Peracetic Acid Analyzer Control System

The image on the left shows a typical installation consisting of the following devices:

• Filter – Typically a 60 micron filter is sufficient to keep particles and debris in the process water from entering the flow cell.
• Analyzer – The EMEC LDS PLUS series of analyzers are user-friendly, and automatically cater to the different sensors that can be attached.
• Flow Cell – The acrylic see-through flow cell incorporates the following items:
  • • Flow Sensor: on the left of the flow cell is a flow switch, and upon adequate flow the silver bullet shaped float rises and triggers the flow sensor indicating to the system that adequate flow is now present, and control functions can be activated.
    • Temperature Sensor: the RTD sensor is located above the silver bullet float, and is used for temperature readout or compensation if required.
    • Sensor: The larger green and beige probe is the Amperometric sensor for measuring the amount of Peracetic Acid in ppm and will be displayed on the Analyzer.
    • The flow cell also contains an inlet pressure and flow regulator, and an easily accessible water sample port.

With water analyzer systems, it may be challenging to accurately calibrate the analyzer due to the process ppm changing from the time the sample is taken, to the time the analyzer is actually calibrated.

For example: the analyzer is reading 1.05 ppm at the time the sample is taken. Then by the time the sample is confirmed by a 3rd party measurement (hand-held or lab test) to be say 1.3 ppm, then by the time the operator comes to calibrate the analyzer, the reading might be lower or higher than 1.05 ppm, so calibrating the controller to 1.3 ppm based on the analyzer initially 1.05 ppm would now be incorrect.

To solve this problem, we can provide a closed-loop water sample to the flow cell which would provide a stable sample to be calibrated correctly. Isolation valves are used to direct the water flow in a recirculated loop to the flow cell, while isolating the incoming process water. The system consists of a re-circulation pump, valves, fittings, and tubing to suit. The container would be supplied by the customer to suit the size and location of the process.

Download the re-circulation block diagram here