O2 Tanks In Cold.

TornWingedAngel1

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Maybe this is a silly question, or maybe it’s been answered for me before and I just simply can’t remember, but google searchs aren’t porving too helpful thus far.

But what are the effects of leaving O2 in the cold? Like, inside a cold car, let’s say.

The company I currently work for we park our rigs inside the garage at the end of the night. O2 stays in the rigs, but the rigs are inside. The company I worked for in Detroit, we were to turn into our O2 D tanks at the end of our shift. (Though I’m not sure if that was for a safety issue or security purposes.)

What, if any, are the effects of cold weather on O2 tanks? I mean, usually the rig’s main O2 tanks at my Detroit company’s was in the cold all the time (not garage, stationed outside) but I was just wondering…
 

medichopeful

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Maybe this is a silly question, or maybe it’s been answered for me before and I just simply can’t remember, but google searchs aren’t porving too helpful thus far.

But what are the effects of leaving O2 in the cold? Like, inside a cold car, let’s say.

The company I currently work for we park our rigs inside the garage at the end of the night. O2 stays in the rigs, but the rigs are inside. The company I worked for in Detroit, we were to turn into our O2 D tanks at the end of our shift. (Though I’m not sure if that was for a safety issue or security purposes.)

What, if any, are the effects of cold weather on O2 tanks? I mean, usually the rig’s main O2 tanks at my Detroit company’s was in the cold all the time (not garage, stationed outside) but I was just wondering…

As far as I know, the only major thing would be that it could decrease the pressure in the tanks due to the decrease in movement of the molecules. I can't think of the exact term for this right now (I want to say entropy but I'm pretty sure that's incorrect). Of course, once the O2 warms back up the pressure would increase back to what it was (or around there).

The metal of the tanks could also potentially be weakened, but it would have to be REALLY cold.

The oxygen inside would be cold, which could be uncomfortable for the patient if it's used before being warmed back up.

I hope this helps.
Eric
 

ZVNEMT

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i think if there would be any problems due to leaving the tanks in the cold, they would have been addressed in the previous winters you company has experienced.
 

MMiz

I put the M in EMTLife
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There is no problem storing oxygen tanks in the cold. I worked for a private provider in Michigan that regularly stored oxygen tanks in the rigs that we left outside in winter.

Oxygen suppliers often store and transport tanks outside in cold conditions. Looking at the NFPA and FDA, both say that outside storage is fine, as long as it's away from combustibles.

Of course I'm not a lawyer, nor an expert on oxygen.
 

lightsandsirens5

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As far as I know, the only major thing would be that it could decrease the pressure in the tanks due to the decrease in movement of the molecules. I can't think of the exact term for this right now (I want to say entropy but I'm pretty sure that's incorrect). Of course, once the O2 warms back up the pressure would increase back to what it was (or around there).

The metal of the tanks could also potentially be weakened, but it would have to be REALLY cold.

The oxygen inside would be cold, which could be uncomfortable for the patient if it's used before being warmed back up.

You are thinking of the Combined Gas Law (A combination of Boyle's law, Charles' law, and Gay-Lussac's law.) Where P1V1/T1=P2V2/T2

The Ideal Gas Law can also be applied I beleive. pV=nRT

(Look them up. I know them, but not well enough to explain here.)

I like the REALLY cold part. ^_^ That would be like liquid O2 type cold! (minus 200???)

And Your last one brings up an interesting point. I beleive that the temp. of the O2 might be the same no matter what the temp is outside. It is because when you release a presurized gas, it cools. (Quite a bit.) I am trying to figure that out right now, but I don't know how to quantify volume for a gas that has been released from a container into the atmosphere. If I figure it out, I'll let you know.
 

medicdan

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Boyle's law, as discussed above applies. The more important question, in my mind is why trucks are being left outside overnight. At least in MA, where is certainly gets cold, OEMS requires all ambulance-certified vehicles to be warm-garaged at all times when not occupied. Waivers can be obtained, but only for non-transport vehicles, and in that case, they need a "Winter Mode" that turns the engine on for a pre-determined amount of time every hour.

The worry about a cold (and ungaraged) vehicle is more about patient care and mechanics. As I understand, diesel engines (which are required for ambulances) are good at idleing for time, but cannot start cold (thus the need for engine block heaters, which, of course, are no good in the absence of a shore line). Keeping the engine (and passenger compartment) warm ensures that when you need to start the vehicle, you don't have a problem, and the patient can be comfortable.

Lastly, ambulances tend to carry equipment and supplies that are temperature sensitive. Everything from Epi pens to AEDs, suction batteries, and sterile water, are all negatively effected by extreme (and cold) temperatures. Oxygen cylinders are the least of your worries.

Reconsider whether what your company is doing is legal in your region, or whether there is (could) be damage to the contents of the vehicle. Again, I dont think there is a problem with a vehicle being in an unheated garage (as long as there is a shore line, with engine block heater), temperatures never approach freezing, and medications are taken out of the vehicle.

Good Luck!
 

DV_EMT

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Cold = Contracting molecules

Hot = Expanding molecules

in a nutshell - unless it's hot out... don't worry bout the tanks!
 

medicdan

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yes, with cold, you are going to have less pressure, not more. That is, of course, why when you fill a bottle it gets warm. Many dive shops, in order to maximally fill their tanks (and knowing they will be out of the sun), fill their tanks in a bath of water.
 

