Massachusetts Wastewater Practice Exam

When a pH recorder indicates a reading significantly higher than the desired level, the first item to check would be the sensor. The sensor is critical in accurately measuring the pH of the solution and can often be the source of discrepancies in readings. If the sensor is malfunctioning or has been improperly calibrated, it could give false readings, indicating a higher pH than is actually present.

The health of the sensor is paramount because if it is staining, damaged, or worn out, it may not respond correctly to changes in pH and will therefore register an incorrect value. Before investigating other elements such as the acid supply or the feed pump, confirming that the sensor is functioning properly allows for a more isolated and accurate diagnosis of the pH issue.

Other components like the acid supply, acid feed pump, and transmitter may play roles in the overall pH control system, but they would not directly cause a misreading at the sensor level. Therefore, starting with the sensor ensures that the foundational measurement is correct before proceeding to investigate other potential issues in the system.