Converting PSI to CFM for CO2 tank

LiquidLumen

Active Member
So I have a CO2 tank and a regulator that I borrowed from a friend's keggerator, does anyone know of a way to convert the PSI of the outcoming stream to a CFM rate :confused: ?
 

pastafarian81

Well-Known Member
are you sure you tried the co2 calc. i just input my room size and desired ppm and hit calc.

http://www.hydroponics.net/learn/co2_calculator.asp


Grow room area: 105 cubic feet
Amount of CO2 required: 0.126 cubic feet
On time: 7.56 minutes

At this flow rate:
If you are using a 20 pound CO2 bottle with a regulator, it will last 174.8 hours.
If you have a CO2 Generator a 5 gallon propane tank will last 540 hours.
 

LiquidLumen

Active Member
are you sure you tried the co2 calc. i just input my room size and desired ppm and hit calc.

http://www.hydroponics.net/learn/co2_calculator.asp


Grow room area: 105 cubic feet
Amount of CO2 required: 0.126 cubic feet
On time: 7.56 minutes

At this flow rate:
If you are using a 20 pound CO2 bottle with a regulator, it will last 174.8 hours.
If you have a CO2 Generator a 5 gallon propane tank will last 540 hours.
The number you get is going to be wrong unless you have the proper flow rate in the calculation....the on time is completely determined by the size of the room and the rate at which CO2 comes out of the tank- it's going to change for different flow rates. Having a picture of the regulator isn't going to do anything- the only information I can get from the regulator is that when my tank is letting out gas, the regulator reads 10 PSI....I'm trying to use that number to determine how many cubic feet per minute that translates to
 

LiquidLumen

Active Member
The number you get is going to be wrong unless you have the proper flow rate in the calculation....the on time is completely determined by the size of the room and the rate at which CO2 comes out of the tank- it's going to change for different flow rates. Having a picture of the regulator isn't going to do anything- the only information I can get from the regulator is that when my tank is letting out gas, the regulator reads 10 PSI....I'm trying to use that number to determine how many cubic feet per minute that translates to
If you look on that site, if you don't enter a CFM value, they automatically insert the value "1" for CFM....so unless you're CO2 flow rate is exactly 1 cubic foot per minute, the calculation is wrong
 

LiquidLumen

Active Member
Ok so I think I have a decently accurate way of measuring you're CO2 CFM rate without using any fancy equipment...granted, it won't be 100% accurate, but I think it's close enough.

Get a large balloon, and run you're tank for a desired amount of time- ideally one minute, but it might have to be less depending on how high of a flow rate your tank puts out and how big your balloon can get before it pops.

So, run you're tank for 60 seconds, fill up the balloon. Then get a 5 gallon bucket, or some other container that would be easy to mark a volume difference, and insert the balloon completely under the water. Mark the initial water level and the water level after the balloon is completely submerged. Calculate the height difference, then use the area of you're bucket to determine the volume. That will be the volume of CO2 that came out of your tank. If your time interval was one minute, and your calculations were in cubic feet, then you now have your CFM rate. I'd do this several times and average the trials to get a more accurate answer. Also, be sure to use the correct units.

I'm going to get some balloons and try this later, if anyone's interested I'll post the results.
 

sqhschief

Active Member
Ok so I think I have a decently accurate way of measuring you're CO2 CFM rate without using any fancy equipment...granted, it won't be 100% accurate, but I think it's close enough.

Get a large balloon, and run you're tank for a desired amount of time- ideally one minute, but it might have to be less depending on how high of a flow rate your tank puts out and how big your balloon can get before it pops.

So, run you're tank for 60 seconds, fill up the balloon. Then get a 5 gallon bucket, or some other container that would be easy to mark a volume difference, and insert the balloon completely under the water. Mark the initial water level and the water level after the balloon is completely submerged. Calculate the height difference, then use the area of you're bucket to determine the volume. That will be the volume of CO2 that came out of your tank. If your time interval was one minute, and your calculations were in cubic feet, then you now have your CFM rate. I'd do this several times and average the trials to get a more accurate answer. Also, be sure to use the correct units.

I'm going to get some balloons and try this later, if anyone's interested I'll post the results.

I'm very interested, let's see the results.
Great idea btw,
 

Jolly G' the Giant

Active Member
I think you need something along this line ... http://www.discount-hydro.com/productdisp.php?pid=323&navid=30 . The regulator you have now, which is for a keg, is a pressure regulator. What you need is a flow regulator, which is the small graduated cylinder sticking out the top of the regulator in the link. They can also be called a FROG ( flow regulated orifice gauge). It'll be installed after the pressure regulator. CFM and PSI really can't be calculated from eachother. Hope this helps.
 
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