There are three typical process-based problems, which damage or deteriorate pH sensors:

• high temperatures
• sensors becoming coated
• mechanical damages
  

In high temperatures the sensor is cooled by PASVE ® pH’s flushing function. In addition, the operating life of the sensor is prolonged when using PASVE ® pH, because the measurement is based on momentary and not on continuous measurement.

The sensor becoming coated is a physical process, where small spots from the pulp accumulate on the sensor’s surface. After the coating has started the sensor gets in a short time a covering layer of dirt to its surface. Regular water flushing prevents the fastening of the first dirt spot, and that is why the entire sensor remains clean. The entire sensor can get damaged or at least the measurement accuracy is reduced, when an effort is made to clean the fouled sensor tip with various treatments.

Mechanical damages directed to sensors are typical when tanks are cleaned. Water can be kept continuously in PASVE ph’s fluid channel, which protects the sensor from getting damaged and drying out during cleaning or maintenance of the tank, without the measurement accuracy or response time becoming deteriorated.

PASVE pH is a safe solution. The safety has been proven already in earlier PASVE types, the construction of which corresponds to that of PASVE pH. The detachment of the sensor in the measurement position is prevented. In addition, the manually-operated valve is equipped with locking of the operating position. Furthermore, the valve handle can be detached, without it the locking can neither be opened nor the valve turned. The valve equipped with a pneumatic or electric actuator can be connected to the control system and from there the customer-specificly designed backups of the operating position can be taken care of. If necessary, the actuator can be equipped with a springset, which returns the valve to a desired position when there is no operating pressure. It is not possible to move the valve by handpower. A double ball sealing to the outer air improves the safety of the operator.

Various design solutions, materials, actuators, limit switches and process connection options enable the suitability of PASVE pH to almost all industrial processes.