Be Careful With Propane Tanks

It's good to have a healthy fear of propane tanks, especially when transporting them - such as to and from filling them up.

The last time I got mine filled I had an incident that gave me a bit of a scare. I usually get 2-3 tanks filled at a time. I take them up to Costco where they're very cheap to fill ($10 in Canada) and I do a load of grocery shopping at the same time. On this particular day I got two filled and on my way home I stopped at a bunch of other stores, making the trip home last well over an hour. I was driving a path-finder which has an open cabin all the way to the back where the propane tanks were sitting upright amongst a pile of groceries.

As I came into the home-stretch I could suddenly smell propane. I turned to look back at the tanks and I saw a combination of mist and liquid propane spewing out of one of them (it may well have been over-filled). There's that moment when you realize you've got a big potential problem - heart starts racing and so does the mind - what to do?

Now luckily all of the windows were at least partially open. However my instinct (rightly or not) was to not apply the brakes - since the spark from the break-light filament could possibly ignite the propane gas. Instead I used the hand break to slow down enough to make a left hand turn into an empty parking lot. Without thinking however, I did turn on the left signal light to make the turn, nullifying the decision not to apply the brakes. After coming to a stop, I took the tank out and being a little over-paranoid I put it on the ground about 20 feet away from the car.

On visual inspection of the tank, I could see that the leak wasn't coming out of the valve where you might expect a leak to occur. Instead it was coming out the bottom of the valve assembly where it attaches into the tank. It's not an out of date tank, nor would a normal visual inspection lead you to believe anything was wrong with the tank (such as rust or a loose fitting). Not being sure what to do, and not being able to transport the tank anywhere (where would I take it anyways?) I called the fire department and they came and took the tank away.

So, bottom line - be careful with propane tanks. It's never a good idea to put them in an enclosed space such as the trunk of a car. It doesn't happen often (at least I don't think), but it's not unheard of for cars to blow up from a leaking propane tank in the trunk, killing the occupants. The trunk fills up with gas, the driver applies the breaks and the spark in the filament ignites it. Just because a tank doesn't look old or have any visible signs of a problem, doesn't mean it's guaranteed to be safe.

 

I think in the US it is not lawful to transport full tanks in an enclosed space.

 

Years ago, I used to smoke while getting gas.


I accept danger with open arms.

 

Thanks for the story. BTW, light bulbs are air-tight. Next time this happens to you, go ahead and use your brakes

 

I didn't know that... thanks for the tip!

 

That could happen only if the filament were open to the gas/air mixture. Filaments are in a vacuum inside the bulb, insulated from outside air.

Stopping was a great move anyway because who knows where or what might set that off?

 

No... but the suspense is killing me.

Edit: Sorry, misread your post... thought you had said, "do you know what might have set it off..." with a follow up post.

 

*argon. A vacuum would "pull" the tungsten off the element when it got hot and decrease its life.

 

Curiosity on the question of light bulb spark creating potential led me to google search for the answer. Turns out it's the switches that appear to be the most common source of the spark for gas explosions. I don't know if there are any switches for the lights in the trunks of cars... but best not stick a propane tank in there anyways. Sorry to be 'captain obvious' here...

 

I stand corrected.

 

We routinely fill propane tanks for the mundane purpose of grilling, too - not just brewing. How would one propose to transport a tank back home from the filling location if not inside one's car?

 

I don't think anyone's suggesting not to use your car where you can at least crack the windows, but it's not a good idea to enclose the tanks in the trunk.

 

This looks to be the driver's fault, not necessarily the propane tank. If you are getting propane don't leave it in a car for multiple stops. Get your propane on the way home.

 

I guess maybe if there is some sort of a pin switch that turns on the trunk light when opened, that could possibly spark. That could turn into a bad day.

 

Cool story Andy.

Glad no one was injured.

 

I use a cardboard box that the tank fits snugly into and the rectangular shape of the box keeps it from tilting over. It may slide a little sometimes, but not far. Great story and it's good to be reminded that we can get too comfortable!

 

There is a switch on the brake pedal to activate the brake lights that has a high enough amperage to possibly ignite the propane if it is worn enough to spark. Do not forget the ratio of air to fuel need to meet a minimum point for ignition too.

Over the years manufactures have changed to low amp switches to reduce the risk of electrical fires as vehicles age. There has also been a shift to fuse panels with computer controlled relays built in that reduce the chances of sparks to almost being impossible.

 

Ha! So not getting home fast enough caused my propane tank to leak?

(Scratches head...)

 

Haha. I'm scratchy too

 

Yeah it doesn't sound like the tank overheated and blew out its over pressure valve.

 

OK, by mass the stoichiometric mixture for Propane is about 15.5:1. Assuming a new Pathfinder, EPA interior volume is 157.8 cu ft at .08 # per cu ft. Standard propane tank holds 20 #'s. Assuming 0 ventilation, your mixture once the tank was empty would be 20:12. So there was risk while the tank was leaking if the Pathfinder was air tight. It is not and the risk was minute...almost laughable.

