Drainage pumps used in buildings include submersible sewage pumps, submerged drainage pumps, vertical sewage pumps, and horizontal sewage pumps. Since the general site in the building is small and the drainage volume is not large, the drainage pump can preferably be a submersible sewage pump. Vertical sewage pumps and horizontal sewage pumps require seismic isolation foundations, and self-irrigation water absorption, and occupy a certain site, so they are less used in buildings.
The flow rate of the submersible sewage pump should be selected according to the design second flow rate of domestic drainage:
When there is drainage adjustment, it can be selected according to the maximum flow of domestic drainage. The flow rate of the drainage pump in the fire-fighting elevator sump shall not be less than 10L/s. The head of the drainage pump is determined according to the lifting height and pipeline loss, and then a certain free head is added. The free water head should be 0.02～0.03MPa. The flow velocity of the water inlet and outlet of the submersible sewage pump should not be less than 0.7m/s, and should not be greater than 2.0m/s.
In public buildings, a spare pump should be set up in each living drainage sump as a unit, and it should be operated interactively at ordinary times. For the drainage of the basement, equipment room, and garage flushing the ground, if there are two or more drainage pumps, the pump may not be used.
When the sump cannot be equipped with an accident drainage pipe, the pump should have an uninterrupted power supply.
When the drainage and water inlet pipes can be closed, the uninterrupted power supply may not be provided, but an alarm device should be provided.
When lifting sewage and wastewater with large impurities, the outlet pipes of submersible sewage pumps in different sumps should not be discharged together.
When lifting general wastewater, the outlet pipes of submersible sewage pumps in different sumps can be considered together for discharge according to the actual situation. When two or more pumps share one outlet pipe, a valve and a check valve should be installed on the outlet pipe of each pump. When the drainage of a single pump may cause backflow, a check valve should be installed. It is not allowed to combine the pressure drainage switch with the gravity drainage pipe in the building.
When the submersible sewage pump lifts sewage containing large debris or more fibers, the submersible sewage pump should be equipped with a crushing device or a cutting-type submersible sewage pump, and a large-channel submersible sewage pump should be used.
When the motor power is greater than or equal to 7.5kW or the diameter of the water outlet is greater than or equal to DN100, the submersible sewage pump can be installed with an auto-coupling device. When the motor power of the submersible sewage pump is less than 7.5kW or the diameter of the water outlet is less than DN100, a flexible hose can be installed. When the sewage collection tank is drained by a submersible sewage pump, an auto-coupling device for fixing the water pump shall be provided to facilitate the maintenance of the water pump. The drainage pump should be able to automatically start and stop and manually start and stop on-site. Multiple pumps can be operated alternately in parallel, and can also be put into operation in sections.