Height and capacity requirements for hotel fire water tanks

I am Daniel Wang, a water supply and drainage specialist. In hotel fire protection system design, the installation height and volume of the fire water tank are key parameters for …

I am Daniel Wang, a water supply and drainage specialist. In hotel fire protection system design, the installation height and volume of the fire water tank are key parameters for ensuring effective initial fire suppression, and they directly affect system reliability and personnel safety. Below, I will combine the Technical Code for Fire Protection Water Supply and Hydrant Systems (GB 50974-2014) and years of engineering experience to analyze these two core requirements in detail.

1. Installation height requirements for the fire water tank

According to Article 5.2.2 of GB 50974-2014, the installation height of the high-level fire water tank shall ensure the static pressure at the most unfavorable hydrant. For hotel buildings:

Class I high-rise public buildings (such as star-rated hotels ≥50 m): shall not be less than 0.10 MPa (i.e., 10 m water column); when the building height exceeds 100 m, shall not be less than 0.15 MPa.
Class II high-rise public buildings (such as hotels <50 m): shall not be less than 0.07 MPa.
Multi-story hotels: shall not be less than 0.07 MPa.

Practical experience: In hotel design, I often encounter insufficient tank height due to inadequate floor-to-floor height. For example, in a five-star hotel (height 80 m), the rooftop tank room was only located above the elevator machine room, with an effective height of less than 10 m. The solution was to add a pressure-maintaining pump and a pressure tank. According to the supplementary explanation in Article 5.2.2 of GB 50974-2014, when static pressure is insufficient, pressurization facilities may be used, but the flow rate of the pressure-maintaining pump shall not exceed 5 L/s.

Engineering case: An international hotel in Shenzhen (120 m high) initially had a tank height of only 8 m, which did not meet the 0.15 MPa requirement. By optimizing the tank position to the highest point of the roof (increasing the height by 2 m) and configuring a pressure-maintaining pump (flow rate 4 L/s, head 0.2 MPa), the system ultimately passed acceptance, and in the fire simulation test, the static pressure remained stable at 0.18 MPa.

2. Volume requirements for the fire water tank

According to Article 5.2.1 of GB 50974-2014, the effective volume of the high-level fire water tank shall meet the fire water demand for initial fire suppression:

Class I high-rise public buildings (such as hotels ≥50 m): ≥36 m³; when the building height exceeds 100 m, ≥50 m³; when it exceeds 150 m, ≥100 m³.
Class II high-rise public buildings (such as hotels <50 m): ≥18 m³.
Multi-story hotels: ≥18 m³ (but shall be calculated in conjunction with the indoor fire water demand).

Special note: For hotels equipped with automatic sprinkler systems, the tank volume shall also include the initial water demand of the sprinkler system. Article 5.2.1 of GB 50974-2014 mentions that when the system includes automatic sprinklers, the volume may be appropriately increased, but shall not be less than 18 m³. In practice, I often calculate based on a fire duration of 10 minutes (hydrant + sprinkler). For example, if a hotel has a hydrant flow rate of 20 L/s and a sprinkler flow rate of 30 L/s, the initial water demand is (20+30)×10×60=30 m³, but the code requires at least 36 m³, so 36 m³ is adopted.

Engineering case: A business hotel in Beijing (height 60 m) originally had a designed tank volume of 30 m³. During review, it was found that according to the code, 36 m³ was required, and the sprinkler system did not have a separate pressure-maintaining unit. We adjusted it to a stainless steel assembled water tank (36 m³) and added a sprinkler pressure-maintaining pump, which both met the code and saved structural reinforcement costs. After operation, in a simulated fire test, the water tank supplied water continuously for 12 minutes, fully covering initial fire suppression.

3. Comprehensive precautions

Tank material: SUS304 stainless steel is recommended to avoid corrosion and contamination. Article 5.2.3 of GB 50974-2014 requires that the tank material be corrosion-resistant.
Freeze protection measures: Tank rooms in northern hotels need insulation, with the temperature not lower than 5℃; otherwise, pipes may freeze and affect water supply.
Water level control: Install liquid level sensors and overflow pipes to ensure automatic replenishment and prevent drying out.

Concluding conclusion: The installation height of hotel fire water tanks shall be strictly implemented in accordance with Article 5.2.2 of GB 50974-2014 to ensure static pressure at the most unfavorable point; the volume shall meet the initial fire water demand in accordance with Article 5.2.1, with consideration of the superposition of the automatic sprinkler system. In actual design, it is necessary to optimize based on building height, system type, and site conditions, and to add pressurization facilities when necessary.

The above are reference opinions. The actual project conditions still need to be further comprehensively evaluated and implemented in combination with specific operating conditions, site conditions, and other factors.

Engineering reference only — verify against project conditions and the latest codes.

Height and capacity requirements for hotel fire water tanks