System Protection Object Classification and Selection
According to Article 3.2.1 of the Code for Design of Automatic Fire Alarm Systems GB 50116-2013, automatic fire alarm systems are classified into Special Class, Class I and Class II protection objects based on factors such as the nature of use of the protected object, fire hazard, and difficulty of evacuation and firefighting. The classification criteria for hotel buildings are as follows: hotels with a building height exceeding 100 m are Special Class protection objects; Class I high-rise public building hotels (hotels with a building height greater than 54 m, or important hotels with a building height greater than 50 m) are Class I protection objects; Class II high-rise public building hotels (hotels with a building height greater than 24 m but not exceeding 54 m) and multi-storey hotels are Class II protection objects. The system selection requirements corresponding to different protection objects differ: Special Class protection objects shall be provided with a control center alarm system and shall be provided with two or more fire control rooms; Class I protection objects shall be provided with a centralized alarm system or a control center alarm system, and the fire control room shall be located on the ground floor of the building; Class II protection objects shall be provided with a centralized alarm system. The centralized alarm system consists of fire detectors, manual fire alarm call points, fire sound and light alarms, fire emergency broadcasting, dedicated fire telephone, fire control room graphic display devices, fire alarm controllers, fire linkage controllers, etc., and the system is required to have control and display functions for linkage-controlled equipment and to be able to transmit information to the fire control room graphic display device. The control center alarm system consists of two or more fire control rooms; the main fire control room shall be able to display all fire alarm signals and linkage control status signals and shall be able to control important fire protection equipment. For large hotel complexes (including hotel, commercial, office and other functions), a control center alarm system should be adopted, with sub-fire control rooms provided in each functional zone and the main fire control room located on the ground floor of the hotel tower. Redundant configuration should also be considered in system design; the main power supply of the fire alarm controller shall adopt the fire protection power supply, the backup power supply shall adopt a battery bank, and the automatic switching time between main and backup power supplies shall not exceed 5 s.
Linkage Control Logic of the Hydrant System
The linkage control of the hydrant system is one of the most important control functions in the automatic fire alarm system, and its control logic design must simultaneously satisfy the dual requirements of GB 50116-2013 and GB 50974-2014 (Technical Code for Fire Water Supply and Hydrant Systems). The linkage control of the hydrant system includes three levels: interlock control (direct start): the actuation signal of the hydrant button shall directly serve as the trigger signal for starting the fire pump, directly interlocking the start of the fire pump through a dedicated line (non-bus type). According to Article 11.0.19 of GB 50974-2014, the hydrant button should not serve as the trigger signal for directly starting the fire pump; however, when the hydrant system is not provided with an automatic fire alarm system, the hydrant button shall still have the function of directly starting the fire pump. The usual practice is that after the hydrant button is actuated, the signal is transmitted respectively to the fire linkage controller and the hydrant pump control cabinet; after receiving the signal, the fire linkage controller confirms the linkage logic, while the hydrant button is directly connected to the pump-start terminal of the hydrant pump control cabinet via a hard wire. Linkage control (bus control): after the automatic fire alarm system confirms a fire, the fire linkage controller starts the hydrant pump through the bus output module. The linkage control logic is usually as follows: the alarm signals of two or more independent fire detectors, or one detector plus one manual alarm call point, serve as the fire confirmation signal to linkage-start the hydrant pump. Manual control: a manual direct control device for the fire pump is provided in the fire control room to directly control the start and stop of the fire pump through a dedicated line (hard-wired). The fire pump control box shall also be provided with on-site manual start/stop buttons and an auto/manual changeover switch. The key design requirements in the linkage control of the hydrant system include: the fire pump shall be provided with a standby pump and the main and standby pumps shall be capable of automatic changeover (automatic changeover time shall not exceed 2 min); the starting time of the fire pump shall not exceed 2 min (the time from receiving the pump-start signal to normal operation of the pump); after the hydrant button is actuated, the pump-start confirmation indicator on the button shall be illuminated (indicating that the fire pump has started, with LED brightness not less than 5 cd/m2). When designing the linkage logic, note that: the start signal of the hydrant button shall be independent of the detector alarm signal of the automatic fire alarm system, ensuring that the fire pump can still be directly started through the hydrant button in the event of a failure of the automatic fire alarm system or when a fire has not been confirmed.
