Rosemount Analytical PERpH-X™ High Performance pH / ORP sensors incorporate several design innovations that prolong the life of the pH sensor in difficult hot processes. High temperatures, fouling, coating and poisoning conditions cause increased deterioration of the glass pH sensing membrane, increased depletion of the reference electrolyte, and increased thermal stress on all sensor components. Use the Model 3400HT/3400HTVP to lower your total cost of ownership and avoid frequent sensor replacement.