Posted By Smurfer Can anyone help me with identifying the likely gases/vapours (NO2?) emitted from a catastrophic release of conc nitric acid, and how I might be able to calculate the amount of gases/vapours released? Thanks Andy

Posted By Robert K Lewis Or even a chemical plant full. Seriously this is not an easy one to answer as far as gas volumes are concerned. It depends on the initial concentration of the acid, temperatures,the amount spilled, humidity and a host of other variables - including the materials with which it then contacts. Unless you are a chemist I would not even attempt this calculation The gases are more straightforward as there is only Nitrogen Dioxide, more strictly Dinitrogen Tetroxide according to many authorities, that will be of real concern - The other possible gases are also acidic but less strongly so. Bob

Posted By Jane Blunt I agree with you there, Bob, but it is worth asking the question of how much. Ultimately you may have to make a decision between dealing with a spill yourself and shutting the door and calling the Fire Brigade. I found this emergency plan on the internet: http://www.uwm.edu/Dept/EHSRM/EMERGENCY/lepc.html It's a good idea to have thought this one out before the day you spill it. It is also a good idea to have thought through all the things you can do to prevent the catastrophic release. Nitrogen dioxide is a very dangerous gas. It has an exposure limit of only 2 ppm (8 hour) and it has a track record of killing people if they are over-dosed. At the time they do not necessarily know that they are being seriously affected. Nitric acid is a very strong oxidising agent, which in practice means that if spilled on the wrong kind of material things can get extremely exciting. This is over and above its behaviour as an acid. See http://www.dailybruin.uc...97/05.28/news.spill.html Jane