Question about fire on a sub

[frau kaleun]

Actually this is a question about something that happened in the movie "Below," where some dudes got burned up. So it's sort of a technical question about something that might (?) happen on a sub.

If you have not seen the movie it's about a US sub in the Atlantic during WWII (supposedly they used a Gato-class for filming if that matters), everything else is irrelevant except for the fact that at one point they have been submerged for a very long time. So they are getting low on oxygen and worried about not just the CO2 content in the air but judging by the dialogue and the gauges they keep looking at, the hydrogen content as well?

Anyhoo during this time the rudder controls become inexplicably stuck and in their attempts to force the issue they completely destroy the big wheel or whatever that they would normally use to steer the boat. So the chief says they will access it by cutting into the line somewhere aft, in proximity to some other things that raise concern about the possibility (I assume) of fire breaking out due to sparks (?) but the chief says it will be a "hydraulic" job with no welding, or something to that effect.

The chief and most of the remaining crew go aft and all the hatches are sealed as a precaution while he and a couple guys get to work. They cut the line and are, I presume, fixing the problem when all the lights go out. Somebody says he knows why (I can't remember the reason) and goes to fix whatever that is. Meanwhile someone in the next compartment opens the separating hatch and starts complaining about them being in the dark and the chief yells at him to close the hatch. It cuts to a scene, I think, of some wires or something starting to glow, presumably because the guy who went to get the lights back on reconnected something or flipped a switch.

Then it cuts to the control room where the officers are talking and the lights flicker. Then they start trying to raise the crew who went aft on the "intercom" but nobody answers. They go check the control room hatch and it's warm. So they open it and go back to find everyone aft all burned up.

So here's my question: I get that when the one guy did whatever he did to get the lights back on, it heated something up or threw a spark and there was some kind of flash fire aft that killed everybody back there, obviously it burned hot and fast enough to do that and then just die out because nothing appears to still be burning when the officers go back to check it out. At first I thought that the guy who opened the hatch caused it by opening the hatch, but it's not like there was anything different in the air in any other part of the boat, it was all "bad" so that doesn't seem to be relevant except that it put more of the boat at risk if there was a fire. Anyway, what exactly happened? Was it the fact that the hydrogen content was so high that started the fire? Was it the combination of that in close proximity to whatever it was they were worried about in the location where they were working (I think they were close to the batteries, I'm not sure)?

I didn't realize that hydrogen was an issue on submarines of that era, I've never heard it mentioned with u-boats - only oxygen vs. CO2. If nothing else watching that movie has made me more interested in getting to know the "insides" of the US subs, because I don't have the layout in my head and that made it very disconcerting watching the movie. I kinda felt the way I did when I first watched Das Boot and could tell by the context that something happening was bad, but didn't know all the technical details of why.

[Aramike]

Perhaps it has something to do with the chlorine gas dangers present from the batteries? Could hydrogen chloride be created?

Excellent query.

[Weiss Pinguin]

I remember reading about the accident on the USS Cochino, involving built up hydrogen gas I believe But IIRC the Cochino was testing out her snorkel.

And IIRC there was a supernatural dealio going on inside the USS Tigershark

[Takeda Shingen]

I know that hydrogen peroxide, responsible for the Kursk disaster, was used as torpedo fuel starting in the 1940's, but I am not sure if it was used during the war outside of fuel for Walther plants.

[bookworm_020]

Originally Posted by Takeda Shingen

I know that hydrogen peroxide, responsible for the Kursk disaster, was used as torpedo fuel starting in the 1940's, but I am not sure if it was used during the war outside of fuel for Walther plants.

The Royal Navy found out to their cost how dangerous hydrogen peroxide is

http://en.wikipedia.org/wiki/HMS_Sidon_%28P259%29

[CaptainMattJ.]

perhaps somebody took a very big, long fart and the spark made it catch on fire? gas leak ftl!

[Diopos]

WWII submarine batteries were of the "lead -acid" type I think. In normal operation (as power sources) there is no hydrogen issue,
BUT
in re-charging mode ,if the voltage applied is not properly controlled, it may function as an electrolytic cell (water electrolysis) and produce hydrogen.

.

[Kazuaki Shimazaki II]

Originally Posted by frau kaleun

I didn't realize that hydrogen was an issue on submarines of that era, I've never heard it mentioned with u-boats - only oxygen vs. CO2. If nothing else watching that movie has made me more interested in getting to know the "insides" of the US subs, because I don't have the layout in my head and that made it very disconcerting watching the movie. I kinda felt the way I did when I first watched Das Boot and could tell by the context that something happening was bad, but didn't know all the technical details of why.

