Playing devils advocate here, given the small volume, the fact that the pipes are aluminium and not liable to spark when broken, or get very hot due to aluminium's exceptional performance as a heat conducter, I reckon you would have to try pretty hard to get a burn. personally the only way I can see a burn happening, is to have the venting gas discharge directly onto a naked flame or a very hot spark. even if the conditions were perfectly organised, i think you would get a flame at the break, and that would only last a few seconds at the most as the gas would vent pretty quickly.

I also think you can rule out ignition through impact pressure, as there would be so many ways for the pressure of impact of a collision to dissipate that I dont think pressure induced ignition would occur.

I think the biggest danger would be gassing yourself through a leak in the evaporator under your dash, but this would be true regardless of the type of refridgerant.

As far as lpg systems being protected by the engine, this is not always the case as the lpg pump that regulates the pressure to the manifold is usually bolted to the wheel arch or similar in a convenient location as it needs to be connected to the coolant system to stop it from freezing.

It is so very rare for cars to catch fire when you compare it to the accident rate.

The good thing is if you do get a leak and are running it on propane / lpg whatever, everyone knows what the smell is and would recognise it immediately. It sets of this little DANGER bell in everyones mind, and anyone with half a brain will bug out.

Having said all that, the cost of having your gas system recharged is not that prohibitive when you compare it to say a set of tyres, and I will probably continue to use the proper refridgerant should my bloody expensive aircon system require regassing in the near future...

__________________
Regards,

Cade.

2001 100 series Landcruiser
100% Bio, 120,000 Km and counting

We'll you're plum out of luck then, 69roadster, because the whole world is soon going crazy (by your definition). If you read the air con press you would know that DuPont et al, the people that currently make and supply R134a will cease production of it over the coming years due to the environmental harm it is understood to cause.

And guess what they are replacing it with??? Drumroll please... HFO1234yf - a FLAMMABLE refrigerant gas that is highly toxic when combusted.

Uh oh... are you ready to sweat in your next air-conditionerless new car, 69roadster?

Excuse me for having a little fun with you just then, but seriously now, although you are entitled to believe whatever you like your beliefs on the blanket non-feasibility of flammable refrigerants are just plain ridiculous and obviously founded on a complete misunderstanding of the real behaviour and risks of this class of fluid and a complete denial of 20 years of commercial use in the aftermarket with not a single cabin fire EVER.

Unfortunately it's not that simple, sir. If you've ever tried to break a new technology into a market that, up to that point, had been totally monopolised for over 50 years by a cartel of extremely cash-rich multinationals, you'd know that your notion that a superior technology should just get accepted purely on it's merits is uber-idealistic non-sense. Add into that mix a massive black, grey and white propaganda campaign full of "bomb" scare tactics and other specious arguments, and the innovator finds himself facing battle on a very steep and uneven field.

I suggest you think more deeply. Do you know how much car manufacturers pay for R134a? Do you for one minute think it is the same price as it costs in the service market?

Secondly, there are a number of car manufacturers that are ready to go with vehicles running flammable HFO1234yf.

Thirdly, there is at least one vehicle manufacturer who is using hydrocarbons at point of manufacture. I'm not at liberty to divulge their name at this time, but the details are expected to be released in the next 4-8 weeks. They are not a major manufacturer though. It's a specialist vehicle manufacturer.
...I'll await your reply something along the lines of "oh, but it's not a major manufacturer so it doesn't count"...

Finally, you have a golden opportunity right here to prove your point once and for all in a manner that I can never compete with - it's on the public record that hydrocarbons have been around in the auto aftermarket for over 20 years. It's also in peer-reviewed publications that in excess of 20 million car-user-years of hydrocarbon use has gone by up to 2004 (much more since then). All you have to do is show this forum the string of cabin fires (or whatever you think is the massive danger) that have occurred since then and you have won and I am silenced once and for all.

So, you gonna step up or just keep swinging your emotion-charged non-theories?

It takes all kinds to make a world, of that there is no doubt.

You are misguided. If you think the info in your post justifies the use of Propane in an auto A/C system you are mistaken.

H1234yf has not been totally approved yet and there are many hurdles for it go through as far a additional safety measures in the design of the a/c system itself to accommodate the fact that is acknowledged that it is what they call "minimally flammable". I'm talking EPA here. They are the ones ultimately control things. Plus, there are some states in the US that have their own laws that completely prohibit the use of any flammable refrigerant in an automobile. EPA will have to convince those states that H1234yf can be used safely before those states will change their laws.
We'll see.

What is being talked about in this thread is the usage of propane (that is HIGHLY flammable) in an existing a/c system with no additional safety features. This is way, different.

