IC Controls Ltd.

Reliable pH measurement in Oily applications


Courtesy of IC Controls Ltd.

pH measurement in the petrochemical industry is frequently extremely difficult. Operating in high temperatures with highly reactive contaminants traditional pH reference electrodes can, in some applications, last only days.

IC Controls 613 sensors reference is designed for difficult applications particularly where fouling or poisoning conditions exist. The reference uses a highly stable non-porous polymetric interface in place of the traditional porous liquid junction used by all conventional reference electrodes. The active reference area is the whole of the outside surface of the polymer, this large contact area means that the electrode is supremely resistant to coatings. Poisoning effects are eliminated because the polymetric reference material is ionicly conductive, but is not porous, consequently electrolyte and process fluids are not exchanged.

The advanced solid-state nature of 613's reference electrode mean they remain extremely accurate and reliable across a wide range of conditions, including:

  • Temperature: 0 to 90°C
  • Pressure:0 to 20bar

In addition, 613 reference is immune to chemical poisoning and sensor fouling

pH Sensor Fouling
One of the major problems for traditional pH sensor technologies in the petrochemical industry is sensor fouling and deposit coating. A layer of debris and/or an oily film can develop over the surface of the sensor. Traditional porous junction reference electrodes are vulnerable as they rely on an electrochemical connection between the process flow and the internal half-cell. If this connection is contaminated then the impedance increases substantially and the measurement becomes inaccurate.

In comparison, the 613's entire polymetric reference body provides the ionicly conductive electrochemical connection. As a result 613 sensors are highly resistant to the effects of fouling and coating. There is no specific junction to become clogged and as long as the outside surface of the sensor remains wet the signal from the sensor will remain stable.

In addition, as the ionicly conductive connection possesses an inherently higher junction impedance than most traditional reference electrodes the increase in impedance due to fouling has a much lower effect even when the fouling is advanced.

When cleaning is necessary, for instance when the coating becomes sufficient to affect the glass electrode, 613's chemically resistant body can be cleaned in exactly the same manner as the glass is, whether by detergent, acid or a caustic wash.

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