Submersible sewage pump is an effective tool and the main tool for urban sewage discharge. The leakage of submersible sewage pumps is a common problem, and there are many reasons for it. Only leakage can affect the normal use of submersible sewage pumps. Single screw pumps cannot achieve abnormal drainage and sewage functions, so we need to pay close attention to the application status.
Once leakage is discovered, we should immediately identify the location of the leakage and solve it.
The leakage of submersible sewage pumps is mostly caused by mechanical seal problems. In order to ensure the stable and reliable operation of the pump, it is necessary to carefully calculate the working pressure of the pump and consider the influence of the pipeline when selecting, paying attention to the temperature, physical and chemical properties of the liquid. During use, it is necessary to follow the operating standards to prevent malfunctions caused by misoperation.
During operation, it is important to frequently review and promptly identify problems. Be careful when inspecting the assembly, and pay attention to the tightness of the spring, dynamic and static ring seals. Only in this way can we extend the service life of the pump, reduce leakage and protection, and ensure normal production supply.
1. Leakage of packing box
The packing is compressed with a gland, and the compression level can be adjusted by the bolts on the gland. If the compression is too loose, it will not achieve sealing; Pressing too tightly can cause significant mechanical wear on the pump shaft and packing, resulting in high power consumption and even the occurrence of shaft hugging. It is advisable for individual single screw pumps to allow water in the water sealed pipe to drip out through the gaps of the packing material. The pressure water inside the pump casing flows into the gap between the shaft and the packing through the small holes in the water seal ring through the water seal pipe, playing a role in guiding water for cooling and smoothing.
2. Periodic leakage
Periodic vibration of the rotor can cause periodic leakage, which is important for submersible sewage pumps because the stator is not aligned with the high and low end caps or the impeller is unbalanced with the main shaft. This situation can shorten the life of the sealing ring and should be inspected, repaired, and adjusted in a timely manner.
3. Leakage caused by the medium
If solid particles in the liquid enter the sealing end face, it will scratch or accelerate the wear of the sealing end face. The deposition rate of scale and oil on the shaft (sleeve) exceeds the wear rate of the friction pair, so that the dynamic ring cannot compensate for the wear. The operating life of the hard to hard friction pair in a single screw pump is longer than that of the hard to graphite friction pair, because solid particles will be embedded in the sealing surface of the graphite sealing ring.
In situations where solid particles easily enter, tungsten carbide should be used as a mechanical seal for tungsten carbide friction pairs.
4. Leakage caused by pressure
High pressure water pumps operating under overpressure and vacuum conditions can cause mechanical seal leakage. During the start-up and shutdown process of the water pump, negative pressure may occur in the sealing chamber due to blockage of the inlet and gas content in the pumped fluid medium, causing dry friction on the sealing end face and resulting in air or water leakage of the internal mechanical seal. The difference between vacuum sealing and positive pressure sealing of single screw pumps lies in the directional difference of the sealing object, and mechanical seals also have directional adaptability. This requires opening the valves of the relevant pipelines before starting the equipment, checking the liquid level, and preventing leakage caused by misoperation.
5. Leakage detection ring leaks
At the high and low pressure interface of the medium pressure pump, there is a rolling joint between the outer circle of the single screw pump impeller and the inner wall of the pump casing, which is prone to leakage. In order to reduce the backflow of high-pressure water from the pump casing to the inlet, measures are taken in the pump structure.
Two leakage reduction methods:
(1) Reduce seam gaps;
(2) Add resistance in the leakage channel.
In summary, there are many reasons for the leakage of submersible sewage pumps, and we need to conduct regular inspections to avoid leakage caused by various reasons. And we need to identify the root causes of various leaks, find the fundamental ways to solve the problems, and fundamentally solve the causes of leaks to ensure that there will be no secondary leaks at present.
