In a small metal fabricating shop, two men were welding aluminium brackets when both men felt dizzy and collapsed before they could get out of the shop. A foreman bringing his truck in to be fixed at that moment opened a bay door and drove in. Seeing the men on the floor, he jumped out and called for help. By the time paramedics got there, the men were fine again. The foreman thinking the men were just fooling around ordered them back to work. He was considering firing them until he saw them weld after the incident. The welds were all black and uneven looking (proper aluminium welds never look this way). Then he realized what had happened and apologized to the men.
What happened?
Answer
The welders had a leaky valve on one tank and passed out when the Argon displaced all the oxygen in the small room they were welding in. The foreman opened the large bay door letting oxygen back in the room and revived the men. The foreman didn’t realize the tank had leaked until after he had seen the bad welds and realized the tank was empty. Then he knew what had happened.