Also, btw, R134 will be manufactured for a long time to come for servicing existing systems as there will be no conversion process from R134 to H1234yf like there is for R12 to R134. There has been no date even talked about from EPA for R134a as far as the cease of production.

Edit:
I didn't mean to come of as an arrogant American by saying that EPA controls things. It's just that we buy so many cars of all makes here. And certainly all manufacturers have to take that into account if they want to ship here. And, I believe most do.

I think you will find the biggest controlling body is not the EPA, not the Government or even automobile unions, but in this particular field it will the largest refridgerant manufacturer - Dupont. it will all come down to which patent they secure next. I firmly beleive the gas the automotive industry adopts will completely depend on dupont's choice of gas system, and any arguements (environmental, safety, toxicity etc just like the old CFC debate) for removal of the old will probably be suited to the selection of the new gas system (if it occurs at all).

__________________
Regards,

Cade.

2001 100 series Landcruiser
100% Bio, 120,000 Km and counting

69roadster,

Since first commercial use as a drop-in replacement for R134a and R12 around 20 years ago, hydrocarbons (the best performance coming from a mix of propane and butane) there have been many theoretical assessments of risk of applying hydrocarbons to motor vehicle air conditioning, both in systems designed for HC's and as a replacement for R12 and R134a.

Your comments and assertions about the flammability are on the same basis as these risk assessments - they are theoretical in nature.

Not surprisingly, the various risk assessments came to very different conclusions, with an almost perfect correlation between the conclusion of the risk assessment and the source of it's funding. One has to wonder why DuPont et al would even fund a risk assessment on a competitors product to begin with.

However, over those 20 years HC's have been used in motor vehicle AC on a scale that is highly significant and to prove with finality whether the product is fit for purpose. The most current (as of 2004) peer reviewed data quantifies that approximately 20 MILLION car-user-years of use of HC's in auto AC had been accumulated up to that point.

As for our company, HyChill hydrocarbon refrigerants are running as I write this in 10% - 15% of ALL cars on the road in Australia.

I think I made a mistake in my last post of making too many points, so here's the million dollar question all on it's own:

Where is the trail of exploded vehicle cabins, injuries and/or dead bodies?

If your theorizing is accurate, it must be evident by now in actual road statistics.

Or is 20+ million car-user-years and 20 years of commercial use not enough for you? Or are HyChill and other HC manufacturers receivers of some supernatural protection from On High for all this time? Or do you still think we need more time? 50 years, 100 perhaps?

John W Clark
Technical Advisor
HyChill

You are right. That is the question. You posted it but didn't provide any answers.
Please provide study results and the details of those studies. Just because you say there are a lot of cars running around out there with it means nothing.

I see. You work for a company that manufactures this stuff. Of course you will defend it and always make it appear that you have won the debate. But, you haven't posted anything in your posts that's any less than a theory than I have.

It's just common sense. Putting a flammable gas in an automotive a/c system where the condenser of that system is at the very front of an automobile, in a very vulnerable place in an impact, is not a good idea.
You can twist this any way you want (and you have done a good job of that) and it doesn't change that fact (sorry, theory).

What are the statistics on car fires caused by flamable refrigerants?
If there are statistics, 69 Roadster, you should be able to provide them that demonstrate cars with flamable refrigerants are a higher risk. If you cant because there are no statistics, its because there is no noteworthy risk.
Knowing the dificulty of getting gas to ignite. (having a few LPG powered cars in my life) getting the stuff to ignite on a regular basis can be difficult, even with a spark plug and high voltage coils.
To get the gas to leak (easy), in the right ratio to ignite (it has about a 4% range of air:gas ratio to be flamable, very hard), followed by a spark at the right time.... If you can find ONE instance of a fire starting from refrigerant I would be surprised. I think the only time it would catch fire is if a fire is already established.

__________________
cheers
Chris.
1990 landcruiser 80, 1HD-T two tank, copper pipe HE+ 20 plate FPHE, toyota solenoids and filters. 1978 300D, elsbett one tank system. 1979 300D veg oil/ diesel blend for now.

In terms of flamability R134 burns too just at a higher temp and the byproduct is very nasty, I would prefer propane any day. I fully agree with the issue regarding big business, they have far too much sway and any system will be designed around the one they want, since they have the patent and the science and the money to put into it why shouldn't it? Well R12, R134 are very good reasons, one not as bad as the other to not belive any big company.

Just like biodiesel and the specifications here in Oz, the bar is set higher than that of the mineral fuel. Its all lopsided and truth suffers always.

I have not heard of issues with car fires and statistics lie just as well as any spin doctor makes them.

