YELLAHEEP
NAXJA Forum User
- Location
- Littleton, Colorado
Did you ever get that head gasket issue fixed?
Welding question
- Thread starter Fred
- Start date
Did you ever get that head gasket issue fixed?
ColoradoRaptor
Headbanging Hillbilly
- Location
- Canon City, Crawlorado
Preasureized CO2 is a liquid and COLD!! CO2 wants to be a gas but for us to store enough of it to use, it needs to be in liquid form! When it is used in Firefighting or Welding methods it converts back to a gas and is very cold!! If it were not for the high temps of welding you would see frost build up on the welding tip! Next time you are around a fire department ask them to demonstrate with their CO2. How do I know this........... maybe because I have been a firefighter since 1993. :dunno:
jimgrms
NAXJA Forum User
- Location
- Oceanside Ca the beach
Used to use co2 bottles to cool our beer when in the navy of course we had the means to recharge the bottles
ColoradoRaptor
Headbanging Hillbilly
- Location
- Canon City, Crawlorado
:roflmao:I remember those days!!! I was a Firefighter/EMT in the Navy and we uuummmm used CO2 for the very same thing.......
atriot:
Frank Z
NAXJA Forum User
- Location
- Colorado Springs
Time for Physics 101.
Liquid CO2 iscreated by increasing the pressure above 5.1 atmospheres, or 74.9496 psi. CO2 cannot exist in a liquid state at pressures above this point and must be stored in a suitable container or pressure vessel. As with all gasses, the temperature of the gas changes as the pressure on the gas changes. Increase the pressure and the temperature goes up, decrease the pressure and the temperature goes down.
Why does this matter? Simple, if CO2 is not kept at a suitable pressure it cannot remain in a liquid state and it would be far to cold to handle. Grab a co2 fire extinghuisher and feel the tank. Is it cold? No it is not, it is the same temperature as the surround air, or ambient. Do the same thing with your CO2 tank for your welder or your powertank that you carry in the back of your rig. It's not cold either. Why? simple the pressure in the tank is high enough to allow the co2 to exist in a liquid state.
What makes the CO2 cold is the pressure drop realized when the liquid leaves the tank via the pressure regulator. Put an air nozzle on end of a hose connected to you tanl and allow enough of a pressure drop for a long enough period of time and you'll see that frost will form on the side of the tank, the hose, and the nozzle itself. Now close the regulator down to the pressure you'd normally use for welding (12-18psi) and see how long it takes to achieve the same result. Hint: you'll be there for a quite a while.
So yes liquid CO2 is cold, but only when there is a suitable pressure drop as it leaves the container.
Liquid CO2 iscreated by increasing the pressure above 5.1 atmospheres, or 74.9496 psi. CO2 cannot exist in a liquid state at pressures above this point and must be stored in a suitable container or pressure vessel. As with all gasses, the temperature of the gas changes as the pressure on the gas changes. Increase the pressure and the temperature goes up, decrease the pressure and the temperature goes down.
Why does this matter? Simple, if CO2 is not kept at a suitable pressure it cannot remain in a liquid state and it would be far to cold to handle. Grab a co2 fire extinghuisher and feel the tank. Is it cold? No it is not, it is the same temperature as the surround air, or ambient. Do the same thing with your CO2 tank for your welder or your powertank that you carry in the back of your rig. It's not cold either. Why? simple the pressure in the tank is high enough to allow the co2 to exist in a liquid state.
What makes the CO2 cold is the pressure drop realized when the liquid leaves the tank via the pressure regulator. Put an air nozzle on end of a hose connected to you tanl and allow enough of a pressure drop for a long enough period of time and you'll see that frost will form on the side of the tank, the hose, and the nozzle itself. Now close the regulator down to the pressure you'd normally use for welding (12-18psi) and see how long it takes to achieve the same result. Hint: you'll be there for a quite a while.
So yes liquid CO2 is cold, but only when there is a suitable pressure drop as it leaves the container.
ColoradoRaptor
Headbanging Hillbilly
- Location
- Canon City, Crawlorado
UUUmmmm.......... that is basicly what I said but at the level most of the readers here could understand!! Even at the low preasures used in welding, the CO2 wil come out COLD! That was a physics 101.......... :attom::speepin:.............:moon:
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Frank Z
NAXJA Forum User
- Location
- Colorado Springs
No, what you said was:
Although there is a pressure drop at the regulator when using CO2 connected an a corresponding temperature drop, the volume of gas is so low that it absorbs enough heat as it travels through the hose from the tank, through the welder, and then through the cable/gun so that the gas is at or just below the ambient air temperature.
This is not correct. Pressurized Liquid CO2 in a tank or extinguisher is not cold at all. The low temperature is a result of a pressure drop when the CO2 leaves the pressurized tank.
Although there is a pressure drop at the regulator when using CO2 connected an a corresponding temperature drop, the volume of gas is so low that it absorbs enough heat as it travels through the hose from the tank, through the welder, and then through the cable/gun so that the gas is at or just below the ambient air temperature.
jimgrms
NAXJA Forum User
- Location
- Oceanside Ca the beach
Way to technical for me If it ain't cooling beer or putting out a fire what good is it :>{)))
Frank Z
NAXJA Forum User
- Location
- Colorado Springs
Well.....
