Under normal conditions in a double-interlocked water control valve, the water pressure under the clapper and in the differential chamber are ___________________.

In a double-interlocked water control valve, under normal operating conditions, the water pressure beneath the clapper and in the differential chamber is equal. This equal pressure is crucial for the proper functioning of the valve.

The design of the double-interlocked valve ensures that both chambers are balanced. When the system is in a standby mode, pressure differentials could lead to unintended valve activation. Therefore, the equal pressure prevents the clapper from opening inadvertently, thus ensuring that the system remains secure and effectively prevents water from flowing until needed.

Understanding this principle is important because it highlights how the valve operates in a reliable manner, maintaining safety and functionality in fire protection systems. The other options do not accurately reflect the operating mechanics of the valve, as they suggest either extreme conditions or imbalances that would typically indicate a fault in the system.