Automotive production lines and 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.
Plant managers must 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 a perfect solution to your shielding gas flow measurement needs. Fox Thermal meters can be calibrated to measure any gas mix. Models FT1, FT4A, and FT4X are built ready to be programmed to measure gas mixes using the Gas-SelectX® gas selection menu tool. When the gas type or gas concentrations change, Gas-SelectX® makes the gas flow measurement switch between these gas concentrations easy with the push of a button!