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Fit_Is_Slo
Fit_Is_Slo Reader
7/29/10 9:35 p.m.

http://www.harborfreight.com/air-vacuum-pump-with-r134a-and-r12-connectors-96677.html you're welcome!

Osterkraut
Osterkraut Dork
7/30/10 9:05 a.m.

So, if I have, say, a Subaru WRX with an AC system that seems a little...weak, will this 12a stuff turn it into a meat locker? Because that would be awesome.

MrJoshua
MrJoshua SuperDork
7/30/10 9:16 a.m.

In reply to Osterkraut:

Oh man, you are missing out! Our WRX has the best AC of any vehicle I've ever owned. On road trips we end up with the Hot/Cold dial just to the left of vertical and the fan speed on 1 to avoid being frozen out. That's with normal factory recommended freon.

Osterkraut
Osterkraut Dork
7/30/10 9:29 a.m.
MrJoshua wrote: In reply to Osterkraut: Oh man, you are missing out! Our WRX has the best AC of any vehicle I've ever owned. On road trips we end up with the Hot/Cold dial just to the left of vertical and the fan speed on 1 to avoid being frozen out. That's with normal factory recommended freon.

Really? I always figured that it was just a weak little AC system... damn, now I fear I may have an issue.

Teh E36 M3
Teh E36 M3 Reader
7/30/10 9:40 a.m.

I had to replace a hose in my wrx a/c last year- you may want to check for a leak. In reply to OP, I purchased an HF vacuum pump posted above and manifold for about $125 total. Worth it. Feel free to borrow if you live in DC area.

blacknblue2
blacknblue2 New Reader
7/30/10 10:12 a.m.

You really don't see the difference in volatility and combustion? As a one time risk manager I can tell you that we looked at the biggest possible disaster. The biggest disaster possible is a gasoline explosion in a car. Very few will survive such an explosion. Ask some people with V12 Jaguars about gasoline fires in the engine compartment. Those people didn't see flash fires such as several ounces of propane create. Add to that the (see MSDS) of 134a pressure/fire.

I guess there could be an existence / uniqueness theorem used to determine who will survive better; a gasoline explosion occupant or a propane fire occupant. The problem would be of real life comparison. For gasoline there are many examples available, even the famous General Motors pickup truck explosions. For the propane in cabin....well we are still waiting for one of the 10 million vehicles to provide the example.

I just have a sneaking suspicion that people that pander the dangers have a financial incentive to do it. Which is the reason I always try to get people to think clearly about the risk/reward. Is the risk really as high as those pushing the danger button? I would say no.

"Some inherent vulnerabilities can never be eliminated fully, nor would the cost and benefit warrant this risk avoidance approach. In most cases, however, it is possible to balance the risk of loss or damage of disclosure against the costs of countermeasures and select a mix that provides adequate protection without excessive cost in dollars or in the efficient flow of information to those who require ready access to it. "

BTW...right now Harbour Freight has a nice vac pump on sale for $80.

MrJoshua wrote: I don't really have a dog in this fight buuuuuut, I see a logical disconnect with saying we have a bunch of gas in the tank so we shouldn't worry about propane in the AC. The difference is, the AC system runs through the interior of the car. AC systems usually leak by the time they are 10 years old and flammable gas leaks in enclosed spaces are a recipe for disaster. Even worse, the reason to change to a new type of gas in the system is if your system is leaking. It is really common in the AC world to just top up a system instead of repairing it. Soooo, the only similar comparison would be to say: I don't worry about propane in my AC because my cars fuel lines run through my passenger compartment and leak a little and that has never caused me any problems before.
MrJoshua
MrJoshua SuperDork
7/30/10 10:52 a.m.
BlacknBlue2 said: Plus ever look at the MSDS sheet on 134a? Take a look where it says, "AUTOIGNITION TEMPERATURE: >750°C " "R-134A is not flammable at ambient temperatures and atmospheric pressure. However, this material will become combustible when mixed with air under pressure and exposed to strong ignition sources."

"mixed with air under pressure and exposed to strong ignition sources" The only place R134a is exposed to pressure is in your AC system. So the only time this could happen is if you got enough air into your system to be a dangerous combination (and no so much that your compressor stops), AND you somehow get a strong ignition source in your AC loop. The likelihood of that is pretty much Zero. Run your fuel lines outside of the passenger compartment (like all cars produced in the last 30 years) and the risk of gasoline lighting in the passenger compartment is almost none. You keep using both of these almost non-existent scenarios to justify putting an easily ignited gas into a possibly leaky system inside of a car. Now if someone with propane knowledge can show me some math proving that 1lb or less propane in the cab of a normal sized vehicle is either impossible to ignite or the cause of such a minor flame that injuries will be minimal or non-existent I will gladly concede.

