Cheap CO2 Flow Meter Review

[karel.public]

Short video update. This rotameter is working very good so far. I picked the right size for my 650l tank and it sits dead center of the scale at 30ml/min.
No jumping and seems to show repeatably the same number (I had different rates set as well)
The knob works better when my main needle valve at the regulator is set to say 60ml/min - so they work in series.
But no problem dialing in 2ml/min increments and does not change with the slightest touch like my main Oxyturbo needle valve.

If you don't hear more from me, than it works...

 

[JacksonL]

I have gone digital…





Accurate to about 0.2 ml/minute, range between 0 and 200ml/min.

I have had it going for about a week now and it tracks my mechanical glass ball flow valve exactly.
Just data for now, but next will come a phone warning system if flow is unexpectedly high or low, and then next I would like to get a stepper motor on the needle valve to see if I can reliably get it to set to a commanded flow level.
No more fiddling with a needle valve, put a ml/minute into the phone and the motor slowly turns the needle valve in minuscule degrees until the flow meter steadies on the right number.

 

[HardeeParty]

PLEASE TELL ME MORE

 

[Bettatail]

I have gone digital…

View attachment 20040

View attachment 20041

Accurate to about 0.2 ml/minute, range between 0 and 200ml/min.

I have had it going for about a week now and it tracks my mechanical glass ball flow valve exactly.
Just data for now, but next will come a phone warning system if flow is unexpectedly high or low, and then next I would like to get a stepper motor on the needle valve to see if I can reliably get it to set to a commanded flow level.
No more fiddling with a needle valve, put a ml/minute into the phone and the motor slowly turns the needle valve in minuscule degrees until the flow meter steadies on the right number.

This is a thermal mass flow meter, you do not need to design a stepping motor for the needle valve, instead, you can connect a proportional valve to control flow rate, then you have a mass flow controller,
what surprise me here is the price of this thermal mass flow meter, in the western countries such thing is about $800+ a piece, and the mass flow controller is about double in price. I have several(bought cheap from ebay), but only use them to measure/monitor the flow rate of the valves and equipment.

 

[JacksonL]

PLEASE TELL ME MORE

5V sensor, I2C signal.
It needs 10cm of straight tube on the inflow side and must be mounted horizontally.
Sends a raw value in the thousands through the signal bus, so it needs calibration against another flow meter. Although, being a mass flow meter I suppose an accurate large syringe could be used to blow a known mass down the tube instead.
I didn’t expect a lot at the price I paid for it, but it is very responsive to even the tiniest change in flow.
Not sure how much I would trust an exact number, I guess it depends whet you calibrate it against. For all our real world applications it’s perfectly accurate though. I’m mostly interested in relative change in flow, for warning systems and adjusting flow.

 

[JacksonL]

This is a thermal mass flow meter, you do not need to design a stepping motor for the needle valve, instead, you can connect a proportional valve to control flow rate, then you have a mass flow controller,
what surprise me here is the price of this thermal mass flow meter, in the western countries such thing is about $800+ a piece, and the mass flow controller is about double in price. I have several(bought cheap from ebay), but only use them to measure/monitor the flow rate of the valves and equipment.

The issue with proportional control valves that move in 0.5ml per minute steps is their price!
Stepper motors, mounting hardware and a mini esp32 comes to about $40.

 

[Bettatail]

The issue with proportional control valves that move in 0.5ml per minute steps is their price!
Stepper motors, mounting hardware and a mini esp32 comes to about $40.

that is true, proportional solenoids are expensive, ...

let me see if I can find any for good price on ebay.