How many impulses must each round of a manual pull station coded alarm signal consist of?

A manual pull station coded alarm signal must consist of three impulses. This requirement ensures that the alarm signal is distinct and easily recognizable. The three impulses form a specific pattern that helps differentiate it from other types of signals in the fire alarm system.

When a fire alarm system receives this coded signal, the unique three-impulse pattern enables the system to identify the nature of the alert as being initiated by a manual pull station. This distinction is particularly important in systems where various signaling methods may be employed, ensuring clarity and reducing the chances of false alarms or misinterpretations during an emergency situation.

Understanding the necessity of the three impulses in the context of fire alarm systems emphasizes the importance of standardized signaling methods for effective communication and response during emergencies.