Guided Wave Radar - An Option for Level Measurement in Hygienic Applications

A special version of the Magnetrol Eclipse 705
is configured for hygienic applications.
Image courtesy Magnetrol

Measurements of a variety of process conditions are utilized to monitor and control operations and output. One general goal of measurement, other than answering the question "how much", is to avoid or minimize any interference with the process itself. A second goal is to not be fooled by the process into returning a false measurement result.

Guided wave radar is based upon the principle of TDR (time domain reflectometry). Pulses of electromagnetic energy travel from the emitting antenna via a fixed waveguide or probe immersed in the target medium. When it contacts the media surface, the pulse energy is reflected back along the probe to a receiving antenna. The instrument actually measures the time elapsed between the pulse transmission and the detection of the reflected return. The time measurement is used to calculate the distance from the antenna to the media surface. The distance calculation, with knowledge of the vessel, can be converted into a value indicating media level or volume. Of course, this is a simplified account of the operating principal.

Guided wave radar (GWR), as opposed to an open style radar level measurement method, uses a probe immersed in the process media to guide high-frequency electromagnetic waves into the media being measured. While it does involve contact by the sensing instrument with the media, GWR eliminates interference from fixtures or structures that may exist within the tank or vessel. The immersion probe waveguide also attenuates the impact of media turbulence and other potential disturbances. The waveguide reduces the potential impact of elements that may adversely impact the measurement accuracy, resulting in greater accuracy and reliability of the measurements.

For hygienic applications, the transmitters are available with 304 stainless steel housings designed specifically for use in facilities with the special requirements for the wetted and non-wetted materials, process connections and surface finishes of hygienic industries. In addition to high accuracy, the GWR instrument output is not impacted by media buildup on the sensing probe.

Share your level measurement challenges with process instrumentation specialists. Leverage your own process knowledge and experience with their product application expertise to develop an effective solution.

Magnetrol Guide Wave Radar Level Transmitter For Hygienic Applications from Miller Energy, Inc.

Guided Wave Radar for Hygienic Applications: Advantages Over Other Technologies

Guided Wave Radar
for Hygienic
Applications

Operating Principle

Guided wave radar is based upon the principle of TDR (time domain reflectometry). Pulses of electromagnetic energy travel via the waveguide. The pulse is reflected when it contacts a liquid surface and the distance is then calculated.

Guided wave radar transmitters are available with a 304 stainless steel housings designed specifically for use in hygienic applications. This instrument meets the needs and requirements for the wetted and non-wetted materials, process connections and surface finishes of hygienic industries.
Features

• Low dielectric measurement capability (εr >_ 1.4)
• Volumetric output
• Quick connect/disconnect probe coupling
• Operates in visible vapors and ignores most foams
• IS, XP, and Non-Incendive approvals
• Ignores coating buildup

Advantage Over Other Technologies

• Advantage over Differential / Hydrostatic Pressure Transmitter:  Replaced by Eclipse due to setpoint shifts, blockage, leakage, installation cost & long term calibration / maintenance

• Advantage over Magnetostrictive: Replaced by Eclipse due to setpoint shifts, turn-down and clean ability & long term calibration / maintenance.

• Advantage over RF Capacitance: Replaced by Eclipse due to dielectric shifts, coating issues & long term calibration / maintenance.

• Advantage over Load Cells: Eclipse is more cost effective and long term cost of ownership is lower due to long term calibration / maintenance.

• Advantage over Ultrasonic: Replaced by Eclipse due to vapors, condensation, temperature restrictions, foaming & turbulence.

• Advantage over Through Air Radar: Replaced by Eclipse due to performance issues on low dielectric media, short range measurement because of dead band issues in small vessels, measurement issues when using false echo rejection from internal obstructions such as agitators and spray balls, signal attenuation from turbulence, foam, condensation and spray from spray balls used during cleaning or product filling. Through air radar can have issues from variable false echoes generated when spray hits the antenna when vessel is filled from spray balls.

For more information see this Guided Wave Radar bulletin:

Guided Wave Radar Level Transmitter For Hygienic Applications from Miller Energy, Inc.