Choose Fire Extinguish Agent

Holy euthanasia, Batman!!

This is like asking whether you should shoot yourself in the head with a .30-.30 or a .30-06. You and fire both need oxygen. Deprive a fire (substitute "you" anytime you want) of oxygen and it dies.

Is this really a confined space as in permit required? Are you at all familiar with occupational safety; if not, please immediately hire a professional.

Hello TVP45!

Clarifying:

1. I don´t want to kill anyone, me included...!

2. I´m aware of the chemistry of fire and the biological effects, thanks...!

3. I`m really not thinking on install this device at home...!

4. The preview post did not answer anything...!

5. The question stills waiting for technical contributes...!

Respectfully!

Just zapped that OT.

I thought your post was right on target!

Both gasses will successfully smother the fire and neither gas is toxic. But nitrogen has a hidden safety hazard factor compared to carbon dioxide. Since most of our air is nitrogen, we will breath a pure nitrogen atmosphere without showing any distress. So people breathing pure nitrogen will not react to the lack of oxygen. They'll continue to breath this gas until they pass out and smother themselves. Carbon dioxide is the waste gas that our lungs are trying to expel. So a person breathing just a higher than normal level of carbon dioxide will immediately notice the bad air and flee. So even though neither gas is toxic, carbon dioxide is the safer fire extinguisher.

Hello redfred!

Thanks for your post!

I´m aware of the hidden potential of nitrogen...and carbon dioxide...!

But, concerning the awareness of exposures to atmospheres with high concentration of these gases:

- Victims may not be aware of asphyxiation for both gases...!

So, it´s not really correct to say carbon dioxide is the safer fire extinguish agent only looking to this propertie!

Nevertheless this issue it´s not the main question!

Respectfully!

lmsr, as you state, both gases are noxious in sufficient quantity to suffocate.

BUT in most cases carbon dioxide at 'normal' temperatures and pressure, does not exist in a liquid state.

So it has the better fire quenching property because it converts from a solid state to a gaseous state right upon release into the atmosphere and thus it has the highest cooling content of the gases....

So CO2 and N both suffocate the fire the same but CO2 also removes heat the quickest as well and is therefore a better choice for fire extinguishing...

I stand to be corrected about this but I'm sure its why most fire extinguishers (gas) are filled with CO2

Hello Electroman!

It´s true. Carbon dioxide at "normal' temperatures and pressure, does not exist in a liquid state"... as nitrogen!

Concerning the cooling effect, discharge a gas from high pressure to low pressure, make/have the cooling effect, it´s true for both gases.

Nevertheless the intent effect is flushing not cooling.

Respectfully!

The main benefit of using liquid CO2 is not so much it's cooling ability as it is the larger amount of CO2 that can be stored in a given volume. A liquid is much denser than a gas is, and CO2 is much easier to store as a liquid than is nitrogen.

I have to disagree with you electroman, CO2 has little or no cooling effect.

From a fixed CO2 installation the CO2 comes out as a solid at -78,50C, but changes straight into a gas (sublimation)..............also check the specific heat capacity of CO2, this is why a high pressurise fog system is better.

You misunderstand my post. The body does not make a cognitive or thinking difference in a response between these two gasses. Pure nitrogen will go in and out of the lungs on every breath like it was normal air. Inhaling pure CO2 will cause an immediate gasping for breath. Your body recognizes this atmosphere will lead to death.

You are looking at it backwards.

It is not the amount of inert that kills you it is lack of Oxygen. Normal air is around 20% O2 and 80% N2 once Oxygen drops below 16% you are in big problems the inert is of no consequence. As the fire is consuming oxygen and producing CO2 the O2 level is going down.

It makes no difference which you choose. One factor that many seem to ignore in a fire is the concept of heat of reaction, endothermic and exothermic. When using a dry powder (messy but effective) the heat of reaction is also absorbed by the chemical reaction of breaking down the Sodium Carbonate as well as the release of carbon dioxide. This is a chemical endothermic action.

If you use a fine water spray - finer the better - you also get rid of the energy in vaporisation of water and the formation of steam-another very good inert gas! In the chemical industry I have found that water fog is the most efficient method - I have it on good authority but no practical experience that fog is effective on electrical fire as is is a poor conductor. This is heat removal by energy transfer.

Foam seems to be a favorite but in the chemical industry it cuts off the O2 but insulates the burning mass and in the case of an exothermic reaction & where no outside oxygen is not used for combustion cannot work.

