Two-Wire Breakthrough Expands Coriolis' Appeal

April 30, 2008
The Wait to Replace Previous Generation Two-Wire Flowmeters with Coriolis Meters Is Over

“We know that customers have been waiting for a breakthrough that would enable them to replace previous generation two-wire flowmeters with highly accurate and reliable Coriolis meters—without incurring the costs of additional wiring and power.”

That wait is over, said Tom Moser, president of Micro Motion, as he introduced the company’s new two-wire 2200S Coriolis flowmeter transmitter at a press conference today at the 2008 Emerson Global Users Exchange in Washington, D.C.

“The 2200S provides Elite performance in a two-wire package.” Micro Motion’s Tom Moser is bullish that eliminating the need for separate power wiring will expand the range of applications for the company’s industry-standard Coriolis flowmeters.

“The 2200S provides Elite performance in a two-wire package,” Moser said, referring to the company’s industry-standard Coriolis flowmeter, which historically has required a separate pair of wires for transducer power in addition to the normal 4-20mA signal wires.

“We use the same sensor and meter body,” he went on, “but the transmitter is different. This means that we can provide the two-wire version of the Elite meter with all three meter body configurations—the standard Elite, the straight-through meter body and the slight-bend body, so the customer can use it in most of the standard applications of a traditional, four-wire Micro Motion Elite Coriolis flowmeter.”

Using the same meter body and sensor means that the performance level will be high, but Moser says the lower power available to operate the sensor means some small loss of performance in the two-wire device.
“This new development expands the range of plant applications that can adopt Coriolis technology,” Moser said, “and does so with the world’s best performing Coriolis device.”

The Model 2200S is a multivariable transmitter with HART outputs for mass flow, density and temperature, as well as a standard 12-20 mADC output (which is intended to be converted using the barrier/adapter developed by Micro Motion to an industry-standard 4-20 mA output) for connection to the DCS.

Accuracy and repeatability remain high for the two-wire version. Mass-flow accuracy for liquids is a flat 0.1% of rate from well below 10% of scale, with a repeatability of 0.05%, also flat across most of the flow range of the meter. Mass-flow accuracy for gases is 0.35%, with a 0.20% repeatability score. Volume flow for liquids matches the mass-flow accuracy, and liquid and slurry density applications have an accuracy of 0.0005 g/cc with a repeatability of 0.0002 g/cc.

The Model 2200S has CSA C1D1 and C1D2 approvals, as well as approval for ATEX Zone 1 and 2 hazardous areas. The meter is approved for SIL1 and SIL2, so it is not necessary to document “proven in use.”

Where will the two-wire Coriolis flowmeter be used? Moser said that it would be best used in high-performance process control, internal accounting and allocation, and for replacing other types of meters, while the four-wire Coriolis would still be the workhorse for peak-performance applications, such as batch-from-empty, continuous air entrainment, fiscal metering and custody transfer, as well as meter verification.

Both the traditional four-wire and the Model 2200S have Micro Motion’s built-in meter verification technology, which determines if the meter itself is operating properly without removing it from the line.

Micro Motion had two customer presentations about the new product. The first came from Micro Motion director of global chemical industry marketing, Tom O’Banion, for Frank Izzo, a longtime senior instrumentation lead at Momentive Chemical, formerly GE Silicones. Izzo beta-tested the two-wire Coriolis meter on a replacement project for an elderly differential pressure flowmeter. The signal wiring and piping for the reactor-purge gas flow application were pre-existing, so the two-wire transmitter saved eight hours of effort that would have been required for power wiring and an estimated $1,500 in conduit and cable. O’Banion pointed out that the eight man hours saved was perhaps more valuable to Momentive than the actual cost savings were.

Dino DeSalvo, a member of LyondellBasell’s central engineering department, spoke next on projects that LyondellBasell expects to do with the two-wire Coriolis. “LyondellBasell faces the challenges of global workforce dynamics,” he said, “as well as standardization of both equipment and operating practices throughout our plants.”

DeSalvo said that the applications LyondellBasell were considering included two-phase flow, high-capacity and SIL/SIF applications. DeSalvo said that he would use the two-wire Coriolis meters to convert volumetric flowmeters, such as high-accuracy turbine and positive displacement meters. “We can upgrade away from older, high-maintenance technologies,” he said, “and reduce the engineering effort on new projects while increasing repeatability.”