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On the Design of Automatic Fire Alarm and Fire Fighting Control Systems for High-Rise Buildings I. Introduction: With the advancement of urban modernization, there are an increasing number of high-rise buildings. According to relevant standards, automatic fire alarm systems must be installed in such buildings. Here, I would like to share my personal views on such designs, focusing solely on the design of automatic fire alarm and fire suppression linkage control systems. II. Overview of the project: Zhongji Fortune Garden is located near the Beijing Asian Games Village. The entire complex consists of a main building and an annex building. There are two basement levels used for civil defense purposes, while the first basement level serves as a parking lot and space for equipment. Floors 1 to 4 are occupied by shopping malls, and floors 5 to 22 are residential units. The annex building houses a water pump room, substation, boiler room, administrative offices, etc. The total construction area is 50,000 square meters. III. Design of the automatic fire alarm and fire linkage control system: 1. Determination of the approach: When designing the automatic fire alarm and fire linkage control system, it is first necessary to identify the architectural and functional characteristics of the building itself. It is also important to understand the facilities provided by other specialized fields in the building’s fire protection design, especially the design requirements imposed by the ventilation and water supply systems on the electrical systems. Based on relevant standards, the nature of the building is determined, which in turn helps to establish the overall structure of the system. In accordance with the Code for Fire Protection Design of High-Rise Civil Buildings and the Code for Design of Automatic Fire Alarm Systems, this project is classified as a Class II high-rise building, and it falls under the category of structures that require secondary automatic fire alarm protection. The automatic fire alarm and fire suppression linkage control system of this building adopts a centralized alarm system, which consists of the following components: A. Fire control room (located on the ground floor): equipped with a centralized alarm controller, bus linkage control panels and multi-wire linkage control panels, as well as a fire telephone switchboard and fire announcement equipment. B. Detection circuits: 1. Temperature sensors: Installed in underground parking garages and other areas where smoke is likely to be present. 2. Smoke detectors: Installed in the elevator lobbies of residential areas, public corridors, and evacuation stairs; in the business halls of shopping malls and in all rooms except bathrooms; as well as in fire pump rooms, substation rooms, elevator shafts, duty rooms, and other public building areas. 3. Fire hydrant button: located inside all fire hydrants (provided by the plumbing department). 4. Manual alarm button: underground parking lots, as well as public areas in the shopping mall and residential sections. 5. Flow indicator and wet alarm valve: provided by the plumbing department regarding their location. C. Control circuit: 1. Fire alarm speakers and audible/visual alarms: Installed in the same locations as the detectors. 2. Fire shutters: Installed in underground garages and shopping malls. 3. Positive pressure exhaust fan: installed on the roof. 4. Smoke exhaust fan: Provided by the ventilation team, including smoke exhaust outlets and fire dampers. D. Others: Emergency lighting and evacuation indication lighting, located as follows: 1. Fire elevators: Provided by the architectural team. Underground garages, shopping malls, public corridors in residential areas, elevator lobbies, and evacuation stairs. The tasks to be carried out by this automatic alarm and fire suppression control system are as follows: the control center monitors the detection circuits; when a fire breaks out in a certain detection area, the detector there captures the signals from the scene and immediately sends them back to the controller in the control center. The controller processes these signals and, once a fire is confirmed, sends out audible and visual alarm signals as well as emergency announcements to the location of the fire ； In addition, the interlocking control sends execution signals to the fire protection devices that need to be interlocked, including turning on the emergency lighting and evacuation indicator lighting ； Start the fire protection pump and the supply fan ； Start the smoke exhaust fans at the fire scene, and open the relevant smoke exhaust openings and fire dampers ； Force the elevator to stop and put the fire elevator on standby ； Cut off non-firefighting power supplies to extinguish the incipient fire. 2. Composition, functions, and features of the control center: The control center is located on the first floor and is powered by two power supplies with automatic switching at the end points; its composition was described earlier. The fire alarm controller selected for this design is the SAN040 intelligent fire alarm controller, featuring an 8-channel design with 127 address codes per channel; only one controller is required. The system features a simple structure and high reliability. By connecting the SAN100 type interlocking control panel to this controller via the internal standard RS—232 port, a full-bus alarm interlocking controller can be formed, thereby replacing the previous control mode that used separate buses for alarms and interlock functions. The interlocking control module, monitoring module, and various detectors all use the same bus, and the interlocking points can be assigned arbitrarily among 8 circuits, which significantly simplifies the wiring requirements. Its main features include: a. Microcomputer-based control with 32Kbyte of high-performance monitoring software; bus data transmission is carried out using PWM, resulting in strong resistance to interference ； b. The connection to the detector and modules is done using a non-polar two-wire system; either a tree structure or a ring structure can be used ； c. It has an internal operational memory (i.e., a black box) that is not lost in the event of a power outage, providing a reliable basis for analyzing the causes of the fire ； d. Automatic detection function ； e. It is possible to “activate” or “isolate” any number of detectors. The interlock control selected for this design is of the SAN100 type, which features: A. a plug-in box structure that can be combined arbitrarily depending on the number of devices to be controlled ； b. The linked devices are connected to the detector via modules on the same bus, enabling full-bus control ； c. The design of the “automatic,” “manual,” and “disabled” switching switches prevents accidental operations. The multi-wire brake control panel selected for this design is of the SAN110 type; it is designed specifically to control the main firefighting equipment in fire protection systems, such as fire pumps, exhaust fans, and supply fans. When connected to the SAN040 controller, it enables automatic control of these devices through interlocking logic, and it is also possible to manually control them using the start buttons on the control panel. 