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Pump Importer Cautions Customers: “Do Your Homework Before Running Centrifugal Pumps in Parallel”

Foremost importers of pumps in Australia provide guide for the use of centrifugal pumps in parallel.

Perth, WA, 19 March 2015 - There are many situations when it is appropriate to run two centrifugal pumps in parallel. However, one pump importer from Perth cautioned his customers and his blog readers to make sure that they pay attention to the particular performance characteristics of their systems and equipment before running pumps in parallel.

Parallel Operation

Parallel operation is a term for running two or more pumps with near-identical differential heads and a common water supply coming from the same inlet and leading to the same outlet. Ideally, the two pumps function as a unit and are able to increase the total flow, which is the sum of each pump’s individual flow.

Pump Curves Must be Evenly-Matched for Optimum Performance

If one pump’s curve is higher than that of the other or others at low flow, it can overpower the other pump or pumps. This can block or stall the pump that is overpowered. Therefore, it is important to evenly match the pump curves at low flows. While they don’t have to be perfectly matched, it is important that they have the matching heads at low flow rates.

This is most often accomplished by matching the “shut valve head” or zero flow head of all pumps working together in parallel. This helps avoid unstable pump curves which can cause surging.

Stepper pump curves provide the most efficient parallel operation because they can help both pumps share loads relatively equally in low flow periods. When the pump curves are flat during periods of low flow, the effect of minor head variations is magnified, causing disproportionately high flow variations.

Other pump characteristics should be relatively equal for the most efficient performance. For example, if one pump is steam turbine powered and another has an electric motor, it can cause variations that become problems during periods of low flow.

Optimal Situations for Parallel Operation

Mike Hurlbatt, owner of Pump Solutions Australasia, an importer of pumps based in Perth, Western Australia, recommends three specific situations as optimal for joining centrifugal pumps in parallel operation. According to Mr Hurlbatt:

“The decision whether or not to use parallel pumps is contingent upon what the user is trying to accomplish and what resources are available. For example, sometimes there isn’t a pump that is powerful enough to do the job on its own in a given space or there are other constraints such as the space not being big enough for a more powerful pump to fit but being perfect for two smaller ones. The second pump is needed to get the job done.”

Mr Hurlbatt concluded: “When the system curve is very flat and flow needs to be varied to accommodate varied demand, parallel operation is a great option. It is also a good idea if you have an operation where one pump shutting down would cause too much disruption. The second pump becomes a fail-safe system.”

Pump Solutions Australasia imports centrifugal pumps and pumps of all varieties to Australia from all over the world. They are known for high quality and knowledgeable customer service. To contact Pump Solutions Australasia, call 1300 922 973 or visit their website: http://www.pumpsolutions.com.au/.