Fog is by far the best - all you need is a high pressure pump (800psi +) and it does not have to be very big one - very efficient. Any one considered using a sodium carbonate solution? It would use up the energy and leave an exothermic material behind on the burning mass.

Halon 1301. Look it up.

Hello lynlynch!

Thanks for your post!

But, the main issue is understand which are the technical variables take into account when choosing between nitrogen and carbon dioxide!

Not choose "one" fire extinguish agent...!

Respectfully!

Hi lynlynch,

All Halogenated Hydrocarbons have been on the prescribed gas list for years, they are CFCs and civilised countries have banned them (also along with CFC refrigerants).

The only area BCF (bromochlorodifluoromethane) extinguishers can be used is in aircraft cabins.........and that's because it is such a good extinguishing agent..........it was used in the military until a couple of years ago.

Hi Mobi,

Does this mean the USA is not civilized?

If you have halon systems currently installed in your company facilities and they are located in the United States, you need to know the following facts:

• You are under no legal obligation to remove systems from service.
• There is no federal legal requirement to remove systems from service by any specific date.
• You may legally recharge your system in the event of a discharge
• Recycled agent is still commonly available for fire system recharge.
• No new agent 1301 is being manufactured
• You should plan the replacement of your systems with a halon alternative.

Cheers!

Hi lynlynch,

...............if the cap fits!!!!!!

I agree that the halogenated hydrocarbons are probably the the best extinguishing agents we have ever had.............and, I think that Australian governments have had the wool pulled over their eyes by minority groups of tree huggers..............you know CFC's and all that. I have always felt that the vast majority of pollution of the ozone layer by CFC's are from refrigerants R12 (Freon) etc, from automotive air conditioning units and domestic refrigerators and freezers (this was when they were used in Australia.........and are still used in many places throughout the world, including the US of A)...........here they now all use 134a..........an HFC (I use LPG)...............interesting to note that these "new refrigerants" (HFC's) have zero ODP............but 1500-3000 times GWP that of CO2..........and if that makes sense...........I am confused.

I think between Redfred and Electroman you have enough to go on for portable devices. Our Fire Co. does not use N, and I have seen only one other company that even had an N bottle. CO² is effective in resuscitation because it triggers a breathing response, (panting) in anyone exposed to higher than normal levels. CO2 is only approved for flammable liquids and electrical fires.

For a Halon alternative in a fixed location, Primex Aerospace FS-0140 is used in confined/inaccessible spaces. Most effective in aircraft.

Or get up with your local County Fire Control official.

A cautionary note.

Those of you who advise CO₂ is OK in a confined space might want to actually try this. It's an interesting experience - make darn sure you have somebody with a respirator who can come in and pull you out. OSHA will pound the living daylights out of you for using CO₂ in a confined space.

Nitrogen is almost as bad, except you won't die gasping and clawing at the door like you will with CO₂.

People really do die all the time from these two atmospheres. Read LynLynch's post. Use Halon.

OK!

It could be Halon! It might be Halon!

But Halon 1301 is a ODS - (Ozone Depletion Substance) with a ODP - (Ozone Depletion Potential) of 11 (means 11 times higher than CFC 11)...!

By the Montreal Protocol it´s not the way...!

Again, the main issue is understand which are the technical variables take into account when choosing between nitrogen and carbon dioxide!

Not choose "one" fire extinguish agent...!

Simplify: I only have nitrogen and carbon dioxide, technically how can i choose?

OK, OK, so you're gonna use one or the other.

So, first, both create toxic atmospheres and you had better be using permit-entry. If you are not using permit-entry, you're playing Russian roulette, screw the Montreal protocol.

If you're using a permit, you monitor the atmosphere and have a non-entry standby person (who, even though they are not gonna enter, still have a respirator or SCBA).

Under those circumstances, go with what your permit compliance officer says (most likely CO₂). If you don't have a permit compliance officer, stay out!

Good luck to you. I've known of close to ten people that have died in confined spaces due to taking it too lightly.

Halon and similar products should only be used for small fires and then only after consulting a fire engineer - not some one who sells them.

The choice of the correct installation will depend upon what you are trying to protect. It appears that due to the responses wrt halon that minds are blocked to portables. In this case the best choice is dry powder - messy but effective in the office environment or CO2. Both are OK for small fires and probably the safest and best for the amateur. Make sure that you have a small hose with a spray nozzle handy to cool and protect until the fire brigade gets there. This does not apply to electrical fires in the home or office use the dry powder or CO2 there.

Factories with fire potential should have sprinkler systems.

