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Product category: Level and tank contents instrumentation
News Release from: Yokogawa UK | Subject: ISC40 conductivity probe
Edited by the Processingtalk Editorial Team on 21 February 2005

Conductivity probe boosts chemicals
productivity

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A novel application of a Yokogawa ISC40 conductivity probe has helped to boost a leading manufacturer's productivity by dramatically reducing manufacturing cycle times for intermediate chemicals

A novel application of a Yokogawa ISC40 conductivity probe has helped to boost a leading manufacturer's productivity by dramatically reducing manufacturing cycle times for intermediate chemicals The conductivity probe is used in a process reactor to detect the interface between the chemical being produced and the layer of waste water which accumulates on top of the chemical during the manufacturing process

The waste water is removed with a 'dip pipe' suction device which moves up and down, and it is important to establish the exact point at which the dip pipe reaches the interface to ensure that all the water is extracted without removing any of the chemical.

Because the conductivity of the water (aqueous phase) is much greater than that of the chemical (organic phase), one obvious way of determining the interface point is to mount a conductivity meter on the end of the dip pipe.

The large swing in the reading when the meter crosses the interface gives a rapid qualitative method of establishing its exact position, irrespective of the actual conductivity value.

The conditions encountered in the process, however, present considerable challenges to the use of conductivity meters: in particular, the tendency of the chemicals to form coatings on immersed metallic electrodes which severely downgrades the sensitivity and accuracy of traditional conductivity instruments.

The Yokogawa sensor, however, uses an inductive technique in which the effects of fouling are mitigated, because the accuracy of the measurement is determined by the cross-sectional area of a 15 mm diameter aperture in the sensor.

In addition, the use of erosion-resistant materials such as PEEK (poly-ether-ether-ketone) means the sensor is able to withstand the harshest of environments.

The ISC40, which is used in conjunction with a Yokogawa IS202 transmitter, can also measure conductivity over a very wide range (from 1 uS/cm to 2 S/cm): more than enough for the changes encountered in the chemical application.

Prior to using the dip-pipe technique, engineers had to remove the waste water by a complex and time-consuming technique that involved transferring the water and chemical between two vessels.

This method was prone to blockages, the clearing of which involved human intervention and hence potential exposure to hazardous chemicals.

Using the dip-pipe technique has eliminated these problems.

The new system has not only improved manufacturing cycle times, but has also reduced operator exposure to solvent vapours and eliminated the possibility of blockages.

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