With the introduction of the magnetic flow meter in the early 1970's it has been a favorite choice for water based flow applications, due to it's, accuracy, stability, rugged full bore design, no moving parts, and ability to operate in heavy fouling applications. With increased wetted material selections almost any liquid, including strong reagents such as acids, bases, polymers, and slurries can be measured, making the magnetic flow meter the preferred flow measurement choice.

Central Station Steam Company® offers two versions of its Cadillac® magnetic flow meters for these applications. The EMAG, which employs a traditional flow tube design and the CMAG, which employs a revolutionary tube design. The EMAG is more cost effective where the flow profiling already exits, but where flow profiling is unavailable the CMAG opens up new and retrofit installations to huge savings in design, layout or reconstruction/modification.

Since the introduction of the magnetic flow meter technology in the early 70's the meter design has remained essentially unchanged or altered other than the electronics platform, which has evolved along with the microprocessor, providing configuration flexibility and some improvements specific to application conditions. However, the underlying limitation of the technology, as with all volumetric or velocity measuring devices, is the requirement for proper flow profiling or piping straight run to ensure measurement accuracy, stability, and repeatability. For typical applications, this means 10 pipe diameters upstream and 5 pipe diameters downstream of piping straight run, which is the case for the Cadillac® EMAG.

In smaller line sizes (1/2' to 4") this piping straight run requirement is typically manageable, but when lines sizes exceed 4" this straight run length requirement becomes very significant and unless designed for in the initial layout is typically not something that can be retrofitted without major reconstruction. Even with design preplanning it becomes very space consuming requiring large buildings or property requirements. For example, a 24" line size, which is fairly average or typical for Water or Wastewater, would require a straight run length of 32 feet to ensure the proper flow profiling for a traditional flow tube design such as the EMAG and all other magnetic flow tubes on the market.

However, with the introduction of the CMAG all of this changes. With a revolutionary flow tube design that eliminates the velocity measurement gradient generated in typical coil/tube designs the CMAG provide a true averaged velocity sample in both axis (cross sectional and longitudinally) inside the flow tube. This allows for turbulent flow inside the flow tube without effecting operational accuracy, repeatability, or stability. What this means for the engineer and end user is a significant reduction in piping straight run requirements and installation location selection for the CMAG.

Below is a set of Tables showing; 1) the straight run required for a Traditional flow tube designs (including EMAG) with an accuracy or +/-0.50%, 2) The straight run required for the CMAG flow tube design with the same +/-0.50% accuracy, and 3) the straight run required for the CMAG flow tube design with a +/-0.25% accuracy, twice the accuracy of traditional flow tubes.