Explosive Mix

[Das_Boot]

I read on another post that there is a formula for the ignition point of butane/propane relative to the parts per cubic meter of the gas.

Intuitivly I cannot see a small bottle of gas, (1 litre) discharging completley into a 40ft boat, reaching that point.

I have no science to back it up. Does anyone think that if I left the gas cannister in the cabin and it did discharge completley would it explode if I lit a cigarette.

 

[tome]

Easy Answer

Why don't you try it? /forums/images/graemlins/smile.gif

 

[Das_Boot]

Re: Easy Answer

I dont smoke. I will order one of my crew to go first. It would also just waste a gas cannister. they cost about £1 or £2.

 

[Danny_Labrador]

Its called the Explosion Triangle - graphic explaination of infinite combinations of fuel/oxygen/heat that will lead to explosion - its possible I guess as the gas would be heavy. Search internet for more info.

 

[tome]

Re: Easy Answer

Now you're getting the hang of this skippering business!

Regards

 

[Das_Boot]

If the gas was heavier than air it would sink to the lowest part of the boat which would be the bilge. Even my bilge holds vastly more volumn than the depreasurised gas cannister. What I am trying to find out is would it ignite and cause damage. My intuition tells me it wont however I dont want to rely on intuition.

 

[iangrant]

A good test is the sniff test - lay down on the cabin floor and sniff hard for about 10 mins, If you're still awake then have a lighted match handy, you'll know when the mix is right.

Ian

 

[Das_Boot]

Have you not heard of science. I am trying to get the facts not wierd tests I can think of a hundred of them. What about having a hamster in the bilge you can rig a bell to his tredmill so as long as you hear the bell you know you are safe. I mean you could just start the engine and wait for the kaboom.
Wouldnt it be better to work it out using science/maths.

 

[ShipsWoofy]

It would be better not to empty gas into the bilge wouldn't you say.

 

[Das_Boot]

I should think so. I am talking about accidental leakage.
I have to go on worst case scenario which is the whole 1 litre cannister leaking into the boat.

 

[davel]

Why not train the hamster to make cups of tea. So long as the hamster is alive and well and living in the bilge (ie no gas) you get a cup of tea in the morning, however if the tea doesn't arrive you know you're in grave danger and should immediately flee the boat.

Coffee could be used as a substitute for tea if required.

 

[Rowana]

Start here -

http://www.ilpi.com/msds/ref/flammablelimits.html

 

[iangrant]

Basic science fact:

Gas in bilge/boat anywhere you don't want it = very very bad

How much needed to go bang:
Not very much

Resultant damage:
No corpse left to offend anyone, no lid on boat

Suggested proceedure:
Buy and fit a gas alarm

Cease worry about gas mix, stop feeding hampster.


Ian

 

[Rowana]

What you also have to remember is that 1 litre canister at whatever pressure it's at, makes a hell of a lot more volume at atmospheric pressure.

I believe that the LEL for propane/butane is somewhere around 2%

Try googling on "Lord trenchard" to see the results of a gas leakage.

 

[Sybarite]

Butane and propane are non-toxic at least for humans.

John

 

[Das_Boot]

At what Parts per million will the gas alarm go off is it worth it for such a small cannister?
Thanks I will have to look it up.
I do not trust gas or hampsters nor will my corpse be offensive as I hope it wont be given the time.
I have tried employing a few hampsters thus trying to uplift their sorry plight but their noncompliance even to basic instructions precludes them from any future plans I might have.

 

[DavidTocher]

A Camping Gaz C270 cartridge contains 220gms of butane. The formula for butane is C4H10 and the molecular weight of butane is 58. Assuming the ideal gas laws 58gm of butane will occupy 22.4 litres at standard conditions. A quick bit of arithmetic indicates that a C270 cartridge, when vapourised, will fill a space of about 1000 litres or one cubic meter. If the explosive lower limit for butane is about 2% then a C270 will fill 50 cu meters with an explosive mixture. A boat with that internal volume below the waterline will displace 50 tonnes of water. One C270 could blow up a very large boat.

The danger in a boat is that a very small amount of gas in a confined space will easily reach the explove limit.

 

[jimboaw]

I wonder if government security agencies (or terrorists) are following this thread? If your door gets broken down at 3am you will know---

 

[Das_Boot]

It is an eye opener thanks for the reply. It is realy counter intuitive to believe such a small amount of gas could be so dangerous.
You would think the nany state would ban gas on board boats.
Mine is going overboard.

 

[Das_Boot]

I see your location is in Naples Florida. Is it realy that bad in America are you not allowed to mention the word explosive. What other words are you not allowed to say. Give us a list.