Redundant pH Probe Systems

Many pH control and neutralization processes must operate continuously. Some of these processes are so critical that they cannot pause for pH probe calibration or other required probe maintenance operations.

ChemIndustrial’s redundant pH probe option provides an elegant way to deal with this problem.

The sensor arrangement in redundant systems consists of dual pH probes in separate probe holders. They are arranged so they both sense the same liquid simultaneously.

In sample streams and other pipeline configurations the probes are mounted in parallel. Valving around the probe holders allows either probe to be removed without shutting down the process.

In vessels, ChemIndustrial uses similar mounting techniques to allow probe removal without shutting down the process.

ChemIndustrial pH control software supports redundant probes with the following capabilities:

• The pH process computer displays real-time values from both probes, and alarms if the difference between them exceeds a set limit.
• pH control action can be based on the value from either probe alone or the average of both probes together. Transfer between probes is seamless.
• Either probe can be taken out of active service for calibration, inspection or replacement. During this period, the other probe assumes full responsibility for sensing process pH.
• Either probe can be calibrated separately, with full support from the prompted calibration routine in ChemIndustrial’s pH Control Computer.
• The redundant probe option integrates with other ChemIndustrial options such as the AutoCalibrate™ automated pH calibration option and the AutoClean™ pH probe cleaning option.

The ChemIndustrial pH control computer’s ability to interface with multiple pH probes is often useful even when redundant probes aren’t needed. For instance, regulations may require a neutralizer discharge stream to be “monitored”. This usually requires a second, independent probe in addition to the one used to control neutralization. The ChemIndustrial pH process computer can interface with the separate monitoring probe, allowing its value to be displayed, recorded, retransmitted and/or logged depending on the options selected by the customer.