Here are the Soviet Navy's comments about hydrogen concentrations, as written out in P.50 of their 1967 Spravochnik Vakhtennogo Ofitsera (Watch Officer's Guide) by Pronichkin A.P. et al and as translated by W.B Cramer:

3. Controlling Hydrogen Concentration
Under no circumstances should the hydrogen concentration in the battery tanks and battry ventilation tubes exceed 3%.

A hydrogen concentration in the atmosphere in excess of 4% (by volume) constitutes a dangerous explosive mixture of great destructive force, which could easily be ignited not only by an open flame, but also by a highly incandescent object or a spark of any origin.

The maximum hydrogen concentration in submarine compartments should not exceed 2.5%. The hydrogen content in the battery compartments during charging, with normal battery ventilation, should be practically zero. The hydrogen concentration in the battery tanks and battery ventilation tubes, as well as the battery compartments if the hydrogen oxidation instruments are not operating, should be controlled using hydrogen measuring instruments. The hydrogen concentration in the compartments using hydrogen oxidation insturments is controlled by thermometer readings on the test instrument.

[frau kaleun]

Well I want to say that they were trying to cut into the rudder line in the battery compartments, because I'm pretty sure it was the location of the job to be done that brought up the concerns about hydrogen. There was a gauge that they kept looking at which showed the concentration, at one point the alarm for it went off and the needle was in the red zone, and the chief just turned the alarm off because there was nothing they could do about it. He checked that gauge before starting the job on the rudder line as well, and I'm pretty sure it was in the same compartment where they were working. I think he'd told the CO that hydrogen concentration was up to 17% at that point. Given how little was actually working on the boat, whatever was supposed to be keeping the hydrogen in check with regard to the batteries probably wasn't working either.

The scene of what happened just before everybody burnt up was of the one guy doing whatever he was doing to get the lights back on, and then a quick shot of what looked like a wire or tube glowing as it heated up. I'm assuming that this was another malfunction because why would anyone make that happen deliberately given the situation? Or maybe the guy opening the hatch from another compartment at just the wrong moment actually did figure into it somehow.

I did read that "hydrogen gas forms explosive mixtures... with chlorine in the range 5–95%. The mixtures spontaneously detonate by spark, heat or sunlight" but I don't remember them mentioning anything about chlorine being an issue at that point in the movie. And in fact I was kinda waiting for that, because I know chlorine leaking from batteries on a submarine is A Very Bad Thing.

[ETR3(SS)]

Ah submarine batteries, one of two things on the boat that was referred to as "the bomb." I haven't seen this movie but after this am quite interested in it. Now on to batteries, hydrogen, and you! As was mentioned earlier when the batteries on a submarine are being charged they give off hydrogen gas. It is extremely important to control the hydrogen levels in the boat as 4% becomes combustible and 8% becomes explosive. Any source of heat will cause the hydrogen to ignite. There was a US submarine (who's name escapes me atm) that had a battery fire at sea and had to be abandoned.

So to answer the question posed this would have been a fire as a result of hydrogen buildup. However at 17% concentration in an enclosed space it would have exploded and tore a hole into the boat.

[Jimbuna]

Originally Posted by ETR3(SS)

Ah submarine batteries, one of two things on the boat that was referred to as "the bomb." I haven't seen this movie but after this am quite interested in it. Now on to batteries, hydrogen, and you! As was mentioned earlier when the batteries on a submarine are being charged they give off hydrogen gas. It is extremely important to control the hydrogen levels in the boat as 4% becomes combustible and 8% becomes explosive. Any source of heat will cause the hydrogen to ignite. There was a US submarine (who's name escapes me atm) that had a battery fire at sea and had to be abandoned.

So to answer the question posed this would have been a fire as a result of hydrogen buildup. However at 17% concentration in an enclosed space it would have exploded and tore a hole into the boat.