With the exclusion of Halon 1301 and of the selection of replacements available for use in normally occupied areas/compartments Nitrogen (FE-13) or Carbon Dioxide are most suitable.

Flushing action is not descriptive of the fire extinguishing agents FE-13 nor CO2, such use of either would be counterproductive and destroy sensitive instrumentation including electronic hardware.

When used appropriately as in place fire extinguishing agents in gaseous form with proper precaution towards personnel in effect warnings including audible alarm, secure power, emergency lighting and announcement, training in use of breathing devices.

When observing all of the above FE-13 is the better of the two.

Hello Bwire!

Thanks for your post, but if i have to choose "one" fire extinguish agent i will not choose FE - 13 because there is a much better choice - "Inergen"...!

The main issue is understand which are the technical variables take into account when choosing between nitrogen and carbon dioxide!

Not choose "one" fire extinguish agent...!

TVP45, a responsible technician/expert does not ignores the rules, accepts then as a challenge!

Concerning the procedures, i agree with you, but this is a issue that i have to think after, now it´s choosing between nitrogen and carbon dioxide!

HarryBurt your post is a very good hint trying to solve the main question...!

Respectfully!

I apologize for seeming blase about environmental rules. I'm a certified tree-hugger from way back. But, when I have to balance human life vs another hole in the ozone layer, bye-bye ozone. There is a straightforward way to satisfy both concerns and I'm afraid I didn't clarify that. Use entry only by permit and follow all the permit regs. See, for example,

http://www.osha.gov/dep/etools/eprcs/prcsappendices.pdf as a starting point.

Check for updates. Since I no longer work around toxic gases, I don't keep up to date.

You have broken your own rule introducing an agent other than the two in question.

The best and safest in regard to personnel and equipment is Halon when introduced appropriately creates zero ozone depletion potential. In a system where ventilation and power are secured at the onset of fire and prior to Halon release then evacuation of all gases allowing recycling of the Halon and proper handling of the toxic and or corrosive gases produced by the fire, most Halon in use today is recycled.

Inergen by definition is a mediocre fire suppression agent, can not be described as an extinguishing agent and is extremely detrimental in regards to personnel within a confined space due to characteristic which are merely alluded to with consideration of gases introduced from combustion.

Hi everyone!

I appreciate all the answers/posts, that´s the real meaning of forum!

We are allways learning!

But once more, the main issue is understand which are the technical variables take into account when choosing between nitrogen and carbon dioxide!

Not choose "one" fire extinguish agent...!

Perhaps no body ask why the great majority of fire extinguisher use carbon dioxide!

Simplify: I only have nitrogen and carbon dioxide, technically how can i choose?

All the best!

Keeping to the sole choice of N₂ and CO₂, I would like to add a follow on to my earlier comment about the gag reflex that CO₂ naturally produces. This natural response can significantly simplify what is required for a "safe" system. Think of the scenario of a leak or accidental release of each smothering agent. Since this will be an accidental discharge there need not be any triggered alarms, smoke, loud "whoosh" of gas or necessarily any known condition. So, since either gas can kill an unsuspecting occupant something must be done to prevent death. This will involve adding an Oxygen deficiency hazard (ODH) sensor system. But since N₂ does not produce a gag response, the ODH will be the only indicator of danger. So this ODH system must be fabricated to a high safety reliability level that may require backup power. I do recommend including using an ODH for CO₂ but since this gas does produce a gag reflex the safety level for ODH detection will be less complicated.

It does not really matter they are both inert and so reduce the oxygen . Are you concerned with a large space or just a hand held extinguisher condition. When push come to shove it is price per cu meter that will matter.

CO2 is heavier and takes longer to expand and may freeze up the expansion chamber. N2 allows a more controlled release.

There's your answer for the technical variables crack a book.

You have overused the term," technical variables" to the point that I'm thinking you are trying to sell this concept to someone else.

It's in almost every post of yours. Your choices are Ni and Co2 so, pick one and live or die with it. It will come down to COST anyway.

Go fish.

Hi lynlynch!

Clarifying:

1. I`m not a salesman...!

2. I`m not a fisherman...!

3. To decide normally could be a question of "live or die" not live only "with it"...!

4. If i want a "coffee talk", without annoying "tecnical variables" i don´t waste my time here, i will prefer to use HI5, MSN or other...!

5. Nobody oblige you to say anything...!

6. If you can not be able to answer nobody will argue with you, ok!

Respectfully!

I am tending towards agreeing with lynlynch.

