Sewage Ejector Pump
What is a sewage ejector pump?
A sewage ejector pump is a pump that is used in cases where plumbing fixtures in a building are in a location below the sewer line such as in laundry rooms or basement bathrooms. The sewage ejector pump manufacturers produce these pumps with aim of elevating sewage to make sure that it can move up and out of the building to the sewer line. So, a sewage ejector pump is needed by people who have their homes with plumbing fixtures that are located at positions lower than the main sewer line.
How does a sewage ejector pump work?
An ejector sewage pump is placed at the sump on the floor of the house. However, the sewage ejector pump does not collect rainwater around the house’s foundation but it collects sewage from drain lines that are connected to the piping system in the basement. When the sewage level in the basin increases to a certain height, there is a moveable float that starts the sewage ejector pump which is responsible for moving the sewage to the sewer line. When the level of wastewater in the basin decreases, the float drops downwards which then turns off the sewage ejector pump. The sewage ejector pump that is aimed for handling sewage from the bathroom needs a lid that is sealed on the basin as well as a vent for passage of sewer gases. A sewage ejector pump needs a valve to be between the pump exit point and the junction with the sewer line helps to ensure that no wastewater can drain back after the sewage is pumped out.
Figure: Working of a sewage ejector pump
Sewage ejector pump Types:
There are various types of sewage ejector pump with different features. However, there are three main types of sewage ejector pumps which are submersible sewage ejector pump, vertical sewage ejector pump, and self-priming sewage ejector pump.
Submersible sewage ejector pump
A submersible sewage ejector pump is submerged in wastewater to be pumped. Their design enables them to work well while still submerged in the tank. A submersible sewage ejector pump is a pump that is widely used. In most homes, the most common sewage ejector pump used is a submersible sewage ejector pump. They are known to be safe and thus mostly preferred. In this type of pump, the submersible sewage ejector pump could be either a single-seal submersible sewage ejector pump or a double-mechanical seal submersible sewage ejector pump. Between these two, the double seal is better. There is a significant difference in cost between these two types of submersible sewage ejector pumps. The main factor to determine which one to use (single or double seal) is based on how frequently the pump will be used. When the pump needs to be operated for hours per day or when it is not to be operated every day, then a single seal submersible sewage ejector pump will be fit for this task. If the sewage ejector pump is intended to be run many hours per day then it would be economical to use a double-seal submersible sewage ejector pump. The submersible sewage ejector is placed at the bottom of the pit and they are manufactured with a rail type system for removing them. The rail system is important for troubled applications and high use.
Vertical sewage ejector pumps
Vertical sewage ejector pumps are large but very durable. As such, the vertical sewage ejector pumps are not common as they used to be because of their cost and size. However, they are still in use and they perform quite well. In a vertical sewage pump, the pumping part is submerged in a pit, while the motor is rested on a plate which is also used to support other parts like pump discharge pipe, shaft, and volume. Vertical sewage ejector pumps are designed with several sleeve bearings, unlike submersible pumps which are permanently lubricated. The sleeve bearings need to be lubricated using grease at least quarterly or as many times as its being used. When the vertical sewage ejector pump is maintained properly, it can be used for a long period. However, the vertical sewage ejector pumps are not intended to be used continuously. Because of the use of sleeve bearings, vertical sewage ejector pumps are recommended for intermittent operation.
Self-priming sewage ejector pump
Self-priming sewage ejector pumps are pumps that are used in operations that do not have much headroom when the pump has to be removed. The self-priming sewage ejector pump sits on a pit. The self-priming sewage ejector pumps are fully primed when they are full of water to be pumped. Once these self-priming sewage ejector pumps are fully primed they remain so unless air is introduced into the casing. A self-priming pump can remain primed for many years without priming again. One of the superb features of these pumps is that they can be accessed because the motor and the pump are on top of the pit. The performance of self-priming sewage ejector pumps is limited by depth. However, in shallow pits, they do perform well. If self-priming sewage ejector pumps are used in deep pits they tend to lose their performance.
Advantages of sewage ejector pump
- Submersible sewage ejector pumps do not need to be primed. They prime themselves as they are placed below the surface of the wastewater to be pumped.
- Submersible sewage ejector pumps are not prone to making noise as they are submerged in the tank reducing noise pollution.
- Submersible sewage ejector pumps are not prone to cavitation because they work while submerged in the wastewater.
- Self-priming sewage ejector pumps are advantageous in that they can handle solids of up to 3 inches.
- A self-priming sewage ejector pump can pump sewage while it is still out of the pit which makes it easier to do repair and maintenance.
- A vertical sewage ejector pump can transport liquids at higher temperatures. Vertical sewage ejector pumps have the pumping part immersed in the liquid without seals that can be damaged by high temperatures.
- Vertical sewage ejector pumps have long maintenance intervals. This happens because the motor and other parts like the shaft are never immersed in the fluid being pumped.
Disadvantages of sewage ejector pump
- Self-priming sewage ejector pumps are it is inefficient because it needs larger clearances to allow them to handle solids.
- Also, self-priming sewage ejector pumps need a large volute to help it in self-priming.
- The vertical sewage ejector pump needs a large headroom due to its vertical position.
- There is a challenge to balance axial thrust due to the overhung pump and the motor, especially at high pressure for the vertical sewage ejector pump.
- Submersible sewage ejector pumps can have their seals corroded with time. When the seals become corroded, fluids can get inside the motor making it operational until it is repaired.
- Submersible sewage ejector pumps are more technical which makes them more expensive relative to non-submersible sewage ejector pumps.
Sewage ejector pump application
Sewage ejector pumps are used in sewage treatment. They are capable to work in sewage because they can transport solid particles without getting obstructed in their entry or exit points. They are designed and manufactured in a way that helps them to reduce particles to smaller sizes making it easier for them to transport.
Sewage ejector pump troubleshooting
Sewage ejector pumps can have technical problems similar to other technical machines. Some of the common problems and their solutions are:
The impeller is blocked. In this case, the pump needs to be removed from the tank and the impeller freedom and shaft rotation observed. The impeller and volute need to be cleaned and any blockage removed.
There is an internal motor defect. When this happens, then the pump needs to be removed, the power disconnected, actuate control switch, and connect to rated voltage. Then a technical expert will perform the repairs and or replacement.
Motor overload tripped. In this case, the pump needs to be given around 10 minutes to cool and then be reconnected again. In case the power trips again, the voltage needs to be checked to see if it is according to the manufacturer’s specifications. If the problem persists, contact an electrician to check the power details and advise accordingly.
The tripped circuit breaker or fuse is blown. In this case, replace the fuse or reset the circuit breaker accordingly. If needed, an electrician can be called to repair the circuit.
Summary
From this article, sewage ejector pump has been studied. It has been found that a sewage ejector pump is used where plumbing fixtures are in position below the sewer line. The sewage ejector pumps are meant to elevate sewage to make it move out of a home basement to the main sewer line.
There are several types of sewage ejector pumps and this article considered three main types which are the submersible sewage ejector pump, vertical sewage ejector pump, and the self-priming sewage ejector pump. The advantages and disadvantages of these three types of sewage ejector pumps were studied. It was found that the advantages of these types of sewage ejector pumps outweigh the disadvantages by a great margin. The sewage ejector pumps as the name suggest are employed when ejecting sewage from the basement of a building to the main sewer line.