Posted From: 22.214.171.124
|Posted on Friday, 07 November, 2014 - 11:29: |
I have never subscribe to conspiracy theories or the big corporate companies doing bad stuff to earn more profit.
I am confused.
I have been studying aircon for certification.
And of course it includes refrigerants. There are many different types and virtually any fluid can be used and has an R number even water has an R number. Nearly all the Rs that are suitable for cars are either chlorine based or petrol based.
Obviously the mention of propane and the Hindenburg airship syndrome comes into play. A story that regularly does the rounds is that a Canadian family was killed by an exploding fridge and of cars in head on collision exploding in a ball of propane refrigerant. Then there is a story about a fridge engineer who was smoking an blew himself up.
My tutor who is Polish disputes these stories as bull do do. He has been using propane for 30 years and back home in Poland everybody does the same. He has seen lots of broken car condensers but no fires or explosions.
He told me the first day that hydrocarbon refrigerants are much better than cfc or hfc or yf. He also said that du Pont know this and have continually encouraged the explosion stories so that they can make an expensive refrigerant that by law is the only one to use. And that all of the post 134a formulations contain usually butane as a oil carrier. Instead of just saying use good quality nice and cheap butane or propane du Pont is insisting that chlorine must be added, so they can inflate the price 10 fold.
He has also worked in India where cooking propane and lpg are regularly used because the Indians think chlorine is far more dangerous and expensive to use in leaky old systems.
He worked with an Indian guy who used a match to find propane leaks. All that happens is a small flame like a gas lighter which goes out with a wet finger.
I took the du Pont bit with a pinch of salt. But now having completed the boys scouts version of air conditioning certification and found out what nasty stuff R12 and 134a is, and the complete lack of creditable explosion stories then I must wonder why du Pont and the USA EPA take such a stance. Fortunately the UK and Europe has not been convinced by the stories and Daimeler Benz has been testing stuff and are leaning towards a propane butane mix aka lpg.
Incidently a cigarette is not hot enough to light propane. And what idiot smokes while using propane that is not going to be burnt. When I hear stories like this I question the truth because while it is possible to blow yourself up with propane one would have to be very unlucky or stupid.
Is du pont guilty of profit instead of the best product for the job.
(Message approved by david_gore)
Post Number: 690
|Posted on Saturday, 08 November, 2014 - 21:37: |
Large leaks of LPG are definitely dangerous. A couple of years ago I was camping with my car club when a nearby camper, not associated with us, made a silly mistake. He was screwing a new gas canister onto his Camping Gaz stove too close to a lit BBQ. On these stoves the canister is a single use item without a valve. The valve is on the stove unit and it pierces the top of the canister to let the gas out. He had forgotten to wind back the combined valve and piercing pin so that as he fixed the canister in place it vented a large cloud of gas which was ignited by the barbie's coals.
He was burned quite badly, although we kept the worst at bay by continually dousing him with cold water until the ambulance arrived. Parts of the fire must have been very intense as it even set the grass on fire!
I'm not certain that air con refilling is yet a DIY proposition even with the kits available today, although they are based on 'real' refrigerant rather than LPG.
Posted From: 126.96.36.199
|Posted on Sunday, 09 November, 2014 - 05:29: |
Silly thing to do. I have never liked the pierce cans, once pierced there's no valve apart from the device valve.
None of the diy air con kits are any good because the system has not been sucked and there's no way to know how much gas is in the system. Using low side pressure is not a good way because on some systems there's a suction throttling valve which varies low side pressure, how would one know it's adjusted right plus how much oil? Plus if a system has a static pressure of say 3 bar and the system has not been sucked then a third of the gas is air. This will kipper the compressor eventually. Also some top up diy cans have a sealer in them.
Unless a vacuum pump is available one cannot diy aircon.
The amount of hc gas for a Shadow is about 750 grams or a litre of lpg. A litre of lpg has about the same amount of energy as a litre of petrol. If it is released quickly then ignited a dangerous fireball will result.
However a car aircon system is robustly made with proper engineered connections. And as we all know cars don't burst into flames when smashed up.
On the other hand we all know stupid people. Trouble with stupid people is that they are not stupid, they just don't think.
Many years ago a mate who is a very clever electronics guy poured a very small amount of petrol on to a fire that was alight. Not realizing the fumes in the tin would flash. The tin flew up wards and came down round instead of square. He knew straight away what had happened. Apart from no eyebrows he was uninjured. Egg cup amount petrol.
There have been fridge explosion caused by r600 butane leaking into the ice box which is air tight and igniting via a thermostat spark. Fortunately cars aren't air tight and the evaporator has a drain.
(Message approved by david_gore)
Post Number: 692
|Posted on Sunday, 09 November, 2014 - 09:17: |
I like the disposable ones with the screw thread. They cost the usual assortment of body parts considering the quantity of gas in them, but it's possible to half fill them from a cheap £ shop fag lighter gas canister. You can get around 3 half fills from each!
