Measuring liquid level in water bottle?

[mattblee]

I came across STM's YouTube video demonstrating how to measure the level of a liquid inside a cup: https://www.youtube.com/watch?v=tHTNjmbO-Go

I'd like to do something similar except for water bottles (of varying shapes, sizes, materials, and liquids). Since the opening of bottles may be small, I'm looking for something with very narrow field of view. Also, because bottles have different heights, we can't reliably place the sensor right on top of the opening.

The bottles may be transparent or not, and may have dark liquids inside of them (or worse yet, carbonated beverages).

Is there a liquid level sensor that can still work under these conditions?

[John E KVAM]

The easy way to think about this is to draw it. Start with the sensor and create an 18-degree cone. That's the shape of the light. Now try to see where you can put the sensor so that both the sensor and the stream of water can shoot down the bottle opening. Is there enough room?

The issues are:

1) Standard water bottles have a very narrow opening.

2) the stream of water reflects as it's entering the bottle.

3) Water - being transparent - is difficult. And we can see it with the sensor - but really require a flat perpendicular water surface. bubbling water - as it's being filled is a really hard problem.

4) The sensor works best if the bottom of the container is not reflective. Clear bottles would be fine. But aluminum ones would give you fits. (The photons hit the bottom and reflect - screwing up your measurements. 

In short, i'd say no, it won't work, unless you could limit the problem in some way. Larger openings, no metal. 

We did well filling soda cups and coffee cups. But both of those have wide openings and we fill relative to the lip of the cup. 

- john

[mattblee]

Hi John, thanks for the insights. I should've clarified, I don't need 2 & 3 above -- that is, I don't need to continuously monitor the level as the liquid is being filled. I just need to figure out the initial liquid level before the filling starts.

Your point about the aluminum bottles is well taken. Sadly, I can't restrict our customers from using aluminum bottles, or bottles with small openings. Is there another method that might work, or is there really nothing on the market for this use case?

Many thanks again.