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| Aha, you are thinking of John Blue's magnetic balls with a sensor behind it.
That just physically shows a position as long as the magnetic ball is being picked up on the sensor, it'd show relative height.
For the flowmeter, it is a paddlewheel flowmeter, but the downside to paddlewheel flowmeters is that often they have a pretty narrow 'accurate' flow line. With ours, the actual paddlewheel is sized such that it uses a replaceable insert 'jet' that stabilizes the stream across the paddlewheel to improve accuracy when flows are low (especially for low flow rates). So, similar to the balls in a visual flow indicator, a certain jet is used for an operational flow range. In the case of ours, there are four colors of jets, which cover off a flow range of 0.04 - 1.53us gpm. As far as accuracy, depending on how where the flow rate is compared to the actual jet, the jets are set up to be within that 3-5% accuracy of actual flow.
Again, comparing and using it as a whole system flowmeter isn't how it has been design, so even little rounding errors between the rows (e.g. 72 outlets on an air drill) can amount to amounts that you'd want to calibrate out to bring in the accuracy out of the box. I think we had our calculations down to like 7 sig. figures, but even then when accumulating over 72 rows there begins to be variance that can be measured overtime for sure, so if we were going so far as to use the accumulate flow rate to monitor the whole aggregate system, you'd want to calibrate the flow/jet more closely.
Over all the flowmeters do quite well across density change as well, generally not needing to be recalibrated, especially as the system is using a rolling average of the rows, instead of an input flow rate. We've found for the purpose of the system, its what folks were wanting. As far as keeping to a 'true' flow rate, it still will aggregate the entire flow x rows flow rate in the sidebar as well to keep tabs on your intended actual, but since it isn't pulling in a speed sensor (or tied to monitor speed), usually how it has been laid in is consistent and accurate enough for sure.
For the ISO/integration approach, the system was built to be a bolt-on, color-agnostic system, but we wouldn't shy away from integrating it into the cab. Only downside is supporting a generic ISO setup isn't in the core function of Wilger's business, so we'd be relying on the focus of specific monitor/brand integration to really put our full efforts into it.
So, back to your questions/observations:
For sure, we have folks/system manufactures from small to large using the components and doing their own setup using our parts. Simply the flowmeter is supplying raw square pulses (4-pole ceramic magnet used, so 4/8 pulses per revolution), and then it's just a matter of using a Cal factor tied in, and pull speed sensor from your microcontroller. Personally, I was a bit spooked of adding a speed sensor as now we have to have some firm idea of where/how the speed sensor should be mounted, and didn't want the system's core function get muddied if the speed sensor spec'd was subpar/etc. Since speed off the tractor was always going to be more accurate (relatively safe assumption), it was going to be a more consistent core function if we kept it to specializing in 'knowing flow'.
We did some density analysis with the jets and it wasn't too crazy difference. We did comparative studies with both density-specific gumbo as well as one of the nastier active ingredient gumbos, and it did vary it, but didn't seem like it was even critical to change the calibration factor even out of the box. Otherwise, with the same jet (as long as that jet isn't too small and actually metering the flow) you'd just change the cal number on the fly in the app if necessary. Again, even early/cold mornings running 32% will flow different in the heat of the day, and most applicators probably aren't adjusting their flowmeter or rates based on the ease of fertilizer density. (Again, I'm not saying that is a good thing that they aren't honing stuff in through the day, but its a bit of a reality of where guys are happy enough with consistency).
We've also had folks even using a singleton flowmeter with fertilizer/innoculant/biological injection with a microcontroller (e.g. had one group setting it into their fertigation setup just for the injection side of things, with the microcontroller getting tied into the irrigation monitor, but also using a light on the box to visually see there is flow occurring (just as indication). it is pretty open-source that way as nothing is encrypted. | |
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Any one use a Wilger Flow Meter
