The standard way of measuring liquid level in a tank seems to be by ultrasound and this method works well in many cases. The issue I have is that I need to measure the level in a tank through an existing opening in the tank, but the water pickup tube also goes theough this opening.
I have used a HC-sr04 and a waterproof option A02YYUW but have encountered problems. The beam seems to reflect off the water pickup tube giving incorrect readings. I tried to use a tube to focus the sound but it seems to reflect off the tube sides rather than the level again giving incorrect readings.
An alternative would be a Time of Flight distance sensor, but the liquid being measured is clear water and the doesn't reflect off the surface accurately.
Ultrasonic seems the only option, but I am open to suggestions. Can anyone suggest a way to focus the ultrasonic or make a TOF reflect off the surface? The range is 3cm to 50cm.
A standard and very popular way of measuring water level in a tank is to measure the water pressure at the bottom of the tank or in an outflow pipe (with no flow).
The water pressure is strictly proportional to the distance from the pressure gauge inlet to the water surface.
A "gauge" rather than absolute pressure sensor must be used, to take into account variations of atmospheric pressure.
I used a JSN-SR04T 'water proof' sensor which I liked because it does not need separate send/receive transducers. Like you I had problems with catching the sides of the container. I made a little aluminium horn that could be mounted in front and that solved the problem. My water tank is a 1,000L IBC, and I can read the level fairly accurately from 900mm (empty) to 150mm (full).
If you do an image search for waterproof ultrasonic sensors, you will see several examples with a built in directional horn. I think you could take your cues for size and angle from those pretty safely.
Thanks for all your replies. I had thought of pressure as an alternative and sourced a transducer. It worked, but this meant suspending the transducer in the water. As this is drinking water I am concerned about contamination, so was looking for a non contact method if possible, but that may be the only way. I am unable to modify the container, which is plastic and has one 60mm opening on the top. I had thought about weight, but the container may not be sited on a flat level surface so not stable enough. The sensor also needs to be removable so can't be permanently fixed to the container.
You don't have to throw the sensor in the tank, you can put a "food grade" tube or hose down to bottom of the tank and connect sensor to that out from the tank. Connection has to be air tight though.
Also, if you want to measure distance, you can place some flat floating element in the tank and measure distance to that.
Interesting. Not sure it would work for my application as the container isn't flat on the sides when vertical and has round sides if laid horisontally. Below is a link to the container I'm using. Water Container
If it’s an aqua roll then it’s movable causing a whole range of other issues such as powering , connecting etc.
The best option is to put the container onto a scale , with some form of bracket to keep it steady
Thanks for the suggestion, but weight not a viable option due to the different ground the container will be sited on. Power isn't an issue as it would be easy to connect to a 5v or even 12v source. I have been trialing an ultrasonic system which has worked but not very accurate, but detachable so I can easily fill the container.
Hang it from something by the handle and get the weight that way .
If aren’t putting it on flat ground anything looking at the water or depth level will be wrong too
You can get level sensors that consist of a run of Reed switches inside a tube. On the outside a float with a magnet operates a switch depending on depth .
A short one (will still read wrong if the ground isn’t level)
Thanks but that is a switch rather than a level sensor. Yes it tells you its full or empty depending on where you place the float but not the current volume.
