VEGA Guided Wave Radar Keeps It Simple

Guided wave radar is the ideal technology to
measure level in liquids or bulk solids across
a number of industries in a variety of process
conditions. These sensors are unaffected by
changing pressure, temperature, or a product’s
specific gravity. And unlike other technologies,
foam, dust, and vapor will not trigger inaccurate
readings or errors, either. Guided wave radar
provides accurate, reliable level measurement
without ongoing maintenance or recalibration.
And with no moving parts, it’s the ideal solution
for retrofitting mechanical technology.

How it works
Guided wave radar level measurement comes from time
domain reflectometry. This technology has allowed people to
find breaks in underground or in-wall cables for decades. It
works like this: a low amplitude, high-frequency microwavepulse is sent into a transmission line or cable, and the device
calculates distance by measuring the time it takes for the pulse
to reach the break in the line and return.
The same principle applies for a guided wave radar sensor.
A probe is mounted onto the tank, vessel, or pipe where a
measurement is needed. A microwave pulse is “guided”
downward by the probe where a portion of the pulse will be
reflected by the solid or liquid material being held in the tank.
The amount of time it takes for the pulse to be transmitted
and returned determines the level inside the vessel being
measured. Conductive materials reflect a large proportion
of the transmitted energy while non-conductive materials
reflect a small portion. The reflective properties of what’s
being measured can determine the effectiveness of this type
of measurement. Since its invention, guided wave radar has
been used to measure level in industries ranging from food
and beverage to chemical and refining.

Types of probes

Guided wave radars use a number
of different probes to make their
measurements. Each different probe
has its own purpose and advantages.
Some are better for making
measurements in liquids or solids.
Others work better with lower
reflectivity materials, thick foam,
excessive buildup, or corrosive and
abrasive materials. These probes
commonly come in customizable
lengths, so finding the right length for
differently sized vessels is relatively easy.

Advantages
Setup and configuration for guided wave radars are about as simple as they come.
VEGA guided wave radars are ready out of the box, configured at the factory for
the probe’s operating span. Users only need to install the sensor and go through the
guided setup procedure to begin receiving accurate measurements within 2 mm.
Guided wave radars need no additional calibration. Other technologies require
users to empty the tank to show the sensor different levels like 0%, 50%, and
100%. This can be time consuming and expensive. Lastly, guided wave radar has no
moving parts. Pressure sensors, floats, and displacers all have mechanical parts that
can wear out, which means additional maintenance and another calibration. All of
this means less time and money spent on setup, maintenance, and troubleshooting.
Unlike other sensors, guided wave radar feels right at home in tight spaces like
pipes, stilling wells, small chambers, and bypass tubes. The very nature of their
guided signal allows an accurate measurement where other sensors cannot go. These
sensors can measure in a number of process conditions and still make accurate
measurements regardless of the environment. This means guided wave radar sensors
won’t fail with changes in temperature,
pressure, or specific gravity. These sensors
are also immune to dust, excessive foam,
buildup, and noise, making them an ideal
sensor across a number of industries.
Guided wave radar is also the ideal choice
for measuring interface simply because
of how it works. The emitted microwave
pulses are constantly traveling down and up
the length of the probe. Most of the energy
bounces back near the surface of what is
being measured, and a level is calculated. Since the remaining energy continues to
flow down the probe and through the liquid, the sensor will receive a second level
reading, giving the user a measurement of the interface point. All that’s needed is an
additional calculation for the amount of time it takes for a pulse to travel through
the different liquids.