Ammonium dihydrogen phosphate (ADP), also known as monoammonium phosphate (MAP), NH4H2PO4, is formed when a solution of phosphoric acid is added to ammonia until the solution is distinctly acidic. It crystallizes in tetragonal prisms.
A 2127 (OTTO) Ammonium dihydrogenphosphate, GR 99%+ Cas 7722-76-1 - used as a fertilizer, but also as dry fire extinguisher.