It is outside the cabin too so risk of frontal accident far outways the risk of 250 grams of gas.

I appreciate your position, I just believe that some big organisations cannot be trusted, sure there is risk, manage it and live with it, you do every day getting out of bed.

__________________
Biodiesel Bandit

Landcruiser 98 B100 (100,000km and still going)
Peugeot 306 xtdt B100
Peugeot 2004 2L 307 HDI Does not like B100

Unless I have mistaken your challenge to me, you are asking me to provide studies showing that something (in this case, HC incidents) doesn't exist.

Such a request is a logical nonsense. No one can conclusively prove that something DOESNT exist. Please think your request through and reconsider.

On the contrary, the burden of proof with such questions must always run the other way - those that contend there is a safety defect trend must demonstrate that trend.

By all means have another go at suggesting by what means I should be required to prove the product is safe. I'm all ears.

The fluorocarbon industry keeps an eagle eye out for each and every hydrocarbon related incident. Every single incident even remotely related to hydrocarbons have been printed up in fluorocarbon industry propaganda outlets, without exception, across the entire history of debate. They even went nuts about one incident in New Zealand until the authorities announced it was an R134a fire.

For what it's worth, please consider this advice: Most assertions made by everyone carry some degree of vested interest or inherent bias. The way you carry on about my (clearly declared) vested interest and your implication that everything I say should be discounted would require that you must discount basically everything that is said and discussed on a daily basis (if you're going to be consistent). On the contrary, one of the best ways to separate truth from error is to seek information from both sides of the fence and identify what statements are commonly agreed upon, either implicitly or explicitly. That common ground has a much higher likelihood of being accurate. In this particular case you will find that both sides agree (my side explicitly, their side implicitly) that there are only a handful of HC-related incidents over 20 years, and the incident reports for those incidents make it quite clear that gross negligence is to blame rather than the product being unfit for purpose. This is a reasonably reliable process for truth discovery and the conclusions should be obvious.

I don't have any problem at all listing here on this forum every single HC-related incident that we are aware of. It is a very short list. Just say the word and I'll do it.

But I suspect that won't be enough for you because you will naturally reject my list out-of-hand because I have a vested interest. If that's the case, just say the word and I'll send you the contact details of any of a number of fluorocarbon propaganda organisations and you can ask them. Be my guest. They'll give you the same list complete with a whole lot of spin to misdirect that facts of each case. But most of the spin is pretty easy to see through. But wait a minute - you'll have to reject everything they say too, otherwise you'll be guilty of inconsistency, won't you?

Your final comment amounts to a suggestion that the 'precautionary principal' should be applied in this case. That line may have worked back in the early days before use was widespread and there was no real-world safety history to refer to. But those days are long gone. Any reasonable person should be willing to accept that 20 years of usage is a long enough period to reveal trends.

At root, your conclusion (in my analysis) is based upon on an incomplete and inexperienced understanding of the product compounded by an insufficiently detailed analysis of risks. You fail to even recognise that there are considerably more hazardous fluids located in prominent locations in the front half of the engine bay, instead you talk like having a flammable substance in the engine bay like it is something new to motor cars. That's all OK though. You're entitled to your opinion. It's your jumping on this forum and throwing around black-and-white simplistic analysis that I take issue with.

Of course I have a vested interest in the argument. However, the record shows I've fully identified myself and thereby declared my interest from the beginning. By the substance of your posts it seems plausible that you have more than just a passing awareness of AC systems and the AC industry, and yet you haven't even provided one jot of identifying information. Some readers of this thread might legitimately wonder what your connections to this subject are.

With respect, produce the evidence supporting your theories. If you still insist there is some way (other than proving the non-existence of something) that I can assist with demonstrating this then spell it out to me.

John Clark
Technical Advisor
HyChill

I have worked at a number of repair shops, and car fires are very rare, But I would say the number one non dileabrate cause would be parking in dry grass, the catalytic converter is very hot and can set stuff on fire very quickly, wiring faults and lose battery would be next, kids sticking coins or foil in the cigarette lighter, Plastic air filter also go up in older cars it they not fitted correctly or the car backfires, which can happen on lpg cars. I have also seen fuel lines drop off or leak, and a bic lighter which found its way into the heater core. the owner said it was like a shot gun going off but it didn't ignite. It maybe possible for the air con pump to run out of oil and get very hot and leak (which Ive seen) and maybe ignite the lpg, but its pretty unlikely and it such small amount of gas anyway. I would be more worried about the misses pulling of to the side of the road and parking in the grass to answer her phone, or the can of lawn mower petrol in the boot.