(This post is also on the shop talk board but I thought I'd post it here to see if anyone has any help to offer)

Hi,

I have four very simple questions. I realise they proberly seem very insignificate to these boards but please give any advice you think might help. When Oxy / Acetylene isn't being used on production lines or large scale work, is liquid oxygen used or simply pressurised oxygen? I use a very, very small tote style torch (That lasts for about 3 minutes welding) that only uses pressurised oxygen.
I only really weld right now as a hobby (I'm 16), but I'm thinking about going in for a certificate this year or next and getting a weekend job at a local blacksmiths who specialise in gates and such. I'm also looking at doing metalurgy at university in a few years. I MIG weld but we have just had a new breaker set put in that will trip if I try and spool wire from the gun near the work, or strike with the wire against the work or more than a centimetre from the joint. I've asked about a welding breaker but everywhere seems to be quoting about £400. I found that when I started using Mapp in the tote rather than Propane I could make brazes look pretty nice. The only limiting features being the clouds of thick black smoke and cob-webs it gives off; and that I can only get 3 minutes from it. :) Does Acetylene produce the smuts of soot?
I'm thinking about selling the MIG and I'll have about £500 - 600 then. I'm considering a Harris 843MX torch (Or I should say shank) to use with Acetylene. Would I be better with a Victors or another make? Are there any inherent problems anyones found with Harris? I've heard only good thing about Harris so far and that they've been making welding equipment for a hundred years is it? It's for use with steel and stainless on things like table joints, gates and possibley small sculptures (If my sister has anything to do with it). Could anyone recommend a good torch if mine isn't the best of choices?
The last thing I know will inspire many replies suggesting I ask the torches manufacture but I will ask anyway... I have absolutely no idea about bottle sizes or the ratios in size. I'm looking to braze / weld (2 - 6mm stainless) / cut (4 - 10mm stainless) for about... 30 minutes to an hour a week and not wanting to refill the cylinders for atleast a month. What sort of cylinder sizes would I be looking at for something like that and would you suggest I get ratio cylinders or both the same? I realise cylinders are very expensive to actually buy, but I'm thinking about buying the cylinders because I've been told rental is around £30 - 40 on average sized cylinders a month. Well if I'm going to keep them for a few years and they're not over a hundred or so it'd be cheaper to buy them yes?

Thanks very much for any help,
John