Diammonium phosphate (DAP) (chemical formula (NH4)2HPO4, IUPAC name diammonium hydrogen phosphate) is one of a series of water-soluble ammonium phosphate salts that can be produced when ammonia reacts with phosphoric acid. Solid diammonium phosphate shows a dissociation pressure of ammonia as given by the following expression and equation:
P = the resultant dissociation pressure of ammonia
T = absolute temperature (K)
At 100C, the dissociation pressure of diammonium phosphate is approximately 5 mmHg. Accordingly, to MSDS of DiammoniumPhosphate from CF Industries inc.