Originally Posted by
rutan around
Hydrogen is an odourless, colourless gas which is explosive when reacted with an oxidant but innocuous of itself.
Ammonia is corrosive so much so that liquid ammonia will corrode most common metal piping including those made of galvanised iron and copper. Concentrated solutions or gaseous ammonia will dissolve mucous membranes....ingest it or breathe it in and you will likely die. Ammonia is a strongly hydrophilic, nonflammable gas but will ignite at a temperature of 1204°F within vapor concentration limits between 15% and 28%. (Paper ignites at 450°F, coal at 750°F). Outside conditions that would support these vapor concentrations are rare. As noted elsewhere, it is easily liquified hence its early use in refrigeration until it became apparent the dangers outweighed the benefits.
Kaz