Fire Water Tank

The Function of Fire Water Tanks

Buildings employing temporary high-pressure water supply systems shall be equipped with elevated fire water tanks. The purpose of installing fire water tanks is twofold:
— To provide the initial firefighting water volume and pressure required during system startup, ensuring emergency water supply in the event of fire pump failure. This guarantees immediate water discharge upon sprinkler activation, enabling prompt control of initial fires and buying time for external firefighting assistance; Second, to utilize the height difference to provide the system with the required water pressure in a quasi-operational state, thereby achieving the purpose of filling the pipes with water and maintaining a certain pressure.

Buildings equipped with a constant high-pressure water supply system that can guarantee the water volume and pressure required for the most unfavorable point fire hydrants and automatic sprinkler systems, or buildings with dry risers, are exempt from installing fire water tanks.

Requirements for Installing Fire Water Tanks

1. For industrial buildings and multi-story civil structures, elevated fire water tanks shall be installed at the highest point of the building and store a 10-minute supply of firefighting water. When the indoor firefighting water demand does not exceed 25 L/s, and the calculated tank storage capacity exceeds 12 m³, a 12 m³ tank may still be used. When the indoor firefighting water demand exceeds 25 L/s, and the calculated tank storage capacity exceeds 18 m³, an 18 m³ tank may still be used.

2. For high-rise civil buildings, the elevation of the high-level fire water tank must ensure adequate static water pressure at the most unfavorable fire hydrant. When the building height does not exceed 100m, the static water pressure at the most unfavorable hydrant shall not be less than 0.07MPa. When the building height exceeds 100m, the static water pressure at the most unfavorable hydrant shall not be less than 0.15MPa. If the above static pressure requirements cannot be met, a pressure-boosting facility shall be installed. The storage capacity of the elevated fire water tank shall comply with the following: Class I high-rise public buildings shall not be less than 18m³; Class II high-rise public buildings and Class I high-rise residential buildings shall not be less than 12m³; Class II residential buildings shall not be less than 6m³. The capacity of the zoned fire water tanks in a parallel configuration for high-rise buildings shall be the same as that of the elevated fire water tank.

3. When an automatic sprinkler system is installed in the building, the elevation of the high-level fire water tank must also meet the minimum operating pressure requirement for the sprinkler at the most unfavorable point. If this cannot be met, pressure-boosting (or pressure-stabilizing) facilities shall be provided.

4. For water tanks shared between firefighting and other water uses, technical measures shall be implemented to ensure firefighting water is not diverted for other purposes. Except for series-connected fire water supply systems in high-rise buildings, firefighting water supplied by fire pumps during a fire shall not enter the elevated water tank. Production or domestic water pipelines shall be utilized as its inlet pipes.

Additional Requirements for Fire Water Tank Installation

1. Tanks combining firefighting water with other water supplies shall incorporate technical measures to prevent firefighting water from being diverted for other uses;

2. Fire water tanks should preferably be filled using domestic or industrial water supply pipelines;

3. After a fire occurs, firefighting water supplied by fire pumps shall not enter the fire water tank. A check valve shall be installed on the tank's outlet pipe;

4. High-rise buildings should ideally have two fire water tanks. This ensures essential emergency firefighting water remains available during maintenance of one tank. The tanks should be connected at the bottom via a communication pipe equipped with a valve that remains normally open;

5. Fire water tanks should be combined with other water supply tanks to maintain constant water circulation and prevent water quality deterioration. Other water supplies may be provided via measures such as drilling holes in siphon pipes;

6. Accessories, installation, and layout of fire water tanks may follow general water supply tank standards and are not detailed herein.

Material Selection for Fire Water Tanks

Currently, numerous materials are suitable for constructing water tanks, with the most common being steel plates, stainless steel, reinforced concrete, fiberglass, and enameled steel plates. Each material possesses distinct advantages and disadvantages.

1. Enameled steel plate tanks prevent water contamination and steel corrosion. They offer quick and easy installation independent of construction schedules, feature a rational structure that is sturdy and aesthetically pleasing, resist deformation and leaks, and have broad applicability.

2. On-site cast reinforced concrete tanks are heavy, require lengthy construction periods, are prone to leaks at pipe connections, and may experience surface material peeling during cleaning.

3. Fiberglass tanks offer unrestricted spatial adaptability, lightweight construction, rust resistance, leakproof integrity, and aesthetic appeal. They feature short service life, excellent thermal insulation, reliable safety, easy installation, and straightforward cleaning/maintenance.

4. Stainless steel tanks are robust, non-contaminating, corrosion-resistant, leakproof, easy to clean, lightweight, algae-resistant, thermally insulated, and aesthetically pleasing with convenient installation. However, they carry a high price tag.

5. Steel plate water tanks welded from carbon steel plates require anti-corrosion treatment on the inner surface, and the anti-corrosion materials must not compromise hygiene standards.