1. Description of Air Pressure Maintenance Device

The air pressure maintenance device, together with the pre-action alarm valve assembly, control panel, air supply unit, and pipeline accessories, constitutes the pre-action system.

The air pressure maintenance device consists of an electrical contact pressure gauge, check valve, pressure reducing valve, control valve, pressure reducing orifice plate, and filter, among other components.

The control panel, air pressure maintenance device, and air supply unit work in coordination to maintain the air pressure in the system-side pipeline network between 0.03 MPa and 0.05 MPa during normal operation, ensuring the integrity of the system-side pipeline network. They also monitor the operational status of all electrified components on-site in real time and provide feedback signals to the fire control center.

Product Standard: GB5135.14 "Automatic Sprinkler Systems—Part 14: Pre-action Equipment"

Design Code: GB50084 "Code for Design of Automatic Sprinkler Systems"

Acceptance Code: GB50261 "Code for Installation and Acceptance of Automatic Sprinkler Systems"

2. Functions of the Air Pressure Maintenance Device

1) During system setup, the pre-action system pipeline network is pressurized to 0.05 MPa via the quick air replenishment valve.

2) After system setup, the quick air replenishment valve is closed, and the upper and lower limits (0.03–0.05 MPa) of the electrical contact pressure gauge are used to control the start and stop of the air compressor.

3) When leaks occur in sprinkler heads or pipelines within the sprinkler network, the pressure in the pipeline network rapidly decreases due to the action of the pressure reducing valve, causing the pressure controller to activate. A low-pressure fault alarm signal is triggered when the pressure falls below 0.02 MPa.

4) Due to the function of the check valve, leaks in one sprinkler pipeline network will not activate the low-pressure controllers of other sprinkler pipeline networks. The leakage alarm clearly indicates the affected area, and when the system pipeline network is activated for water filling, it prevents water from flowing back into the air compressor, avoiding accidents.