Argon is a favorite gas used in many vacuum brazing shops since it is an inert gas that will not react with any of the metals being heat treated or brazed in those vacuum furnaces. Thus, dry argon (as measured by a dewpoint meter right at the furnace) is often used for partial-pressure brazing applications, for rapid-cooling needs or merely as a gaseous atmosphere to allow better conduction of heat between components inside the furnace. But argon can also be dangerous or even lethal!  

Argon is an odorless, colorless and tasteless gas. Because it is heavier than air, it will to flow to the lowest spot, often down into holes or pits built into your shop floor. Many companies build those pits in their shop floors so that equipment can be lowered down into them, thus eliminating the need to add height to the ceilings of the buildings. When people enter these pits in the shop floor to work on the equipment, they may unknowingly be breathing argon that has flowed into and filled that pit. Then, with no warning, they can collapse, having passed out from argon asphyxiation. If they are not quickly pulled out of the pit, they can die in a matter of minutes.

True Story: Some years ago, a worker went down into a pit in a shop to work on the bottom of a tall piece of equipment. He apparently did not know that the argon being piped into the shop area had been leaking and had filled that pit. As he was working on the base of the equipment, he collapsed from argon asphyxiation. His buddy must have been walking by and noticed him lying on the floor of the pit. He quickly climbed down the ladder into the pit to see what was wrong with the first worker to try and help him. This happened on a Friday evening. They were found in the pit on Monday morning, both dead. The rescuer was slumped at the bottom of the ladder with the first guy on his shoulder.  

REMEMBER: Argon is heavier than air. It doesn’t mix with the air but replaces it instead! As the pit fills with argon, the air is pushed out. Thus, no oxygen remains to support life!