A little bit of topic ...
I have of these TL-136 (0-1m) pressure sensors for my pond on my desk (they are available in different ranges). They are a bit pricy, but should work fine.
I tried to use the water proof ultra sonic sensors too but they have a minimum sensing distance around 0,4-0,5m - which is a game stopper for me. A non waterproof ultrasonic sensor died quickly cause by the harsh outside conditions. Also I have all the parts (ping pong ball, pipe, transparent case for a DIY ToF range sensor VL53L0X - Time-of-Flight ranging sensor - STMicroelectronics ... but no time
If you have access to the outside of the tank a pressure sensor like these
should work. I use them to supervise my pumps. They should work not only with water (Tip: Be carefull with electrodepotentials - one of these corroded away in weeks connected to the metal pipes of the pump where others isolated by plasic pipes look as new 50cm downstream after 3 years.
I only need a range of 0-10cm to make sure that the skimmers work as intended and the balanced system with 3 connected ponds is not blocked to avoid that the circulation pump drain some ponds downstream while overfilling the ponds before.
BTW you don't need to have sensors installed to be able to test my node. You can easily inject test messages (with fictive measured heights), like in the example flow on my readme page.
Would really like to have some folks that could test it before I publish it on NPM, because it would be a pity if something goes wrong with somebody's tank due to some stupid bug in my code...
If you're using ultrasonic to measure level in a tank, the sender really ought to be in the middle of the top not off to one side; and the tank shouldn't have internal baffles or horizontal ribs. This rules out most heating oil tanks!
One way to mitigate is to mount the ultrasonic unit in a short pipe, then fit the pipe to the tank. I suppose the tube acts as a 'waveguide' and seems to avoid the spurious signals from side reflections. I found it'll even work around bends, so you can mount the sender horizontally with an elbow fitting onto the downtube. My particular oil tank has a 2" top connection, so the sender is fitted at the top of a 300mm piece of 50mm waste pipe with a threaded boss on the bottom which screws into the filling neck.
It seems to be more repeatable than my Mk1 version - which was a pressure sensor on top of the sight tube. This arrangement worked, but was very temperature sensitive due to the trapped air column in the sight tube.
An unexpected advantage seems to be that this bit of tube with wires, an aerial, and a clear lidded box with a Wemos in, seems to have deterred the local oil thieves - neighbours have had their oil stolen, mine has been left alone....
@impvan,
Thanks for this usefull info!
So I assume you could also use a bended pipe to estimate the length of an underground tank, if you are not sure about the dimensions...
I've had the sensors for a couple of days, but been busy with stuff for a charity I volunteer with. A quick test with the JSN SR04T ultrasonic sensor shows a slight difference between the actual and measured distance in the setup I'm using, but I'll see if I can figure out what's causing it. It does seem to be pretty reliable though.
Hi @impvan,
Could you please share a quick scetch of how this looks like, because I have a hard time to imagine it.
I only found this discussion, where bgunnarb has been so kind to show pictures of his own solution:
But he explicit says that the sensor needs to be mounted at the bottom end of a (30 mm outer diameter) plastic tube. While you say it needs at the top of the tube. It makes indeed more sense to me to install it at the top of the small tube, since the tube itself is used as a 'waveguide'. Here my quick scetch:
On the other hand, don't you get reflections inside the small tube when you install it at the top of the tube? Will need to find some time to experiment with it...
I assume you use a short (30 mm) tube because for a longer tube, the (good water) reflections won't find their way back into the tube?
