We in the industry, generally are led to believe that Nitrogen, an inert gas, is by association with the word inert , also “safe”. This information resides somewhere deep inside of our subconscious mind, where we store a database of things that are “safe” and “dangerous” . Thus if anybody says “Hydrogen”, immediately the subconscious light bulb (alarm?) goes off and we carefully listen, work or design whatever it is that we are working on, which is related to Hydrogen.
In the same way, if somebody says “Nitrogen”, we immediately associate it with safety purging systems, tank blanketing systems, inertness and generally the subconscious tells us “Oh, its only Nitrogen. Nothing to worry about!” and we drop our guard while listening, working or designing or whatever it is that we are doing with respect to Nitrogen. We are in other words, lulled into a false sense of security.
However, we should now drill into our subconscious mind ( and also into the heads of our colleagues who handle Nitrogen), that Nitrogen can be very very deadly. It can act as an asphyxiant and choke a person to death in less than 40 seconds! When the US Chemical Safety Board started investigating accidents involving Nitrogen, they found that 85 nitrogen asphyxiation incidents occurred in the workplace between 1992 and 2002 . In these incidents 80 people were killed and 50 were injured. There is a very informative bulletin at the CSB website on this issue, please download it and print it out, then stick it on your Safety notice board/bulletin board. It can be a lifesaver for somebody.
Nitrogen tends to displace Oxygen from the air, whenever it comes in contact with it. Thus if a continuos flow of Nitrogen is released into air, the Oxygen level in the air depletes very fast and can choke a person who is breathing this Nitrogen rich air. Thus a worker who is carrying out a vessel inspection in a typical petrochemical plant (where the vessel most likely was purged with Nitrogen to rid it of explosive vapors), or somebody who is even standing near an open manhole of a vessel that has Nitrogen purging on, is at risk. Don’t believe me? Read the incidents mentioned in the CSB document above and you will.
It is always better to equip workers with Gas Monitors that detect the level of Oxygen and sound out an alarm, when the level drops below the normal level of 20.8%. It does not cost much and can save many lives. However the main reason is not the lack of instruments and devices, it is the subconscious alarm in the head that has to go off at the mention of the word “Nitrogen”.
Comments are always welcome, as usual!