MrJoshua
MrJoshua SuperDork
7/30/10 12:04 p.m.

This topic really makes me want to propose the idea of testing the explosiveness of propane in AC systems on the Mythbusters forum. I know they are really soft science, but passing the idea on to them might stop this strange urge I have to put a pound of propane in the interior of one of my junk cars and throw matches at it and see what happens.

Hocrest
Hocrest Reader
7/30/10 12:10 p.m.
MrJoshua wrote: ...to put a pound of propane in the interior of one of my junk cars and throw matches at it and see what happens.

DO NOT DO THAT!!!!!!

Unless you video tape it to share with the rest of us

blacknblue2
blacknblue2 New Reader
7/30/10 1:43 p.m.

I guess you don't heat your home with natural gas or as many do out in the countryside....propane? Talk about a lot of stored Btu's, many people have those big tanks with propane coming into their cabin. There is a big difference between chance and probability. There was a guy that recently burned to death at a gas station. It was from his cell phone. Now Snopes.com says it can't happen but it did.

http://www.cbsnews.com/stories/2004/05/14/tech/main617547.shtml

"Firefighters believe the cell phone ignited vapors coming from the car's fuel tank as it was being filled.

It doesn't take much of a charge to ignite gasoline vapors, New Paltz fire chief Patrick Koch told WCBS-AM's Peter Haskell. "Anything, really. Women's nylon stockings when they get out of a vehicle, that can cause a spark, too."

I run Jags and one of their faults is in the emission system, vents in the wings etc. On hot days when the emission system is plugged, you can get into your car and breath very, very heavy fumes of gasoline. Now if you remember physics, gasoline fumes are the dangerous thing, more dangerous than the liquid. You don't get explosion from the fumes because there isn't a car around that is so tight that the fumes can puddle in any great measure.

So if you want to create the perfect scenario such as a mythbuster, you would have to seal the car, create a situation where loss of pressure is allowed and create an ignition force and have no moving air in the car.

On the other hand 134a is a know carcinogenic and I guess it is an acceptable risk to some people and they can assume the risk that it is better to die slowly from a leaking system of 134a. And gets even better if you are a guy because the cancer of choice that it causes is testicular cancer.

Hydrogen is highly flammable over a wide range of concentrations but a hydrogen fueled car is less dangerous than propane or gasoline. So simply because something may have a greater combustion point does not make it a greater risk.

I think you are missing the point of acceptable risk over the ratio of probability.

There are acceptable risks; there are unacceptable risks and then there are people that worry about improbable risk. I just think you are focusing on the improbable risk of propane. It isn't an impossible risk for a fire in the cabin from leaking propane but it is improbable. Neither is it impossible to have a meteorite go through your roof, its just improbable.

http://www.universetoday.com/51647/meteorite-smashes-through-roof-of-doctors-office-video/

It would be fun to watch mythbusters blow up their little dummy. It can be done but it would probably need to be set up as an improbable situation.

well

MrJoshua wrote:

BlacknBlue2 said: Plus ever look at the MSDS sheet on 134a? Take a look where it says, "AUTOIGNITION TEMPERATURE: >750°C " "R-134A is not flammable at ambient temperatures and atmospheric pressure. However, this material will become combustible when mixed with air under pressure and exposed to strong ignition sources."

"mixed with air under pressure and exposed to strong ignition sources" The only place R134a is exposed to pressure is in your AC system. So the only time this could happen is if you got enough air into your system to be a dangerous combination (and no so much that your compressor stops), AND you somehow get a strong ignition source in your AC loop. The likelihood of that is pretty much Zero. Run your fuel lines outside of the passenger compartment (like all cars produced in the last 30 years) and the risk of gasoline lighting in the passenger compartment is almost none. You keep using both of these almost non-existent scenarios to justify putting an easily ignited gas into a possibly leaky system inside of a car. Now if someone with propane knowledge can show me some math proving that 1lb or less propane in the cab of a normal sized vehicle is either impossible to ignite or the cause of such a minor flame that injuries will be minimal or non-existent I will gladly concede.

Osterkraut
Osterkraut Dork
7/30/10 1:45 p.m.
Teh E36 M3 wrote: I had to replace a hose in my wrx a/c last year- you may want to check for a leak. In reply to OP, I purchased an HF vacuum pump posted above and manifold for about $125 total. Worth it. Feel free to borrow if you live in DC area.

