How empty is empty

[Ron66]

So my argon tank is getting pretty low. How low should I let it get before I declare it's empty? With my mig I stop at about 150 to 200psig because the welds start getting pretty oxidized.

[Rodsmachineshop]

just like a scuba tank any under 200 psi your getting not true gas. pluss running a tank empty is a invite for moisture . that why i like gas from airgas they evac all tanks before fill to remove moisture . ever hear stirring a tank.

[Ron66]

So I googled it and I couldn't find "stirring a tank" I doubt my gas supplier pulls a vacuum on my tank. Maybe I'll go to airgas next time.

[Rodsmachineshop]

if a tank sits along time the mix gas separates so a lot of old time welder roll the tanks on the ground or crack the tank open for a few seconds to agitate the gas's it really works on mig tanks the most . since the co2 rise to top and you get spatter weld since argon lays at the bottom of the tank . would like a gas mixer but they cost a lot http://www.ebay.com/itm/Smith-Weldin...item519883e713

[Ron66]

I made one. See my post under welding projects. You really don't need much to spin the tank. Don't know how well it would work for a 125 tank though.
http://www.everlastgenerators.com/fo...93-Tank-roller

[Rodsmachineshop]

i just lay it on the floor flat and roll it lol

[Ron66]

We have gas mixers like that for medical anesthesia gasses we use to calibrate equipment at work. They cost a fortune but it's the only way to ensure the right mix of gas.

[Rodsmachineshop]

anesthesia oligest thats a hard job

[Ron66]

Not me. I'm an electrical engineer by trade. We design patient monitors for use in MRI rooms. I think anesthesiologist have a lot more responsibility than I would care for.

[Rodsmachineshop]

that for sure they have a rough job one mistake and there screwed

[Brian Ski]

would like a gas mixer but they cost a lot

I thought you were the guy that told me to drill a small hole in the tank and insert a coat hanger chucked in a drill. You said it was cheap and did a great job.

[Rodsmachineshop]

no i said use a plasma cutter lol

[Jules The Great]

Not wanting to be rude and contradict what anyone else here as said but I use every last drop.

If you are welding to a code or spec then you obviously need to follow it.

For your home shop despite what anyone else here may assume if it is coming out under pressure which it does till it stops hissing than it is just as pure as it is at 2000psi. Obviously weld quality is a good tell

Now for my tig as the pressure gets lower I have to turn up the flow rate as the pressure getting to it is lower to a point. That may also work for your MIG gas but then you would have to remember to turn down the regulator again with the new bottle.

Also all gas places have to do a full purge of gas bottles before they refill them, and when they test them how ever often that is they send a camera down inside to make sure it is not rusted.

You are paying for the gas and they do not give you a refund if you return a bottle when it still has gas in it so might as well use it all

[Brian Ski]

Not wanting to be rude and contradict what anyone else here as said but I use every last drop.

For your home shop despite what anyone else here may assume if it is coming out under pressure which it does till it stops hissing than it is just as pure as it is at 2000psi. Obviously weld quality is a good tell

I would say I do the same... Run them until they are dry. As long as you are not leaving the valve open when you are done you won't get moisture in the tank.

Also a couple points... Argon, Oxygen, Co2 I run them dry. Acetylene I can run low and it will slowly build pressure back up and the acetylene escapes from the pores when I let it set. It can sure last a long time.

But what has brought up that I have never thought of is that a Argon Co2 mix should be rotated or stirred. I never have. I can see them separating over time. I have a tank that will last me a good year. So they have time to settle. Argon compresses into a high pressure (2000 psi tank pressure) and Co2 only compresses to about 200 psi and then turns into a liquid. I can see them separating. I still run them down. But good conversation.

[Winky]

Not wanting to be rude and contradict what anyone else here as said but I use every last drop.

If you are welding to a code or spec then you obviously need to follow it.

For your home shop despite what anyone else here may assume if it is coming out under pressure which it does till it stops hissing than it is just as pure as it is at 2000psi. Obviously weld quality is a good tell

Now for my tig as the pressure gets lower I have to turn up the flow rate as the pressure getting to it is lower to a point. That may also work for your MIG gas but then you would have to remember to turn down the regulator again with the new bottle.

Also all gas places have to do a full purge of gas bottles before they refill them, and when they test them how ever often that is they send a camera down inside to make sure it is not rusted.

You are paying for the gas and they do not give you a refund if you return a bottle when it still has gas in it so might as well use it all

Some good points ... I've always switched tanks when it still shows there's a tiny bit left so I would always be sure my welds were shielded ... perhaps I shouldn't be so wasteful.

[fdcmiami]

run them till they are empty. why throw money away.

[Winky]

just like a scuba tank any under 200 psi your getting not true gas. pluss running a tank empty is a invite for moisture . that why i like gas from airgas they evac all tanks before fill to remove moisture . ever hear stirring a tank.

Thanks Rod that makes me feel good about what I've always done ... around 200 PSI I switch out and I too go to Airgas they are awesome!!!

[everlastsupport]

run them till they are empty. why throw money away.

I do the same.

If I hear gas and see outout pressure in range, I use it. Never had a problem yet. I can run a 250 a long time after the gauge hits 0. Main thing is the output gauge. I used to swap when they hit 0, and saw I wasted quite a bit of gas one weekend where I have to just keep going. Finished the job and used for a for time after. So now I run them all the way out. Also, keep spares if you can..

[Tacoma747]

I keep a spare tank and run it till it's dry... I have two lease size (300cf?) cylinders so it takes me a LONG time to run out of gas, if the 'separation' thing really happens, I don't see how it hasn't screwed up my welds, cause I can run on one tank 1-2 years normally with this size tank (for MIG welding).

As for TIG, a 160cf tank will last me probably 10 years, haha.