Gas Mix Question

[Dunny]

When it comes to moving on from the small CO2 canister that came with my welder do I need a pre mixed gas (Argon / CO2 in the same canister) or 2 separate bottles with a 2 port regulator that allows the gases to be mixed in the proportions I choose?

I don't even know whether the latter is an option but when checking out gas suppliers locally they seem to carry the 2 gases in separate canisters as opposed to premixed.

Thanks

D

 

[Wallace]

Pre mixed Argon/Co2 for mild steel Mig welding. Have a search on the forum for the Volkzone BOC deal and rent free bottles from other suppliers.

 

[Dunny]

Follow up question....how many 20L bottles would a hobbyist use in a year? I don't have a project on the go yet so occasional use for now - so 2 x 20L max?

D

 

[rikrobson]

..how many 20L bottles would a hobbyist use in a year?

simple answer much welding are they doing?

to work it out we need to know how much they weld on average and the fill pressure of the bottle.

assuming its 200 bar then each bottle will hold 20 x 200 litres, which is 4000 litres of gas

we will assume its 10l per minute flow per minute. Then we have 400 mins per bottle of welding time

say we weld for 2 hours per weekend and the trigger is actually only open for half that time then we have 60 minutes per week. then the bottle will last 6 weeks. if they wel more then the bottle will last less, if they weld less the bottle will last longer.

so to answer you question approximately 8 bottles per year, but could be more or less dependong on their welding.

I doubt that they will use this much and would expect a couple of bottles a year

 

[PTvor]

Gas mixers are an option.

See here.

http://shdesigns.org/Welding/gasmix.shtml

I don't know who sells them in the UK or what they cost.

But most people choose a gas mix for what they mainly intend to do (say 93% Argon, 5% CO2, 2% O2 for light steel) and compromise with it on occasional heavier metal.

You could also have argon mix for light stuff and pure CO2 for heavier stuff.

As for which gas deal is the best, that very much depends on how much you are going to use. Then as pointed out before, the number of welding hours you get out of a cylinder depends on the pressure, the capacity and the rate of flow.

Don't forget that an hour of actual welding time with gas flow is really quite a lot for the average hobbyist, even one practising a lot and if you have a flow meter so that you are not wasting gas you can be quite economical.

 

[Dunny]

Thanks chaps.

At the moment I am only practicing and as I don't have a project yet it will be this way for a while. I figure I would be lucky to do 2 bottles a year at the moment an therefore local gas supplier is probably most economical until a project comes along (probably a car restoration).

D

 

[Wallace]

Ignore the regulator gauge for setting the flow, add a flow meter on the regulator outlet or get a peashooter for measuring at the nozzle like this;

 

[skotl]

Do definitely check out the BOC offer thread, and have a look here for info on cylinder sizes.

Note that the link says "Argoshield" but it's "Argoshield Light" that you want for MIG. I started with a PD size but, believe it or not, the Y size is actually cheaper because that's what BOC pushes on the hobbyist offer. The Y contains over ten x the amount of gas that PD does, but is cheaper on that hobbyist tariff

 

[Dunny]

Thanks Skoti

D