Sometimes the required operating conditions for a system are beyond the reach of a single, standard pump. In many cases, it might be cheaper to use multiple standard pumps in series or parallel rather than buying a heavy duty pump. The following post walks you through Finish Thompson centrifugal pump in GA series and in parallel so that you can select the correct method depending on your application.
Centrifugal Pumps In Series – High Head/Low Flow Applications
Putting your Finish Thompson centrifugal pumps in GA series, or connected along a single line, will let you add the head from each together and meet your high head, low flow system requirements.
This is because the fluid pressure increases as the continuous flow pass through each pump, much like how a multi-stage pump works. For example, if two of the same pumps are in series, the combined performance curve will have double the head of a single pump for a given flow rate.
For two different pumps, the head will still be added together on the combined pump curve, but the curve will most likely have a piecewise discontinuity. As the system pressure builds, remember to consider the pressure ratings of the downstream pumps and seals to avoid equipment damage!
Finish Thompson Pumps in GA Series With Control for Constant, High-Pressure Applications
In situations where a high, constant pressure is required, consider adding speed control to the final pump in a series. This configuration achieves the high pressure that is needed, while keeping a low flow, because the fixed-speed pump feeds into the speed-controlled pump, which adjusts its output with a pressure transmitter to add only enough head to maintain a constant pressure.
Pumps In Parallel – Low Head/High Flow, Or Low Head/Varied Flow Applications
Putting your pumps in parallel, or connected to any number of line branches so that each handles a division of the flow, will help you reach a low head, high flow operating point that a single pump cannot supply. Additionally, this system configuration gives you flexibility by permitting the switching of parallel pumps on or off in order to adjust to variable flow conditions.
Going back to our pump curves, the combined curve for parallel pumps is created from the addition of the flow capacities of each pump. Two of the same pumps will result in double the flow while two different pumps will result in the addition of the flows.
Pumps In Parallel With Control – Low Head/Varied Flow Applications
In cases where a variable flow and high efficiency is required, consider adding speed control to each pump to achieve good performance and to operate pumps closer to their best efficiency point. In this configuration, two scenarios can occur – either one pump can fully run while the other adds flow when needed, or both pumps can run at reduced speed and adjust as needed.
Running a pump at full speed causes you to move past the best efficiency point on the right side, lowering efficiency and causing potential issues. With two controlled pumps operating at partial capacity, you can still have control over the flow while running each pump closer or to the left of its best efficiency point, resulting in a more efficient operation.
Overall, this configuration offers a wide range of operating conditions and opportunities for better efficiencies in order to meet your variable flow needs.
Need help choosing the right Finish Thompson pump for your application? Call us now at (404) 363-6000 and one of our experienced professionals will be happy to answer your questions and help you make an informed decision.