The first type installation environment:
Install the axial flow deep well pump in the water well. When the pump sucks water in the well, it is easy to form a vortex and cause a funnel phenomenon, which will cause cavitation, which will affect the water supply and even cause damage to the pump. Therefore, the specification requires: It should meet the requirements of its reliable operation. When the pump discharge flow is 150% of the design flow, the minimum submergence depth should be no less than 3. 20m above the water level line at the bottom of the impeller of the first pump, and the altitude of each increase by 300m, the deep well pump The minimum submerged depth should be increased by at least 0.30m; see the diagram below for specific practices:
The second type installation environment:
Install the axial flow deep well pump in the fire pool. Because the depth of the axial flow deep well pump is required to be large, the depth of the fire pool is generally not too deep. If installed normally, the fire pool will be very deep, which will increase the fire pool. The cost of civil works is not economical. Therefore, in the “Technical Specification for Fire Water Supply and Hydrant System” GB 50974-2014 Article 5.1.9, it is recommended to adopt the setting of deep pit water absorption. The specific method is as follows:
When an axial-flow deep well pump is installed on a fire-fighting water source such as a fire-fighting pool, the bottom of its first pump impeller should be lower than the lowest effective water level line of the fire-fighting pool, and the submergence depth should be calculated and determined according to hydraulic conditions, and should meet the requirements The effective water storage capacity or effective water level of the water source can be fully utilized; when the design flow rate of the pump is greater than 125L/s, the submergence depth should be determined according to the performance of the pump, and the cavitation allowance of the pump should be met;
Third: General requirements for the installation of axial flow deep well pumps
1、A set of axial flow deep well water pumps should be provided with at least two main water delivery pipes connected to the fire water supply loop network. When one of the water delivery pipes is overhauled, the remaining water delivery pipes should still be able to supply all the design flow of fire fighting water supply;
2、The suction pipe of the axial flow deep well pump should be provided with an exposed stem gate valve or a butterfly valve with a self-locking device, but when the concealed stem valve is installed, there should be an opening scale and mark.
3、The outlet pipe of the axial flow deep well pump should be equipped with a check valve and a rising stem gate valve; when a butterfly valve is used, it should have a self-locking device;
4、 When the diameter of the suction pipe and the outlet pipe of the axial flow deep well pump is greater than DN300, electric valves should be installed;
5、 When the motor of the axial flow deep well pump is set in the open air, rainproof facilities should be installed; the axial flow deep well pump should also meet the other requirements of the “Outdoor Water Supply Design Specification” for the axial flow deep well pump.
6、When the lowest water level of the fire tank is lower than the center line of the outlet pipe of the centrifugal water pump or the water source water level cannot guarantee the suction of the centrifugal pump, the axial flow deep well pump can be used, and the installation method of wet deep pit should be installed on the fire water source such as the fire tank.
