• Suitable for waste water applications, with built-in preamplifier.

• Extra long service life.

• Easy mounting in tanks and reservoirs.

• Built-in preamplifier permits installation at a distance up to 200 m from measuring instrument.

• Cleaning head (optional) for electrode auto washing.

The online redox (ORP) sensor CH 250 I can be used with the RX 250 and RX 250 / W controllers or with the RX 255 online redox meter.

It is designed for  measurement of the redox potential (ORP) at waste water treatment plants (urban and industrial) and is also suitable for industrial water treatment applications, redox monitoring in public waters (rivers, lakes, reservoirs) and redox potential measurement in chemical, pharmaceutical and food industry.

It is suitable for immersion mounting in tanks and reservoirs.

It can measure the redox potential from -2000 to +2000 mV within the temperature operating range 0 - 60°C.

The type CH 250 I sensor consists of a PVC housing which carries the redox Pt electrode and the reference electrode at the lower end, while the upper end is equipped with a waterproof 5 pin connector.

A signal preamplifier is located inside the PVC housing, sealed with epoxy resin.

This design allows easy installation, connection with a single cable to the panel instrument and, due to the built-in  preamplifier, accurate and noise-free operation, even with a 200 m long cable.

A platinum (Pt ball) half cell and a silver / silver chloride reference half cell are used for the redox potential measurement.

The robust construction and the sensor design with a separate refillable and renewable reference electrode, provide reliable operation under conditions that conventional sensors fail to operate.

Our long experience in design, manufacturing and installation of pH and redox measurement and control systems, has shown that the reference electrode accounts for the 70 - 80% of the problems that arise in the pH measuring process, because of clogging of the liquid junction and / or pollution of the internal electrolyte.

In the most cases the only possible solution is to replace the redox electrode.

For this reason we gave extreme care to the reference electrode's design of the CH 250 redox sensors.

The glass fibres type liquid junction, with considerable contacting area, allows free flow of the internal electrolyte to the solution under test, minimizing the clogging problems.

At the same time the flow rate of the reference electrolyte is very low (compared with the total electrolyte's volume), avoiding the contamination of the internal solution and eliminating the need of frequent refilling and recalibration.

The lower part of the reference electrode with the electrolytic liquid junction is removable, providing:

• Easy replacement of the reference filling solution.
• Easy cleaning, regeneration or replacement (if necessary) of the reference liquid junction.
• Extra long service life (several years) without replacing the redox electrode.

The CH 250 I redox sensors - transmitters are available in two housing types:

• The type CH 250 I (standard type) :            stem length 94 cm.

• The type CH 250 I / L40 (short type) :         stem length 40 cm.

(total length, including the waterproof plastic cover of the electrical connectors)

Both types can be equipped (optional) with the type SCB 21 I cleaning head for automatic electrodes' cleaning (water jet type).

The online redox (ORP) sensors CH 250 I come with a 10m long interconnection cable type CL200/10 (different length on request).