What Size Welding Gas Cylinder for MIG,TIG, Ar & CO2?

What Size Welding Gas Cylinder for MIG,TIG, Ar & CO2

What size of welding gas cylinder will be appropriate for you? Well, it depends on several factors. Firstly, what kind of welding you are using. Then, on what scale are you welding. Of course, the welding gas requirements will be different for hobbyists, while professionals require more gas.

After reading our previous article, you must know what kind of welding gas best suits your tasks. Now, a wise welder should estimate the gas usage for his welding processes. If you are wondering how to manage your welding gas resources and your budget, My Welding Yard is again here to help you with this guide.

Commonly used MIG/TIG Welding Gas Cylinders

Being an owner of a welding yard, I have vast experience of almost all welding types. I have seen most of the hobby welders or house owners use 40, 80 or 125 cf tanks of Argon or MIG gas mixture throughout my career.

All three of the tanks mentioned above have their plus points and specifications. I would recommend you to buy a medium or small-sized tank if you are not a professional welder. You will be comfortable with their sizes, and they will not be heavy on your pocket.

You may choose to buy the biggest of the three tanks, but you will have to compromise on the portability. The other two tanks can easily be dragged to any place in the house or your small welding yard. On the other hand, the biggest one is most likely to be kept in the same location. Though you can use long pipes, it will be risky because the larger the pipe more will be the probability of leakage points.

It is a good idea for a professional welder to keep a 125 cf tank and a 40 cf tank in your welding yard. You would be thinking the reason. The answer is that you can do heavy-duty welding at your place, and for mobile welding, you can carry your small tank with you.

Another thing that needs to be mentioned here is the refilling of tanks. Small tanks are more comfortable to refill. It turns out the more considerable tank costs double in filling as compared to the smaller ones.

Welding Gas Tank Specification for MIG/TIG Welding

Mostly, Argon or MIG welder tanks blend has the following standard specifications:

40 cf (V)
80 cf (Q)
125 cf (D)
22 in
35 in
45 in
6 ¾ in
7 ¼ in
7 ¼ in
Empty Weight
24 lbs
47 lbs
58 lbs
Full weight
28 lbs
56 lbs
71 lbs
Full Pressure
2015 Psi
2015 Psi
2015 Psi

Though these were the figures that I have been working with, they may vary due to different reasons. These specifications are significantly less likely to depend on the manufacturer. Temperature is an essential consideration since gas properties change with temperature constraints. You should double-check the tank’s size or other features before buying.

I have seen tanks with their sizes represented by letters. You can see different capitalized letters written with volume in the above table, which are symbolic for tank sizes. We have also mentioned the pressure and weight values to ease you in picking the right welding gas tank for you.

As a beginner, you should consider buying gas tanks from local suppliers. They can give you better and deep insight into the specification details and also you would be sure whether the tank is refillable. Moreover, they can guide you about other factors like climate and handling of gas tanks.

Best 100% Argon Cylinders for TIG

40 cu/ft 100% Argon
80 cu/ft 100% Argon
125 cu/ft 100% Argon

How long do MIG/TIG Welding gas Tanks last?

Another question that I answer to amateur welders is how long do these gas tanks last. Is there any proper calculation that estimates their duration? Of course, there is an appropriate method.

Here comes the term ‘flow rate’ of the welding gas. How long the tank will serve you depends on the flow rate at which you use the welding gas. Usually, it lies in 10 to 40 cubic feet per hour (cfh).

The comprehensive formula to estimate the hours your welding gas tank will last is as follows:

Gas welding time (hours) = Volume of tank (cf) / volume flow rate of tank (cfh)

Let’s see, you use a 125 cf welding gas cylinder at 25 cfh, putting these values in the formula gives you 5 hours duration of your cylinder.

Another comprehension made from the above relation is that the gas welding time will be more if the tank’s volume is more extensive. Also, the more the volume flow rate, the less the welding gas bottle will be.

