What condition must be met for a pressure tank supervisory signal in a pressurized limited water supply?

In a pressurized limited water supply system, it is essential for the supervisory signal from the pressure tank to indicate both high- and low-pressure conditions. This is because maintaining proper pressure levels is crucial for the effective operation of fire alarm and suppression systems.

When both high and low-pressure signals are monitored, it ensures that the system can respond appropriately to various operational states. A low-pressure signal may indicate that the water supply is insufficient to meet the demand, which can compromise the effectiveness of the fire suppression system. Conversely, a high-pressure condition might suggest a potential failure in the system, which can also be dangerous. By having a supervisory signal that covers both scenarios, it allows for proactive measures to be taken to mitigate any risks associated with pressure fluctuations within the water supply.

This comprehensive monitoring is vital for ensuring the overall reliability and safety of fire protection systems, as it facilitates appropriate responses to maintain operational integrity.