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| Volumetric measurement of liquid in transparent container |
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| speechsupply:
I'm working on a way to measure the amount of water in a container. The container is transparent, has no lid, and is made of glass or plastic. It holds 3 liters = 101 oz and stands on a tabletop mostly. But, due to various challenges, I would prefer to measure the volume from beneath. ( To avoid dipping a MPXx2051 or float into the water) Using a strain gauge is def. a viable option but I would prefer to have a sealed enclosure with no external moving parts. Requirements for accuracy and precision are quite low. If I have to present actually numbers, I would say that a resolution of around 100 ml. with a +- 10 ml accuracy would suffice. Possible solutions are: ** Updated ** A. Use a Sharp GP2Y0A41 or similar and hopefully manage to detect the water level. Will try this within the next couple of weeks. B. Capactive sensing on the outside of the container. This solutions violates the desire to only monitor from beneath, but could be a preferable solution to weight cells. // Thanks to: forrestc, and larsdenmark for the suggestion. C. Container resonance? Is this viable, also in plastic containers? D. ideas? Let me hear what you think :) |
| EmmanuelFaure:
What are your requirements in term of accuracy and cost? |
| jpanhalt:
Several years ago a participant on another forum tried to measure the surface distance to water with that device. She had trouble getting good reflection without adding something to the water. Maybe your experience will be different. I did a very crude experiment with a TOF laser distance measuring device and bounced off the bottom of the container. Since the speed of light is considerably different in air versus water, given a fixed distance above the bottom, I could estimate the depth of water. |
| larsdenmark:
Knowing the required accuracy and response time would help a lot to direct the idea generation. Is the container connected to anything while the measurement takes place? Weighing the container would be the obvious thing to do. You could also shine a laser on the surface of the liquid at an angle and detect where the beam hits a detector on the bottom. Try to measure the capacitance between two electrodes that are connected to the side of the container and see if you can correlate that to the water level. You could use the resonance of the container (that will depend on the level of water), but you'll probably need some special (crystal) glass to get a good resonance. Also if the resonance is within the audible spectrum then this will be rather annoying to listen to. |
| DTJ:
Maybe looks as the products made by Onno Sokki who make some accurate fuel flow instruments and see how they do it. At least some of them use a strain gauge. https://www.onosokki.co.jp/English/english.htm |
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