We have made calculations for a time duration of gas tanks with various assumed flow rates:

Cylinder Volume Flow Rate
40 cf
80 cf
125 cf
10 cfh
4 hrs
8.0 hrs
12.5 hrs
15 cfh
2.7 hrs
5.3 hrs
8.3 hrs
20 cfh
2.0 hrs
4.0 hrs
6.3 hrs
30 cfh
1.3 hrs
2.7 hrs
4.2 hrs
4 cfh
1.0 hrs
2.0 hrs
3.1 hrs

The significant factors that govern the variation in the above calculations are these:

  • There may be different pre/post settings of the gas cylinders, which can lessen their lasting time. Be careful of those settings.
  • There is a pressure regulator on the welding gas bottles to control gas speed and pressure. Keep an eye on its readings as well. Further, also check the knobs, which must be tight. As a safety measure, we advise you to set your regulator to a ‘0’ reading before leaving your welding yard.
  • Gases expand at higher temperatures. Hence, always use welding gases at low pressure in summer. You need to adjust the gas regulator according to the surrounding temperature.

We have discussed the pure Argon for MIG mix gas cylinders with 75% Argon and 25% carbon. Well, the scenario differs when we have a pure carbon gas cylinder.

Our favorite Mixed gas Cylinders for MIG Welding

40 cu/ft 75% Argon 25% CO2
80 cu/ft 75% Argon 25% CO2
125 cu/ft 75% Argon 25% CO2

Pure Carbon Gas Cylinders for MIG Welding

Accepting the truth that gas blends are safer for MIG, welders prefer to use CO2 gas cylinders because they are way cheaper than the gas blend.

Keep in mind that:

  • Carbon Cylinders do not come with volume as sizes. Instead, they are calibrated according to their weight in pounds.
  • These tanks use unique pressure regulators that fit in the threads of the tank opening. That means along with the cylinder, you have to order a gas pressure regulator as well.

CO2 gas tank specifications and Expected duration:

Size (Lbs)
Height x Weight (Inches)
Cubic Feet
Use Time
10.5 x 3
30 min
18.25 x 5.5
2 ¼ hrs
20.5 x 7
4 ½ hrs
27.5 x 8
8 ¾ hrs
47 x 8
22 hrs

Checking the Gas Left in your Cylinder

As a welder, you would not like to run out of gas suddenly. That’s why we keep looking at regulators after regular intervals. It is simple to know the gas left in your tank when working with Argon or gas blend. As the pressure goes down, you come to know your tank needs refilling.

In CO2, the pressure check is not that reliable because the pressure noticeably drops when the cylinder is near the end. It turns out that weight can be used effectively to guess the remaining time of the tank.

I concluded from my experience that when your pressure reads 1500 psi, the tank is left with ¾ of the total gas. And, when you have utilized half of your gas, the pressure will read 1000 psi.

Here, I would mention that you need to be aware of your gauge reading and keep adjusting for a constant volume flow rate. Again, you need to check for temperature while welding. A gas like CO2 changes its temperature readily with temperature. So, you will have to keep the gauge at full reading for appropriate pressure at low temperatures. You will be concerned about the needle of the pressure regulator that might be stuck for a while. This situation happens when you have set the gauge at its maximum. Don’t worry; it will move automatically after a time.

A General Myth about Welding Gas Tanks available Online

I have met so many confused customers who were doubting the welding gas cylinders available online. Mostly the welders believe in the myth that online stores sell empty gas tanks. But it is not the case. I have been ordering hydro-tested and refillable welding gas cylinders online, and they worked well for me at a reasonable price.

Frequently Asked Questions FAQs

In what units the welding gas is measured?

Welding gases are measured by volume, and the most commonly used units are cubic feet. (cf)

How long will a 20 cubic feet argon cylinder last?

In industries, argon is consumed at 25 cubic feet per hour. Hence, your 20 cf cylinder of argon will last almost one hour in MIG welding. At the same time, it will last for nearly half an hour of TIG welding.

Can you MIG weld aluminum with 75 25?

Yes, you can MIG weld aluminum with 75 25. It contains 75% argon mixed with helium and other gases. Pure argon gives excellent results for aluminum welding, but its mixture also gives strong weld and is less expensive.

Final Say

I hope after reading and understanding our instructions, you will be able to select the most suitable welding gas bottle for you. If you find this article helpful, do let us know in the comment section. Please don’t keep your hands from mentioning improvements for us. Plus, do share your experience with us!

Hello Everyone, I am James from Kentucky and been into this welding fiasco for 13 years in that time I have worked as a private welder and did most of the auto restoration work. In this recent, COVID-19 outbreak I decided to start a welding blog and share welding tips along with product reviews.

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