Electromagnetic flowmeter for unrestricted measurements

In the water and wastewater industry, high measurement accuracy from electromagnetic flow metering is indispensable for optimal process control.

It has long been an industry standard that any electromagnetic flowmeter installations require at least five straight run pipe diameters upstream and two pipe diameters downstream from the electrode plane in order to comply with the specified accuracy. Why? Electromagnetic flowmeters like stable flow profiles.

Pipeline bends (Figure 1), valves, insertion devices and tee-fittings disturb the flow profile of measured liquids, resulting in increased measurement errors. In many cases, the upstream and downstream pipe lengths are simply not available. Plant operators had a choice — either comply with the recommended installation guidelines or install a flowmeter which can sufficiently handle the changing flow profile. Flowmeters with constricted measuring tubes were developed in order to condition the disturbed flow profile. This worked, but a sensor tube restriction results in a pressure drop and thus increased pumping/energy costs.

Figure 1. Influence of a 90° bend on the fluid velocity profile through a pipe.

The Proline Promag W 0 x DN is the world’s first electromagnetic flowmeter without measurement tube restriction to allow reliable flow measurement independent of the flow profile and mounting location. With the full bore design — there is no pressure loss across the flowmeter. Reliable measurement values and flexible installation are now a combination and no longer a contradiction. Without the need for any inlet or outlet runs, they are particularly suitable for installation in tight spaces, such as compact systems or skid packages. The Promag W 0 x DN can easily handle swirling flow profile that occur downstream of obstacles such as pipe bends and insertion devices, tee-junctions and even downstream of unknown obstacles such as build-up on pipe walls, protruding seals or different inside diameters.

Innovative measurement signal analysis

The new and innovative measuring concept of Promag W 0 x DN features multiple measuring electrodes that detect the flow. For DN25 to DN80, two pairs of measurement electrodes are installed. For DN100 and above, three pairs of measurement electrodes are installed. This generates a substantially higher density of measured data than for standard devices. Together with the refined signal analysis, reliable measurement results for swirl conditions are also possible.

Transmitters for seamless system integration

The Promag W 0 x DN can be combined with different transmitters: as a compact version (Proline 300 and 400) or as a remote version (Proline 400 and 500) with up four outputs. Proline transmitters make no compromises in terms of performance and accuracy. The digital signal processing begins in the intelligent sensor and is the basis for a reliable, highly accurate measurement. Full access to all measurement data, including diagnostic data acquired by Heartbeat Technology, is possible at any time thanks to digital data transmission or the freely combinable inputs and outputs.

Application examples

Applications for the Promag W 0 x DN full bore flowmeter are numerous and can enable large cost savings both during the design and construction phase of projects.

A great application for the Promag 0 x DN would be use on dewatering skids in the mining industry. Mine dewatering has a number of critical objectives such as the controlling inflows to create workable conditions, reduced blasting costs and reduction of haulage costs. Additionally, the water itself is important for its role in mineral processing, dust suppression and slurry transport. On some sites, there may be hundreds of dewatering skids which each require the use of flowmeters. It’s very common for connecting pipes to have mis-matching internal diameters (Figure 2). This can result in a large disturbance to the flow profile and inaccurate measurement results for a standard flowmeter. When considering the number of dewatering skids on site, this combined inaccuracy could be enormous. With the Promag W 0 x DN, an accuracy of at least 0.5% is guaranteed in these applications.

Figure 2. Influence of mis-matched internal diameter on the flow profile.

There are many Promag W 0 x DN applications in the Water/Wastewater industry too. Let’s consider a de-salination plant, where inlet flowmeters can often be 1000 mm or more in diameter. In a standard electromagnetic flowmeter installation, you would require a significant length of straight pipe on both the inlet and outlet to ensure the flowmeter measures within its nominated accuracy. With the Promag W 0 x DN, this is no longer an issue, and the flowmeter can be installed directly before or after bends (Figure 3). This can result in significant cost savings during the construction phase. We can apply these benefits not only to the inlet section, but throughout general plant operations. There are numerous opportunities to reduce the footprint of an installation with the Promag W 0 x DN.

Figure 3. The Promag W 0 x DN can be installed directly before or after pipe bends.

Flow metering across industry has trended towards an increasing reliance on accuracy and reliability. With the Promag W 0 x DN, both of these have been addressed for applications that were previously impossible with standard flowmeters.

For further information, visit cx.endress.com/au-promag-w-0dn.