have i been conned

[Bill Edwards]

You're best using a 'pea shooter' type of flowmeter, using a pressure gauge on its own is next to useless.
As you are just pull the torch trigger and turn in the regulator until you get a nice hiss, don't put too much down to what the gauge tells you it will vary for different people depending on their gas lines (how much resistance they have).

Pea shooter flow meters don't cost much and are worthwhile, you'll then use the correct quantity of gas (8 to 10 lpm for normal jobs is fine) rather than guessing.

 

[Maker]

the bottle has 3600 psi stamped on it, i would have though it would be full when you purchase it from the depot, 1000 is going going to last how long on average? is there a calculator i can use or something that will give me at least an idea of how long this gas is going to last? Even if its supposed to be 1000 i clearly have not much less...... think ill take it back tomorrow. hate being ripped off

Really dont see the point in a bottle capable of three times as much gas not being filled, just as well diving is not like that or i would have been dead years ago

You can calculate how long it will last with regular compressed gasses with the equation : Tank volume (L) * Tank pressure (BAR) / Flow rate (LPM) = Total welding time (Minuets).
To calculate the welding time with CO2 you need :
Weight of liquid (kg) * 534 / flow rate (LPM) = total welding time (Minuets)

The 534 is because 1 kg of CO2 is 534 litres of gas according to air liquide. I have just made up the CO2 calculation so if it's wrong then please correct me.

You're best using a 'pea shooter' type of flowmeter, using a pressure gauge on its own is next to useless.
As you are just pull the torch trigger and turn in the regulator until you get a nice hiss, don't put too much down to what the gauge tells you it will vary for different people depending on their gas lines (how much resistance they have).

Pea shooter flow meters don't cost much and are worthwhile, you'll then use the correct quantity of gas (8 to 10 lpm for normal jobs is fine) rather than guessing.

Do you mean the peashooters that go on the end of the torch or the ones that go after the regulator?

 

[Bill Edwards]

Do you mean the peashooters that go on the end of the torch or the ones that go after the regulator?

Well they're the same idea. Get one that goes onto the regulator, these normally have a screw that you adjust the flow with - set some pressure on the regulator then tune the flow with the screw on the shooter.
The type that go at the torch don't do anything other than measure what is coming out, not like the type that are fitted as part of the system and are always in place and give control.

 

[Wallace]

You might notice the pressure gauge rise slightly when the weather gets warmer as the gas expands. Just to scare you there is a safety burst disc on the valve that ruptures if the pressure gets too high and lets ALL the gas out in one go! Don't worry though as you have more chance of winning the lottery than happening as BOC are not in the habit of overfilling bottles.

Do you mean the peashooters that go on the end of the torch or the ones that go after the regulator?

By 'Peashooter' Bill means one of these. Useful and cheap if you use more than one machine at different locations as long as you don't keep losing it!

 

[Maker]

Well they're the same idea. Get one that goes onto the regulator, these normally have a screw that you adjust the flow with - set some pressure on the regulator then tune the flow with the screw on the shooter.
The type that go at the torch don't do anything other than measure what is coming out, not like the type that are fitted as part of the system and are always in place and give control.

I use the torch one because, the way I see it, once the regulator is set it won't change.

 

[Wallace]

Each type has it's merits, personally I like a flowmeter you can glance at especially on the Tig and take my homemade peashooter onsite if using someone else's kit. One thing you can't do with a peashooter is a dead head leak test by blocking the torch and checking for flow on the meter.

 

[normspanners]

Just to scare you there is a safety burst disc on the valve that ruptures if the pressure gets too high and lets ALL the gas out in one go!

I was in greece a few years ago in a holiday complex and wanted 5min peace from screaming kids by the pool etc so went for a walk round the gardens which led to the back door of the bar, as I walked along side the wall getting to the end of my 'quite walk', to the side of the door was stood the delivery of c02 cyls leaning on the white wall in the full glare of the mid day sun. I was about 2metres away and BANG !!!! the relief let off on one cyl letting the contents out in virtually one go . I literally near s**t myself all I wanted was a 5mins quite time!! went back with my ears ringing.