One hell of an excellent answer....one I would never be able to better

I'll post this to support the above

Hydrogen gas (dihydrogen or molecular hydrogen)[10] is highly flammable and will burn in air at a very wide range of concentrations between 4% and 75% by volume.[11] The enthalpy of combustion for hydrogen is −286 kJ/mol:[12]
2 H2(g) + O2(g) → 2 H2O(l) + 572 kJ (286 kJ/mol)[note 1] Hydrogen gas forms explosive mixtures with air in the concentration range 4–74% (volume per cent of hydrogen in air) and with chlorine in the range 5–95%. The mixtures spontaneously detonate by spark, heat or sunlight. The hydrogen autoignition temperature, the temperature of spontaneous ignition in air, is 500 °C (932 °F).[13] Pure hydrogen-oxygen flames emit ultraviolet light and are nearly invisible to the naked eye, as illustrated by the faint plume of the Space Shuttle main engine compared to the highly visible plume of a Space Shuttle Solid Rocket Booster. The detection of a burning hydrogen leak may require a flame detector; such leaks can be very dangerous. The destruction of the Hindenburg airship was an infamous example of hydrogen combustion; the cause is debated, but the visible flames were the result of combustible materials in the ship's skin.[14] Because hydrogen is buoyant in air, hydrogen flames tend to ascend rapidly and cause less damage than hydrocarbon fires. Two-thirds of the Hindenburg passengers survived the fire, and many deaths were instead the result of falls or burning diesel fuel.[15]
H2 reacts with every oxidizing element. Hydrogen can react spontaneously and violently at room temperature with chlorine and fluorine to form the corresponding hydrogen halides, hydrogen chloride and hydrogen fluoride, which are also potentially dangerous acids.[16]

http://en.wikipedia.org/wiki/Hydrogen

[Bubblehead Nuke]

Ok.. lets nuke this out:

To have a prolonged fire you must have fuel and air.

*IF* they had a hydrogen explosion, they then had a flash fire that would have quickly consumed all the available oxygen in the compartment. Once all the oxygen was consumed then fire would have gone out. Depending on how long and how hot the fire was, you may have smoldering insulation and other combustable materials. This is a reflash BEGGING to happen.

Lets say they got lucky and it did not catch anything else on fire and they just had a flash fire and snuffed itself due to lack of oxygen. When they opened the hatch they would find people dead due to the heat and burns as well as people dead due to a lack of oxygen.

About the 'rudder failure'. Well, that would have been handled simply by isolation of the hydraulic pressure( read: close a valve) and take manual control of the rudder spool valve and position the rudder in local control mode. Unfortunately, this would have made for a very short movie.

For the sake of argument, lets presume that this boat has an ignorant crew or a piss poor design. *IF* you cut into a pressurized hydraulic line you are going to get a fine mist that comes out. Think of it was a fuel injector on your car. You are going to get a nice mix of a flammable vapor in a large amout of air. Add a high heat source (glowing wire or hot sparks from a grinder) and you have that common occurance call combustion. Just like a car engine.

Again you are going to quickly consume all the availabe oxygen in the air and the fire will snuff itself out and you will find bodies bunt and dead or just dead.

A fire on a boat is a BADDDDD thing. Next to flooding it was our most trained on thing.

[Rockstar]

Lead acid batteries do 'gas' when being charged producing a hydrogen gas by-product. This hydrogen gas is lighter than the air around you so it will accumulate in the overhead nooks and cranny's of the compartment. Securing the charger may have not been enough. They should have exchanged the compartment atmosphere as per IAW before firing up the cutting torch.

Unfortunetely when that someone, sans qualified electrician, flicked the switch without checking the circuit he caused one big bang. Hollywood did the rest.

[frau kaleun]

See, that's part of what confused me - that whatever happened was bad enough to burn up everyone aft behind the hatch that stayed sealed, but the only indication of a problem on the other side of that hatch was the lights flickering. Nobody in the control even seemed to notice that - they didn't catch on that there was a problem until they couldn't raise anyone else on the ship and realized the hatch was warm. Then they go aft and of course it was dark, but the only indication that there had been a fire or explosion was that everyone aft was dead or dying. Just seemed hard to believe that something that bad could happen on a submerged sub and the people on the other side of a hatch wouldn't feel or hear something, much less that there wouldn't be more obvious, if not critical, damage to the sub itself and not just the crew in those compartments.

Really it was the only part of the story where I kinda went "huh?" because even though I could easily suss out what the script said must've happened, it just seemed odd even knowing that, okay, clearly they haven't aired out the boat in a long time, stuff is probably leaking out from all kinds of equipment, and oh no something got hot and they made a point of showing it getting hot. Then there's a flicker of the lights forward and a warm hatch and everybody aft is dead and... that's it? Even if it's a completely realistic scenario, I don't think it was spelled out clearly enough for the casual viewer who wouldn't necessarily know enough to put it all together.

Of course the casual viewer would probably just accept that something bad happened and now all these guys are dead, and not wonder about where the hydrogen was coming from, lol.

[ETR3(SS)]

Well look on the bright side, if this were a modern hollywood movie there would be an overly exaggerated thermonuclear explosion that threatened to wipe California off the map...and that would have been the entire movie.