Printable View
It's actually pretty close. R290 is much nicer at high compression ratios. In A/C units it's a wash. It was more the blend vs R12 or R134a I was referring to with the cap tubes.Quote:
Originally Posted by scarry
From memory DanCap has both R290 and R600a in it now, so the maths is there.
No worries,thnks.Quote:
Originally Posted by BradC
But I never use it,I use the trusty capillery selection tables out of the old Kirby blue book,R22,502,and 12.
Then adjust if needed for 134a,and 404a,using experience and grey matter[bighmmm].
I can’t remember having an issue for many years,and we do this stuff all day.
The engineers at our main suppliers use the same tables as well.
I also have all the capillery selections for every Orford refrigeration cabinet ever made,so I use them to double check my calcs as well at times.
Anyway,I should have a look at the Dancap,particularly for HCs.
I had an enquiry once from a lab seeking a refrigerant mix of Methane, Ethane, Propane, Neon, and Nitrogen. Apparently for use in a super low temp refrigeration system in a laboratory.
Looking into it through Google, turns out you can get (in an experimental capacity at least), cooling down to 70 Kelvin (-203 degrees Celsius), with a cascade refrigeration system.
https://www.google.com/url'sa=t&rct=...aKI79klED6s58W
Sounds like a gas mix for a multi-stage auto-cascade. That’s witchcraft.Quote:
Originally Posted by Toxic_Avenger
I was wanting for someone to come forward and say they have knowledge of people quite happily using bbq gas in their aircon systems.Quote:
Originally Posted by johnp38
Then grab the popcorn while reading the nay sayers responses .[smilebigeye]
I was on a shed roof helping fix a dudded solar install a few years back and the guy we were doing it for was underneath gassing his sons car with bbq gas, he had converted an old fridge compressor into a vacuum pump as well.
He was a qualified fridgy and actually did explain a lot to me about the commercial gases, most of which went over my head. What I did take away from that was that there were a lot of others out there besides him who knew their stuff and did one thing on the job but were quite happy using lpg/bbq gas in their own cars aircon systems.
Something about that was what was used before commercial interests skewed things their way.
When a triple point is involved (the temp and pressure at which a solid liquid and gas state are achieved simultaneously), then yeah, witchcraft indeed!Quote:
Originally Posted by BradC
Yep.Quote:
Originally Posted by Toxic_Avenger
Welcome to the world of CO2. [emoji33]
I wasn't "nay saying" as such. The fact is propane as a single gas at normal summer vehicle condenser temperatures (>60C) has almost 50% higher pressure than the gasses it's replacing. That is why there is an Iso-Butane content in the replacement gasses to lower the pressures. Each system is obviously designed with a safety margin, but when you use a much higher pressure gas (and I'd count a 150% high side pressure as "much" higher) you get closer to the margins, especially with older R12 systems that had burst discs in them. Even the static pressures on the evaporator inside the car in the sun on a stinking hot summers day are high enough to pose a problem.Quote:
Originally Posted by johnp38
Yeah, it'll work and it'll probably be ok because the manufacturers build safety margins in.
I have no problem with Hydrocarbons and I blend and use my own, but they use a blend for a reason. As far as I can see, Hydrocarbon blends are available to everyone over the counter without licensing restriction, so there is really no excuse for bodging it.
Ask a fridgie if they'd put R22 in an R12 system because they couldn't be arsed getting the correct gas and see what sort of reaction you'd get.
Correct.Quote:
Originally Posted by BradC
It would be an interesting situation if you needed to be licensed to buy propane. No more shrimp on the barbie, hehehe.
But the legalities of working on the system is how it is policed. ARC also require licensed operators to maintain vac pumps, leak detectors, recovery cylinders and reclaim cylinders for the purposes of evacuating a system before it is worked on to prevent release to atmosphere.
Same concept as how I can buy as many circuit breakers, cabling, GPO's as I want, but shouldn't do my own electrical work, to the letter of the law. Just because you can buy it, doesn't mean you can do it.
Thankfully if the system is already empty there are no fluorinated refrigerants present and ARC have no jurisdiction. I found out recently I can buy hfo-1234yf (not that I’d want to) but because of the zero ODP and low GWP ARC have no control over it. Never know, in another 20 years it might be legal for me to work on this stuff again, just like it was prior to when I left the country in 2003.Quote:
Originally Posted by Toxic_Avenger