The drainage pumps used in buildings include submersible sewage pumps, submersible drainage pumps, vertical sewage pumps and horizontal sewage pumps. Since the space in the building is generally small and the drainage volume is not large, submersible sewage pumps and submersible drainage pumps can be used as drainage pumps first. Submersible sewage pumps are generally used in important places; vertical sewage pumps and horizontal sewage pumps require the installation of seismic isolation foundations, self-priming water absorption, and occupy a certain space, so they are rarely used in buildings.
The flow rate of the drainage pump should be selected according to the design flow rate of domestic drainage in seconds:
1. When there is drainage volume adjustment, it can be selected according to the maximum hourly flow rate of domestic drainage. The flow rate of the drainage pump in the fire elevator sump is not less than 10L/s. The head of the drainage pump is determined by the lifting height and pipeline loss calculation, and then a certain free water head is added. The free water head should be 0.02~0.03MPa. The flow rate of the suction pipe and outlet pipe of the drainage pump should not be less than 0.7m/s, and should not be greater than 2.0m/s. In public buildings, a standby pump should be installed for each domestic drainage collection tank as a unit, and it is advisable to operate alternately at ordinary times. For drainage of the basement, equipment room, and garage to wash the ground, if there are two or more drainage pumps, the standby pump can be omitted.
2. When the collection tank cannot be equipped with an emergency drainage pipe, the water pump should have an uninterrupted power supply;
3. When the drainage inlet pipe can be closed, the uninterrupted power supply can be omitted, but an alarm device should be installed.
4. When lifting sewage and wastewater with large impurities, the outlet pipes of submersible sewage pumps in different collection tanks should not be combined for discharge.
5. When lifting general wastewater, the outlet pipes of submersible sewage pumps in different collection tanks can be combined for discharge according to actual conditions. When two or more water pumps share a water outlet pipe, valves and check valves should be installed on the outlet pipes of each water pump. When the drainage of a single water pump may cause backflow, a check valve should be installed. It is not allowed to combine the pressure drainage valve with the gravity drainage pipe in the building for discharge.
6. When the submersible sewage pump lifts large debris, the submersible sewage pump should be equipped with a crushing device; when lifting sewage containing more fiber, a large-channel submersible sewage pump should be used.
7. When the motor power is greater than or equal to 7.5kW or the outlet pipe diameter is greater than or equal to DN100, a water pump fixed autocoupling device can be used;
8. When the motor power of the submersible sewage pump is less than 7.5kW or the outlet pipe diameter is less than DN100, a hose mobile installation can be set. When the sewage collection tank is drained by a submersible sewage pump, a water pump fixed autocoupling device should be installed to facilitate the maintenance of the water pump. The drainage pump should be able to start and stop automatically and manually on site. Multiple water pumps can be operated alternately in parallel or in stages.
