Product category:
Level and tank contents instrumentation
News Release from: Magnetrol International | Subject: RADAR level transmitter
Edited by the Processingtalk Editorial
Team on 16 February 2004
Selecting a radar level unit for the
application
Radar (microwave based) level transmitters handle tough and changing process conditions, and applications are growing: how do you choose between the two types available?
Awareness of your exact process parameters can save you money! Measurement of liquid level can be challenging, as the sensor involved is fully exposed to process conditions inside the vessel Mechanical instrumentation was once the bedrock of level control, but gradually gave way to technologies such as differential pressure, RF, magnetostrictive, ultrasound and others-technologies that offer improved accuracy and reliability without complex and costly mechanical operating systems
This article was originally published on Processingtalk on 22 May 2003 at 8.00am (UK)
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However, over time it became apparent that many of these newer electronic technologies had significant application sensitivities that could be both difficult to work around and result in unnecessary cost.
This concern was a key factor leading to the development and increased usage of Radar (microwave based) level transmitters, as they handle tough and changing process conditions well.
There are two basic types of radar level measurement.
Further reading
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The Eclipse guided wave radar handles the most complex and extreme liquid level measurement applications: with single and dual flexible probes, it also measures solids with dielectrics down to 1.9
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The smart EZ Modulevel of Magnetrol International is the first displacer transmitter with SIL (Safety Integrity Level) data according to IEC 61508, meeting the integrity requirements for SIL2
The first, air radar, was originally developed for storage or inventory applications.
The second, Guided Wave Radar or GWR, is generally used in process applications.
However there are exceptions to the rule for both types.
This article will focus on the product features of Guided Wave Radar that match lesser or greater process conditions, to help readers select the most cost-effective unit for their installations.
GWR level transmitters start at GBP1100 and range to over GBP2500, so how do you choose? First we consider process conditions such as temperature and range.
Inexpensive GWR transmitters are generally limited to applications under 150C and ranges of 5 m or less.
They can come in plastic enclosures (Valox) and lack digital indicators.
They are primarily simple loop-powered transmitters that transmit an industry standard 4-20mA signal to a remote device.
Transmitters in this price range also usually require reference points on the probe or antenna for calibration.
This means you must either move the level, and calibrate your 4 and 20 mA points with a push button, or use a device known as a shorting bar to simulate level if you want to change from the factory settings.
This approach is great for OEM's and other light duty applications where the level can be moved for set up.
It is also a good choice in the water and wastewater industry, where low price is a major factor.
In this category you are usually replacing capacitance or ultrasonic transmitters.
The Magnetrol Horizon 703 is an example of this type of radar transmitter.
Next step up the ladder are calibration-free units that require no reference points on the probe for setup.
They also have integral digital displays and easy menu-based configuration.
HART communications allows easy and remote set-up from a handheld device.
Enclosures with windows are available in easy clean plastic and metal.
They can be used in general purpose or hazardous applications.
A nice feature is the ability to add true sanitary sensors (3A and EHEDG approved) for the food, dairy, and pharmaceutical industry at very reasonable cost.
Models like the Magnetrol Horizon 704 fall into this category.
At the top of the ladder are products such as the industry standard Eclipse 705, that offer dual compartment aluminium or stainless steel enclosures.
These enclosures can be rotated and offer a quick disconnect feature.
Flexible settings like field selectable failsafe mode and adjustable dampening complement better than 2.5mm repeatability.
Advanced applications such as interface level measurement are fully supported.
Temperature tolerance is to 400C, pressure to 345 bar, and the range is to 15 m.
It is even rated for critical SIL (safety integrity level) shutdown applications.
It is an intrinsically safe or explosion proof device, ideally suited to critical refinery applications.
A local remote mount electronics feature gives installation flexibility. Request a free brochure from Magnetrol International ...
Awareness of your exact process parameters can save you money by helping to ensure that you select the correct radar level transmitter for your needs and price range!.
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