I have a Tank Level Sensor Ultrasonic Long Range Wireless on/partially in a water tank. It communicates a reading every 30 seconds just fine and without fail. I put this into service about 16 days ago. For the first week it properly reported level and was used to control a filling pump. The last fill brought water level up to 500mm, but probably 480-500mm due to some reporting lag (it is set to turn off at 530 though). It reported 500 and has been locked at 500 except for a brief blip on April 6 when it reported 1380mm, which triggered the pump to fill. Level very quickly rose (not jumped, but way faster than the pump can fill) back to 500 in 30 minutes with the pump on. This would have filled the tank to maybe 300mm at most. The sensor still reports 500 and has ever since.
I just had a local mechanical tech unplug the probe for 2 minutes and then plug back in. they did not power cycle the board since I didn’t want them to open the circuit box. It reported 500 the entire time.
Why will it not provide ANY readings below 500? The sensor does hang down perpendicular to the water surface, so it should get good soundings.
I really cannot have this sensor glitch like this since the site is 100 miles away and remote. I plan to go to the site at the end of the week and try to figure what is going on. Any suggestions or indications that warranty work should be required would be helpful. Any advice would be helpful. Thanks.
The sensor will either provide the incorrect reading or always output 500mm for distances below 500mm.
Would you like to measure distances below 500mm? If so, this may not be the best option. We should consider a sensor with a maximum range of 1.5 meters or 5 meters instead.
I would be happy to have some noise, then at least it is probably working. Being locked at 500 (even when unplugged) feels like something has failed terribly.
The tank is 2.5 meters high. Filling to 600-650mm is fine.
This is a test site for another installation of 2 other tanks 6m high each. Ideally we would use the same type of setup everywhere, but these issues are casting doubt on that. The pressure sensor we have from NCD feels more consistent although a little jittery.
If NCD software “power cycle the sensor before every read operation” how it is stuck at transmitting 500s even when the sensor was unplugged? Are we looking at a board failure?
The tank ran empty last night, so there was 2.5 meters of void that it missed and the levels all the way down.
if the sensor is unplugged it will send 0. when you removed the probe how long was it removed ? if you remove the sensor during sleep cycle and plug it back it wont do anything.
No there is no issue with the board.
There is a giant column of water above the pump providing pressure that does not jump around like that. I can smooth it out with a median filter window with 9 readings.
The sensor having issues is the Tank #3 Level Sensor on the “Tank #3 Level Control” flow.
Note that I am now smoothing pressure and temperature in the flows, which I was not in the earlier graph. Well median 5 was implemented on half of that pressure graph. It didn’t make a huge difference until I changed it to use a 9 number window median.
Tank Level sensor – If there is any build up due to condensation will cause it to read 500 all the time.
Pressure sensor – accuracy of the sensor is ±0.5%FS. so in the 500psi case the max error should not be 5psi. internally we take 5 samples and discard the first 4 and then send the 5the sample to user.
Hi @gmyoungblood Additionally, let me share with you the tank sensor implementation guide for the ultrasonic sensor probe we use. This document includes a list of recommendations to help you with the proper installation and implementation of the sensor in a tank. You can use it as a reference.
Thanks, I am mounted like Figure 2 on page 8. However, it is in an enclosed water tank. There is likely condensation on the sensor. It IS in a water tank and a tank of that sizes creates a thermal mass which almost always creates a temperature differential and condensate. I would have thought this would be a standard condition for most tanks and thus tank level sensors would be able to work under such conditions!?.
Does my sensor have the humidity and condensate features mentioned on p. 14?
What can be done to fix this situation? How can this work in this very common situation? Thanks.
As you can see I get a lot worse performance with transient spikes for a reading that normally hovers around 21.4 but can have transients of 3 or more readings that range from 35 to 14.
If I take the median of 9 readings it starts to look like
which is improved. But there are still lots of transient spikes being filtered and median of 5 or 7 did not cut it at all. So I am keeping the middle of 9 readings and tossing the others after the sensor takes 5 and tosses 4. That is a lot of out of specification error.
Is the pressure sensor out of specification and needs repair?
Is the ultrasonic sensor worthless in this application or fixable?
a. If worthless what is NCD willing to do? Return for credit to get a pressure sensor?
The NCD website says nothing about condensation as an issue and this is not universally a problem for all ultrasonic sensors. Some are designed to deal with this as described in the document linked above. It is advertised as a tank level sensor by NCD, which feels like there should be a number of caveats clearly listed about this on the website.
@Eduardo_Mtz I cannot reply because I am in some kind of usage timeout??? So, I can only reply by editing a prior post.
Why would I go with your proposed solution over a pressure sensor? What is NCD willing to do about my existing sensors?
Hi @gmyoungblood , yes, it’s very likely that humidity and condensation are affecting the readings of the ultrasonic sensor. In this case, I could recommend a radar-based level sensor, as radar sensors are inherently less sensitive to these conditions compared to ultrasonic sensors, which can be disrupted by condensation or temperature variations. For radar sensors, some customers use the Vega Radar sensor as the probe:
This NCD box can power up the sensor and read it at same time using battery:
You can buy the Radar sensor directly from Vega or we can build the complete system.
Please take a look at this and feel free to let us know if you have any questions.
Thank you,
Eduardo M.
It has been confirmed than condensation is the problem. We wiped the sensor and it started reading properly again.
So what are good solutions to mitigating condensation?
I have heard to apply RainX? Is that a real solution? Does it cause any issues?
I have heard to warm it above dewpoint? Something like a camera lens heater could be used to warm it up to 95-113 degrees F. Would that cause problems? The tank is remote so how in the world to supply power? Seems like it would need 20K mAh overnight and then a day of power so solar and battery? Seems like an expensive solution.
