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George65
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Posted: 17 January 2018 at 11:52pm | IP Logged Quote George65

renewableMark wrote:


Wow! I just assumed it would go BOOOOOOOM.


Most people hear or see the word "gas" and usually do. For some reason most people are scared/ paranoid about gas because they don't understand it and it makes a noise when released.

I was trying to tell a guy a couple of years ago that in order for anything to go bang it needs oxygen. He wasn't buying it. I pointed to his car, and said you know the electric fuel pump in that thing had petrol running right through the motor?
Wouldn't believe me till I got one and showed him and the mechanic came over and verified it.

I don't have a Vac pump so what I do is Flush with LPG and fill and bleed down the system a couple of times having given it a run. Gets most of the moisture out that way and all the air. The receiver Dryer removes any remaining moisture but there shouldn't be much.

For doing a fridge you would have to put on a tail if it didn't have one which most don't and at least have a set of scales to weigh the charge in. Haven't had much to do with domestic appliance stuff but what I have seen all goes by weight of charge and most don't list pressures at all. If you could look up the pressures then you can put the charge in by gauges.... at half whatever they say.

I think 600g would be for a larger system. Subarus take about 350-400G on average depending on model and year. In any case, you are only going to be putting in half, max 300G.
For anything to burn/ explode, it has to be mixed with air at the proper ratio.
Can't remember off the top of my head, but I think the LEL is about 2% and the upper flammability is around 10% air. This means if you have 1% LPG in your garage or more than 10%, it won't light off. Being twice the weight of air, LPG sinks to the floor where it will spread out unless Disturbed. Pretty sure 300-600G isn't going to go off in a garage because that's basically the amount in a can of roach bomb and it takes a heap of them to make an explosive mix in a room.

When I was into bio making there were all these Ill informed safety zealot fanatics that used to go on about the explosion risk of methanol.
They would crap on about having to install explosion proof switched and light fittings and ensuring all electrical appliances were switched off and only use good TEFC motors and so it went.

I said that's over the top garbage, all you have to do is leave the garage/ shed door open and have a fan just out the door blowing fresh air in along the floor. the air movement will stop the vapor level building to flammable ( or toxic) levels and you don't have to worry. Unless you were throwing the stuff around the shed arsonist style, you couldn't cause a fire if you tried.
Typically, that was just too simple for the zealots and although a number of knowledgeable people including 2 Chemists confirmed I was correct, they wouldn't have it.
I'm convinced some people WANT to ignore fact if their false beliefs are more dramatic and requite more complicated, expensive and inconvenient solutions.

I read studies concerning LPG in cars involved in accidents.
They said the amount in an AC was too small to be of concern. They said firstly any rupture of the AC causing a leak will have the gas go down and spread out and it is highly unlikely there would be NO air movement to disperse it quickly.
They said secondly, even if the gas did ignite, it would burn out quickly and not generate enough heat to set something else on fire . They said in order for something to trigger the gas, any leaking fuel would also be ignited and would have abetter chance of a self sustaining and therefor more dangerous fire.

They also noted the Hysteria over hydrocarbon refrigerant flammability even among people with LPG fueled cars that had 60-80L of the stuff in the other end of the car
Which they felt was quite safe and no problem.




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Boppa
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Posted: 18 January 2018 at 12:17am | IP Logged Quote Boppa

I remember landcruisers were around 600, the hilux was the same, the smaller cars actually had a bit more at 700, strangely they used the same amount for the crewcabs as the single cabs tho

I never bothered doing the weighing thing tho, I just went by pressure- 40 was good, above that was bad lol so I just kept adding until it ran at 40- dont know what pressure would be good for lpg, I suspect lower

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yahoo2
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Posted: 18 January 2018 at 1:40am | IP Logged Quote yahoo2

I usually recommend fitting ball valve/ taps close to the end of the gauge hoses.

it is possible for someone to unscrew a pressurised hose with the engine running and burn their hand. not likely but its possible.

when I first saw this stuff I got excited about the aerosol cans for topping up seasonal vehicles but we use so much of it now we went with the big gas bottles.

edit
just to be clear on this, 410a systems wont work with propane, it needs a gas mix that matches its specific properties (minus 60). Even then it may not work because some of these systems have their cycling switched using the gas pressure.

