Gas explosion

[SteveA]

I've just attended a demonstration where half a kilo of gas(propane) was put into a structure, a bit like a 20' container, in a stoicheiometric mixture and then ignited - what a shock. We were about 100yards a way and the blast force was astonishing - it has made me think that a diesel or spirit stove would be a better idea rather than our present gas cooker.
I reckon that if more people saw this demo there would be a big decline in gas on board.

<hr width=100% size=1>

 

[VirgoVoyager]

Steve

That must have been quite a sight! The destructive effect of such an explosion on one's beloved craft would be pretty devastating. This is the reason why boats registered on our canal system have to pass a stringent gas system survey. If you read the guidelines produced by British Waterways, they make eminent good sense and we should all be following these. A good example of bad practice is the frequency with which "use by" dates on gas hosing are ignored - I recently came across an installation on a yacht where the hose was dated "1981"!! Nuff sed!

The application of common sense and good practice will make any gas installation completely safe. You also have to balance any slight risk against those associated with paraffin or alcohol which alos have their dangers if not used correctly.

Stuart

<hr width=100% size=1>

 

[Jean]

Have you also seen the effects of a similar test using ordinary baking floor (airborne), for example? This too can be quite dramatic when it is in a closed vessel!

<hr width=100% size=1>

 

[Dave1258]

I made a similar posting over on MoBo, imagine being fast asleep on your boat in the Marina moored stern on shoulder to shoulder at peak times.... when next door goes BANG!!.
A 20' gap minimum twixt craft is a safety margin to consider, after all we all carry gas for cooking/heating needs.

<hr width=100% size=1>Someday my ship will come in, and with my luck I'll be at the airport!!

 

[graham]

Seeing the demo would at least make people a bit more carefull.Perhaps we should lobby the RYA to produce a video.

Most of the gas explosions I have read about occured after a small leak built up unnoticed over several hours.

The simple routine of switching off at the bottle regulator unless actually using gas would have saved many vessels and lives over the years.

Gas explosions on boats dont occur often but are so devastating when they do you cant afford to be complacent.

<hr width=100% size=1>

 

[qsiv]

Thats why I'm soo glad to be all electric on the current boat. The new race boat will have an alchohol cooker, as I still dont want gas (and who's going to cook on it anyway!). A 12V kettle will answer the more important needs!

<hr width=100% size=1>

 

[Fill]

There's similar not so obvious hazards too.

When getting ready to go ashore and using the spray deodorant (or perhaps the rest of the crew have just complained) check the propellant on the aerosol.

The propellant is usually a happy mixture of butane and propane. Making a really good (if highly dangerous) blowtorch, or simply putting a load of inflammable gas in the bilge for you.

We saw the blowtorch effect demonstrated at a firefighting course when the demonstrator got a very respectable gout of flame from a standard deodorant.

<hr width=100% size=1>Fill

 

[Omatako]

We have a routine of turning the gas off at a valve in the gas locker and allowing the flame to die as it exhausts the gas suppy in the line. That as well as properly functioning thermocouples on the cooker burners does it for us. We have never heard the gas alarm.

Interesting about aerosols, as it happens we don't use them but I wonder if the volume generated by normal use is enough to be a practical problem?

<hr width=100% size=1>

 

[SteveA]

After seeing that demo leaving 20' between craft wouldn't make any difference - it would probably need to be more like 200'!
I think a video would be a good idea; if anyone from the RYA would like to take this on I could give them the contacts.

<hr width=100% size=1>

 

[Twister_Ken]

A kettle will take care of the pot noodles, but how are you going to warm-up the Mars Bars?

<hr width=100% size=1><A target="_blank" HREF=http://www.writeforweb.com/twister1>Let's Twist Again</A>

 

[poter]

I am just about to put a new gas system into Shady & having inspected the old I was shocked to see that the hose is circa 1987, well past renew date.

