What is carry over in boiler water system?

It is a harmful condition in which water is carried over from the boiler to the steam space. It may be cause due to the contamination of boiler water by excess of salts or oil. Foaming occur because of them. Also, too high of the water level, excessive boiler loads, and sudden load changes could also lead to this problem.

If it really happens, perform the water test and check the result, check to see any contamination for the water treatment equipment, chemical and the procedure.