The purpose of the Firenor active pressure pulse compensator (APPC) is to protect the firefighting systems from damage by preventing pressure surges in the firewater distribution piping due to a deluge system or other water consumption systems activation before water pumps have started. Should a high flow firewater using system start before the fire water pumps, it will drain water from the ring main, creating a vacuum in the upper portions of the piping. To prevent this dangerous situation, a pressure control valve will discharge low pressure air into the upper sections of the firewater ring main. The system then continues to dynamically control the pressure in the firewater ring main by increasing air flow to avoid vacuum. This ensures that the entire system is properly pressurized at all times and prevents pressure surges in the firewater ring main.