(1) Water inlet pipe: The water inlet pipe of the water tank is generally accessed from the side wall, but also from the bottom or top. When the water tank uses the pipe network pressure into the water, the inlet pipe outlet should be equipped with a floating ball valve or hydraulic valve. Float ball valve generally not less than 2. The diameter of the float ball valve is the same as that of the inlet pipe. Each float ball valve should be equipped with an access valve in front of it. (2) Outlet pipe: the outlet pipe of the tank can be connected from the side wall or the bottom. The bottom of the outlet pipe connected from the side wall or the top of the outlet pipe mouth connected from the bottom should be 50 mm higher than the bottom of the tank. The outlet of the water pipe should be equipped with a gate valve. The inlet and outlet pipes of the water tank should be set separately. When the inlet and outlet pipes are the same pipe, check valves should be installed on the outlet pipes. When it is necessary to install a check valve, the swing check valve with less resistance should be adopted instead of the lifting check valve, and the elevation should be more than 1m below the minimum water level of the tank. When living and firefighting share the same water tank, the check valve on the fire outlet pipe should be at least 2m lower than the pipe top of the domestic water outlet siphon (when it is lower than the pipe top, the vacuum of the domestic water outlet siphon will be destroyed, and only water flow out of the fire outlet pipe can be guaranteed), so that the check valve can be pushed with a certain pressure. Fire reserves really come into play when a fire breaks out. (3) Overflow pipe: the overflow pipe of the water tank can be connected from the side wall or the bottom, and its pipe diameter is determined according to the maximum flow into the discharge tank, and should be larger than the water inlet pipe L-2. No valve shall be installed on the overflow pipe. The overflow pipe shall not be directly connected with the drainage system. It must be used for indirect drainage. The overflow pipe shall be protected from dust, insects and flies, such as water seal and filter screen. (4) Discharge pipe: the water tank discharge pipe should be connected from the bottom of the lowest place. The water tank for fire fighting and living table is equipped with a gate valve (interception valve should not be installed), which can be connected with the overflow pipe, but not directly connected with the drainage system. In the absence of special requirements, the drain pipe diameter is generally DN50. (5) Ventilation pipe: the water tank for drinking water shall be provided with a sealed cover, and the cover shall be provided with an access hole and ventilation pipe. The vent can be extended indoors or outdoors, but not to the place of harmful gas. The mouth of the vent should have a filter screen to prevent dust, insects and mosquitoes from entering the vent. Generally, the mouth of the vent should be set downward. Valves, water seals and other devices that impede ventilation shall not be installed on the ventilation pipe. The ventilation pipe shall not be connected with the drainage system and ventilation duct. The snorkel is usually DN50 in diameter. (6) Level gauge: Generally, glass level gauge should be installed on the side wall of the tank to indicate the water level on the spot. If the length of one level gauge is insufficient, two or more level gauges can be installed up and down. The overlap of two adjacent level gauges should not be less than 70 mm, as shown in Figure 2-22. If the water tank is not equipped with the liquid level signal timing, the signal tube can be set to give the overflow signal. The signal tube is generally connected from the side wall of the tank, and its height should be set so that the bottom of the tube is flush with the bottom of the overflow tube or the overflow water surface of the flare. The pipe diameter is generally DNl5 signal pipe, which can be connected to the washbasin and washing basin in the room where people are often on duty. If the liquid level of the water tank is interlinked with the water pump, the liquid level relay or signal is installed on the side wall or top cover of the water tank. The commonly used liquid level relay or signal includes floating ball type, rod type, capacitive type and floating flat type. A certain safety volume should be maintained for the high and low electric hanging water levels of the water tank with water pump pressure. The maximum electronic control water level at the moment of pump shutdown should be 100 mm lower than the overflow water level, while the minimum electric control water level at the moment of pump start should be 20mm higher than the design minimum water level, so as to avoid overflow or cavitation due to errors. (7) Water tank cover, internal and external ladder
