The key factor in choosing an sewage pump is its usability and reliability. The appropriate sewage pump can be selected based on the installation location of the pump, the liquid flow rate, the device head, and the liquid medium, etc. 

Flow rate: The flow rate of the sewage pump should be selected based on the drainage second flow rate (unit: L/s); when there is a drainage volume adjustment, it can be selected according to the maximum drainage hourly flow rate (unit: m3/h). Head: The head of the sewage pump is determined by the lifting height, after calculating the pipeline loss. 

If the medium to be conveyed contains certain solid substances (such as sand), this issue makes the requirements for the sewage pump in terms of motor capacity, bearing arrangement, and pump body sealing higher than those of ordinary water pumps. Generally, self-priming sewage pumps or submersible sewage pumps should be selected. When selecting and ordering, it is essential to clearly understand whether the sealing performance and capacity of the sewage pump you choose are appropriate. 

The drainage pumps used in buildings include submersible sewage pumps, submerged drainage pumps, vertical sewage pumps and horizontal sewage pumps, etc. However, vertical sewage pumps and horizontal sewage pumps require the installation of isolation foundations, which occupy a certain amount of floor space. Therefore, they are less commonly used in buildings. 

Inside buildings, with a smaller site and a smaller drainage volume, submersible sewage pumps and submerged sewage pumps can be given priority. Among them, the submerged sewage pump can generally be used in important places. It has a compact overall structure, small size, low noise, convenient movement, simple installation, significant energy-saving effect, easy maintenance, no need for a pump room, and can work underwater without the need for a pump house, greatly reducing the project cost. 

Some key points to note: 

In public building facilities, for each drainage collection tank, one backup water pump should be installed. During normal times, these pumps should operate alternately to reduce the long-term load operation of the pumps and extend their service life. 

When extracting wastewater with large impurities, the outlet pipes of the submersible sewage pumps in different collection tanks should not be connected and discharged together. Considering that when the submersible sewage pump lifts wastewater containing large debris, it is most suitable to be equipped with a crushing device. When lifting wastewater containing a lot of fibrous substances, a device for cutting or a large-channel submersible sewage pump can be used. 

When extracting general wastewater, the discharge pipes of the submersible sewage pumps in different collection tanks can be combined and discharged according to the actual situation. 

When two or more pumps share a single outlet pipe, valves and check valves should be installed on each pump's outlet pipe. If single pump drainage may cause backflow, a check valve should be set. Pressure drainage cannot be discharged together with the gravity drainage pipes within the building.