Large-scale weld shops often need to keep several different types of gases on-hand to account for different types of welds on a variety of metals and joining techniques. These gases are called shielding gases and are used to improve the quality of welds.
These gases are categorized as either inert or semi-inert gases and are commonly used in several welding processes including arc welding and MIG or TIG welding. The presence of atmospheric gases can reduce the quality of the weld or make the welding process more difficult. These shielding gases may be used in order to protect the weld area from oxygen and water vapor.
When choosing a shielding gas or gas mix, the three most important properties are their thermal conductivity and heat transfer properties, their density relative to air, and the ease with which they undergo ionization. Choosing the wrong gas can lead to a porous and weak weld or to excessive spatter, thus causing labor productivity inefficiencies to correct errors, re-do weak welds, or clean spatter drops. Either inert or semi-inert gases will be used for this purpose. Most popularly, helium and argon (or a mixture) will be used as the shielding gas. Pure argon and helium are generally used for nonferrous metals.
Also important for shielding gas applications is the surface type to be welded. Welding a flat surface requires higher flow than welding grooved materials, since the gas is dispersed more quickly. Faster welding speeds, in general, mean that more gas needs to be supplied to provide adequate coverage. Additionally, higher current requires greater flow and more helium than argon is generally required to provide adequate coverage.
Shops need to be able to manage and track their use of shielding gases for inventory and efficiency accounting purposes. Fox thermal mass flow meters can be used to measure the flow of these pure or mixed shielding gases whether at high or very low flows. The exceptionally broad measurement range (up to 1000:1 turndown, 100:1 typical), low pressure drop, and direct mass flow measurement of gases in standard volumetric units makes the thermal mass flow meter by Fox Thermal Instruments a perfect solution to your shielding gas flow measurement needs. Fox meters can be calibrated to measure any gas mix. The Model FT1 is built ready to be programmed to measure 2 or 3-gas mixes of any of the gases listed below (full list of gases available on the FT1 is shown on our Model FT1 Product page). For a weld shop that may need to change the concentrations of gases depending on the weld type, the Model FT1 makes the gas flow measurement switch between these gas concentrations easy with the push of a button!
Common gases and gas mixes for use as shielding gases are:
- Argon-carbon dioxide
Read more about Pure gas applications.
Fox Thermal Instruments strives to design and manufacture the most innovative and reliable thermal mass flow meter products to our customers. All Fox meters measure mass flow rate and are available in insertion and inline models. Fox models FT1, FT2A and FT3 are mass flow meters and temperature transmitters providing isolated 4-20mA and pulse output for flow rate, and a 4-20mA pulse output for process gas temperature or a second flow rate output.
Fox flow meters are often calibrated to measure air flow. Please review the product features for Models FT1, FT2A and FT3 for further information about our thermal mass flow meter products. If you’re not sure which meter is right for your shielding gas application, use our Help Me Choose app to find the ideal meter or Contact Us today!