Exploding caravan

I reckon you might be right there Kimba. Anyway as others have said, fortunately the occupants & surrounding park tenants were not injured.
A bit scary though!
That was an interesting comment as well about the Vietnam Vets who were not woken by the sound of the blast. Just goes to show what those poor buggers were exposed to in serving for our country. Cheers

Barry,
Some of them slept thru 13 rounds of mortars at " The Horshoe" FSB in Vietnam in 1970.
Jim

hi all
i have always had serious doubts about the way caravan manufactures have designed the front bootson there vans
(all with the focus of the owner having a secure from criminals -boot to lock stuff in)

imho to wrongly store and hold electrical chargers and batterys and fuel containers and gas bottles in some instances and i wonder how the relevant authorities can allow such designed vans to be registered and passed as safe in the first place something is amiss with these organisations including insurance companies????????????????
regardless of the type of battery sealed or others batties and chargers should not be in the same compartment
() under a car bonnet is different as there is a lot of air off the fan passing through to expell any such gases

chargers have relays and switch gear that can give off a spark enough to set of an explosiion and i have personelly over the years seen 3 batterys explosions when the hydrogen gas was triggered by a spark and its powerfull stuff
no i did'nt cause the problems but was lucky enough in each case to be far enough away not to get injured
and yes like bantam says it congregates in the upper areas of a cavity or enclosure and is not visible
cheers

When we had our centre mount ski boat (for those who dont know this is a boat with the motor mounted roughly in the centre of the hull) generally most of these have a hatch/hood/cover what ever you like to call it, over the motor to protect from noise,burns, and generally a good family boat allowing for rear seating etc and normally not really that fast. First thing i did when we bought ours was put in 3 12V computer fans, when I turned the key the motor wouldnt even turn over for the first roughly 8 seconds (relay controlled), 2 of the fans would be sucking air out from the hood compartment while the 3rd was sucking in fresh air (didnt really need the 3rd fan) but was just to ventilate the hatch compartment before there was any big spark from the contacts from the starter motor JUST INCASE there were any fumes trapped under the hood. It wasnt a common thing to happen but had seen it happen before when my old man use to race/ski boats etc and he always use to tilt the lid back for a few seconds before he hit the key, Like this for eg.......
http://www.dailyexaminer.com.au/story/2012/01/30/fire-risk-boaties/

Comments like that really STINK! LOL

Two batteries in the front boot,both unscathed.
Jim

I think your on to something there Kevin.......Battery might have got overcharged and the gas has gone KABooooom!

Hi Bantam. I am extremely interested in what you are saying. I have two 9kg LP gas bottles in my boot along with a 2KV generator. There is also an AGM battery under the lounge seat on the RH side of my van. What sort and size of ventilation would you suggest. At present there is only a 20mm drain hole in the front boot. Thanks,Bob.

If your AGM battery is a sealed gel type, then it shouldn't explode or leak gases.....

Here is Bantam's ventilation test.

If you where locked in and farted in the space in question, how quickly with the smell disipate.

If its not nearly as quickly as in open air its not quick enough.

I'd like to say I am shocked.....but I'm not.

The manufacturers and sellers of many of these vans must be completely ignorant of the risks.
They are all too keen to pander to the desire to have everything hidden away.

The gass bottles should not be in there at all.

If you turned up at CIG or Airliquid to fill or exchange bottles, they would not let you drive out their gate with any gas bottle in any enclosed space

Gas bottles should be mounted where there is free and open ventilation and that means big holes as a minimum...big as ya head...better still on the drawbar.

What is realy concerning is you have LPG and petrol stored in the same compartment......the flamable liquids guys are realy concerned about this combination, it has been implicated in some serious accidents involving spontanious ignition.

NOW
consider that LPG cylinders are the fuel of choice for improvised explosives in many areas of the middle east.
A 9KG LPG bottle contains a very large amount of fuel and leaks must be expected.

Put bluntly gas bottles should not be enclosed at all.

Now the generator...it contains fuel......there is a reason you petrol tank is mounted outside the pasenger compartment of your car...in the past many cars had the fuel tank mounted inside the boot....fair enough it was vented and filled outside the car...but I doubt you will find a car with a fuel tank mounted inside the boot these days.......does that tell you something.

If you open the boot on ya caravan and you smell petrol fumes at all....you are dragging a bomb arround.......all it needs is a source of ignition.

Again we are talking free flowing ventilation....it may require forced ventilation from a bilge blower or such

The problem is that this has not been thaught about in the design....where else is there to put it.........OH BTW where do you carry your fuel supplies?

It is illegal to carry petrol in jerries mounted on the rear of a vehicle.

NOW to the battery.
Unfortunately many people labour under the misconception that AGM batteries are completly sealed......they are not and cant be.
But people persist in mounting them in unsuitable places.

However the risk here is much lower than the other two.
ALL batteries can vent explosive fumes, even AGM if it is run at high temperatures and or overcharged...for some AGM 45C is above its recommended operating temperature.

