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RadarTron - Frequently Asked Questions |
Can I take a sensor calibrated for sand and use it on other materials? Can I use RadarTron's sampling feature for on-the-fly batch correction? Which is the best output choice, 0-10 volts or 4-20 mA? My material is hot. Can I use RadarTron in this case? This page answers these questions and others.
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Can I take a sensor calibrated for sand and use it on other materials? Sometimes yes, sometimes no. If the material is similar to sand (density of 80 to 150 lb per cu. ft.) and moisture range is 1 to 20% full scale, there should be no problem. If its density or moisture range is widely different, however, you may not have enough adjustment range on the Zero or Span controls. Ideally, you should contact our plant for advice. If the sensor has not been shipped, we can set it up for the material; we have many samples already and we test new materials every week. If we have no experience with your material, we will ask for a sample. This ensures that your sensor will not only work but will be precalibrated when you receive it.
If you have a range of materials, each with its own sensor, they should all be set up in this way. If you need to keep a spare sensor for replacement, it may be suitable for some but not all of the materials. Again, call us for advice.
Our advice is free - take advantage of it before you take delivery.
Can I use RadarTron's sampling feature for on-the-fly batch correction? Some batch controllers correct the aggregate target weights on the subsequent batch, based on the moisture value measured on the previous batch, while others recalculate the target during the weighing period, based on the current moisture value. Both systems have their merits and both can use the "sampling" mode of operation. The moisture average is started when the feed gate opens and continues during the fast and slow or jogged feed. The analog output is updated continuously and a reading can be taken at any time. This is much better than using the "direct fast" mode, which has a built-in response time of several seconds that limits the accuracy when immediate results are required.
The SAMPLING mode is the best for both on-the-fly and next batch measurement.
Which is the best output choice, 0-10 volts or 4-20 mA? Both have their place and many times you don't have a choice. Most of the North American batching computers use the 0-10V standard while most PLC based systems (like our BatchTron) use 4-20mA. Unless you must choose the 0-10V standard, always use 4-20mA; it is slightly more accurate, especially over long cable runs, and allows connection of both the batch controller and the digital display if needed (in series). The digital display requires 4-20mA as its power source and will not operate on 0-10V.
Always use 4-20mA when you can.
My material is hot. Can I use RadarTron in this case? RadarTron is rated for temperatures up to 140 degrees F (60 degrees Celsius). Above this temperature, accuracy will be impaired and above 212 deg. F ( 100 deg. C), the electronics will cease to function. You can protect the sensor by installing it in a tube, mounted within the bin, at our recommended angle and insertion depth. The tube must be sealed to the outer rim of the sensor at its far end and be wide enough to allow free circulation of air. A free circulating or forced air supply should be provided to keep the RadarTron body temperature as low as possible. In extreme cases, replace the air tube with a 1/4" to 3/8" copper water pipe coiled around the portion of the sensor inside the bin. The ceramic faceplate can be allowed to reach 100 deg. C. continuously but above this temperature the silicone sealant will deteriorate.
These techniques will allow operation in steam heated aggregate bins and in hot foundry sand, plus many other applications. Call for more details or download application note.
Hot materials require special installation precautions. Call us.
Can I install RadarTron on a conveyor?
It's possible but you won't get the accuracy that you can get when it is installed in a bin. For this reason, we suggest that you try to locate it in the bin that feeds the conveyor if possible. A second alternative exists if the conveyor feeds a second belt, when you can install a chute between the two. Make the opening of the chute onto the lower belt too small to accommodate the flow and allow it to purposely overflow at its upper end, directing the overflow again onto the lower belt. The chute will pack the material, making accurate measurements easy. Call us for full details.
How can I view the moisture in several bins simultaneously? The simplest way is to use a separate digital display for each sensor. The panel-mount sensor is suitable for installation in a small cabinet or large control panel. Alternatively, a single display can be used for many sensors with a rotary switch which selects one bin at a time. If a computer display is desired, the PCL-711S PC computer board allows up to 8 sensors to be displayed in engineering units with trend graph and recording software included. This board can also be used with your own custom software in Visual Basic, C++ or other languages.
Whichever way you want to do it, it is simple. Call us for details.
Why do my sensors burn out for no apparent reason?
Several customers have had premature failures of their RadarTron sensors; typically the circuit board shows burn marks under chip Z1 and Z3, plus the microwave sensor is damaged. This is most likely due to a poor ground connection between the control cabinet and the plant frame. Voltage surges entering the cabinet through the power or phone lines find the shortest path to ground, which is through the RadarTron or load cells. The solution is to install a short, thick ground conductor between plant frame and control cabinet.
See our Tech tips page for more details.
Online application request RadarTron cost/payback analysis (.PDF file, 34K)
Product Index Aggregate moisture sensor Mixer water dosing
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Last updated: November 07, 2004