How to Choose the Right Cylinder Size for Welding?

Table of Contents > 1. Key Factors That Affect Gas Cylinder Choice 2. The Most Common Shielding Gas Cylinder Sizes     2.1 How to Calculate if a Shielding Gas Cylinder Is Going to Last Long Enough?     2.2 What Is the Best Cylinder Size for Beginner Welders?     2.3 How to Choose a Cylinder Size for Your Welding Applications? 3. MIG/MAG Welding Cylinders (CO(2) Cylinders)     3.1 Common CO(2) Cylinder Sizes     3.2 CO(2) Tank Use Time 4.0 How to Check How Much Gas is Left in a Cylinder?     4.1 How to Calculate Remaining CO(2) in the Cylinder 5. Final Thoughts 6. 🧐 How to Choose the Right Cylinder Size for Welding FAQ

Gas welding methods, such as MIG or TIG welding, require external shielding gas protection. Choosing the right shielding gas for the application and metal type is critical for high-quality welds.

However, that's not the only challenge during welding. Many welders, especially beginners, wonder how much gas they need. Shielding gases come in cylinders, and using the right size is crucial for cost-efficient operations.

In this article, we will help you choose the right cylinder size for your applications. The key is to find a perfect balance between enough gas and portability, so let's explore the options.

 Aluminum MIG Welding with 100% Argon Shielding Gas
Source: https://www.youtube.com/watch?v=3XgIVbJNeiU

Key Factors That Affect Gas Cylinder Choice

Shielding gas cylinders come in various sizes, from small ones for a few beads to enormous cylinders for large shops. Your goal is to choose a cylinder that strikes the right balance between portability and capacity for your applications.

Simply put, you don't want to use a cylinder that needs refilling every day. But you shouldn't use the largest cylinder that won't fit your shop or garage either.

MIG Welding in a Small Garage Workspace
Source: https://www.youtube.com/watch?v=_A2KdkBCBbY

So, to make the right choice, you will need to consider the key factors, including:

• Amount of welding you do: Do you lay a few beads, or do you weld larger projects and weldments?

• Frequency of welding: Do you weld every day, or just a few times a month?

• Gas flow rate: Do you weld in a draft-free area where you can get away with 15-20 cfh, or do you need higher flow to protect the welds?

• Available space in garage or shop: Do you weld in a small garage or dedicated shop with enough floor space?

Answering these questions will greatly help you set your goals straight. Once again, balance is critical for uninterrupted work and a clutter-free workspace, both of which promote safety.

But let's see what your options are.

The Most Common Shielding Gas Cylinder Sizes

Shielding gas cylinders vary in size, which directly affects the amount of gas they can store. Most commonly used cylinders for MIG and TIG welding can store from 20 cf (cubic feet) of gas (Argon or Argon/CO2 mix), up to more than 300 cf.

Common TIG Welding Gas Cylinder Sizes
Source: https://www.youtube.com/watch?v=X1OuWvuWDEk&t

Here is a quick chart of the standard shielding gas cylinder sizes and their dimensions:

Note: Keep in mind that actual sizes and dimensions may vary by the gas and supplier. Use this only as a reference chart, and check the actual sizes when buying a cylinder.

Understanding the basic ratio between volume and size will help you create a picture and compare it to your goals. For example, 300+ cf cylinders are approximately 55 inches tall and weigh 130–143 lbs, so bigger is not always better. However, if you spend hours under the hood daily, they can be most cost-effective for your work.

How to Calculate if a Shielding Gas Cylinder is Going to Last Long Enough?

The goal when choosing the right cylinder is to have enough shielding gas to complete the project without refilling it. To calculate if the cylinder is going to last long enough, divide the volume of the tank by the shielding gas flow:

Available welding time (hrs) = cylinder volume (cf) / gas flow rate (cfh)

For example, if you are using a 40 cf tank with a 20 cfh flow rate, you get 40 cf /20 cfh = 2 hours of welding time. Although it sounds simple enough, this is just a rough estimation. In reality, the consumption may vary with temperature differences and the number of starts and stops.