It makes your soda all fizzy.
It makes your soda all fizzy.
Stang5lgt
NAXJA Forum User
- Location
- Parker, CO
Any kind of gas being blown on something that does not burn is going to cool a hot object. How would a radiator in your car work if it did not pull heat from it with air? So there is nothing you can tell that would make me believe that CO2 or Argon coming from the end of your gun does not have some cooling effect. As I understood CO2 is colder coming out that is why you can turn up the amps and get deeper penetration thanks to the cooling effect of the gas, otherwise you get a molten puddle. So unless the gas is being heated to the temp of the weld before it hits it has to be cooling it.
ColoradoRaptor
Headbanging Hillbilly
- Location
- Canon City, Crawlorado
So then changing the physical state of CO2 does not alter temperature.......... The solid form of CO2 is called Dry Ice, last time I checked dry ice was cold!! Liquid form of CO2 is cold, not as cold as the solid form but cold none the less and the reason you cannot feel it is the storage container insulates it! Take another gas, Nitrogen and turn it into a liquid......... VERY COLD..... now turn it into a solid SUPER VERY COLD!!
ColoradoRaptor
Headbanging Hillbilly
- Location
- Canon City, Crawlorado
You are correct Stang! Physics 101, the transfer of heat via radiation, convection or cunduction WILL take place in the welding process!! CO2 is and will always be a shielding media BUT it does have a cooling efect reguardless of what anyone else says!! I may be a Redneck but I am a certified Firefighter that has been welding since gradeschool..........
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Frank Z
NAXJA Forum User
- Location
- Colorado Springs
Well you are certainly entitled to your opinion, but the facts don't support it. The gases used for welding are shielding gases, not cooling gases.
http://en.wikipedia.org/wiki/Shielding_gas
http://en.wikipedia.org/wiki/Shielding_gas
ColoradoRaptor
Headbanging Hillbilly
- Location
- Canon City, Crawlorado
You are correct Frank, we are all entitled to our opinions! I do not need Wikipedia as I still have my books from welding school. I am not disputing the gasses purpose in welding BUT the laws of physics still apply to the welding process and therefore DOES have a cooling effect!!
Frank Z
NAXJA Forum User
- Location
- Colorado Springs
And my job is moving heat. I've been in the HVAC/R trade for a lot years and I know what I'm talking about. I was also a Welding Inspector when I worked in the Aerospace biz for Martin Marietta. I was responsible for weld inspection on ground transportation hardware and space flight hardware. I worked my way up to a Quality Engineering position and wrote processes for all kinds of inspection process including Non-Destructive Inspection and Non-Destructive Testing for Welding ...so yeah I know what I'm talking about.
No two gases are alike. They will all have different temperatures at the same pressure. I'll use a couple common refrigerants as an example.
R12 at 20 psi is 19 Deg. F
R22 at 20 psi is -5 Deg. F
Increase the pressure and the temperature goes up:
R12 at 100 psi is 90 Deg. F
R22 at 100 psi is 59 Deg. F
CO2 is no different. Change the pressure and the temperature will have a corresponding change. The change of state is a result of the addition of heat or the removal of heat. It's called the Latent Heat of Condensation or the Latent heat of Evaporation, depending on which change of state is taking place.
Yes Dry Ice is cold, approx -110 Deg F., and it does not change to a liquid state at atmospheric pressure, instead in undergos sublimation and goes directly to a gasous state. It is a solid so the pressure and temperature changes that affect CO2 in a gaseous state do not apply. Not sure where you are going with this.
Will heat be transfered from a hot material to a gas that is at a temperature that is lower than the molten puddle? Sure. Is there enough heat removed quickly enough to have an adverse effect on the weld? No. There simply isn't enough gas at a sufficiently low temperature to provide any noticeable cooling effect.
Frank Z
NAXJA Forum User
- Location
- Colorado Springs
That reply was intended for the previous post, not yours.
Frank Z
NAXJA Forum User
- Location
- Colorado Springs
If you don't agree with me, how about the American Weld Society? They are THE authority on welding.
http://www.aws.org/w/a/wj/2002/09/feature1/index.html
- Location
- Colorado Springs, CO
Jeez, that was SO 2007. I just need to get rid of some really obnoxious vibes, tilt the front pinion up, replace the front springs, shocks, upper control arms, front brake lines, usual boring jeep stuff. :laugh3:
Fred
Boostwerks.com
NAXJA Forum User
- Location
- Colorado
lol, seriously.
Are me and Frank the only professional welders here? I manage a 50,000sq/ft structural steel fab shop BTW. :dunce: I guess they'll have to do they're own penetration tests to find the answer themselves.
Stang5lgt
NAXJA Forum User
- Location
- Parker, CO
LOL need someone to pat ya on the back? Frank is a HVAC tech. Since you like wiki so much. http://en.wikipedia.org/wiki/Management. Last time I check Management does not do anything other look over your shoulder. LOL
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