No leak. Thought maybe there was, borrowed a pressure gauge, all numbers in the green. AC is just weak.

MrJoshua
MrJoshua SuperDork
7/30/10 2:06 p.m.

In reply to blacknblue2:

You are most likely right that it is an improbable risk. I would argue that it is more probable than the 2 situations you use to justify the risk, but this is the internet and I'm just arguing. Mythbusters would absolutely find a way to blow it up, its what they do! Hopefully though, somewhere in the process you could see if is a probable or improbable risk. Do they put the sulfur stench in the possibly but improbably flammable freon replacements?

pilotbraden
pilotbraden Reader
7/30/10 2:16 p.m.

My gut feeling is that a major leak (losing all of the R12a quickly) would happen on the nose of the car due to a collision. I am planning to use either R12a or propane on my Nissan next week. I will post the results or my obituary.

blacknblue2
blacknblue2 New Reader
7/30/10 8:51 p.m.

Yes, they put something in that smells. It isn't sulphur but other chemicals such as mercaptan, ethyl mercaptan, thiophane, and amyl mercaptan.

Mythbusters did take a shot at propane tank explosion..........

Myth.............

"A person can shoot a propane tank and make it explode.

Myth busted

(Based on a scene in Casino Royale.)

First, the Build Team decided to test whether it was possible to breach a propane tank with Bond’s 9mm handgun. They found that 9mm rounds were not powerful enough to breach the tank, but shotgun shells and .30 caliber rifle rounds were more than enough to pierce the tank. They then fired armor piercing rifle rounds at a tank filled with propane, but could not get the tank to explode. Not even tracer rounds were successful. Finally, the Build Team resorted to extreme measures. They found that the only sure way to make a propane tank explode was to use high explosive or a high powered Gatling gun firing incendiary rounds. The Build Team concluded that Bond (and most people) would not normally have access to such weaponry, busting the myth."

So yep it is what they do, blow things up and they will go the the nth degree to make it happen.

I spent 35 years in construction risk management and a great majority was working for bridge construction companies. Many, many times our team had to overcome someone's preconceived idea of a risk that was improbable. It was as though they heard something one time and it became a cult to them, a quasi religion. Once they realized that yes it was possible but very, very improbable, they would release their preconceived ideas and move forward. I just don't understand why there are people that worry about something that has never happened. Even if it did happen once, one in over 10 million vehicles using AC hydrocarbons should be within any persons normal risk tolerance.

That is really all I was trying to say.

MrJoshua wrote: In reply to blacknblue2: You are most likely right that it is an improbable risk. I would argue that it is more probable than the 2 situations you use to justify the risk, but this is the internet and I'm just arguing. Mythbusters would absolutely find a way to blow it up, its what they do! Hopefully though, somewhere in the process you could see if is a probable or improbable risk. Do they put the sulfur stench in the possibly but improbably flammable freon replacements?
phil8192
phil8192 New Reader
8/4/10 11:26 a.m.

In reply to MrJoshua:

Duracool and other forms of propane have an odorant added, so you'll quickly know if you have a leak at concentrations that are too low to even cause a fire or explosion. R134a has no odorant and breaks down into phosgene gas when exposed to flame. Do you still feel like taking a drag on that cigarette or stogie in your car while you're driving?

pres589
pres589 HalfDork
8/4/10 11:42 a.m.

Saw a video during training for work at a Firestone store of what was supposed to be the cooling system of a car filled with propane and a spark in the interior used to set of a fire. Well, more like an explosion, the car was obliterated.

Gas in the tank is kept in a metal bin, basically, while people do things in car interiors like smoke cigarettes and plug things into the cigarette lighter jack and that sort of thing.

I thought R134a kits were pretty cheap, why are people mucking around with this stuff?

Edit: Found this which talks about the legality (or lack there-of) of this stuff;

http://www.epa.gov/ozone/snap/refrigerants/hc-12a.html

Junkyard_Dog
Junkyard_Dog HalfDork
8/4/10 11:54 a.m.
tuna55 wrote: Folks, I have to charge my AC in the Volvo (1991 940 wagon because the high side fitting leaked) and I also have to convert it from R12.

I thought that car was converted to R-134a. Maybe I'm just running out of working brain cells.

sobe_death
sobe_death Reader
8/5/10 5:51 p.m.

Don't mind me, I'm just posting here for prosperity

MrJoshua
MrJoshua SuperDork
8/5/10 6:38 p.m.

In reply to phil8192:

I don't smoke, so no problem there!

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