Gases in the cylinder expand and contract with changes in temperature and pressure, thereby affecting volume. In addition, if you have pre-flow and post-flow settings, they can also speed up the consumption.

However, rough calculations will help you estimate if there is enough gas for your needs and projects. Frequent refills are actually pricier since they include additional trips and downtime. Nonetheless, as a beginner or hobby welder, having a large tank can be unnecessary and take up a lot of storage space.

What Is the Best Cylinder Size for Beginner Welders?

For most hobbyists, beginners, and home welders, 80 CF tanks provide the best value. With an average flow of 15-20 cfh, these provide roughly 4-5 hours of welding time and are portable and easy to store.

80 CF vs. 200 CF Tank Size Comparison
Source: https://www.youtube.com/watch?v=TC1plUM_-gE

Here are the most common uses for the different-sized cylinders

Welding Gas Cylinder Size Chart
Source: https://www.youtube.com/watch?v=LkBajnQdr-w

As noted, 80-125 cf is a sweet spot for most home and hobby applications. These tanks have sufficient volume for various welding applications and don't require frequent refills (in hobby MIG and TIG applications).

In addition, medium-sized cylinders are not super heavy or large. Most commonly, these weigh 56-71 lbs (when full), and they are 35-45 inches high. As a result, they won't take up too much space in your shop and garage, while still providing enough gas for uninterrupted work.

How to Choose a Cylinder Size for Your Welding Applications?

Although volume is often crucial when buying a gas cylinder, other factors matter as well. You need to consider frequency, portability, project size, and available storage. Here are some recommendations for your most common welding applications.

• DIY Projects and Repairs: If you weld only a few times a month for occasional repairs or DIY projects, you can go with small cylinders (20-40 cf). A limited volume shouldn’t be an issue for you, and the tank won’t take too much space. Portability and space-saving in occasional welding are crucial, so you don’t need a too-large cylinder. However, if you weld weekly or more, consider a larger tank (80-125 cf). 

• Home and Garage Hobby Welding: Medium-sized cylinders (around 80 cf) provide a good balance between portability and volume. These are ideal for home and garage hobby welding, especially if you weld quite frequently. They won’t run out too quickly, but they still don’t take too much space in your garage.

• Small Fabrication Shops: If you are running a small fabrication shop with frequent TIG and MIG welding, you will need a 100 cf or larger cylinder (125 cf+). These are ideal for frequent applications, including large projects, fabrication, and weldments. In the fab shop, you will need consistent flow rates and won't have unnecessary interruptions.

• Industrial, High-volume Welding: Professional, industrial, and high-volume MIG and TIG welding need large cylinders. Commonly, these are big, fixed 300+ cf cylinders that can, and must, run day and night. In high-volume applications, large cylinders offer the best value because they reduce unnecessary downtime. Frequent refills are actually time-consuming, increasing the overall costs in industrial welding applications.

MIG/MAG (GMAW) Welding Cylinders (CO2 Cylinders)

Due to lower shielding-gas costs, many welders turn to CO2 for MIG welding. CO2 is much cheaper than inert gases because it is an abundant byproduct that is easily captured.

People use it in various applications, such as breweries, aquariums, scuba shops, and welding. It is not uncommon to use 100% CO2 shielding, resulting in a welding process called MAG (Metal Active Gas).

100% CO₂ for MIG Welding
Source: https://www.youtube.com/watch?v=pTsithkxj8U

Welders often use CO2 in MIG, especially in a mixture with Argon, but keep in mind that cylinders for pure CO2 are different. There are two major differences:

1. Fittings: CO2 cylinders use CGA 320 valves and fittings, whereas inert gas cylinders, such as Argon or Helium, use CGA 580 fittings. You cannot use the same regulator you would normally use for Argon. The regulator won't fit, and it can freeze as the CO2 expands from liquid to gas.
2. Measuring volume: Although CO2 is a gas, it is measured by weight rather than volume. In cylinders, CO2 is stored as a liquid that maintains constant pressure until almost empty. Although pressure may vary slightly with temperature, it remains consistent at 750–2000+ psi. That's why the industry sizes CO2 tanks by weight, not by volume, unlike Argon/Helium.