Posted From: 188.8.131.52
|Posted on Sunday, 09 November, 2014 - 10:47: |
I use taymar gas for my general blow lamp stuff and lighter fuel for the mini blow lamp/soldering iron and calor propane in the big burner should I feel a need to tarmac the drive.
While I was sucking a car aircon out I thought that the customer is paying for a vacuum which has nothing in it. So the customer is paying for nothing and I am being paid for nothing.
If I could invent a can of vacuum then I could sell cans of nothing to diy air conditioners.
(Message approved by david_gore)
Post Number: 329
|Posted on Friday, 05 December, 2014 - 05:42: |
some local attorneys made a big case when their client sued his apartment owner after he was burned by a window air conditioner: someone had charged it with propane and it sprang an evaporator leak and spewed flames. Ouch.
Posted From: 184.108.40.206
|Posted on Friday, 05 December, 2014 - 09:33: |
I have seen these window air conditioners and some are very poor quality. HC refrigerants are dangerous in poor quality( liable to leak) systems. A sniffer leak detector is a must. These systems have about 750 grams of R290 propane. Which does not last long when the aircon leaks. A sniffer will shut the aircon down and the gas will leak out and dissipate. A large leak will last seconds.
Some air con systems are designed to use HC gas. So recharging with HC gas should be legally ok.
The problems arise when a stupid engineer uses HC gas in a system designed for R12 say. The aircon will work better on HC but the lawyers will question it should someone get hurt.
If the system was meant to have HC then the blame goes to the maker.
I will only fit 134a in cars for customers. Because that's what the manufacturers say. If I had HC in my car I would most definitely fit a sniffer to the evaporator, and also remove the HC if selling the car, until the manufacturers say HC is ok. Which is not going to happen.
I have been told that lpg and 10% R12 blend doesn't burn. I notice that some alternatives to 134a are lpg and 134a.
Unfortunately if one asks the government they refer to the makers and say R134a. They don't actually ban others but won't approve them.
Incidentally I was told the biggest danger of window air con was the unit falling and hitting someone.
(Message approved by david_gore)
Vladimir Ivanovich Kirillov
Post Number: 44
|Posted on Tuesday, 23 December, 2014 - 00:31: |
Bob AC is something I am still getting my mind around simply because I have 4 air conditioned cars and I won't let anybody work on them but me. But I have a friend who was a sniper in the Vietnam war so naturally he is barking mad and has an arsenal locked up in a container in outback Australia for reasons that not even he can explain. He told me LPG is the only way to go with air conditioning in cars. I have life long certificates for the installation and repair of LPG into cars. When I did the course the local cop was there to give us all the drum that if we didn't be careful with LPG we would get the go to jail card free. The college showed us a film of an LPG tank sitting on a bonfire. People think LPG tanks explode. They don't.The valve blows out followed by a long jet of flame. There was a taxi in Sydney many years ago that exploded and it blew up because LPG somehow leaked into the passenger area and the passenger lit up a cigarette and boom. Well as you know smoking is not good for your health. What I do know about LPG is that its heavier than air so like a sneaky snake it will sit down in every crevice it can find just waiting for a naked flame. Obviously the leak in the taxi must have been large as I can't understand how you would get a flame from a cigarette lighter down on the floor when you are sitting on the rear seat upright and lighting up. Of course you don't have too go far to find a taxi driver to tell you strange things do often happen in the back of taxis. So I would not use LPG on any car air conditioning because evaporators can leak and they are on the inside not the outside of the firewall. But here is something weirder. Australia has far too many politicians so naturally we end up with quite a few crazy laws. They banned R12 here and then we had to use R134A. When I imported my Cadillac and the Camargue into Australia from the USA I had to get a certified US air conditioning mechanic to degas both vehicles and provide a certificate. Here's the kicker. Even if both the cars had R134A I still had to have the cars degassed. I can't work out why. This law is so strict that if the car arrives without that certificate customs will put the car back on the ship and the importer has to pay the price to send the vehicle back to whatever country it came from. Nasty. Now household air conditioners use R403 if I am not wrong which I am told has more ozone depleting gas that either R12 or R134A. So you throw out your household ac and it gets crushed. It does not get degassed into any storage tank. I had a mate called Mad Col. Mad Col used to run a scrap metal business next to his caravan in a public caravan park. Most naughty, not allowed of course but Mad Col was the type of chap that the park manager didn't even think about tangling with because Mad Col was actually quite mad. He would degas the R403 straight into the beloved atmosphere with totally impunity. Not one or two but hundreds of household ac units lost their gas compliments of Mad Col. But at any rubbish dump here you will see tons of household airconditioners but there is no degasser certified or not. I worked with one of largest panel beater companies in Sydney. AC units were not evacuated using an evacuator they were simply opened and green gas would blast out while everybody said run. What I also learnt about LPG is that if used as the fuel system for a car it puts out a miniscule amount of naughty pollutants compared to petrol. So why didn't the government legislate in compulsory LPG. Why did they force the car companies to produce cars with such hideous complexity like computerised electronic fuel injection which believe me forced every mechanic to be a rocket scientist in order to diagnose the faults which appear frequently, very frequently. I'm afraid I do believe in conspiracy and big business back door deals with governments world wide and lets sell a pack of bull to the public via our mates in the media. Oh and here's another one. Media yap yap recently has announced that the car manufacturers are about to make cars that will have computer systems which you can't diagnose with the present scan tools. They the car manufacturers have decided that nobody but nobody is getting either the information nor the new scan tools to diagnose the faults on the new cars except the dealerships. Wacky do. Well it does not really worry me at all because I am a firm believer that new cars are over complicated pieces of junk. If I won one in a lottery I would get rid of it quicker than a New York gangster's bullet. As for the dealerships - only desperate or starving mechanics work for them because they are the biggest slave driving employers bar none. Now Bob tell me what to do - should I use R134A in the Camargue or do you have some secret formula because believe me I can get R134A and all the equipment and use it certified or not. In fact I will use kangaroo rectum gas just to keep the Camargue away from most of the certified AC loons I have known. And Bob believe me I have a lot of kangaroos at my disposal.
