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Electromagnetic Flow Transmitters: Remote Electronic Display Backends for Magmeters

Quick Answer: A remote electronic display backend for a magmeter moves the transmitter and display away from the flow sensor. This lets engineers read flow rate, total flow and faults from a panel or wall mount up to 100 m away. Silver Automation Instruments supplies electromagnetic flow transmitters with remote electronic display backends for DN15 through DN2000 lines with 4-20 mA HART, pulse and RS485 Modbus outputs.

What Is a Remote Electronic Display Backend

Most electromagnetic flowmeters ship in two forms. A compact magmeter keeps the sensor and transmitter in one housing. A remote display backend splits the two. The sensor stays in the process line. The transmitter electronics sit in a separate panel or wall mount. A shielded signal cable links the sensor to the remote display.

Remote backends do not change the measuring principle. The meter still reads flow by detecting voltage across electrodes in a conductive liquid. The advantage is physical separation. You can put the sensor in a flooded pit or a hot zone. The display stays in a cool dry control room.

Silver Instruments builds remote backends with signal cable lengths of 5 m, 10 m, 20 m, 30 m and 50 m. Longer runs are available on request.

Why Engineers Specify Remote Display Backends

Here is the thing. Plant engineers usually select remote display magmeters for practical site reasons. The sensor location is hard to reach. The process temperature is high. Or the sensor sits in a hazardous area and the display must stay in a safe zone.

We have seen this on customer sites many times. A wastewater plant in Chile put a DN300 magmeter in a below grade concrete pit. The pit filled with rainwater during a storm. The remote display stayed dry in a cabinet 40 m away. The flow signal did not fail.

In another case a paint manufacturer in Vietnam needed a DN80 magmeter for solvent based product. The sensor area ran at 55 °C continuous. The wall mount display went into a corridor with normal room temperature. PT100 temperature sensors were also wired to the transmitter for process logging. The display showed flow rate in cubic meters per hour and total batch volume.

Outputs and Wiring Details That Matter

A remote display backend must send data to PLC DCS or local indicators. The standard output from Silver Instruments is 4-20 mA HART. This gives one analog signal plus digital diagnostics over the same pair of wires. For totalizing, a pulse output is common. Many water and wastewater sites also ask for RS485 Modbus RTU.

Because electromagnetic flowmeters require a minimum fluid conductivity, check your liquid before ordering. Most magmeters need at least 5 µS/cm. Some industrial units can work below 3 µS/cm but accuracy may shift. For high viscosity products like glucose or edible oil above 500 cP the meter still reads volume flow. The output remains stable because the magnetic field does not depend on viscosity.

Some heat metering versions accept PT100 inputs. The transmitter then calculates mass flow or heat flow when density is entered manually. You can get kg/h on the display for water based liquids. For chemicals check the density value supplied by your lab.

ATEX Zone 1 approval is available for remote display backends. The sensor and the local junction box can be rated for gas or dust zones. The remote display panel stays in a non hazardous area. This lowers cost and makes maintenance safer.

Installation and Field Notes

In practice the cable between sensor and remote display should be a single continuous shielded run. Avoid splicing. Ground the shield at one end only. Most engineers skip this part and then chase signal noise later. Use the cable length specified in the order. Do not cut a 30 m cable to 3 m unless