However if it does work it will certainly reduce the electrical load quite a lot.



Edited by yahoo2 on 18 January 2018 at 2:11am


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Madness
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Posted: 18 January 2018 at 7:36am | IP Logged Quote Madness

If you search around on the net it is easy to find pressure charts for the type of gas you are using. Measure the temperature and fill to the appropriate pressure. Gauges have the temp on them for some types of gasses. You can always test if it is getting cool and always add just a bit at a time.

Yahoo I have filled a couple R410a ACs and it worked fine there is hydrocarbon replacement gas available for R410a systems too. I know some of the automotive part stores are agents for the stuff. Ozchill is one supplier.

This video may be helpful.

Edited by Madness on 18 January 2018 at 7:44am


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Posted: 18 January 2018 at 10:22am | IP Logged Quote yahoo2

Yep thanks,
the only thing is there are a few quirks with high pressure reverse cycle systems to think about. Particularly those designed to be multi head units and to be used at sub zero temps.

phil was talking about an oil heater circuit, that is there to prevent a condition called low superheat.
with most hvac systems it can be calculated by temperature and adjusted out with the amount of refrigerant and/or adjusting the tx valve.

it is possible for some systems to return large amounts of unevaporated refrigerant back to the pump diluting the oil in the sump, wearing the bearing and floating oil down the pressure side, the heater is there to stop that happening.

it is not likely to go low superheat just being used as an AC on a hot day but modern multi head systems are asked to do some weird stuff, reverse cycle heating, water heating, dehumidifying. I have seen an outdoor unit frozen solid and still running the compressor, that's not going to do it a lot of good.

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Posted: 18 January 2018 at 10:54am | IP Logged Quote Phil23

Gizmo wrote:
She sprung a leak?


But it's all good now!!!!!!!!!

Had a visit from the man with a new bottle of 410 first thing this morning.

2kg of gas later & I'm getting a cool house again.

He also added a bit to my Fujitsu multi-head.

That's something I've been chasing for years.

It's installation recommended additional charge of:-

.0-50m pipe      0g
50-60m pipe    250g
60-70m pipe    500g


I'm up around 48m of pipe work & always felt the system was a touch low on gas;
bit of gurgling at times when all heads were on.

Something you would hear if awake at 2:00 in the morning.

Spoke to 2 different installers & all had different reasons as why it didn't need to be done.

I figured it could have been down a bit from the start, either cause of tolerance, or a possible bit lost on install.

Anyway it got another 200g as well.

Will just have to see if it's made any change.



Cheers

Phil.
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George65
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Posted: 18 January 2018 at 12:47pm | IP Logged Quote George65

Boppa wrote:
dont know what pressure would be good for lpg, I suspect lower



Hi chill and other manufacturers of the glorified LPG recommend half the pressure of 134a on the high side.

I went to get my Restricted Recovery License a few years back, What a complete Joke!
This is to enable you to return recovered refrigerant from car AC and other things like fridges and aircon units back to suppliers for disposal. They are all " Supposed" to be bled down and be certified before they are recycled/ sent to scrap.
They were also paying for the recovered gas at one stage.

My father has a wrecking yard and the trade journals were always full of these ads about having to have the gas recovered properly from vehicles or million dollar fines applied and we will come get you etc.
father rang every Fridgy in town and none of them were interested. he said I'll give you 20 cars and you can do them in one hit. Nup, too busy.
I read about this restricted recovery license and looked into it. This is so you can handle refrigerants and get the bottles and sell it back which all has to be licenced and documented. Rang ARCTICK whom control all the refrigerant and are the industry kindergarten teachers and found out about it.

Guy said I'll send you all the study material, when you think you know it ring me back and we'll go from there. Was going to need 2 licences, $500 a year ea.
Father said I'll pay for them just for you to do mine. I Thought there must be a load of yards like him, I see an opportunity here!

Studied material which was primarily the usual over the top safety crap and most of the rest I knew from mucking round and what mechanic had shown me.
Ring back ARCTIK and say OK, where do I do the test. Oh, it's not set up yet, find a licenced guy to put you through it. They log onto our site and it tells them what you have to do. Errrm.