 

[Wallace]

Used to hear of the burst discs going on paintball cylinders occasionally where they were overfilled. One team of muppets used to fit two burst discs and overfill each game. One of them had an overfilled 20oz go off in his car on the motorway and another had a 20oz split the bottle and unravel, it was under his bed and went through the matress like a piece of shrapnel and he was in bed at the time!

 

[normspanners]

OOOH MATRON !!! I dont think that will fit in the-r--- oh its has.

 

[ford34/2]

Does the Tare weight not indicate the weight of the Empty Bottle?? TW14.2 Kg. When the guy fills my bottle its by weight on a set of scales, and he gives the gross weight on the receipt (oops sorry a bit of paper)

Stan

 

[AndyStobbs]

Daft question, but if we know Co2 liquifies at a fairly low pressure, how does it stay as a gas when mixed with Argon in a cylinder of argoshield that could be filled to twice the pressure at which co2 liquifies?

 

[marlinspike]

OP, you probably know already, but the best deal on Argoshield light from BOC is the Volkszone deal - there is a thread about it. Most outlets don't seem to know about it so you are best setting it up with the Head Office.

 

[voipio]

Daft question, but if we know Co2 liquifies at a fairly low pressure, how does it stay as a gas when mixed with Argon in a cylinder of argoshield that could be filled to twice the pressure at which co2 liquifies?

The partial pressure of the CO2 remains below it's liquification point.

 

[normspanners]

The partial pressure of the CO2 remains below it's liquification point.

how can it ? if it is in with the argon.
I thought it was because it was in suspension before being compressed, and because the molecules were separate they stay separate.

 

[mike 109444]

how can it ? if it is in with the argon.
I thought it was because it was in suspension before being compressed, and because the molecules were separate they stay separate.

Ah there's a ball bearing in side and you have to shake it like a spray can.....

 

[normspanners]

Ah there's a ball bearing in side and you have to shake it like a spray can.....

I wondered what the handle at the top was for,
Right I have tried this method and it is very difficult,---------- I have run off my line twice now,----------- mainly because my helmet came off----------I have tried practicing rubbing my stomach whist hitting my head, but now my head hurts,
any help would be welcome.

 

[hotrodder]

http://en.wikipedia.org/wiki/Partial_pressure#Dalton.27s_law_of_partial_pressures

Praxair's take on filling Ar/CO2 blends http://www.praxair.com/~/media/Nort...ets and Brochures/Gases/P8307AStarblend3.ashx

Various stuff about shielding gas quality in general inc ionisation potentials, thermal conductivity, dissociation, purging etc. Pages 4 & 5 touch on cylinder filling and stratification... http://www.polysoude.com/images/sto.../Influence_of_the_welding_shielding_gases.pdf

 

[normspanners]

The partial pressure of the CO2 remains below it's liquification point.

I was thinking that you meant the co2 remained at one pressure and the argon at a higher pressure within the same cyl which made me think How?? when it is all at one pressure.
I see what you mean regarding the partial pressure, this is during the refilling process it is that the cylinder is filled with co2 to under its liquification pressure so that it remains a gas, then the argon is pumped into the partially filled cyl which the co2 is forced into suspension / diffusion within the argon, the mix is then compressed to the higher pressure required, with pure argon.
The resultant co2/argon mix will remain a gas but the co2 is in suspension within the argon.

 

[txargyll]

Thanks all, reckon my questions is well and truly answered...... as soon as i have finished this load im getting a y cylinder of argoshield light from BOC, already spoken with them and reckon the price is right to at least give it a go for a year, the rental is a pain in the **** but the gas versus the co2 is not much difference really. Its a pity i have no way of comparing each gas before i go head long into a boc contract but there you go thats the way it is. hope its worth it but i am going to get the most out of my co2 first and if its fine ill just stick with it and save the dosh on rental.