The saddle-type delayed water flow indicator is an important component of the wet automatic sprinkler fire extinguishing system. It is mainly composed of a valve body, a shell, a sealing ring, an air delay device, a switch assembly, a connecting plate, and blades. The saddle-type water flow indicator is generally installed at the beginning of the fire main pipe in each partition of the system. It can convert the water flow signal into an output electrical signal and send it to the electric control box or the fire control center to display the area where the sprinkler sprays water, so as to monitor the system and alarm. When a fire occurs, the sprinkler sprays water, the water flows in the pipe, and the blades in the impact water flow indicator are offset and tilted in the direction of the water flow. The air delay device is turned on. If the blades do not return to their positions after the delay setting time is reached, the micro switch is triggered to output an electrical signal. When the water flow stops, the blades and the push rod are reset, and the electrical signal is eliminated. The alarm signal is sent after a certain delay to prevent false alarms caused by instantaneous water pressure fluctuations in firefighting.