Measure how full a CO2 bottle is with sensor or electronic regulator


I am looking for a sensor or electronic regulator that can be coupled to a CO2 gasbottle.

I want to measure how full the bottle is. I will then link this with Arduino to an app that will tell me when its close to empty so I can replace the bottle.

I have looked on the internet but I am seeing that people are saying it is unsafe to couple sensors to a C)2 bottle.

My knowledge is very limited and any help will be appreciated.


What type of CO2 bottle? The type welders use can be pressurized to more than 20MP or 3000 PSI. An industrial type sensor is needed.

Thank you so much for the quick reply. I have attached a picture of the bottle.

The bottles might become bigger in size later as requirements change.

Is it safe to put a sensor on a bottle like this?



I guess you could "tee" a sensor into the high pressure gauge port on the regulator, but the valve on the cylinder (bottle) would have to be left open or "cracked" at all times. There are many manufacturers, like Omega, Turk, Rexroth, etc., but they ARE expensive.

The easiest thing is to weigh the bottle, accurate and non Intrusive. Take a Tare measurement when you put a fresh bottle on .

You cannot safely put a sensor upstream of the regulator and one down stream will tell you nothing until the bottle virtually empty.

CO2 is stored as a liquid , so until the liquid has all gone the pressure upstream of the regulator won’t change either ( partial pressures etc) . You might be able to detect the liquid level with a series of temperature sensors on the outside ( try feeling with you hand) , but only when the bottle is supplying gas .

I guess you could meter the volume of gas used ?

Per hammy you weigh the cylinder. CO2 is like LPG (Liquid Propane Gas). When in the cylinder it's a liquid. While the pressure depends on temperature at for example 20 degrees C (68 F) the pressure will be about 57 bar (827 PSI). The problem is as the liquid turns to gas and is used that pressure remains pretty constant right till the pressure suddenly drops and the tank or cylinder is empty. This is why a quick check of a CO2 fire extinguisher (hand held) or a backyard grill propane tank consist of weighing it. You go from full pressure to no pressure like right now, poof.

They do make temperature strips which can be placed on the outside of a cylinder which will afford a good idea of what remains as liquid in the tank but other than that it's about weight and not pressure. Some tanks are setup on permanent scales.


Thank you very much. From my own reading this weighing it also came through strongly. Appreciate all the input.


You could try the relatively inexpensive DS1603L on the bottom of the tank to measure the liquid C02 depth. Calibration required. Also, the tank would need to be on a small stand, so as not to crush the sensor. Won't work if the tank bottom shell is too thick. Datasheet and a library by @wvmarle can be found here: