How does the density of argon compare to air?

Argon is heavier than air, which is a crucial characteristic that impacts its use in welding. Air is primarily composed of nitrogen and oxygen, with an average molecular weight of approximately 28.8 g/mol. Argon, on the other hand, has a molecular weight of about 39.9 g/mol. This increased molecular weight makes argon denser compared to the average composition of air.

In the context of Gas Tungsten Arc Welding (GTAW), this density is significant because argon, being heavier, tends to settle down and can effectively displace air, creating an inert atmosphere around the weld area. This inert atmosphere protects the weld from contamination by moisture and other reactive elements present in air, ensuring a clean and high-quality weld. Additionally, because argon displaces air rather than mixing with it, it helps to maintain the quality of the weld by reducing the possibility of oxidation or other undesirable reactions during the welding process.