The steam which is finally used for power generation, i.e. the steam which goes to the turbines has to be ultra pure. This implies that the water used for generating this steam should be in its purest form. Monitoring the pH value of the feed water gives direct indication of alkalinity or acidity of this water. The ultra pure water has pH value of 7. In steam circuit it is normal practice to keep the pH value of feed water at slightly alkaline levels. This helps in preventing the corrosion of pipe work and other equipment. Typical points in the steam circuit where pH should be monitored are : Drum water, High pressure heaters, Make-up condensate, Plant effluent, Condenser, Cooling water.