Linkage control logic of the smoke control and exhaust system
The linkage control of the smoke control and exhaust system is one of the most complex control logics in the automatic fire alarm system, involving the coordinated action of multiple devices such as the mechanical pressurization air supply system, mechanical smoke exhaust system, smoke curtains, smoke exhaust fire dampers and others. According to Section 4.5 of GB 50116-2013, the linkage control of the smoke control and exhaust system shall follow the following logic: Linkage control of the mechanical pressurization air supply system: After a fire is confirmed, the air supply outlets (normally closed multi-blade air supply outlets) on the fire floor and the adjacent floors above and below shall be linked to open, and the corresponding air supply fans shall be started at the same time. The air supply outlet opening signal shall be fed back to the fire linkage controller, and the fire linkage controller shall link to start the air supply fans after receiving the air supply outlet opening signal. For the control of the air supply fans, manual direct control devices (hard-wired control) shall also be provided in the fire control room. Linkage control of the mechanical smoke exhaust system: After a fire is confirmed, the smoke exhaust outlets (or smoke exhaust valves) and makeup air inlets (or makeup air valves) in the fire area shall be linked to open, and the corresponding smoke exhaust fans and makeup air fans shall be started at the same time. The smoke exhaust fans shall be capable of manual start, and after the smoke exhaust fire damper at the inlet of the smoke exhaust fan (closing by fusion at 280 degrees) closes, the smoke exhaust fan shall be capable of being interlocked to stop. Linkage control of smoke curtains: After a fire is confirmed, the smoke curtains shall be linked to descend to confine the smoke within the smoke control zone. The descending height of the smoke curtain shall not be less than 500 mm, and fixed or electric types may be used. Linkage control of the smoke control air-conditioning system: After a fire is confirmed, the air-conditioning system in the fire area (including the fresh air system and exhaust system) shall be linked to stop, to avoid fueling fire spread and smoke diffusion. Linkage control of the makeup air system: After the mechanical smoke exhaust system starts, the corresponding makeup air system shall be linked to start (the makeup air volume shall not be less than 50% of the smoke exhaust volume). Design points: The control of pressurization air supply outlets and smoke exhaust outlets (valves) shall adopt the bus-based linkage control mode, with control signal transmission and status feedback realized through input/output modules; For the control of air supply fans and smoke exhaust fans, in addition to linkage control, two methods—manual direct control in the fire control room and on-site manual control—shall also be provided to ensure control redundancy. During linkage logic design, attention shall be paid to: The pressurization air supply system and the smoke exhaust system shall be linked by zone, to avoid simultaneous start-up of the whole building causing fan overload and uneven air volume distribution, and attention shall also be paid to the residual pressure value in the antechamber not exceeding 30 Pa (excessive pressure will make evacuation doors unable to open).
Key points of system linkage commissioning and acceptance testing
Commissioning and acceptance testing of fire alarm system linkages are key steps to ensure system reliability and functional integrity. GB 50116-2013 and GB 50440-2007 (Technical Code for Urban Fire Remote Monitoring System) specify the content and methods of acceptance testing. Acceptance testing should cover the following main items: Fire detector testing: Use dedicated test equipment (smoke applicator, heat applicator) to simulate fire scenarios and test the alarm function of smoke detectors (response time shall not exceed 30 s) and heat detectors (response time shall comply with product standards, generally not exceeding 40 s), while also testing the detector fault alarm function (after removing the detector, the control panel shall issue a fault signal within 100 s). Manual call point testing: After pressing the manual call point, the control panel shall receive the alarm signal and display the alarm location, with signal feedback time not exceeding 10 s. Fire linkage controller testing: After setting the linkage logic, simulate fire alarm signals to verify whether linked equipment operates according to the predetermined logic: fire pumps shall start within 2 min; smoke control and exhaust fans shall start within 15 s; fire shutter doors shall descend to the floor within 60 s (fire shutter doors installed on evacuation routes shall descend in two stages: after smoke detector activation, descend to 1.8 m above the floor; after heat detector activation, descend to the floor); fire emergency broadcasting shall play automatically after fire confirmation, and fire sound and light alarms shall start simultaneously with a sound pressure level of not less than 60 dB at any location; fire elevators shall be forced to descend to the ground floor and feed back status signals, with the forced descent time not exceeding 60 s; non-fire power supplies shall be automatically cut off with a delay (typically 30 s) after fire confirmation, and occupants shall be notified via broadcast before cutoff. Fire emergency broadcasting testing: Test broadcast clarity (sound pressure level 15 dB above background noise, at least 60 dB), correctness of broadcast zones (which shall be consistent with fire compartments), and alternating playback function with sound and light alarms (broadcast playback time 10–30 s, sound and light alarm playback time 10–30 s, alternating). Fire communication testing: Test the call quality between the fire telephone switchboard and each extension (fire pump room, fire fan room, power distribution room, elevator machine room, etc.). Comprehensive system linkage function testing: Simulate fire scenarios on a standard floor of the hotel, trigger different combinations of detectors, and verify whether the system linkage logic is correct.