Discussion on water replenishment and water level

Discussion on the water replenishment and water level setting of fire water tank

Abstract: This paper discusses how to reasonably and reliably set the water replenishment and water level monitoring alarm signal of fire water tank according to different combination settings when the current specification requires that the domestic drinking water tank should be set separately from other water tanks, such as singular and plural, past tense, compound words, roots and so on

key words: fire water tank make-up water level signal

1 question raised

in order to ensure the quality of drinking water in civil buildings, gbs0015-2003 ((building water supply should first take the resource-saving development road drainage design code) stipulates in article 3.2.8: "drinking water tanks (tanks) should be set separately from other water tanks (tanks)". Therefore, in the design of building water supply, at present, domestic drinking water and fire water are no longer stored together and shared water tanks are set up, but fire water is stored separately, using a special fire water tank, or the fire water is stored together with domestic miscellaneous water under a certain load in the shared water tank of domestic miscellaneous water and fire water, so that the water tanks of domestic drinking water and fire water meet the relevant requirements of the specification, Ensure the quality of drinking water. Due to the change of water supply and storage methods, the requirements of water replenishment, pump start-up level and alarm level of fire water storage tank are different. To ensure that the fire water consumption in the fire water tank is not less than the specified requirements and is not used, corresponding measures must be taken to reasonably and reliably set up the water replenishment and water level monitoring alarm signals of the fire water tank. According to the relevant requirements of fire water storage, this paper puts forward some views for reference

2 the container throughput of different combinations exceeded 6.6 million TEU; The ratio of logistics cost to GDP of the whole society is reduced to less than 18%

(1) when the building is equipped with domestic miscellaneous water and fire water hydration tanks, and the water inlet of the tanks is provided by special domestic miscellaneous water pumps, the stored fire water is reliably guaranteed due to the technical measures that are not used (domestic miscellaneous water pump start signal and domestic miscellaneous water outlet siphon elbow) and the continuous replenishment of domestic miscellaneous water pumps. Therefore, the start and stop signals of the water tank make-up pump can be set according to the high and low water levels of domestic miscellaneous water. At the same time, it is advisable to set the water level monitoring alarm signal of fire water storage (the position can be determined according to the form of fire water storage and water tank) under the water level line of the make-up pump and the orifice of the domestic miscellaneous water siphon, so as to ensure that the water storage and water storage of fire water are not used. See Figure 1,

Figure 1 Relationship between domestic miscellaneous water and signal water level of hydration water tank for fire protection

(2) when the fire water in the building is stored separately (i.e. special fire water tank) and the special fire water tank make-up pump is used, in order to ensure the water storage of the fire water, the starting water level of the make-up pump should be the lowest water level of the fire water storage in the water tank, and set on the monitoring and alarm water level of the fire water storage. As for the setting of the stop water level of the make-up pump, the water stored in the water tank is generally not used under non fire conditions, only a small amount of evaporation and leakage, and the amount of make-up water required is relatively small. Therefore, under the condition that it is not affected by the fluctuation of inlet water surface, it is sufficient to appropriately raise a certain height to stop the pump water level (because the water loss of evaporation and leakage is small, it generally does not affect the hourly opening times of the pump). The overflow alarm signal of the water tank and the position of the overflow pipe of the water tank can be set according to the specification requirements, and set at a certain distance below the water level of the make-up pump of the fire water tank according to the fire water storage volume and the form (area) of the water tank. See Figure 2 for the signal water level relationship of the special fire water tank

(3) when the fire water in the building is stored separately (i.e. special fire water tank), and there is a domestic drinking water tank in the building, a small special fire water make-up pump can be set to pump water from the domestic drinking water tank to make up water to the special fire water tank, but measures to prevent water interruption should be added. Its water level setting is the same as that of point (2), and the relationship between signal water level of special fire water tank is shown in Figure 2

(4) when the fire water in the building is stored separately (i.e. special fire water tank), and there is no domestic and drinking water tank in the building, when the variable-frequency water supply equipment is used to make up water, an electric valve with the same pipe diameter should be set on the inlet pipe of the fire water tank according to the requirements of the specification, and the electric valve should cooperate with the variable-frequency pump to make up water for the special fire water tank, The high and low water level signal in the fire water tank is the opening signal of the electric valve of the water inlet pipe

Figure 2 signal water level relationship of special water tank for fire protection

(5) when the special water tank for fire protection is used in the fire water supply system of the building, in order to ensure the fire water storage capacity in the water tank, the demand for water level control and the requirements for the operation of the make-up pump (including the number of starts and stops of the pump in an hour and the influence of water surface fluctuation). The water storage volume of the special water tank for fire protection should be slightly higher than the water consumption for various types of fire protection required by the specification, and a certain adjustment buffer volume should be reserved to enable the make-up pump to operate normally

(6) the determination of the overflow water level alarm signal in the fire water tank should be interpreted in accordance with article 3.7.7 of GB50015-2003 code for design of building water supply and drainage: "... the relationship between the alarm water level and the maximum water level and the overflow water level: the alarm water level should be about 50 mm higher than the maximum water level, the small water tank can be smaller, and the large water tank can be larger. The alarm water level is generally about 50mm away from the overflow water level. If the inlet pipe diameter is large, the inlet water flow is large, and it needs to be closed manually or electrically after the alarm, the emergency shutdown time should be given. Generally, the alarm water level is 250-300 mm away from the overflow water level", It is set between the maximum water level and the overflow water level, and it is determined according to various factors such as the volume of the water tank, the diameter of the inlet pipe, the flow of the inlet pipe, the closing mode of the inlet valve, etc. At the same time, the distance between the maximum water level and the overflow port should also be higher than the 50mm height required by the domestic drinking water tank, so as to meet the requirements of the setting distance of the overflow water level alarm signal

3 conclusion

in the actual engineering design, according to the different settings and water replenishment methods of the fire water tank, the domestic miscellaneous water tank and the fire water hydration tank or the special fire water tank should correctly adopt different alarm levels such as starting and stopping the pump, monitoring and overflow, so as to avoid the secondary pollution of the quality of domestic drinking water and unreasonable system settings, and ensure the safety and reliability of the quality of domestic drinking water and the fire protection system

References:

[1 GB 50015-2003, building water supply and drainage facilities