Oxygen vs. Compressed Air

[Engine6SAFD]

I have read in two different sources that have called the SCBAs we wear oxygen bottles. When I confronted one author about the fallacy, I was scolded and told to ask the thousands of firefighters of the particular department if they were oxygen bottles. I've been in the fire service for a pretty long time and I scuba dive, and I have never heard of anyone using oxygen. If I am wrong let me know, but if anyone else thinks right, please let me know.

[firenresq77]

Nope, no Oxygen here......... Don't know of ANYONE around here using oxygen.....

[LeuitEFDems]

I'm guessing...like many other things, people use "oxygen bottle" for a general name....like "kleenex" instead of calling them tissues...
I personally would NOT want to go into a fire wearing an O2 bottle on my back. Don't want a bomb strapped on my back...may just be a personal thing..

[arhaney]

I must have seen this 20 or 30 times in the press, Why not just strap some explosives on your back?

[arhaney]

Oh, by the way, who is this goofus author so I won't read anything of his.

[cozmosis]

If you'd post a reference to the author's work, I'm sure that we'd all be glad to set him straight. Compressed air it is.

[SamsonFCDES]

Crazy as it sounds...

NASA, Chicago Fire Department Sign Agreement
NASA HQ Public Affairs Office (NASANews@luna.osf.hq.nasa.gov )
Wed, 19 Apr 1995 15:58:44 -0400

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Jim Cast
Headquarters, Washington, DC April 19, 1995
(Phone: 202/358-1779)

June Malone/Bob Lessels
Marshall Space Flight Center, AL
(Phone: 205/544-0034)



RELEASE: 95-51


NASA, CHICAGO FIRE DEPARTMENT SIGN AGREEMENT


Fire fighting could be safer and more efficient in the
future thanks to an agreement signed today between NASA and
the City of Chicago.


The agreement opens the door for NASA's Marshall Space
Flight Center, Huntsville, AL, and the Chicago Fire
Department to work together to apply space program
technologies to improving fire fighting and other emergency
services.


Fire Commissioner Raymond E. Orozco met with NASA Administrator
Daniel S. Goldin and Marshall Director Porter Bridwell in
Chicago at 2 p.m. CDT today to sign the Space Act agreement.
They also began discussing various technologies that could
be transferred to the department to enhance fire and other
emergency services.


"The Chicago Fire Department is a strong innovator in
testing, developing and adopting new methodologies and
technologies for emergency services," said Goldin. "NASA is
looking forward to working with them to explore ways space
technology can be used to enhance emergency services.
Ultimately, it will be the American people who benefit from
what we accomplish here."


A number of candidate activities have already been
identified for joint study. The Chicago firefightersU
principal interest is in developing a personnel locator
system which will enable on-scene authorities to locate,
track and, if necessary, rescue firefighters within a 2,400-
foot area of operations. This also would enhance the
command and control capabilities of senior people directing
fire-fighting operations.


Chicago's second priority is in having NASA, through
its Marshall Center, attempt to adapt dynamic structural
analysis techniques to determine if a structure is in
imminent danger of collapse. Such a device might be able to
provide in real time the vibration "signature" of a
structure. Studies have indicated that there is a
"signature" change prior to a structure collapsing. Such a
device would provide fire officials with a means of
determining when a structure has to be evacuated by
firefighters, potentially saving them from harm.


The Chicago Fire Department also is interested in
developing a new portable air-breathing apparatus for use by
firefighters. The current device has several drawbacks
including expense, weight and a long activation time.
NASAUs knowledge of liquid oxygen technology will form the
basis for an evaluation of the feasibility of using liquid
oxygen in a new breathing apparatus.


Other research possibilities include identifying the
location of an emergency 911 call made from a cellular
telephone, and developing the capability to warn hearing
impaired drivers of an approaching emergency vehicle. The
Marshall Center already has been working on such an
Emergency Vehicle Alerting System. This device would assist
drivers with hearing loss and those operating in a high
noise environment, such as a school bus full of children.
The system would alert the driver and provide information on
the emergency vehicle's distance and direction of approach.



- end-


NASA press releases and other information are available
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service. Questions should be directed to (202) 358-4043.

Found here.

http://www.qadas.com/qadas/nasa/nasa-hm/0114.html

LOL, can you imagine the the ridiculous explosion the first one of these things that ruptures will cause, there wont even be time to say OH SH...

[12TruckIrons]

You really have to think this one through. Everybody is saying walking around with 02 is akin to having a bomb strapped to your back. But only if the cylinder ruptures, and really just how many cylinders have you seen rupture during your time in the fire service? Personally I have never seen it or even hear of it. And no matter what if its compressed gas or LOX a cylinder rupture is going to be catastrophic for the wearer and anybody close by. So any talk about it becoming a bomb is more or less unfounded. The only issue I see with using LOX is the mask seal, if you have a bad seal or get a hole in your LP hose then you could have an issue that needs some serious and quick work to correct.

[LeuitEFDems]

One thing I meant in my post about a bomb strapped to my back is the flammability of O2 vs compressed air. If you have a bad seal with fire nearby..get a leak in the hose, with O2, you'll be a walking flamethrower compared with compressed air that doesn't have the same flammibility.
I wouldn't want to have ANY cylinder on my back that broke the valve off...flammible or not. Catasrophic failure for any gas.

[mcaldwell]

12TruckIrons is right on the money. If you have a conventional SCBA bottle failure while wearing your pack, the bottle contents are the least of your worries. You would be one hurting FF.

