Editor’s note: Our apologies to Dan Kay. Here at Industrial Heating we lost track of this third part of a July blog. But it’s never too late to be reminded of an important subject. Parts 1 and 2 can be found in June and July.
1. Oxygen sensor: If you use argon in your shop, then always place an oxygen sensor in any hole or pit in your shop floor into which people may enter. If the argon level gets too high, thus reducing the amount of air present and the amount of oxygen available to breathe (there should always be about 20% oxygen in the air), the oxygen-alarm should sound-off loudly and perhaps also be wired to a bright blinking light (not just in the pit, but also in the shop area near the pit) so that anyone caught in that situation is immediately warned to get out of the pit!
2. Harness: Additionally, if the person needs to climb down a ladder to get to the floor of the pit, then it is also wise to be sure they are wearing a harness with a rope attached to the top of the ladder (or to a railing around the top of the pit) so that the person can be pulled out of the pit without having to risk other people’s lives to have to go into the pit to try to bring that first person out.
3. Air blower: It is wise to also have an “air-mover” (fan, blower, etc.) that circulates fresh air into the confines in which people are working. Make sure (by using a hose, flexible-piping, etc.) that fresh air is indeed being blown into the work zone from outside the pit or enclosed work area, and make sure to have it blowing for several minutes before entering the space to work.
Note about bottom-loading vacuum furnaces: If the hot zone is still very warm when anyone tries to stick their head into the bottom of the raised hot zone, be aware that HOT argon will be much less dense than room-temperature argon and, thus, may not exit the hot zone as fast as one might think! Yes, there may be real danger even with a vertical hot zone that opens on the bottom. Use wisdom, and be careful!
Additional warning about diffusion pumps: Argon can also be trapped in a diffusion pump. Someone reported a couple of years ago about just such a situation. “There was a worker who took the top off of a diffusion pump (poppet valve) and reached in to replace an O-ring. He was overcome by the argon when he stuck his head down into the diffusion pump.”
Welders, beware! It is not uncommon for welders to work inside enclosed spaces (such as pressure vessels, etc.), and their welding torches often use argon as the shielding gas. Unfortunately, many welders have been involved with argon-asphyxiation accidents. So, welders also need to take proper precautions when entering enclosed spaces to weld (such as wearing a portable oxygen sensor, wearing a harness, having an observer outside, etc.).
A closing note about fan motors in furnaces using argon: Mike Mercer (Mercer Technologies Inc.) reports that it is possible to hurt your cooling-fan motor if argon is used as a backfill gas. He suggests that a good way to protect the motor is to make sure that the cooling fan runs on 240 volts and not on 480 volts.
Argon is an inert gas. It works well in many brazing applications, but it is also a very dangerous gas. In fact, there are reportedly far more deaths every year that result from the use of argon gas than from all other gasescombined!
Be wise! Be aware! Be safe!