# Question regarding D tanks



## train54 (Feb 6, 2013)

Hey guys I'm trying to answer the following question, but am not sure what the answer is...

"Per government standards, what is the minimum amount of oxygen you must have in your portable cylinders?"

I am trying to figure the answer for a portable D O2 tank.


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## mycrofft (Feb 6, 2013)

Which government? Peru?


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## NomadicMedic (Feb 6, 2013)

And while we like you, we're not going to do your homework for you.


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## Household6 (Feb 6, 2013)

Do you think a D tank has a different minimum requirement than an E or M tank?


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## mycrofft (Feb 6, 2013)

Slightly off subject, an USAF survival tech guy (i.e., ejection systems and survival gear) said that O2 cylinders were never to be drained flat or they wold need purging with dry air then refilled. Was that enlsited-guy poppycock or what?

OP, let us know, we're interested. Hint: "E     M     S     A    ".


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## Household6 (Feb 6, 2013)

mycrofft said:


> Slightly off subject, an USAF survival tech guy (i.e., ejection systems and survival gear) said that O2 cylinders were never to be drained flat or they wold need purging with dry air then refilled. Was that enlsited-guy poppycock or what?
> 
> OP, let us know, we're interested. Hint: "E     M     S     A    ".



If any compressed gas tank, not just O2, is drained, atmospheric pressure can push air back into the cylinder, contaminating the interior.. You knew that, didn't you?


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## mycrofft (Feb 6, 2013)

*emptied O2 cylinders...*

In a closed system it shouldn't, but if it is _just_ the cylinder I can see it...but back through the pressure reducer? Can't hurt.


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## train54 (Feb 7, 2013)

So I have researched this all over google and found a few things. 

1. My partner said "200 liters is = 10 LPM X 20 minutes"

But idk if I believe that...

2. An online calculator told me the answer is 825 psi

http://www.google.com/url?sa=t&source=web&cd=1&ved=0CBYQFjAA&url=http%3A%2F%2Fwww.monroecc.edu%2Fdepts%2Fpstc%2Fbackup%2Fparaoxca.htm&ei=HtoRUZGYGI7s9AS9hYG4CA&usg=AFQjCNFB_2T-rBx2DhUcSIOSSDDVL6X5QA

3. Found this equation: 

duration of flow in minutes = (gauge pressure - safe residual pressure) x constant flow rate in liters per minute

Constant = 0.16 for D tank

Gives me 1050 psi (I think? Lol) 

4. One of the fto's and I feel like the answer is 500 psi. 



Not sure which is right...



n7lxi said:


> And while we like you, we're not going to do your homework for you.



I came here because I'm confused. Thanks for your help...



Household6 said:


> Do you think a D tank has a different minimum requirement than an E or M tank?



I think so... Not sure though. Different volume tanks require more/less psi to hold same amount of O2, right?



mycrofft said:


> Slightly off subject, an USAF survival tech guy (i.e., ejection systems and survival gear) said that O2 cylinders were never to be drained flat or they wold need purging with dry air then refilled. Was that enlsited-guy poppycock or what?
> 
> OP, let us know, we're interested. Hint: "E     M     S     A    ".



I don't know why it would...

E M S A???


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## Medic Tim (Feb 7, 2013)

train54 said:


> Hey guys I'm trying to answer the following question, but am not sure what the answer is...
> 
> "Per government standards, what is the minimum amount of oxygen you must have in your portable cylinders?"
> 
> I am trying to figure the answer for a portable D O2 tank.


Not sure what it is like where you are but where I work the minimum O2 that can be in a tank and in service is 500 psi. 
Your best bet is looking at your state ems website as it probably has all the minimum standards for ambulances to be in service.


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## ThadeusJ (Feb 7, 2013)

Can you please define "amount"?  Volume, pressure or some other measurable quantity? For example, you can have the same "amount" of pressure in your M and D cylinders, but vastly different volumes.  As a student you have been told many times before, "always give the units of measure with your answers".  

It's a poorly defined question.


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## Household6 (Feb 7, 2013)

Medic Tim said:


> Not sure what it is like where you are but where I work the minimum O2 that can be in a tank and in service is 500 psi.
> Your best bet is looking at your state ems website as it probably has all the minimum standards for ambulances to be in service.



Yes, I agree.. Ours are wupposed to be switched out at 500 psi to avoid running out on the next call. But that allows EMS a cushion in there between running out, and having the tank reach too low..

train, I think you're way over thinking this!!! This is a simple answer, all the way across the board for every tank. Every O2 tank, regardless of size, holds the same amount of psi when full: 2000 pounds. That's why regulators are interchangable between all tanks. You don't need a "D" size regulator, you can use the same one on a MM, as a D, right? D hold 350 liters, E holds 625 liters; but both tanks hold the same psi..

The reason tanks shouldn't go below a certain level is because you run the chance of atmospheric pressure pushing back into the tank and contaminating the interior. Sea level atmospheric pressure never changes for the most part. 

Your formula there is great and everything, but what that's giving you the flow rate of different tanks. We're not worried about flow rates right now. We're worried about the amount of psi required in a tank to prevent contamination of CO2 or other gasses..

I'm the PITA student that always asks my PA "WHY? Why do you do it that way, instead of xyz?", and he's patient enough to explain the reasoning to me. If you read this, will you remember it?


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## leoemt (Feb 13, 2013)

train54 said:


> Hey guys I'm trying to answer the following question, but am not sure what the answer is...
> 
> "Per government standards, what is the minimum amount of oxygen you must have in your portable cylinders?"
> 
> I am trying to figure the answer for a portable D O2 tank.



There is no government minimum. I have depleted many O2 tanks. So I guess the minimum would be at least 1psi 

There is a requirement as to how many tanks we have on board, but not the amount of O2 inside.


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## mycrofft (Feb 13, 2013)

As far as corporate requirements, it varies. The oxygen company I work very sporadically for says no less than 1/2, my former full time employer (a customer) said 1/4.


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