I will be installing an all rubber gas hose system (no copper...more joints to leak)with a new govenor AND most importantly new accessable 1/4 turn gas valves, one by the cooker one by the heater & one back in the locker.

It should be noted that most households have some form of gas useage and the instances of gas explosion are very, very, rare, a lot less than oil heater fires.
gas is as safe as any fossil fuel and only requires sensible use to keep it that way. I am of the opinion that if you can cut down on the number of joints you go a long way to minimise risk, but it also makes great sense to isolate at the source ie the bottle, when not in use.

You are quite right to raise the issue, but the only way to improve safety is education, & getting a video showing a gas explosion is not the way, Imho
The building industry brought in a draconian set of health & safety measures along with compulsory risk assesments, and guess what... the death rate has hardly changed, yes there has been a decline in accidents but all H&S officers now agree that constant education will be the only way to reduce risk. This also applies to any sport/hobby that has a certain amount of risk attached & the RYA should raise awareness to risk through education.

Gas cooking is a very small risk & we are much more likely to be knocked down by speeding MB's following cross channel ferries. (see MBO forum) on thier first trip to "France". (Nahhh!!! can't be!)

poter



<hr width=100% size=1>

 

[chriscallender]

"I will be installing an all rubber gas hose system (no copper...more joints to leak)with a new govenor AND most importantly new accessable 1/4 turn gas valves, one by the cooker one by the heater & one back in the locker."


Unfortunately the boat safety scheme says that "flexible hoses should be of the minimum possible length, and at any rate not exceeding 1metre" or something like that. I agree with your commonsense approach, however I had to remove a setup nearly indentical to what you described and replace it with copper and more joints in order to get insurance.

Although I did take the opportunity to fit a bubble leak detector and a remote solenoid at the same time. Doesn't make a lot of sense to me but there we go. It had to be done anyway.

Chris

<hr width=100% size=1>

 

[claymore]

And what's the point of having an alcohol cooker - we'd only drink it

<hr width=100% size=1>regards
Claymore
/forums/images/icons/smile.gif

 

[poter]

Chris I understand why you installed copper, but where is the reg to say that its mandatory? I would be very interested.

Maybe a corgi reg installer is out there & can tell us why???

poter.

<hr width=100% size=1>

 

[halcyon]

You should see a wooden boat that has had a gas explosion, sides flat on ground, deck scattered around. The owner was finally found walking back from the chandlers. wondering what the bang was.


Brian

<hr width=100% size=1>

 

[l'escargot]

There is a good guide <A target="_blank" HREF=http://www.calormarineshop.co.uk/installation/you_the_gas_installer.htm>here</A>

<hr width=100% size=1>

 

[Tai_Lam]

As a mining engineering undergraduate I was involved in a similar demonstration at ICI Ardeer. What is not often appreciated is that coal mines are ventilated not to allow men to breath, but to remove heat from oxidising coal and to ensure the volume of gas seeping from the coal is never allowed to reach the explosive limits of between 4% & 15% of the air volume. Get this wrong and you ruin everyone's day!

In a marine context a properly installed and maintained installation should present only a small risk. However if using gas I would have the fewest number of joints in the system and fit detectors. If the system develops a leak, it will only take a few cubic feet of gas to make the atmosphere explosive.

<hr width=100% size=1>

 

[qsiv]

Don't be daft - just place against the hull, and the heat generated by skin friction will have them warmed up nicely.

<hr width=100% size=1>

 

[chas]

In a previous incarnation, I worked for an LPG company in the early days of butane powered aerosols. There was a lovely story about a wife cleaning a loo with a butane powered aerosol product. Later, husband wandered in to respond to a call of nature (a sitting one) with a fag in his mouth. He threw the fag end into the loo and the resulting explosion did quite a lot of damage!

<hr width=100% size=1>

 

[extravert]

I thought there already was a demo video. I certainly saw one when I did my yachtmaster shore based about 8 years ago.

<hr width=100% size=1>One day, I hope to own a real boat.