But the fuems from AGM should be in small amounts.

SO it should be vented to outside air..a slotted vent at the bottom and the top of the space may be sufficient.

This whole management of flamables in caravanning and 4wding is something that is taken far too lightly and does not get given anywhere near enough thaught.

cheers

G'day Bantam

Thanks for both your contributions. We all (or at least the less practical or less scientifically minded amongst us) rely on manufacturers and dealers to keep us out of trouble, and it's good to be remined of the sorts of things we should be thinking about.

Cheers
John

Bantam, you commented "It is illegal to carry petrol in jerries mounted on the rear of a vehicle".
So how do these 4wds pass a roadworthy with the jerry can holder mounted on the rear bar like a lot do. Most manufacturers made a rear bar with spare wheel holder and jerry can holder on the back.
My 80 series passed its roadworthy with a jerry can sitting in the holder.
I have been pulled over numerous times for breath test and random checks and never had it questioned.

Josh

Their for carrying Diesel.
Dave.

The presence of the jerry can holder is not an issue because it could be used for carrying water or diesel ( Dieseil is " combustable" not " highly flamable").

The fact that somebody passes a roadworthy or for that matter a machinery inspection with a noncompliance is no proof that anything it is in fact legal.
Faults an noncompliances get overlooked every day.

If you are to carry jerry cans containing dangerous goods of the catagory of petrol, they must be outside of the peasenger compartment or other enclosed space but within the outer profile of the vehicle and adequately protected....

if you want detals chase up the dangerous goods standards and legeslation.

Most of the jerry can holders on the rear of vehicles are completely unprotected and outside the bumper line...therefor illegal for carrying petrol.

It is possible to carry dangerous goods on the rear of a vehicle, IF it is inside the bumper line, but satisfying the "adequate protection" requirement makes it very difficult indeed.

cheers

Yep, that's what I said. Only In 4 words. :)
Dave.

In response to a similar discussion on another forum, a member recounted an in the face hydrogen explosion on a machine he was working on.

the battery was mounted fairly open, but was enclosed on 3 sides and there was a sort of hood above.
The hydrogen gas had gathered in the space under the overhead hood, a spark from the charger clip and kaboom

No damage, no marks not even missing eyebrows, just a pounding heart, a mild ring in the ears and a need to change his underwear.

That is a thing to be aware of, because hydrogen is lighter than air, it will gather under overhangs and it the upper parts of spaces.

If it were not lighter than air, the space may be too big to get the right air fuel ratio.......but because the hydrogen will gather in the upper part and it has a such a wide viable air fuel ratio it will tend to be explosive in much smaller amounts and in larger spaces that would otherwise expected.

SO
If ventilating for hydrogen make sure the upper vents are at the very top of the space.

cheers

I always remember an episode in a small-country town garage in the 1960's. Harold was a very good mechanic and very orderly, and he had a small room built inside the garage where he kept and charged batteries.
A farmer client brought in a flat battery to be tested and charged if O.K.

The farmer returned late in the day to pick up his battery. He said - "How's my battery going, Harold?"

Harold replied, "It's still going! I reckon it's 2/3rds of the way to the Moon by now!!" [:-)

Poor old Harold had gone into the battery room to check on the battery, and had created a spark with an alligator clip as it was removed. The room was full of hydrogen due to a "gassy" battery, unbeknowns to Harold, and the room exploded - along with the battery! It blew the fibro-asbestos wall out of the room.

Poor old Harold got a hell of a fright, and it made the message of hydrogen gassing in confined spaces, a real one to him. Surprisingly, he'd been in business many years up to that point, and had never had a hydrogen explosion before, despite charging serious numbers of batteries. It appears the battery conditions have to be just right, to get a "gassy" battery.

Cheers - Ron.

I have seen connections inside these front compartments, where say two lines join into one, also have seen the flexi pipe from the bottle run into these compartments and then have a T connection, one for gas hot water systems the other for the stove, if this connection was leaking which would let the gas sit inside the compartment, then if you have battery set up with inbuilt charger, fuses, relays etc, light, then enough gas with a spark, kboom.................

Yes you could be right about the gas lines but a gas explosion almost always results in fire or at least scorch marks - not evident - so i believe it was hydrogen from the battery same bang but much lower combustion temperature therefore no fire or scorch marks
Hydrogen explodes at far less consentrations therefore less fuel to cause a fire
Kev

Thanks Kev, new batteries were dangerous but didnt know the exact facts. Learn some thing new every day....Cheers...........

But in order for the hydrogen to vent from the top its volume must be replaced by air entering from the bottom. Hence the need for vents at both top and bottom.

Absolutely.

Both top & bottom venting is a necessity.

Remember, hot air doesn't rise!

It's displaced upwards by denser cold air.

Bit like a brick in a bucket of water.

Cheers

Phil