Due to the intense pressure associated with the pressure acid leach process, the previous sensors were only lasting a couple of days. The Turtle Tough sensor is now providing pH measurements that are accurate and reliable, and the sensors require very little maintenance compared to the previous sensors. They are lasting upwards of 5-10 times as long with far fewer maintenance requirements. This has not only reduced the cost of ownership, but more importantly provided confidence in measurement and improved process control.

Dissolved chlorine gases were deteriorating sensors so fast that calibrations were attempted twice a day, with a new sensors being used every 1-2 days. A special glass formulation was required for this application to provide chlorine and dissolved gas resistance. The Turtle Tough sensor provided much greater accuracy and was able to survive for months at a time, providing as much as a 12 times gain in life expectancy.

A large chicken farm ‘s pH sensors were only lasting 1-2 weeks in the wastewater treatment and water discharge monitoring locations. The wastewater treatment required the pH to be lowered from pH 10 to pH 4 to precipitate the solids out. The pH then needs to be raised to between 7 and 10 at discharge to satisfy local environmental regulations.

The high pressure acid-leach process at this nickel cobalt plant was destroying pH sensors. The initial problems were so severe that it made it near impossible to control the process. At many critical measurment points sensors were being destroyed within days, sometimes hours.

Several unique Turtle Tough sensor designs have been used throughout the plant to acheive the desired lifetime and performance. We are using some of our most extreme reference junction configurations, with triple junction, acid/fluoride resistance, sulfide resistance and teflon silicon sealing. The most extreme sensors requiring preamplification are typically mated to our TT-3TX and existing Rosemount analysers, while less demanding applications are utilising existing Yokogawa analysers.

A large sugar refiner wanted to reduce the cleaning and calibration frequency of the pH control system in their evaporation and boiling sugar refining process. High temperature, calcium deposits and viscous sugar syrup required aggressive cleaning and time consuming calibration. They were also experiencing frequent sensor failure and the replacement time was slowing production.

We designed a Turtle Tough sensor with a thick wall, crack resistant pH glass sensing element, combined with a specially engineered ultra-high temperature resistant non-porous conductive polymer reference system. By closely matching the expansion coefficients of all the components we were able to reduce sensor failure from the severe temperature cycling. A temperature sensor was embedded in a sealed design to avoid failure, which is common failure mode of many sensors. The resulting sensor greatly lowered maintenance frequency and sensor failure providing a greater product yield and reduced operating costs.