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Universal differential pH water quality sensors

Routine sensor replacement is a necessary maintenance step in continuous online pH monitoring.

The Sensorex SD7500 Universal Differential pH Probe extends the working lifetime of sensors, reducing maintenance frequency, without compromising accuracy and reliability, according to the manufacturer.

Universal compatibility with virtually any brand of conventional pH transmitter enables an upgrade of existing sensors for industrial and municipal wastewater treatment and neutralisation; metal finishing and plating; wet fume scrubbers; chemical processing; and other online water quality and process applications.

The SD7500 probe measures process pH differentially with three electrode sensors: a process pH electrode, a pH reference (actually a second measuring pH electrode in a known pH 7.0 buffered cell solution protected by a replaceable salt bridge reference junction), and a titanium ground electrode. The result is a highly accurate differential pH measurement that is virtually unaffected by ground loop measurement errors.

The three electrode design, coupled with durable Ryton Polyphenylene Sulfide (PPS) body construction, resists process contamination. The double junction construction of the replaceable salt bridge further guards against fouling, even in highly aggressive chemical environments. Automatic temperature compensation with an accurate Pt1000 RTD ensures pH measurement accuracy over a wide temperature range.

Differential pH sensors are designed so the double junction salt bridge and the buffered reference cell solution can be replaced in the field by on-site operators, at a much lower cost than total sensor replacement. Compared to conventional combination sensors, differential pH sensors provide measurements of greater stability, over longer periods of time, with less downtime and maintenance. Typical sensor service lifetime ranges from 3 to 5 years.

With a self-powered preamp and combination sensor output, the SD7500 Differential pH Probe can be used with most conventional online pH/ORP transmitters and controllers. This enables drop-in replacement in existing process installations, as well as easy integration into new systems. Manufactured in the USA, Sensorex’s SD7500 probe is backed by a two-year limited warranty.

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