Abstract: An underground metro station needs a highperformance outdoor fire hydrant system. As a result, the Technical Code for Fire Protection Water Supply and Hydrant Systems (hereinafter referred to as the specification) is thoroughly examined. A new classification method for outdoor fire hydrants, water supply types, and rescue types is proposed. Some new understandings about the firefighting and rescue requirements in the specification are put forward as follows: (1) the design flow of an outdoor fire hydrant should be guaranteed; (2) the design flow of an outdoor fire hydrant should be supplied to the fire site on time; and (3) the conditions for firefighters should be provided. The antecedents and consequences of the building′s firewater volume, water composition, and function are analyzed. On this basis, a new understanding of the design water volume of an outdoor fire hydrant in an underground station has advanced, that is, it should be determined in principle following the specification, but can be reduced to at least 20 L/s for a single water source underground stations with particularly difficult conditions. Meanwhile, to meet the firefighting and rescue requirements, new requirements have been put forward for the design innovation of various firefighting facilities, including: (1) For single water source underground stations that cannot be equipped with outdoor firefighting water tanks, the firefighting water tanks should be designed according to the standards for outdoor firefighting water tanks. (2) For underground stations with a single water supply, the two water pump adapters must be designed within 15~40 m of the fire tank, and the parking and operation space of fire engines must be considered. The number of water pump adapters should be strictly controlled. Meanwhile, the waterpump adapter and necessary outdoor fire hydrants for the water supply should be installed. Outdoor fire hydrants and outdoor fire tanks serving the same function should not be shared across the main road. Similarly, water pump adapters and corresponding outdoor fire hydrants or fire tanks for water supply should not be designed across the main road. (3) It is recommended to set rescue outdoor fire hydrants within 5~40 m of each entrance and exit.

Key words: underground metro station, firefighting and rescue, design flow of outdoor fire hydrant, water supply type outdoor fire hydrant, rescue type outdoor fire hydrant