You seem to be 'guiding' this discussion for some reason and you are not contributing to it in any meaningful manner.

There. Fixed that dumb "off-topic" vote. You are spot on. I don't know what the OP is angling for. Portugal has confined space entry regs. Is he trying to avoid them? Does he not know them? Is he a troll?

I'm going to assume that this is an occupied space?? I'm not sure if it's nomally occupied or occupied only in particular situations (periodic maintenance?). If so, you may be able to (depending on local code requirements) build in an alarm/delay to the system that will allow for reponse by the occupants. Depending on the nature of of the space/work performed you might consider:

- "escape bottles" small SCBAs that would allow them to escape the atmosphere created by the extinguishing agent.

- Immediate evacuation.

Hi Imsr,

Can I just say this as you have some good answers already.

PRICE really should not be a factor in your choice at all!

You need a very specific fire retardant/extinguisher, and whatever the cost it must be fitted .................. Simple as that.

Carbon Dioxide is my choice.

Take care and good luck.

Even though lmsr did ask for advice on CO2 or N2 for his fire suppression, Halon 1301 is hands down the best fire putter outer ever; it doesn't smother it, it just makes fire not work. Plus you can breathe it long enough to exit the space after its release. The dangerous side product gas from using it comes after its exposure to the fire/heated materials. Too bad possible death from cancer from above is worse than immeditate death from fire. One other thing, you try to use non-damaging/easy cleanup fire extinquishing agents for electrical fires. True the fire will cause damage, but water will ruin what the fire did not; that's why CO2 is used. Dry power (e.g., PKP) will work but causes a hell of a mess in the equipment.

Please don't even mention using water on an electrical fire...!!!!!

For obvious reasons.....

High pressure fog (1000psi) is not the same as a water jet! and the cooling effect with the production of an inert atmosphere is very effective - steam does not conduct electricity - if you are in a chemical factory then it is the best thing and firefighters do not have the time to worry about where the electricity is or if it is functioning although it would be advisable to cut all power.

I started my romance with fire suppression as a hose handler then after experience and study advanced to fire team leader and in due course to fire team section leader.

Our primary was fire and damage control of shipboard boiler rooms and associated machine spaces. I can assure you the boiler rooms were equivalent to 15000-25000 sq/ft. In these occupied spaces Halon and CO2 systems were installed and the power terminations were outside of the space.

In the above scenario a fire team may encounter pitch dark, fuel oil smoke filled compartments with fire from above and below open catwalks and flaming bilge sloshing onto them as the ship founders in the sea. Getting that fire out is paramount, Halon will do that as the fire teams perform a salt water cool down an yes there is steam created then preventing reigniting/spontaneous combustion.

It irks me that someone could prevent lifesaving fire safety systems being employed and substitute mediocre systems instead due some politically correct mandate based upon an assumption.

In the OP's situation I would suggest employing both CO2 and Nitrogen installed systems.

Please see the following link as to why nitrogen is a poor choice, in addition to the excellent reason that it is a suffocating agent and undetectable by smell or other body responses.

Incidentally, CO₂ systems incorporate mechanically actuated warning bells to alert personnel that gas is being released. Also, I think the latent heat of sublimation or evaporation of CO₂ is greater than any effect of expanding nitrogen gas, and thus helps more to cool the area.

http://wiki.answers.com/Q/Can_Nitrogen_be_used_as_fire_extinguisher

I think setting up mechanically actuated bells is within our abilities and having a backup system ready to go after the bells have sounded but the CO2 system fails can't be a bad idea.

I don't know what you've heard or read but the cooling effects of an installed CO2 fire suppression system are minimal for the fuel source categories described by the OP.

I'm with you 100% in that the thermal effect is minor here, but others have mentioned it, and to that extent it looks like a bit of advantage for CO₂. The bell I described is a standard feature, so far as I know. It is actuated by the flow of CO₂ through the piping system, so it works even in the event of power failure. That said, in a noisy engine room environment, the bell might not be heard. The body's response to excessive CO₂ levels is a second level of defense, absent in the case of nitrogen. (Take a breath in a controlled-atmosphere fruit storage room, and you're flat on your butt within seconds.)

The new alternatives to Halon 1301 might also be promising, but for whatever unknown reason, the OP has restricted the options to carbon dioxide and nitrogen.

I prefer a klaxon to bells and yeper I've experienced a light-headedness when I quickly opened a shipping container filled with potatoes and stepped inside

for whatever unknown reason, the OP has restricted the options to carbon dioxide and nitrogen.

