Ammonia/Air Flammability Limits
Ammonia/Air Flammability Limits
(OP)
The flammability limits of ammonia/air mixtures are well documented at atmospheric pressure, but I am looking for the limits at pressure up to 140 psig. I know that at 130 psig the lower flammability limit is around 11.2-11.5% by volume. Does someone know where I can find a graph or table with the flammability limits at various pressures?





RE: Ammonia/Air Flammability Limits
UFLp = UFL + 20.6 (logP +1)
P is given in megapascals. UFL is the vol% in gas + air at atmospheric conditions, in this case 25%.
In the case in question, at 140 psig (=157 psia = 1.082 MPa) the estimated new UFL = 25 + 20.6 (log 1.082 + 1) = 46.3%. Showing the sensitivity of the UFL to pressure, and the broadening of the explosivity range.
The same comment I made then, I repeat here:
When the pressure is atmospheric P = 0.1 MPa, the log becomes -1, and the addition cancels out.