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Liquid Metal
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CO2 is an inert gas, but it reacts with metals when they are in a molten state.
Strictly speaking, Argon and Helium are both Noble gases (alongside xenon, neon and krypton) no matter what temperatures, pressures etc you expose them to they will not react with anything.
CO2 on the other hand reacts to increase the temperature of the arc and aid the wire melting off and therefore increase penetration.
Liquid Metal
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Inert gases, noble gases................hang on a sec this is frying my noodle lol
Yes argon is a noble gas, as is helium.
CO2 is an inert compound gas, which will react at a certain temperature/pressure range.
Nitrogen has some of the properties of an inert gas as its very unreactive, but is not inert, as it will form compounds with other elements ie with O2 to make nitric oxide.
Im sure i remember Pure Nitrogen being used as a purge gas by somebody i worked with once on a specific job. Not positive though????
Yes argon is a noble gas, as is helium.
CO2 is an inert compound gas, which will react at a certain temperature/pressure range.
Nitrogen has some of the properties of an inert gas as its very unreactive, but is not inert, as it will form compounds with other elements ie with O2 to make nitric oxide.
Im sure i remember Pure Nitrogen being used as a purge gas by somebody i worked with once on a specific job. Not positive though????
I was listening to some 'bod' on the radio a while back, and he said that while there was no threat of using all the Helium up.
It was more to do with costs and production, as they wanted it all for filling gizmos
That makes sense, kinda like oil in that we're running out but keep finding more and/or it becomes profitable to bother with the hard to get at stuff as the price goes up. AIUI helium, at least high purity 'fresh' stuff is typically cyrogenically distilled from natural gas?
Helium was the origional shielding gas used with TIG (hence it being known as heliarc in some circles) so you've not got much to lose by trying it... if what you've got isn't pure* enough the tungsten will soon tell you, flow rates are gonna need to be higher than with argon and an argon flowmeter will misread due to the difference in gas densities
* welding grade argon is usually at least 99.996% IIRC sometimes written as grade 4.6
Liquid Metal
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Diving grade???
Divers that go beneath a certain depth (dont know what depth it is though) breath heliox, a mixture of helium and oxygen, usually in saturation diving. Breathing pure helium you would asphyxiate, as helium is a noble gas it would be the same as breathing 99.999% argon surely
As far as i know, below a certain depth and pressure, the nitrogen in air becomes toxic, as dose the usual concentraion of oxygen in the air, so divers breathe a mix of helium and a lower percentage of oxy than is in fresh air which is usualy 21-22%
Rrunnach
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Usually 30 metre and below, nitrogen narcosis can kick in, depends on many factors. Seen a few guys narc'd over the years. I would never dive with a bad drunk!
Can't speak for other parts of the world, in the North Sea, commercial divers can be in sat at any depth below 10 metre, possibly nitrox, then other cocktails after 20 metre mark......................
I suspect that divers mix diving grade helium (or whatever) with air or oxygen before they jump in the water
More than pure enough for welding then just don't ask me to suggest any amperage settings. I've only used pure helium once before and that was having a play with DCEN welding ally in America
Jan
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I was listening to some 'bod' on the radio a while back, and he said that while there was no threat of using all the Helium up.
It was more to do with costs and production, as they wanted it all for filling gizmos
By 'gizmos' I assume you mean MRI scanners. The ones that need their super-conducting magnets kept at cryogenic temperatures with liquid helium.
HMB
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Yar
Yep many different cocktails of trimix or heliox gas depending on depth and time. Also gas diffusion within the blood stream and a few other factors involving He ( its got its own unique problems for divers ) get taken into account
>16% normoxic
<16% hypoxic
16% being baseline O2 level required to support life at 1bar pressure (sea level )
Yarp diving grade as per boc label
Yep many different cocktails of trimix or heliox gas depending on depth and time. Also gas diffusion within the blood stream and a few other factors involving He ( its got its own unique problems for divers ) get taken into account
>16% normoxic
<16% hypoxic
16% being baseline O2 level required to support life at 1bar pressure (sea level )
Liquid Metal
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Jan
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As a Tyke the last time the thermometer took a nose-dive like that I was strongly tempted to throw on another string vest!
HMB
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Ouch just picked up a small cylinder of alushield universal (no bigger than pub co2 cylinder). Gas was £113. Better bloody work