Posted From: 220.127.116.11
|Posted on Tuesday, 23 December, 2014 - 08:01: |
Lpg in air con most definitely works better. The flammable gas bit is easy to engineer out by using an indirect system.
I hear tales of lpg explosions but never car air con. The tales that are true are usually caused by someone doing something daft.
Lpg can get into sewers and explode. But a litre of lpg will disperse quite quickly and once the concentration is below 3% it won't explode. Above 10 it won't explode.
I have been involved in several lpg conversions from petrol. And my understanding is that leaks in the main line before the vaporizer if large will starve the engine which stalls and the valves shut. If the supply hose to the manifold leaks then the same happens this hose is under vacuum. So these systems are as safe as petrol. Of course I can interfere with bits and make it not safe.
If we never did any thing because someone could do something stupid then we would do nothing.
Metal knife in toaster to get toast out.
Your air con.
I would do only what is legal in your territory. I believe that all states in Oz except Queensland allow HC R290 to be used. The fire issue is for you to decide. The worse danger as I see it, is that the evaporator could suddenly split and dump 750grams of LPG into the car and it goes bang. The evaporator box has a drain and lpg is heavier than air, which would take care of small leaks which to be a problem won't last long because the gas will run out. A leak that takes 6 months to empty isn't going explode. Cars arnt water tight. Note fridge lpg and cooking lpg aren't the same.
134 will work best if the throttling valve is gutted and a temp sensor fitted to the clutch relay. The condenser pressure and heat are higher for 134 so a fan in front of the condenser is needed in hot hot places. In the UK us whinging poms don't need the fan because days over 28c are rare. But we do get high humidity so we tend to use aircon to dehumidify, rather than cooling which is easier for the air con.
We in the UK take a different approach to certificates. My certificate for air con is automotive only and mostly about refrigerant handling and the safety. It's an open book 2 hour multiple choice, that takes on average 1 hour. Basically the questions make the candidate refer to tables and charts to hive the correct answer proving that one understands things. Its then up to the certificate holder to apply the data correctly. The course is designed for engineers not novices. I already know about seals and gaskets etc for example. The tutor said that he leans stuff from his trainees because they are skilled engineers.
Legally if a garage works on air con without certificates and nothing goes wrong then fine, but if it does go wrong then the excuse that we didn't realise that the expansion valve was blocked because our mechanic does not know about air con won't be accepted because once a garage takes a job on legally they are experts. Fortunately this doesn't happen because British people in business are responsible enough to know that it's dangerous without the knowledge. That's the official line. Meanwhile the environmental guys send out leaflets to reinforce safety etc.
The modification to the throttling valve is in the tech stuff on this site. This appears to be a case of removing the piston thing and spindle and blanking off with a plate and gasket. The sort of thing one could file up in the shed. Stainless would look nice. The valve ends up as a place to charge the system and to connect the balance calipilery to. In place of the now defunct valve is a temp bulb switch that's fitted next to the expansion valve bulb. This switch cuts the compressor at 0.5c so that the evaporator can't frost up. Also a high pressure and low pressure switch for safety. Low pressure protects the system from starting with low or no gas. And high pressure to protect the compressor from over working. Fit new dryer about £40, clean dead bugs from condenser. Straight any bent fins. Paint matt black. You must pull a deep vacuum to boil out moisture. 29.5 hgins. For 1 hour. To test for leaks compressed air and soapy water is fine. But vacuum after.
Incidently lpg pressures are lower and kinder to compressors.
And recently I helped fit a lpg leak sensors in a mate's boat. They are quite small. The circuit shuts the bottle solenoid valve. We tested it with a butane blow lamp and it shut the gas instantly.
I don't let others work on my cars because they only do the minimum. Where as I like to paint stuff and oil nuts and bolts. Because I am a fuss pot.
(Message approved by david_gore)