What is the supervisory signal range for a pressurized water tank level?

The correct answer is that the supervisory signal range for a pressurized water tank level is typically set at +/- 3 inches. This range is established to ensure accurate monitoring of the water level within the tank while allowing for minor fluctuations that could occur due to environmental factors or system operations.

The +/- 3 inches range strikes a balance between providing sensitive detection of significant changes in water level and preventing false alarms that may arise from normal operational variances. This helps in maintaining the integrity of the alarm system, ensuring it remains effective without being overly responsive to transient changes that do not indicate an actual issue.

In contrast, wider or narrower ranges might not be practical. A broader range, such as +/- 5 inches or -12 inches, could lead to missed alerts for critical levels that may require immediate attention. On the other hand, a narrower range like +/- 1 inch could result in frequent false alarms, causing alarm fatigue and undermining the reliability of the monitoring system. Hence, the +/- 3 inches range is the ideal compromise for effective supervision of pressurized water tank levels.