pH Measurement in Paper Mill Headbox

Raw pulp typically has a higher pH than is desirable for paper
making. The addition of alum or sulfuric acid, either to the recycled whitewater feed or to the stock upstream of the fan pump, helps lower the pH to an optimal level. This lower pH level promotes binding of the fibers into the paper sheet. pH measurement in the paper mill headbox is difficult because of the high degree of suspended solids present in the pulp, making sensors prone to clogging and fouling. pH sensors in this application often require frequent cleaning and replacement. The Rosemount™ 396P pH/ORP Sensor was specifically designed for harsh, high suspended solids applications like paper making. The reference junction in the Rosemount 396P pH sensor has a high resistance to coating due to its large surface area and small pore size, greatly reducing the maintenance costs and downtimes typically associated with frequent sensor cleaning and replacement.