Foxbat

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And Your last one brings up an interesting point. I beleive that the temp. of the O2 might be the same no matter what the temp is outside.
These are two different things. Temperature of O2 in the tank is the same as the temperature of the environment it is in (after it has been there for a long time) and it further cools down upon expansion.
As of how to quantify the drop in temperature after expansion, I suspect there are many factors in this, such as at what velocity and flow rate O2 escapes the cylinder; furthermore, it's a transient process and the temperature of escaping O2 will probably vary in time.
 

lightsandsirens5

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These are two different things. Temperature of O2 in the tank is the same as the temperature of the environment it is in (after it has been there for a long time) and it further cools down upon expansion.
As of how to quantify the drop in temperature after expansion, I suspect there are many factors in this, such as at what velocity and flow rate O2 escapes the cylinder; furthermore, it's a transient process and the temperature of escaping O2 will probably vary in time.

Ahhhh....yes O Knowledgable One. However, this lowly EMT was refering to the temp to which the O2 is cooled upon release.

Since once the gas is released into the atmosphere, the volume can increase infinatly (almost:rolleyes:), then the pressure would decrease infinatly (again, almost:rolleyes:). Thus my thinking was: With this direct inverse variation between volume and pressure, temp. must remain constant.B)










(Now that I say that it sounds incorrect.:blush: I must go dig my physcis textbook up. Later peoples.)
 

KB1MZR

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As far as I know there is nothing against the oxygen left in the cold. CT OEMS requires all certified vehicles to be left in 60 degree or higher temperature so if we have to leave a vehicle outside it needs to be kept at a constant 60 using heaters etc. But, for my POV i leave oxygen in my car 24/7 in the winter and what I do is keep a couple of hot packs in my oxygen bag and if the oxygen were that cold I would just wrap a hot pack around some oxygen tubing, just make sure its not hot o2 for ur patient.
 

RescueYou

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No problems that I know of. Prolonged exposure may cause decreased pressure, but it shouldn't have a big effect. Heat on the other hand....
 

usalsfyre

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No problems with the average tempature variations. We have outside storage for our spare tanks and have tempature variation from about 20 to 115 degrees throughout the year and don't have a problem. Your drugs on the other hand...
 

WarDance

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The major concern is the metal tank in the cold but I don't think that will be an issue in your area. The area I live does get cold enough for this to be an issue.....

However, as mentioned before, the drugs should be the main concern. Too hot or too cold is no good.
 

Foxbat

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Ahhhh....yes O Knowledgable One. However, this lowly EMT was refering to the temp to which the O2 is cooled upon release.
Sorry if I sounded arrogant or something, it wasn't the intent. I still think it's impossible to get it from just PV=nRT.
 
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TornWingedAngel1

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Heh, I'm glad to see a thread filled with such input.

As far as I know there is nothing against the oxygen left in the cold. CT OEMS requires all certified vehicles to be left in 60 degree or higher temperature so if we have to leave a vehicle outside it needs to be kept at a constant 60 using heaters etc. But, for my POV i leave oxygen in my car 24/7 in the winter and what I do is keep a couple of hot packs in my oxygen bag and if the oxygen were that cold I would just wrap a hot pack around some oxygen tubing, just make sure its not hot o2 for ur patient.

This is why I'm asking. I just recently bought an O2 tank and wanna make sure I can keep it stored in my car. I live in the Chiago-area, so it can get pretty damn cold in the winter.

The hot pack idea is a good, idea, and I'll do that. I just wanted to make sure there were no dangers from leaving it in my car in the midwest cold. (Or heat, I guess, but that's not as big of an issue in the midwest, I'd think.)
 

medichopeful

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Heh, I'm glad to see a thread filled with such input.



This is why I'm asking. I just recently bought an O2 tank and wanna make sure I can keep it stored in my car. I live in the Chiago-area, so it can get pretty damn cold in the winter.

The hot pack idea is a good, idea, and I'll do that. I just wanted to make sure there were no dangers from leaving it in my car in the midwest cold. (Or heat, I guess, but that's not as big of an issue in the midwest, I'd think.)

May I ask why you bought an O2 tank?
 

medicdan

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As far as I know there is nothing against the oxygen left in the cold. CT OEMS requires all certified vehicles to be left in 60 degree or higher temperature so if we have to leave a vehicle outside it needs to be kept at a constant 60 using heaters etc. But, for my POV i leave oxygen in my car 24/7 in the winter and what I do is keep a couple of hot packs in my oxygen bag and if the oxygen were that cold I would just wrap a hot pack around some oxygen tubing, just make sure its not hot o2 for ur patient.

I remember reading somewhere... and I will look up where... that trying to head O2 that way just doesnt work. Oxygen (and other noble gases) dont have a high enough specific heat capacity, so even if you warmed it up significantly at or near the bottle, if the environment is cold, it's all lost along the way in the tubing.
Saline and other fluids, OTOH, may benefit from being warmed before a call (thus the commercial warmers), because they hold temperature more efficiently (specific heat capacity).

EDIT: C/O Wikipedia, some numbers:
Oxygen (at 25c/77f) has a heat capacity of 0.918 Joules /(Grams*Kelvin)
Water (and other minerals inside) (at 25c) has a heat capacity of 4.1813 J/(g*K)

Thus, Water holds a temperature roughly four times as well as oxygen ( at 77*f), or oxygen looses heat four times as fast as water. Does this make sense?
 
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