... with a complete phosphorous chemical industrial, from yellow phosphorus. 1-Hydroxy Ethylidene-1,1-Diphosphonic Acid (HEDP)CAS No.: 2809-21 ... dosage of 1-10mg/L is preferred as scale inhibitor, 10-50mg/L as corrosion inhibitor, and 1000-2000mg/L as ... with eye and skin, once contacted, flush with water. 1-Hydroxy Ethylidene-1,1-Diphosphonic Acid (HEDP)