Replacement pH Sensors
pH Electrodes, and pH Probes

Unlike the rapid advances made in electronics the advance made in pH sensor technology have been more leisurely so any of our new pH Electrodes will usually work with our original pH instruments.

The biggest changes in pH sensor technology have been in the mountings and in the change from the P90S refillable electrodes to the newer PS90S sealed electrodes introduced in 1999. At this time the old calomel reference which contained mercury was discontinued. The original refillable pH electrode system had a 5/8” BSP thread which was changed to prevent the new sealed pH Sensors being fitted to the refillable dip tubes and being filled with the liquid salt bridge solution.

The original pH electrode holders made by many of the international instrument companies with separate glass reference and auto temp comps. These have now been replaced with sealed combination pH electrodes - which often outperform the originals and are very much simpler to maintain.

Look out for our new PS100S dip pH electrode with built in temp comp all manufactured in Kynar (PVDF) and the tuff tip pH sensor version PTT100S also in Kynar or PVC.

pH Probe Model P90S/R90S

pH probe, pH electrode, pH sensor Model PES2 - PES4 or PES7

Model P90S/R90S pH electrode / redox electrode system for submersion into open tanks, pits or sumps. Original systems were filled with 3.8 molar KCL solution and had a sight glass at the top. The electrode mounted via a 5/8” BSP thread now obsolete as the electrode contained mercury. Manufacture ceased in 1999.

Replacement pH Probe

Replaced with PS90S pH probe sealed or RS90S Redox probe sealed - which has a larger thread to prevent fitting the new electrode to the flooded holder. The pH Electrode / Redox Electrode is identical in size to the original, please advise the length required.

Model PES2 - PES4 or PES7

Model PES2 - PES4 or PES7 pH electrode system for submersion into open tanks, pits or sumps. Manufactured from PVC or Kynar and Polypropylene some had a stainless steel riser tube fitted with LB J-Box on the electrode top. (Commonly called the walking stick pH electrode). Manufactured from 1984, many still in use.