3. Detection circuit: The detection circuit includes detectors, manual alarm buttons, fire hydrant buttons, water flow indicators, pressure switches, etc. The selection of components for this circuit will not be discussed in detail here. It should be emphasized that manual alarm buttons must be installed in prominent locations at the entrances and exits of each floor, at a height of 1.5 meters. Moreover, the walking distance from any point within a fire compartment to the nearest manual alarm button must not exceed 25 meters (this requirement is in line with JGJ/T16—92; the national standard GB50116—98 requires a distance of 30 meters). 4. Fire alarm broadcasting system and alert devices: This design incorporates a bus-based fire alarm broadcasting system. Under normal conditions, it is used for playing background music and regular announcements; in the event of a fire, the control center’s output unit sends commands via signal lines to the relevant audio-visual alarm drive modules or the bus-based fire alarm broadcasting modules. In the case of a fire in the basement, the systems are activated in all floors below as well as on the ground floor ； In the event of a fire on the first floor, it will connect to all the floors below ground, as well as the first and second floors ； In the event of a fire on the second floor or any higher floor, the lighting in that floor as well as the adjacent upper and lower floors should be turned on first to assist evacuations of people on site. The power of the fire alarm speakers should be no less than 3W, and it must be ensured that the walking distance from any point within a fire compartment to the nearest speaker does not exceed 25 meters. Based on the layout of each floor, a certain number of bus fire alarm broadcast modules are installed on each floor to control the speakers in different areas of that floor. To ensure that fire alarm signals are sent to the affected areas in case of a fire, this design includes not only a fire emergency broadcasting system but also a certain number of fire alarm devices such as electric bells and light alarms, which are installed at the entrances and exits of main passages, at stairwells, in elevator lobbies, next to manual alarm buttons, and beside fire hydrant buttons in each alarm area. 5. Fire telephone system: The fire telephone system is a multi-line system; the capacity of the telephone main units is determined based on the requirements of the project. In accordance with relevant standards, fire telephone extensions are installed in the fire pump rooms, power distribution stations, main ventilation and air conditioning rooms, elevator shafts, duty rooms, and control centers ； Telephone jacks are installed at the manual alarm buttons on each floor, and the control center’s telephone switchboard uses a radial wiring scheme to connect them to the fire telephone extensions and telephone jacks. The call connection between the fire alarm switchboard and telephone extensions or jacks is direct; the lines are wired separately, forming an independent fire communication network. Since the floor areas of the various floors are not very large, a single telephone line is shared among the telephone jacks located in the building’s layout areas. The capacity required for the telephone main unit in the control center is more than 60 lines; therefore, a main unit with a capacity of 80 lines was chosen. 6. Fire linkage control system: The fire linkage control system is the output unit of the control center, which sends control signals to both fire-fighting equipment and non-fire-fighting equipment. In the unit responsible for handling fires once they are detected, the function of the fire control interconnection system makes its reliability extremely important, as it is directly related to the success or failure of fire extinguishing efforts. The fire linkage control system in this design is a linkage control system that combines a bus-based linkage system with a multi-wire system. Upon confirming a fire, they initiate a series of fire-fighting measures, such as starting the fire pumps, spray pumps, positive pressure exhaust fans, and smoke control systems based on the operation of flow indicators, wet-stem alarm valves, and fire hydrant buttons; activating alarm devices, switching to the fire alarm system, stopping elevators, turning on emergency lighting, and cutting off non-fire-related power supplies. It is important to emphasize that, whether it is a bus-based interconnection system or a multi-wire interconnection system, the design must be closely integrated with the design of the primary and secondary circuits of each connected device. It is necessary to consider how many commands the control center needs to send to such devices, as well as how many status signals they need to return to the control center, before selecting a control module that meets these requirements. At the same time, in accordance with relevant regulatory requirements, a hardwired connection must exist between the control center and the fire pumps, positive pressure supply fans, smoke exhaust fans, emergency lighting systems, and distribution panels. This ensures that the control center can carry out both logical, automatic control of these important fire protection devices, as well as manual operation for direct and intuitive control. The real-time operating status of these devices is also displayed directly on the control panel. Manual operation buttons are provided at each of these devices to allow for effective control in case of failures in the fire control center or other unexpected situations.