AHowellPG (Customer) asked a question.
I'm trying to determine what the best selection would be for flow detection, not how much, just "is it flowing".
Using the sensor selection tool, Ultrasonic seems to be the right choice, but in my research online I'm seeing that they don't work well in a dusty environment and could be damaged or falsely trigger with dust.
Specific use case is we have Hopper bottom tanks for grain that have an air actuated slide gate on the bottom dropping directly into a belt conveyor. We're metering flow using the slide gate to not overload the belt conveyors and elevator legs. What's causing us trouble is seed pods/junk building up at the slide gate and eventually plugging the gate, stopping flow. Ideally if the flow stops, an alarm goes off and "hey go unclog the gate" starts going and stops the belt conveyors from running unnecessarily.
My initial thought is below the slide gate in the transition to the belt conveyor, drop a sensor at a 90° angle to the grain flow the transition is a 12"x12" square and we rarely open the gates more than 50% leaving plenty of space on the backside of the gate for a sensor to not get an impact directly, I'd just be using the sensor to determine "is there flow" and if no flow after X time (connecting to a BRX so no logic on sensor required) then sound alarm and start shutting down the conveyors.
I use Capacitive Proximity sensors all over for tank level monitoring, but I don't think they'll detect the distance needed for this.
Would an ultrasonic sensor be the ideal method to detect this? If not, suggestions?
Thanks in advance, this community has been awesome to learn with!
Radar is best for grain.
You can also program an exercise routine into your slide gates.
I'm utilizing Radar for bin level indication, which works pretty well, however the radar sensors available on AD seem to be limited to water level indication, and I'm not really looking for a level indication, more of a presence indicator. Unless I'm understanding your suggestion incorrectly.
With the way the system is setup, it actually has an inherent ability to exercise the gates as they are air operated, and we opted to locate the valve body inside the building so it wouldn't be out in the elements, the pistons are all weather rated to -20F. With the distance the airlines run, and with the adjustable backstop we put in moved out of the way, the gate continuously seeks its target position which causes uneven flow, seeking anywhere between 10% and 70% continually, which for very dirty lots is actually a great benefit since it seems to prevent further clogging, seed pods suck. However, with the uneven flow that causes, it slows down overall throughput so not the ideal way to run when unnecessary.
I've not used any radars from AD, there are great products available elsewhere for bulk solids level and object presence.
Tom's suggestion of current sensing on the belt could work if your flowrates are high enough to cause a significant change in load, may need to be looking for a percentage change overtime vs absolute change as base load may vary with season and wear.
I'll have to do some digging around the googles then, I've been pretty pleased with the sensor variety of AD's offerings, but we have had to source a few items elsewhere. Any pointers on specs to be keeping an eye out for? I have a rough idea of what I'd be looking for but I'm open to any suggestions.
His suggestion was good, and I've used a few transducers, however in this application I think they won't quite fit the bill unfortunately.
VEGA makes great radars and their vibronic rods are the best thing I've used for point level in grains. You could repurpose one of their radars for this but not really the intended use. They do not come with any additional IO so you'd need to use the 4-20 signal to do the work.
IFM has vehicle/object detection radars that can be configured over IO Link using their vision software. Here you can set the detection field of view and return strength required to switch the output on. If you just need a signal and setup one time is adequate, configure it with IO-Link then just use the outputs. Or add a master and do whatever else you'd like with it.
Those vibronic rods are super neat... We're using capacitive prox sensors to achieve the same result, but that's kind of cool to see as another option. The only downside we've had on the prox sensors is temperature change. Cold weather primarily seems to degrade their accuracy and when they're being used as a full tank sensor... can get a little annoying pretty fast.
I'm not sure if the IFM would fit the bill for this... but... it is giving me other ideas. ha!
Thanks for the pointers.
I replace a lot of the capacitive sensors, pressure pads, rotary indicators, etc with the rods due to reliability. One misfire of a sensor is a PITA and costs a lot.
The R2D200 is pretty capable, don't be dense like me and try to configure it through Moneo. Use the Vision Assistant, much easier to work with. And put it all in a VM, could just be my luck but ifm software runs a lot of junk in the background when not in use.
I use a current transducer on the belt. Anything below ____ amps flags an alarm.
Pretty good idea, I've not checked to see if it sees it as a significant enough load, it's a few 5hp motors running them, however the distance from bin to output on a couple of them would make the target amperage vary or be undetectable, at least I think it could be. I know this is done often with elevator legs, and I'm already using some on elevator legs to get a rough bu/h calculation since we've not found a great solution there without adding damage to the grain yet, but these conveyors are long and fed from 3-5 different locations along the belt.
I wonder if you could mount a pair of these just below the 12 x 12 output gate:
https://www.automationdirect.com/adc/shopping/catalog/sensors_-z-_encoders/light_grids/detection_light_grids/mi301-c
If they are tripped at all you would know grain is flowing, if none of the beams are tripped then you know nothing is falling through the beams.