design flow and head. Finally, select ESP from the Types list box and select 3600 from the Speeds list box, then click Search.

Select the ESP 4x3-10 pump at 3560 rpm from the selection list.

Choose Cost Analysis from the black toolbar along the top of the screen.

In order to perform an Energy Cost Analysis, PUMP-FLO® must know the annual operating load information for your pumping system. This includes the desired flow rates, duration, and the energy costs per kWh.  You will now enter an operating load profile to generate an Energy Cost Analysis.

Under Motor, verify that Fixed speed is selected.

Enter the following Operating Load data.

 Flow US gpm $$\frac{Hrs}{yr}$$ $$\frac{ Cost}{kWh}$$ 400 4000 0.08 350 1000 0.08 300 3000 0.06 250 500 0.06

Now click Calculate.  The Motor / Drive % Eff, Pump Speed, and Pump hp are automatically filled in with data from the catalog’s motor table.  Note the total annual power consumption and fixed speed costs for this pump, 244402 kWh and $17,702. To compare operation of the pump at variable speed, in the Motor section, switch to the Variable speed (VFD) option and click Calculate. The Motor / Drive % Eff, Pump Speed, and Pump hp will change to reflect operation using a VFD. Note the total annual power consumption and fixed speed costs for this pump, 181979 kWh and$13,691.

In this scenario, you can save over \$4000 annually by operating this pump using a variable speed drive. This savings is realized because your pump is able to scale back its speed to achieve the desired flow rate, instead of throttling the downstream flow with a control valve.

If we look at the above operating scenario, at 250 gpm a fixed speed pump would be creating 278 feet of head (see Figure 1) while using 30.5 hp.  From evaluating the system resistance curve, only 100 feet of head is required to pump the fluid through the system.  The additional 178 feet of head would need to be dissipated through a throttling valve in order to achieve the desired flow rate of 250gpm.  This is lost energy.

Figure 1: Fixed Speed Pump operating at 250 gpm

If we look at the same operating condition except with a VFD pump (Figure 2), the pump’s operating speed would reduce to 2220 rpm which would achieve the 250 gpm flow rate desired.  This flow rate is now achieved using only 9.26 hp.

Figure 2: VFD Pump operating at 250gpm

Additional costs can be entered to determine the total Lift Cycle Cost of the pump, such as the purchase price of the pump, operating costs, and decommissioning costs. Those will be multiplied over the time frame you specify under Term of Cost Analysis. You can enter an interest rate and inflation rate to factor in the changing Cost of Money. Your total costs are reported at the bottom of the page.

Finally, a Printed Report of the cost analysis you just created is available by going to the Printed Reports menu on the black toolbar at the top of the screen and choosing Cost Analysis.