High flow accuracy using the world’s first full bore electromagnetic flowmeter.

Accurate flow measurement is paramount in water pump stations for optimising process control, monitoring, and overall efficiency. Traditional electromagnetic flowmeters, however, demand specific straight pipe run lengths – typically five pipe diameters upstream and two downstream – to achieve their stated accuracy. This requirement stems from their sensitivity to flow profile disturbances. Stable, uniform flow profiles are essential for these meters to function correctly. Deviations from this ideal flow, such as swirling or turbulent flow caused by upstream obstructions, can significantly impact measurement accuracy.

In a recent raw water pump station (RWPS) upgrade, engineers faced a significant challenge. The planned flowmeter installation location presented several flow obstructions. A DN300 to DN400 expansion joint was situated directly upstream of the intended flowmeter placement, and a gate valve was located immediately downstream. These obstructions were guaranteed to disrupt the flow profile, making it difficult to achieve accurate measurements with a standard electromagnetic flowmeter.

The engineers were presented with two options, each with its own drawbacks. The first option was to comply with the recommended straight pipe run requirements. This would necessitate a costly and time-consuming pipe re-routing project to create the necessary upstream and downstream straight sections. Such a modification would not only add significant expense to the project but also potentially delay the upgrade's completion. The second option was to find a flowmeter capable of handling the distorted flow profile caused by the existing obstructions. This approach required identifying a meter that could maintain accuracy despite the less-than-ideal flow conditions.

The solution lay in selecting a more advanced electromagnetic flowmeter designed to address such challenges. The Promag W 0 x DN by Endress+Hauser, with its full-bore design and multiple electrode measurement pairs, proved to be the ideal choice. Its full-bore design minimised any additional pressure drop within the pipe, an important consideration in pump station applications. Critically, the multiple electrode pairs allowed the meter to effectively measure flow even with the swirling and uneven flow profile created by the upstream expansion joint. This capability eliminated the need for the costly and disruptive pipe re-routing project.

Beyond its ability to handle challenging flow conditions, the Promag W 0 x DN by Endress+Hauser also offered significant advantages in terms of commissioning and maintenance. The flowmeter incorporates Heartbeat Technology, an onboard self-verification tool. This innovative feature provides fully traceable and documented verification of the meter's functionality. During the RWPS upgrade commissioning, Heartbeat Technology allowed the engineers to verify the flowmeter's performance quickly and efficiently. The verification process, accessible through the meter's built-in web server, was completed in a fraction of the time required for traditional external verification methods. This significantly reduced commissioning costs and minimised downtime.

The results of this installation were threefold. First, installation costs were significantly reduced by eliminating the need for pipe re-routing. Second, the flow measurement accuracy of ±0.5% o.r was guaranteed, even in the restricted installation environment, thanks to the meter’s multiple electrode pairs and its ability to handle variable flow profiles. Finally, commissioning costs were lowered due to the rapid and efficient verification provided by Heartbeat Technology. The Promag W 0 x DN by Endress+Hauser proved to be the perfect solution for this challenging application, demonstrating the value of selecting the right flowmeter for specific installation conditions. It highlights how advanced flow measurement technology can not only ensure accuracy but also streamline installation and commissioning processes, ultimately contributing to a more efficient and cost-effective water pump station operation.