There is a list of people that will help on our site. Righto then.
Look on list, not one single person in or around Sydney. Get back to authority guy, is there anyone else cause I'm not planning to go to Melb, bris or broken hill anytime soon. he'll ask around.

Guy from central coast gets back to me. Not happy. Says I'm on the board of the enviromental save the world refrigeration association or what ever it was, guy told me what you want, I went to their site, there is no test there for me to put you through, rang him back and guy says just make sure he knows what he's doing and you think he's OK and sign off on it and well give him the license.

Guy says Pigs arse, something happens and they come back and say did you test him on this inappropriate thing or that and I say no and i'm screwed.
Guy apologised to me and said nothing personal mate but it leaves me wide open and I have everything I own on the line here. I said I understand, but what is going on with this? I told him why I wanted it, I said trying to do the right thing here and they are threatening to sue you if you don't do what they say but no way to do it.

Guy said yeah, I can see where you are coming from and we will get onto it. Even the arctic guy doesen't actually know the rules and regs, you only need one licence, giving the recoved gas back is what we want not putting more barriers in people way to do the right thing.

Father was still worried about them getting him so I rang solicitor mate.
Told him the story and he said Tell your father not to worry. If that's the case where they don't even have a test for a licence so he can comply, there is no way in hell they fine you and if they try let me know because your father will make a lot of money from it.

I was still keen to do it as there were a lot of wrecking yards where I lived so I started ringing and saying who recovers your gas now and what do you pay?
I got laughed at. They said none of the cars that comes here ever has gas ( sarcasm) in it mate, they are all accident damaged. Yeah, ok then.

Must have rung 20 yards and some of them outright told me they didn't give a sh*t about it and they weren't going to pay to have the gas taken out when they could turn a bolt and that was it.

I got back to artic and found NO ONE was checking on it, NO one had been fined and I was the first and only ever idiot to inquire about the restricted recovery license.
Also found a huge hole in the law. Law is the last owner Must ensure the gas is recovered. Only licenced person can recover it and it's illegal to bleed it to atmosphere. I said that's OK then. We can unbolt the compressor and leve the system charged because we get enough that are already out of gas from accident damage and don't sell much AC stuff anyway.

Guy says no, can't do that, last owner is responsible for it. I ask who is the last owner?
The person that the car was registered to, the insurance company that paid out policy and then sold wreck , the wrecking yard that bought the car or the scrap yard that bought it off them when they were done with it.
They tried to say it was the wrecking yard. I said but the scrappy pays us for it and is therfore last owner. But it's your responsibility guy insists. Says who? Can you send me a copy of the relevant act of legislation? Errrr, ummmm...

Rang legal mate again, he laughed. He said where there is ambiguity it favours the defendant, don't worry.

So despite all the hoo haa about refrigerant recovery, very few people do anything about it. I got on to one guy in Melb that does it for a stupid cheap price but he's a greenie and basically doing it out the goodness of his heart to save the planet and laughed when I said about making money from it.

Maybe things have changed a bit now, Maybe they haven't.
I got Dad an old refrigerant bottle and he pushes what he can into that with the car running, when it's running. When he fixes a car and needs to regas the AC he puts it back in from the bottle.

If we are concerned who the car is for, we use BBQ gas because there is no regulations on that. It's a fuel not a refrigerant so not breaking any idiotic laws.
It would apply to the LPG sold as a refrigerant but once people know more about what that actually is you can bet they won't be bothering with the expensive restricted stuff.


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johnmc
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Posted: 18 January 2018 at 10:45pm | IP Logged Quote johnmc

Good Day All ,
LPG based refrigerants R290 ,R600 is used in millions of fridges world wide
to reduce greenhouse gases CFCs. check Elgas web site .
Motor vehicles refrigerant R134a chlorofluorocarbons (CFCs) can be replace with
LPG or LPG derived refrigerant (Hychill)
The amout of LPG required to replace the R134a is about 1/3 the weight.
Say the weight of R134a is 1kg then you only require about 334 grams of LPG.

With the Aircon operating, the amount of the Aircon compressor suction side pressure for the correct LPG gas required, will be about 15 PSI .

Their are many sites on the web describing how to charge your refrigeration unit.
Also bear in mind that almost all aerosol spray cans use non smelling LPG. as the propellant.

john


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