Submersible sewage pump is the abbreviation of submersible sewage pump. Based on the principle of submersible pump, the pipeline adopts anti-clogging design, and is used for first-level lifting, intermediate lifting and sludge return, etc. It is mainly used in municipal engineering, building construction, industrial sewage and sewage treatment scenarios, for transporting sewage, wastewater and rainwater containing solid substances and long fibers.
The two common installation methods
The installation conditions of submersible pumps are simple, and they have a wide range of flow coverage. They are one of the most commonly used lifting equipment in water treatment projects, especially in small and medium-sized projects. The common installation methods of submersible pumps mainly include two types: coupled installation and mobile installation.
Coupling installation connects the pump to the pipeline through a coupling device. The pump can be separated from the outlet pipeline, making it convenient for maintenance. When the pump needs to be repaired, it can be lifted by a lifting device. Coupling installation is suitable for various specifications of submersible sewage pumps and is the most commonly used installation method for submersible sewage pumps. The coupling device is supplied as a complete set by the equipment manufacturer.
Mobile installation refers to the situation where the pump outlet pipeline is directly connected to the water surface through a flexible hose. The submersible pump is placed on the bottom of the water tank by its own weight or suspended on a lifting device via iron chains. Mobile installation does not require a coupling device or a fixed base on the bottom of the pool, making it easy to move. During maintenance, the pipeline can be lifted together with the pump. At the same time, due to the installation method, it is difficult to withstand large torques and is only suitable for small-sized submersible pumps.
(1) Minimum operating liquid level
Pumps with a power of 11kW or above can choose to install a motor cooling system to cool the pump. If no cooling system is selected, the motor will be cooled directly by the pump medium. The minimum liquid levels corresponding to the two different cooling methods are different. The direct cooling method requires a liquid level higher than that of the method with a cooling system.
In the installation condition diagram provided by the manufacturer, the distinction is made using solid triangles "▼" and hollow triangles "▽". Among them, "▼" indicates the presence of a cooling system, while "▽" indicates the absence of a cooling system.
In the installation condition diagram of the above case, when a cooling system is present, the effective minimum liquid level distance from the bottom of the coupling device is 570mm; when no cooling system is present, the distance is 785mm. That is, with a cooling system, the effective liquid level can be 215mm lower.
(2) Planar Opening and Positioning
When installing the submersible pump in a coupled manner, the opening on the plane should take into account the minimum installation size of the submersible pump. In the case, the A view shows the size of the minimum installation hole of the pump, 1000×700mm.
When positioning, the edge of the pool where the guide rod is installed serves as the reference line. This is because the positioning of the submersible pump is accomplished by the guide rod connected to the coupling device, and the position of the guide rod is determined by the edge of the pool. When positioning the bolts of the coupling base, the edge of the pool also serves as the reference line. According to the above case, the position of the bolt hole 253mm away from the edge of the pool should be determined first, and then the positions of the other two bolt holes can be determined based on the spacing of 350mm between the bolt holes.
The most important dimensions ultimately reflected in the drawings are: the position and size of the openings on the top surface, as well as the location and specifications of the embedded anchor bolts at the bottom (typically designed with reserved holes for post-concrete pouring).
The top guide rod is usually fixed using expansion bolts.
(3) Electrical protection measures
Since the submersible sewage pump operates underwater, there may be situations such as water leakage that could damage the pump. Therefore, prevention measures are necessary. Taking a certain submersible sewage pump manufacturer as an example, the measures adopted include:
Pumps with power less than 7.5kW are equipped with motor winding overheating protection elements and water leakage probes. Pumps with power of 11kW and above are equipped with motor winding overheating protection elements, float switches, and water leakage probes. Pumps with power of 30kW and above have additional water leakage probes installed in the upper cover of the motor.
The overheat protection component is placed within the stator winding of the motor. In case of abnormal operation, when the winding reaches the set value of the overheat protection component, the motor will be stopped by the overheat protection device of the electrical cabinet.
The water leakage detector is used for water leakage detection. When water enters the motor side, it triggers an alarm and stops the machine through the electrical control cabinet. The float switch is used to detect whether the mechanical seal on the motor side is or if water has entered the motor chamber. Once water leakage is detected, it triggers an alarm and stops the machine through the electrical control cabinet.
In the electrical installation of submersible pumps, the design of the electrical control cabinet needs to be carried out based on the selection criteria and the electrical requirements provided by the manufacturer, in order to achieve the protection effect.