I have never heard of a failure during firefighting. A few during filling, but that shouldn't necessarily be much worse than the standard compressed air.

I think that if they can figure out how to do this safely, the time benefits would be dramatic. Maybe we could even see still smaller bottles too.

[Engine58]

Its just another thing to add to the misunderstood job that we do... Ask any person off the street...What do firefighters wear on there backs..they'll say oxygen tanks...like said before its just one of those things they use the name in general

[Engine6SAFD]

12TruckIrons has a very valid point. But unless your department is still using negative pressure SCBAs, you can have some serious problems if you dont have the right seal. Once that air starts letting go, you and your team will be in trouble. And I admit, I stand semi-corrected. Only semi because CFD is only looking at the possibility. But I'm not sure I would want any liquid gas strapped on my back, let alone Liuid O2. I mean liqid O2 is something like 300 times more dense than O2 gas, I think that would be like a bomb on your back.

[Engine6SAFD]

I dont know the author of one of them, it was some website about the Chicago Fire Department, but the other book was "So Others Might Live" it was a general histoy or the FDNY.

[Chris309]

SCBA tanks are filled with filtered, compressed atmospheric air. There is no additional oxygen added at any time. The oxygen content of untreated atmospheric air is generally 21%.

As far as the comments regarding oxygen being 'flammable', it is NOT. Oxygen SUPPORTS COMBUSTION. Oxygen in and of itself is NOT a flammable or combustible element. What happens is any materials that become enriched or soaked in a high enough percentage or concentration of oxygen will ignite and burn faster than normal.

That being said, having an SCBA tank filled with a higher percentage of oxygen would put the user at undue risk for the following reason. Any expelled air from the mask would vent into the atmosphere and potentially soak the user's turnout gear with a high concentration of oxygen. This will severely compromise the inherent flame retardant properties of the gear, and could cause the material to combust. A prime example I remember reading about was a fire in the back of an ambulance a while back. The patient was on oxygen with a non-rebreather mask, and a spark ignited the patients hair, face and nearby linen. The fire ignited and burned rapidly due to the presence of the oxygen.

As far as the comments that filling an SCBA tank with pure oxygen will make it more dangerous than atmospheric air, there may be some truth to that, but the bottom line is that ANY catastrophic failure of an SCBA tank will almost certainly severely injure or kill the wearer.

And incidentally, breathing anything more than the normal 21% of oxygen in atmospheric air is actually quite harmful. Our lungs are already 99% saturated with oxygen breathing normally.

[Adze39]

Originally posted by Engine58
Its just another thing to add to the misunderstood job that we do... Ask any person off the street...What do firefighters wear on there backs..they'll say oxygen tanks...like said before its just one of those things they use the name in general

You are right on the money.

Most people don't know/understand the difference between Oxygen and Air. If you ask these people what they are breathing, they will say "Oxygen", when it only makes up a fifth of what they are actually breathing. They think air and oxygen are the same thing.

[HM604OH]

First of all, some SCBAs do use 100% oxygen. They are called rebreathers and one of the most common is the BioPak. Even though I don't care for them, they have been used for firefighting.

Chicago has used rebreathers for their rescue companies for decades due to the problems associated with the deep tunnel project. The project has created the need for SCBA units with 4-6 hour capabilities. The units used by CFD in the past were the same type used for mine rescues and were stored and maintained at the Fire Academy (built on the site of Mrs. Oleary's barn). I know that these units had many limitations and that the department was looking into other options. That may be the link to NASA.

NASA has done some research on the practical application of LOX for SCBAs. This could be especially valuable for a WMD response where personel would need to spend extended periods of time on supplied air.

[oldman21220]

We had MSA's in 1964 with oxygen bottles, so at least at one point in time they did exist.

[ScottCook]

Originally posted by SamsonFCDES
Crazy as it sounds...
NASAUs knowledge of liquid oxygen technology will form the basis for an evaluation of the feasibility of using liquid oxygen in a new breathing apparatus.

I wonder if they meant liquid air here. Seveal years ago, FireHouse or FireRescue ran a profile of the Kennedy Space Center FD and they used the liquid air packs. And, my former employer used one for a different application way back in the late 80's. If memory serves, they provided about 4 hours of breathing air.

As crazy as it sounds, and I'm not advocating it, but straight O2 in an SCBA would have its advantages:

- In the same size SCBA, you'd have more time. Remember, we breath harder/faster under physical stress because we need the O2, not the nitogen and other stuff in air.

- Consequently as a result of the above, and theoretically, we could make true 30 minute cylinders smaller.

That being said--and some of the divers here could speak more on this than I could, been a long time since I watched fish--I wonder if there would be any benefits to using NitroNox?

[kst9995]

Another county's emergency manager showed me a SCBA that ran off liquified oxygen at a hazmat training. It looked like he was wearing a suit case on his back. It was a pretty neat system. Not only did it give several hours of breathing time but because your air source is liquified and must expand prior to breathing, the SCBA itself also is designed to cool the wearer during use. He said it was or will be certified for firefighting uses in the near future.

[jaybird210]

I can't believe nobody local has caught this:

Fire Commissioner Raymond E. Orozco met with NASA Administrator
Daniel S. Goldin and Marshall Director Porter Bridwell....

Orozco hasn't been commissioner in at least 5 years. Somebody closer to the city give the exact years. Methinks this is a REALLY old bit of news, even if it is true....

I would think there might be something like this for a rebreather or closed-circuit type SCBA.