Could be it's not for fire suppression We never know

When plants are still living, they convert carbon dioxide to oxygen. But when you harvest them, they turn into animals and convert oxygen to carbon dioxide. (Yes, this is a bit facetious, but not far off the mark.) Specifics may vary, but this conversion basically burns off sugars and degrades the quality of the fruit or vegetable in question. UC Davis has good Web info on desirable storage atmospheres for various products, in addition to being prominent in oenology. Sorry, off topic. (Maybe--after all, some topics are reasonably related to other topics.)

Re fixed installations.............an audible and visual alarm is required in Australia and in marine applications............both should be able to be heard and seen from anywhere in the space, even above the noise of running machinery. This occurs on a detector (thermal, smoke, etc) sensing a fire and in an automatic system there will be a delay, usually long enough to completely close the space down and for personnel to vacate the space.

In a fully manned situation the fixed installation should be on manual control...........the fire can then be assessed to see if it can be extinguished by conventional means, e.g. extinguishers, fire hoses etc.........if this is not possible, or deemed dangerous, once the space has been closed down, head count taken, etc. the fixed installation is manually operated.............it is carried out this way because a small fire in an enclosed space can produce very large volumes of smoke..........of course breathing apparatus is required

NOTE:- .............for those who continually refer to the cooling effects of CO².................please, please, forget it...........CO² has little or no cooling in fire fighting.

Thanks, and we had covered the subject well in previous conversation so I didn't reiterate.

I have been in a space having breathing apparatus when it were necessary to deploy Halon to protect human life. It was quite helpful to have the fire out while using fog and water to then cool the heated surfaces to prevent reigniting.

The danger to personnel when using Halon without breathing apparatus is of course inhalation of the heated gas but one would only need hold their breath for one minute after release of the Halon to prevent such, good to know if presented with the scenario.

Hi everyone!

I'm concerned with a large space (ship/marine applications) not just a hand held extinguisher condition.

It's a normally occupied space.

It will have a buid up fire alarm, acustic and visual that only actuates after operator order.

It will not work by "cooling" but by "flushing".

Before follow the rules and legal procedures, including breathing apparatus, the main question still`s:

- I only have nitrogen and carbon dioxide, technically how can i choose?

All the best!

By doing your own research on the attributes of theses two gasses. (I hope you've done some additional research other than just asking us.) Consult with others you trust on their opinions about your choices. (You've certainly done that here. But you might want to find somebody that you know has done this before.) Tabulate the pros and cons for each gas. Now use that gelatinous grey matter that resides behind your eyeballs and choose.

If you don't think that you are qualified to make this choice, then discuss your lack of credentials with whomever gave you this task. But, you cannot abdicate your decision to us.

This site it´s supose to be:

"CR4 – The Engineer`s Place for News and Discussion"...!

Clarified.

Thank you for nothing!

"There are 2 types of people. People who know and people that go around"

He so much wanted to shit but only farted...

Just one other problem that you may face on large vessels is the time it takes to close down the space before activation of the fixed installation, using CO₂ or N...........when you consider that a B Class fire can double its size every 11 seconds........this is not something one really wants.

Can you explain why you only have the choice of CO₂ or N..........this just seems ironic to me that if one puts safety of the crew and vessel, below the cost of fitting a proven, better fixed installation in the machinery space, i.e. high pressure fog, then I am afraid I would be offering my services elsewhere. High pressure fog that can be used as soon as the alarm is sounded, before personnel clear the space.......it may also allow crew to don breathing apparatus and fight the fire by conventional means without the fire getting out of control.

By the way Imsr is it a Flag of Convenience vessel you work on?

What a load of rubbish -

Best of luck to you all.

Bye

Call up your local welding supply house, and they will give you some current prices on cylinders of nitrogen and carbon dioxide. Ask for how many SCF they hold (since that is what each gas will expand to). CO₂ taxes might ding you for about $15/ton, but that won't make any difference. The self-alarming aspect of CO₂ is one of the most salient technical details you need to know, and yet you ungratefully fail to acknowledge this point--instead asking for some other mysterious "technical reason." And then you insult "redfred", whose contributions have been excellent.

No wonder your other goofy post on this was quickly hammered.

Thank You Sir. I am honored.

The regulations of whichever governing classification body (ABS, Lloyd's, etc.) may dictate the choice agent, and may also give (and require) calculations.

Hi Tornado,

Yes, I am aware of that fact, and as far as I am know all major Classification Societies have approved the high pressure mist/fog systems.