Trans fill questions

[pescador775]

Commercial argon has max allowable 0.5 ppm THC and 4 ppm water. This is acceptable for use in an oxygen clean booster. Argon is separated by cryogenic process, same technique used for other gases such as for oxygen.

 

[pescador775]

Not sure what's in welding argon. Some grades are mixes with 25% carbon dioxide. That stuff could rot your shorts. Ask for "zero gas" or zero grade. Bear in mind that what are considered impurities to commercial users, like 0.1% oxygen and nitrogen, are not a problem for our use.

 

[cool_hardware52]

I would agree that you should avoid welding gases that contain CO2. These are commonly used for "Mig" (Microwire Inert Gas) welding. This is sometimes referred to as "wire welding". C-25 is a common designation, that's 25% CO2 and 75% Argon. Other blends are used, including some that have a small percentage of O2, but these are pretty uncommon, I doubt you'd find Mig gases other than straight CO2 and C-25 in stock at most suppliers. In my experience the blended gases are more expensive than industrial argon.

Shielding gases for "Tig" (Tungsten Inert Gas) are true inerts, i.e. either Argon or the much less often used Helium. Helium BTW is where the term "HeliArc" came from. Today most Tig welding uses cheaper Argon.

If you ask your gas supplier for "tig welding argon" you should be fine.


Tobin

 

[rjack321]

Whatever you do, just don't say "scuba" "breathing" or "diving" while at a gas supplier. They have no clue about these things and life will be a PITA if they think you are doing anything with their gases other than what they understand.

Don't ask don't tell.

 

[Thalassamania]

Starting pressure * Volume of larger tank = Ending pressure * (sum of tank volumes)

 

[MikeFerrara]

Starting pressure * Volume of larger tank = Ending pressure * (sum of tank volumes)

Except that the second tank may not be emty to start with. This works always
P1V1 + P2V2 = P3V3

Where V3 = V1 + V2 and volume is actual colume (water capacity)

 

[Thalassamania]

Except that the second tank may not be emty to start with. This works always
P1V1 X P2V2 = P3V3

Where V3 = V1 + V2 and volume is actual colume (water capacity)

Yes, but American's never know the water volume.

 

[MikeFerrara]

Except that the second tank may not be emty to start with. This works always
P1V1 + P2V2 = P3V3

Where V3 = V1 + V2 and volume is actual colume (water capacity)

I had to edit that. I typed a 'X' where I should have put a '+' and that wouldn't have worked. It's correct now.

 

[pescador775]

I developed this equation for purposes of determining the pressure drop of a supply tank or the equilibrium pressure between two tanks, a large (supply) tank and a small (fill tank). P is "pressure" in psi. PR is "pressure ratio", C is "capacity'' in cubic feet.

Pressure drop in supply tank = P(S) - P(F) / (PR + 1)

PR = [P/C fill] / [P/C sup]

In other words, to determine the pressure ratio for a given set of tanks; first, divide the pressure by the capacity of the fill tank. Do the same for the supply tank. Divide the first by the second. If you record the PR number for your tanks and you will not have to calculate twice. From then on you can subtract the two pressures, divide by one number and you're done.

To determine the equilibrium pressure, eg, the final pressure in the supply tank (and fill tank if the two are to be equalized), subtract the answer to the above from the starting pressure of the supply tank. As you guessed, it will work even if the tanks are not brought to equilibrium. So, it works if you just want to know the pressure drop in your supply tank and/or how many PP fills are available at some set pressure you can get from a supply tank.
Edited after checking my notes and having a beer.
Pesky

 

[MikeFerrara]

I developed this equation for purposes of determining the equilibrium pressure between two tanks, a large (supply) tank and a small (fill tank). P is "pressure" in psi. PR is "pressure ratio", C is "capacity'' in cubic feet.

Equilibrium Pressure = P(S) - P(F) / (PR + 1)

PR = [P/C fill] / [P/C sup] In other words, to determine the pressure ratio for a given set of tanks; first, divide the pressure by the capacity of the fill tank. Do the same for the supply tank. Divide the first by the second.

Hope this helps somebody.
Pesky

The euqtion I gave

P1V1 + P2V2 = P3V3

gives euqlization pressure if you rearrange to solve for P3...(P1V2 + P2V2)/V3 = P3 = equalization pressure