Once you start welding, CO2 expands from a high-pressure liquid to a gas. However, you are still buying cylinder sizes based on CO2 weight.

Common CO2 Cylinder Sizes

Due to its versatility, CO2 finds use in various industries. Cylinder sizes vary by application, from small 1-1/4 to giant 100 lb tanks. However, these are the most common CO2 cylinder sizes used for welding:

Keep in mind that dimensions may vary between manufacturers and suppliers. These are approximate dimensions, and for precise numbers, contact the supplier.

CO2 Tank Use Time

Since CO₂ cylinders are typically rated in pounds, estimating welding time can be simplified using the gas expansion ratio. This allows us to convert liquid CO₂ weight into usable gas volume for flow-based calculations.

Available welding time (hrs) = (CO₂ lb × 8.74) ÷ flow rate (cfh)

If we assume an average flow rate of 20 cfh, we can estimate the approximate welding time for different cylinder sizes:

Once again, these are just rough estimations. In reality, gas consumption may vary depending on environmental conditions, post-flow and pre-flow, arc duration, and other factors.

If we compare CO2 to Argon/CO2 cylinders, a 10 lb CO2 cylinder would be a perfect match for most light-duty fabrication, hobby, and home projects. Considering the dimensions and welding time, it offers the best balance between volume and portability.

How to Check How Much Gas Is Left in a Cylinder?

Having your gas run out in the middle of a weld is the worst thing that can happen. To avoid these inconveniences, check the cylinder before welding. Here is how to check the amount of gas left in a cylinder.

Argon (Argon/CO2) cylinders: To read the remaining gas, use a dual-gauge regulator, such as the QB01 Argon/CO2 Welding Flow Meter Gas Regulator. One gauge helps you read and adjust the gas flow (cfh), and the other reads the cylinder pressure.

Full tanks typically have a maximum pressure of 2015 psi. As you use the gas, the pressure drops. For example, if the pressure reads 1000 psi, you have roughly half a cylinder left.

However, as mentioned, these are just rough estimations. Pressure can drop due to drastic temperature changes. Also, poor regulator quality can lead to inaccurate results, so make sure you buy it from a trusted supplier, such as YesWelder.

As the pressure drops, you will also have to adjust the flow. So, pay attention to both gauges as you weld. The best practice is to set the flow to 0, then adjust it for the next job.

How to Calculate Remaining CO2 in the Cylinder

For CO2 cylinders, don't rely on the pressure gauge. As noted, CO2 cylinders maintain consistent pressure until almost empty, at which point the pressure suddenly drops. Instead, look for the tare weight (TW) specified by the manufacturer.

Tare Weight on a CO₂ Cylinder
Source: https://www.youtube.com/watch?v=1GEMiVoQ9YI

A tare weight is the weight of the tank when empty. You can find a stamped number labeled TW on the shoulder of your tank. To calculate the amount of gas, measure the tank's current weight and subtract the tare weight:

Remaining CO2 = Current Weight - Tare Weight (TW)

For example, a tank with a TW of 8.9 lb that currently weighs 10 lb has 1.1 lb of CO2 (~9.5 cf) left. Use a bathroom or kitchen scale to weigh the entire tank. For maximum accuracy, remove the regulator or subtract its weight if you need a precise measurement. However, its weight is often negligible, especially for rough estimates.

Final Thoughts

Shielding gas plays a crucial role in welding, protecting the molten weld puddle from contamination and ensuring the highest-quality welds. Shielding gases come in cylinders, and choosing the right size is crucial for convenient welding.

The larger the cylinder, the more gas it holds. That means you can weld longer without a refill, which is, in most cases, the most cost-efficient option. However, storing gas in large cylinders is bulky and can take up a lot of space.

Meanwhile, small cylinders are favored for their portability and ease of fabrication. They are ideal for on-field repairs and occasional welders who don't use too much gas. The key is to find a cylinder that holds enough gas for your project while being portable.

🧐 How to Choose the Right Cylinder Size for Welding FAQ

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