What type of pressure is used in a water-based fire alarm system?

In a water-based fire alarm system, "wet pressure" refers specifically to the pressure maintained within a sprinkler system where water is kept in the pipes at all times. This type of system is commonly used in fire protection to ensure that when a sprinkler head activates—typically due to the heat of a fire—water is immediately available to suppress the fire.

The term "wet pressure" indicates that the system is filled with water, allowing for quick response times when fire is detected. By keeping water readily available in the system's piping, it ensures that activation leads to immediate water discharge, which is crucial for effective fire suppression.

Other options discussing different pressure types do not accurately describe the operation principle of a typical water-based fire alarm system. Low pressure for initial activation and high pressure for rapid response may not apply universally across systems, as water-based systems often rely on controlled wet pressure rather than fluctuating between low and high pressures. Similarly, the use of compressed air pressure is not relevant in the context of a water-based fire alarm system, as that pertains to dry pipe or pre-action systems but not directly to the water being utilized for suppression in a sprinkler system.