Beverage CO2 and welding shielding gas are purchased for different acceptance criteria. For carbonation, obtain gas identified and documented as suitable for the intended food use. For welding, select the mixture for the base metal, welding process, filler wire and applicable welding procedure specification (WPS). A purity percentage or a cylinder's trade label does not establish suitability for both jobs. [S1][S2][S5]
Compare the application, not just the purity number
| Application | Selection starting point | Important boundary |
|---|---|---|
| Beverage carbonation | Documented food-use suitability and the purchaser's contaminant specification. | Food law and customer requirements are not replaced by a headline purity percentage. [S3][S5] |
| Mild-steel MIG/MAG | C25 (75% argon / 25% CO2) or another mixture permitted by the wire and process. | Pure CO2 is also used in suitable applications, with different arc and spatter characteristics. [S2] |
| Stainless steel, solid-wire MIG/GMAW | A manufacturer-specified low-active-gas mixture. | Do not treat C25 as a general stainless-steel recommendation. [S1] |
| Stainless steel, gas-shielded flux-cored wire | The shielding gas stated for that particular wire. | Some stainless flux-cored wires use 75% argon / 25% CO2; this does not establish suitability for solid wire. [S1] |
| Aluminum MIG | Argon or a suitable argon/helium mixture. | Do not substitute a CO2-containing steel-welding mixture. [S2] |
Why 99.95% is not a universal food-use rule
Neither “food grade” nor “beverage grade” should be reduced to one worldwide legal percentage. EIGA Doc 126/20 distinguishes food additives, processing aids and ingredients, and summarises EU and JECFA specifications as understood when that edition was issued. Those distinctions matter: a supplier specification, an industry guideline and a legal requirement are not interchangeable. Confirm the current rules for the market and intended use rather than treating this article as a compliance certificate. [S3]
Specify the required assay together with relevant impurity limits, testing and acceptance documentation. A higher assay alone does not demonstrate food-supply-chain control. EIGA's food-gas guidance also addresses identification, traceability and hygiene. [S5]
Stainless, mild steel and aluminum need different shielding choices
For stainless MIG, Miller describes argon- or helium-rich mixtures with less than 5% CO2. Its guidance separately identifies 75/25 argon/CO2 for suitable stainless flux-cored wires. These are different process and consumable cases, not conflicting universal rules. Follow the filler manufacturer's recommendation and applicable WPS; any required procedure change must go through the relevant qualification process. [S1]
For aluminum MIG, Miller identifies argon and argon/helium mixtures and warns that CO2 introduces weld contamination. Its C25 guidance concerns mild steel, not a universal mixture for every metal. [S2]
Supplier and cylinder suitability require controlled decisions
Supplier count is not a substitute for food-gas controls. EIGA Doc 125/20 requires documented filling processes and addresses inspection, traceability and controlled changes of container service; it does not impose the blanket “different suppliers” rule previously stated here. The same document allows container service changes under documented cleanliness and control procedures. It therefore does not support a claim that a cylinder's prior industrial service permanently disqualifies it. [S4]
This is not permission for a user to swap cylinders, regulators or hoses between systems. Ask the gas supplier to confirm food-service suitability and have the responsible installer assess the actual installation. Unknown history or missing acceptance documentation is a reason to stop and resolve suitability, not to assume equivalence. [S4]
Procurement checks before ordering
- State the intended food or welding application and the specification used for acceptance.
- For food use, request identification, traceability and quality documentation appropriate to the agreed specification. [S5]
- For welding, identify base metal, filler classification, transfer mode and the gas allowed by the consumable instructions and WPS. [S1][S2]
- For dry ice used as food, confirm that its source CO2 is certified for food use and that production and delivery preserve hygienic handling. [S5]
The industrial gas reference provides broader terminology. This article is a procurement comparison, not a food-safety approval, installation instruction or qualified welding procedure.
Editorial correction, 23 October 2026: The previous version generalised stainless shielding-gas mixtures and made unsupported universal purity, supplier and cylinder-history claims. Those statements have been replaced with application-specific boundaries and primary guidance.