cost of welding gas?

How do you calculate how much your shielding gas is costing you per minute? If I
have an M sized tank of C25 (capacity 125) and I'm running it 20 cubic feet per
minute at 20 psi, how many minutes will that flow?
Is there a primer somewhere online or in a book that breaks this down?
Grant Erwin
Reply to
Grant Erwin
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Is that 20 cubic feet per MINUTE or per HOUR?
I think that a simple division would suggest that at 20 cfH, it would last for 125/20 hours, or approximately 6 hours (note that also some gas will be left in the tank). You divide the fill cost by 6 (hours) and then by 60 (min/hr) to get the cost per minute.
Say your fill cost is $48.
Cost per minute = 48/(125/20)/60 = 12.8 cents per minute or $7.68 per hour.
i
Reply to
Ignoramus20878
Ah. I think I'm beginning to see where I was led astray. If it's CFH, and the tank is rated in cubic feet then the math is trivial. Thanks.
GWE
Reply to
Grant Erwin
"Grant Erwin" wrote: (clip) I'm running it 20 cubic feet per minute at 20 psi, (clip) ^^^^^^^^^^^^^^ The part I don't get is the "20 psi" part.
Reply to
Leo Lichtman
It doesn't matter. The psi. All that matters is flow per time. All the pressure does is push the gas out through an orifice. ERS
Reply to
Eric R Snow
Actually, it may matter. The flowmeters are calibrated for one gas, at one pressure. If this is a one-piece, non-adjustable TIG regulator, the flowmeter is probably calibrated for Argon or CO2 at the regulator pressure. In the most general case, flowmeters are calibrated at STP, so if the system is at 20 PSI gauge pressure, that is 2.3 Atmospheres, and so the flowmeter will read somewhat low.
But, assuming the flowmeter was calibrated at this pressure, for this gas, then PSI makes no difference in the gas consumption.
Jon
Reply to
Jon Elson
Connect a running time meter to the gas on contactor relay of your mig welder and read it when the bottle runs dry. Divide the cost of the gas cylinder by the number of minutes recorded on the timer.
John
Reply to
John
You have to convert the numbers to volume of gas at standard pressure to come up with a valid answer.
John
Reply to
John
Is the tank pressure higher that the regulator pressure? If the tank is 100 PSI and the regulator is set for 20 PSI then 1 cf in the tank will be 5 cf after the regulator.
When the tank pressure drops the expansion will also drop. So the calculation is not trivial.
Bill K7NOM
Reply to
Bill Janssen
the cubic feet capacity of the tank refers to quantity of uncompressed gas at atmospheric pressure. I have a 300 c.f. tank, but it does not occupy 300 ft of space (equivalent to 10 refrigerators). It only occupies perhaps 5 cf or so.
i
Reply to
Ignoramus20878
Are you still figuring the bid on that 3'x3' cube project? How did that work out??
Reply to
Emmo
The project wasn't actually a 3x3' cube. I just posed that as an ubersimple design that anyone could comprehend with no drawings, to learn how you guys do bidding. I figured it one way, then I figured the number of inches of weld and cost it out the other way, they were within about 2%. I didn't get the job but it wasn't because of my numbers, I couldn't store the customer's jig long-term since my shop is in my house and my shop is too small so it would have to sit outside, and in the town where I live this would result in losing my business license.
I did learn a lot by bidding the job, though.
Grant
Reply to
Grant Erwin
I'm pretty sure you could plug me into a regulator and i would be good fer a few beads. I'll even supply the oxygen you bring the dune buggy frame
Reply to
daniel peterman
Try to find a man named Don Holder. not the same person Don Smith in Michigan. very brilliant men with a rich history. Kalamazoo area we grew up together and they are way smarter than I Good friends of mine Both are welding genies and have won many awards for their prowess behind the Tig and stick.
Reply to
daniel peterman
Try to find a man named Don Holder. not the same person Don Smith in Michigan. very brilliant men with a rich history. Kalamazoo area we grew up together and they are way smarter than I Good friends of mine Both are welding genies and have won many awards for their prowess behind the Tig and stick.
Reply to
daniel peterman
It's inconsequential for low pressure like 20 PSI. Ig's responses were right, except that the delivery PSI will determine how much gas gets left unused in the bottle. If "full" is about 2150 PSIG (146.3 bar) 20 PSIG (1.36 bar) is better than 99% depleted.
Reply to
Don Foreman
Thanks for the correction. After I posted It accured to me that the capacity as I stated would require a large tank.
So I stand corrected (informed).
Bill K7NOM
Reply to
Bill Janssen
If this is the usual rotameter (ball in a tapered tube floweter), the accuracy will be affected by downstream pressure, but is relatively insensitive to the regulator setting. In other words, backpressure due to restrictions between the flowmeter and atmosphere will affect accuracy more than the pressure at the inlet to the needle valve, which is upstream from the flowmeter.
Ned Simmons
Reply to
Ned Simmons
Take the bottle hire charges, divide by 365x24x60
Prices round here, the gas itself is free 8-(
Reply to
Andy Dingley
Its indeed in CFM/H
Gunner, who pays $18USD + $3 for a 135 CF tank of Argon OR C25
"Pax Americana is a philosophy. Hardly an empire. Making sure other people play nice and dont kill each other (and us) off in job lots is hardly empire building, particularly when you give them self determination under "play nice" rules.
Think of it as having your older brother knock the shit out of you for torturing the cat." Gunner
Reply to
Gunner Asch

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