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Cheap flow meter 0-25 lpm?

Jadeit

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Is there a small, inexpensive sensor that can be connected to an 8mm tube and can measure the amount of gas passing through 1 to 25 liters per minute?
I don't need anything extra accurate
I just need to replace this something small with a digitally processable output
 

BradtheRad

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Place several photosensors alongside the column. The indicator rides up and down, darkening a sensor in turn. Determine which photosensor it is, convert to electronic value. Use 10 sensors and you can make a readout zero to 9.
 

Jadeit

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1. LZQ-7 2-20l has a height of 120mm, the height of the device for which I need it is 70mm. The game over .
2. In general, if the scale you are serving is non-linear, the bottom m and the small resolution at the top is a large step. The flow of 2 or 3 liters is a difference of 50% and 19 or 20 of about 5%.
3. Even if I use photo transistors in SMD 1206, the real resolution will be 2.5 mm. With a scale length of 80mm, a resolution of 32 that's 5 bits. With great non linearity, that's not enough


LPM.png
 

danadakk

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Real hi resolution would be to use linear CCD array -

1610974546219.png





Thermal flowmeter - https://www.analog.com/media/en/tra...transducer-interfacing-handbook/Chapter13.pdf


Regards, Dana.
 
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FvM

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Jadeit

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Yes we did not specify what is expensive
And yes, this is exactly expensive.
I know these flowmeters, but they are unnecessarily accurate for the given application and especially very expensive .
I need to measure the flow of argon, setting the amount is manually by a throttle valve, it's about the MCU to be able to check the flow and if it is out of range to start beeping .
The flow is set between say two to 4 and then between 6 and 8 and exceptionally 14 to 16 liters / min
As I said, 7 bit precision is enough for me, but I need to fit in $ 30
I thought I would find a small Chinese aperture flow meter with a differential pressure sensor, but I didn't find anything
 

FvM

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Make your own pressure drop or Venturi nozzle flowmeter with a cheap differntial pressure sensor.
 

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