# O2 tank duration.



## Shrek929 (May 31, 2015)

Hello, First off I do not have much vent experience. So, How do you find out how long a O2 tank will last during a vent transport. I know how to figure out tank duration from a free flow device but I'm lost in figuring out the vent formula. Thank You in advance.


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## COmedic17 (Jun 1, 2015)

Oxygen Tank Conversion Factor * Remaining Tank Pressure (psi) / Continuous Flow Rate (L/min) = duration of flow.


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## Smitty213 (Jun 2, 2015)

COmedic17 said:


> Oxygen Tank Conversion Factor * Remaining Tank Pressure (psi) / Continuous Flow Rate (L/min) = duration of flow.



Just figured I'd throw this in for convenience...
Oxygen Cylinder Conversion Factors
• D Tank = 0.16
• E Tank = 0.28
• G Tank = 2.41
• H/K Tank = 3.14
• M tank = 1.56


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## Aprz (Jun 2, 2015)

Shrek929 said:


> I know how to figure out tank duration from a free flow device but I'm lost in figuring out the vent formula.


I think that means he knows how to calculate it using liters per minute (LPM), but the ventilator probably doesn't say how much LPM it is using.

My best guess would be that it says in the ventilator manual or you could guess the LPM via using FiO2 = 20 + (4 x LPM).

FiO2 = 20 + (4 x LPM)
(-20) + FiO2 = 20 + (4 x LPM) - 20
FiO2 - 20 = 4 x LPM
(FiO2 - 20)/4 = (4 x LPM)/4
(FiO2 - 20)/4 = LPM
LPM = (FiO2 - 20)/4

So if the FiO2 is 40, which I think is pretty standard, then...

LPM = (FiO2 - 20)/4
LPM = (40 - 20)/4
LPM = 20/4
LPM = 5

Then you can use the equation COmedic17 said.

I am only guessing. I'm not even sure if my guess is sane or would be accurate.


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## akflightmedic (Jun 2, 2015)

Smitty213 said:


> • D Tank = 0.16
> • E Tank = 0.28
> • G Tank = 2.41
> • H/K Tank = 3.14
> • M tank = 1.56



You forgot the MT cylinder.


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## Carlos Danger (Jun 2, 2015)

What type of vent is it?

The operators manual will have the consumption rate listed somewhere.


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## ThadeusJ (Jun 2, 2015)

You gotta check the manual as there are many factors in calculating vent consumption: FiO2, internal bleeds/leaks (some can use a few LPM just to drive internal components), PEEP level, small leaks in the circuit, etc.   If you are in non-invasive mode and have an intentional leak (again, depends on gteh vent used), that will increase your consumption as well.


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