Supersize me: Dealing with oversized centrifugal pumps

Aug. 7, 2015
Oversized pumps could lead to control issues and wasted energy.

Centrifugal pump systems with flow throttled by a control valve are ubiquitous at process plants. Unfortunately, the majority of pumps are oversized, which both poses problems regarding controllability and wastes energy.

Pump oversizing occurs for two major reasons. First, a system’s pressure drop must be calculated rather early in planning using estimates for pipework and its fittings. Unfortunately, values taken from the literature, for example of flow resistance coefficients of valves, may vary widely. Consequently, dynamic pressure losses are somewhat shaky. Static pressure differences usually are better defined. Hence, planning engineers must add some safety margins. Correcting a pressure drop calculation much later when pipework has been designed does not really solve this problem. Some margin also might be added to the rated flow. Second, the pump’s manufacturer adds safety margins, too, to ensure the pump meets guaranteed performance, in particular if the liquid handled is not water. So, it is nearly impossible to avoid installation of oversized pumps. Hence, the only realistic option is to adjust a pump based on experience once the plant is operating.

To learn more about centrifugal pumps, read “Overcome Oversizing of Centrifugal Pumps” from Chemical Processing.

Sponsored Recommendations

Filter Monitoring with Rittal's Blue e Air Conditioner

March 28, 2024
Steve Sullivan, Training Supervisor for Rittal North America, provides an overview of the filter monitoring capabilities of the Blue e line of industrial air conditioners.

Limitations of MERV Ratings for Dust Collector Filters

Feb. 23, 2024
It can be complicated and confusing to select the safest and most efficient dust collector filters for your facility. For the HVAC industry, MERV ratings are king. But MERV ratings...

The Importance of Air-To-Cloth Ratio when Selecting Dust Collector Filters

Feb. 23, 2024
Selecting the right filter cartridges for your application can be complicated. There are a lot of things to evaluate and air-to-cloth ratio. When your filters ...

ASHRAE Standard 199 for Evaluating Dust Collection Systems

Feb. 23, 2024
This standard ensures dust collection systems are tested under real-world conditions, measuring a dust collector's emissions, pressure drop, and compressed air usage. Learn why...