How is pH affected by flowrate?
pH itself is unaffected by flowrate but the measurement of pH can be. In most conventional applications (not high purity water) there will be very little influence of flowrate on a pH measurement. Small effects may occur at the reference electrode junction (diaphragm) and cause variations on the order of ± 0.1 pH for flow velocities past the sensor tip from 0-2 m/sec. The volume flowrate depends on the pipe size. Pressure may have some effect since it directly affects the reference junction, forcing trace amounts of process material into the junction. At very low or very high pH (<4 or >10 pH) this will have greater effect and could be on the order of ± 0.2 pH for large pressure changes, depending on the application. Cycling high pressures and flowrates will cause slight compression and expansion of electrolyte contents, cause electrolyte dilution or contamination in the junction and will shorten the life of a pH sensor. Maximum sensor life and performance are achieved by locating the
