FLUID HANDLING
R86 RADAR
MAGNETROL
THE ELUSIVE SEARCH FOR NON-CONTACT
RADAR NIRVANA
When it comes to measurement, the
ultimate goal for operators in the process
industries is to find a trouble-free, loop-
powered level transmitter that can be
mounted, wired and forgotten.
As instrument shops’ staffing has been
whittled back to a minimum, it has become
the goal of many manufacturers to meet
that challenging need for “plug and play”
devices.
So, how close have we gotten to applying
two wires and walking away? This blog post
explores the search for non-contact radar
nirvana and how radar technology has
evolved over the years.
A History of Radar Advancements
In the late 1990s and early 2000s, low-cost,
loop-powered radar burst onto the scene. It
was enthusiastically applied due to its ability
to work even in the changing conditions
that plagued the most popular technologies
of the time.
No longer would changing specific gravity
ruin the accuracy of DP cells or displacers, or
changing dielectric spoil the performance
of RF capacitance devices, or vapor space
changes affect the propagation consistency
of ultrasonics. In short, a new age was upon
us.
Radar had already evolved into two
variations: Non-contact/through-air
(antenna-based) and contact/guided wave
(probe-based).
In a perfect world all transmitters would
be non-contact so they would not have to
contend with contacting the dirty, coating-
prone, turbulent liquids that can wreak
havoc with performance and mechanical
integrity.
However, since guided wave radar (GWR)
employs a metallic probe, a highly efficient
electrical path is provided to propagate the
signal. This allows for extremely strong radar
reflections from the liquid surface, thus
providing excellent performance in difficult
conditions.
A Love-Hate Relationship
Non-contact radar (NCR) slowly became
the technology many people love to hate.
Theoretically, NCR can be so effective it
should be everyone’s first choice.
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PECM Issue 33
It is small and easy to install. This means
that measurement in tall tanks does not
necessitate a long, expensive and unwieldy
probe like GWR, and the device sits up high
in the tank, away from the tank contents.
However, the vagary of launching an
electromagnetic signal into space and
waiting for its return is fraught with
potential complications: false reflections
from objects in the vessel, severe turbulence
that can scatter the signal and foam that
can absorb it are just some of the issues
that exist to render NCR ineffective. Users
reported challenges getting these devices
ideally configured, which discouraged
others from using them.
How Circular Polarization Helps
Electromagnetic energy can be launched
using linear or circular polarization.
Linear polarization has a constant E-field and
needs adjusting to avoid sidewall reflections.
To remove these launcher adjustments,
the new Pulsar® Model R86 non-contact
radar transmitter from Magnetrol® employs
circular polarization which has a rotating
E-field. In this way, no antenna adjustment
is necessary during commissioning, getting
the user closer to the “plug and play” goal.
The Goldilocks Dilemma When configured properly, the Model R86
can be everyone’s go-to transmitter. Having
said that, no transmitter ever made is totally
trouble-free.
Two of the keys to the effective use of
NCR are correct installation and proper
configuration. Installation includes avoiding
sidewall and false target reflections. But if problems occur, MAGNETROL should
have the ability to diagnose them quickly
and bring the device back on line as fast as
possible.
Configuration is getting the gain
(amplification) settings just right. This is the
“Goldilocks dilemma”— it can’t be too hot
or too cold—too hot (excessive gain) and
the echo saturates (distorts), deteriorating
accuracy; too cold (insufficient gain) and the
weak signal is lost. That means no more waiting for the trouble-
free, loop-powered level transmitter that can
be mounted, wired and forgotten. Non-
contact radar nirvana is finally here.
Optimal configuration is not an impossible
task, but it is one that has eluded many
good instrument personnel.
For more information about this
new innovation in non-contact
radar, visit r86.magnetrol.com