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By Jim Montague, executive editor
The most sophisticated measurement capability isn’t worth much if users can’t afford to put it where they need it. To get their data at less cost, some users are implementing two-wire solutions that provide power and communications over one cable. One of these is Yamatake America’s MagneW Two-Wire Plus (TWP) magnetic flowmeter, which performs at a fraction of four-wire installation costs. This is because the output loop also provides MagneW’s low-voltage power, and so only one wire pair is needed.
Frank Chan, shop supervisor at Sherwin Alumina, Gregory, Texas, replaced several vortex flowmeters with three MagneWs to measure steam in its aluminum precursor-related process because solids sometimes interfered with the vortices by fouling the sensor on the flowtube. “MagneW only has an electrode on the flowmeter, so there’s no interference with the flow,” says Chan. “And since neither flowmeter uses 110 V power, we could make a direct replacement and didn’t have to run new wire.”
Yamatake America’s MagneW Two-Wire Plus magmeter costs four or five times less to install than four-wire magmeters.
Easson adds that McKee’s well pipes only emerge from the ground for limited straight runs, while the flows transition between multiple diameter pipes as they move from the upstream discharge pipes to their downstream check valves. “This is a terrible place to measure flow, but our Yamatake flowmeters did it,” says Easson. “We also added parameters to eliminate data spikes and detect empty pipes, which further reduced headaches.”
Brent Fowler, design engineering manager at Osmose Inc., Grifin, Ga., uses 12 MagneWs to help switching among the two to four chemicals it combines to make batches of wood preservatives. “We also recently went to a thicker, more viscous chemical, but we found we could no longer use the paddle-wheel or turbine flowmeters we used before,” says Fowler. “Both our old and new flowmeters check pulses per gallon and totalize them to determine gallons measured. However, the viscosity change affected the pulses and caused some accuracy issues. The MagneWs resolved this and have been completely accurate.”
Doug Hammell, process engineer, and Bruce Valentine, instrumentation engineer, both at Cytec Industries Inc., Willow Island, W.V., say they use nine MagneWs to control water flows to 11 scrubber systems, which remove mineral acids and organics from its process-vent emissions. The bulk chemical manufacturer previously used local-display flowmeters, but switched because its environmental permits now require it to monitor the scrubbers’ flows, transmit signals every five minutes and store the results in a database.
“Because the two-wire flowmeters combine signal and power, they’re a lot cheaper to install and are just as accurate as four-wire flowmeters,” says Hammell. “We used to have some reliability problems with our previous flowmeters, so when they failed, we installed Yamatake’s MagneWs, and we’ve had no problems with them. We’re also looking at using Yamatake’s flowmeters in the organic-fluid applications in our batch process.”
Donny Dunlow, instrumentation mechanic at International Paper’s mill in Franklin, W.V., reports his facility uses 30 to 40 MagneWs to manage water, whitewater from bleach and chemical flows in the bleaching section of its two-part filtering area.
“We used four-wire devices before, but they needed 110 V runs for power in addition to the 4-20mA loop,” says Dunlow. “Yamatake’s two-wire feature means we have one cable for 24 V dc power and our 4-20mA communications, and this cuts our installation costs for labor and time in half. We also save a lot on conduit because we now have one run instead of four. Because we’re taking back the same signals as before, we found that the two-wire also ran at the same speed as a four-wire over a one week period.”
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