It is obvious that with phosphoric acid solutions having rich of %solids which are easily prone to fouling in heat exchangers , pipes , flash chambers ,condensers etc., Hence before admitting to the evaporators , it is depicting good results as evaporator performance is concerned when we reduce solids content. 1. Maintain high vaccum & low temperature restrict to high temperature operation which reduce supersaturation. 2. Always maintain level above calendria which will not allow the liquid to boil in calendria. 3.Operating under low level which tends to foul heat exchanger easily ( with no sufficient velocity) & as per pump performance characteristics curve.(cavitation) owing to which definetly cause imbalence in pump.