The thing is, you were also carrying around up to 117# of much more dangerous flamable liquid at the same time contained by plastic, synthetic rubber and with a ACTIVE electric pump and electric fuel level sender right there and the wiring connections to them IN THE TANK with the liquid.

Sure, crap happens and propane can leak. But I guarantee you miles driven, that car and the others like it driven by the idiots on the roads were 1000 times more likely to kill you. I would even bet the threat of that total weight 40# metal tank flying up and hitting you was higher than the leaking gas.

Good story, but please understand that the specificity of the mixture required to even create a flash-over is so specific that you need not worry unless you are in a confined space.

Edit: gas is not more volatile, it just has a very wide range of vapor pressure/mixture at which it is flamable...the volume is the main concern.

 

The legal issues surrounding propane transported in an enclosed space will not arise unless something goes wrong .. your insurance company can deny coverage, and even if Joe Jackleg hits you and it's 100% his fault, you might be ticketed.

 

Scratching my head at this weird language you are speaking.

 

Let me describe it like someone described how rotary engines worked...wait, never mind. One involves spinning Doritos and magic combustion fairies, the other involves science, yo.

 

hahahahaha.... makes perfect sense now. It was the magic combustion fairies that did it.

 

Holy flirking schnitt, you went way into the science for this thread!

 

I do not like fear mongering (and I do not believe that was the original poster's intent) so wanted to slap a little science on it. One of the reasons we still have trademarked, proprietary refrigerants in our home and auto AC is because of fear mongering. Folks here in the US (and more commonly in Central and South America) have been replacing R12/R22 with Propane or isobutane for decades. It is safe on a relative level because the volumes are low and the "cabin" large...but there is a 1:100,000,000 chance of a fatal outcome.

LPG and natrual gas (methane) are VERY dangerous in high volumes, confined spaces and with low air movement (even that one can decrease risk without the other two). Neither will find their natural fuel air mix without chance, particularly specific air movement or really bad luck unless fed through a controlled orifice with a control air introduction method. For most people, the natural radiation in sunlight is more dangerous.

 

They are real...ask any rotary owner. The engines only run when certain spells are invoked or the fairies are fed pizza (obligatory Dresden Files reference).

 

I think many of you are WAY overthinking things concerning propane tanks in cars. Everybody is worried about the explosive contents leaking out into an enclosed space... But ignoring the fact that we're driving around with tanks of gasoline under out cars.

Sure, leaks can happen and cause fires... But so can fuel tanks. RDWHAHB (just not while driving with a propane tank in your trunk! lol)

 

Yeah OP, you been skooled!

 

And never intended as such. I fully understand the fear and acknowledge it as real. The source is often ignorance (not stupidity) of were the danger lies.

 

I know. Your post was very good. I was just playing.

 

Well stop that! This is a serious forum about serious issues! Now back to combustion fairies...

 

Regardless of the possibility or otherwise of making a perfectly stoichiometric mixture inside of any specific vehicle, (and regardless of claims of science around the air:fuel ratio), fuels still burn well away from perfect stoichiometric ratios, and there are also secondary concerns around personal well being if you accidentally get a lungful of compressed gas rather than the regular air which we are used to breathing.

It's not too hard to imagine scenarios whilst when driving a few seconds of blackout or even mild disorientation could lead to unfortunate results.

It should also be noted that there is a vast difference between a flammable liquid with a moderate vapour pressure (petrol) and a compressed, liquified gas. If the contents of your gas tank escape, they will not flash to vapour. If the contents of a propane tank escape, they will extremely rapidly turn to gas. As noted above the hazard is not limited to formation of a combustible air/fuel mixture, there are physiological effects to be wary of too.

Whilst I'm not sure that the OP's suggestion of a healthy fear is quite necessary, it never hurts to reinforce the fact that if you are transporting potentially dangerous materials it pays to treat them with respect. Your car manufacturer (Ford Pintos aside) will generally be paying careful attention to the placement of your gas tank to give it protection in case of an accident. They don't know what you are doing with your propane tanks.

 

Why are you referring to the stoichiometric mixture? For an explosion it does not matter if the explosion burnt cleanly. Propane is explosive at a gas/air mixture of between 2.1-9.5%. It does not have to be specifically at the stioch. mixture. And above 9.5% you'd find yourself being asphyxiated.
So once approx 1/4 of a pound has been release in that Explorer you are at risk of an explosion with an adequate ignition source. The risk would be low if good ventilation is in place

 

You don't happen to be an engineer by chance... or at least taken a engineering ethics class in collage?

 

Not quite. Unfortunately I'm an engineer by genetics, rather than by qualification

 

The pinto was an excellent case study... Unfortunately the University considered it to be such a good case study the used it in 3 out of 4 years of professional development / engineering ethics!
...Sorry for the Off Topic

 

I just like the "almost laughable" part.

 

You should write some screen plays! You certainty could of hit the brakes with a small propane leak of 1-2min. Heck you could of even had a smoke!