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Submersible pumps are a highly popular type of pump with many applications. These are specifically designed to be submerged in the liquid to be pumped and as a result, need to be waterproof. There are many types of submersible pumps available on the market for several different applications.
If you’re looking for a submersible pump for your well, sewerage system or for draining flood water but you’re not sure how to find the best one for you, this article has all the information you need to know on submersible pumps and how to choose the right one for your purpose.
What is a Submersible Pump?
A submersible pump is a powerful, single-unit device that’s specially made for deep wells from depths of 25-400 ft, but they can be used for several other purposes as well.
The pump is designed to sit fully submerged in water and contains a hermetically sealed motor which is close coupled to the rest of the pump body to prevent water from leaking in and causing damage.
These pumps are used for drawing water from wells, drainage of floodwater, sewerage pumping, emptying ponds or as pond filters. They’re among the most popular types of water pumps on the market since they’re easy to use and require less maintenance than other pump models.
This is considered to be a type of multistage centrifugal pump. It sits at the bottom of the well in a vertical position and generates very high pumping power.
Features of Submersible Pumps
Submersible pumps contain both surface and downhole components and may have additional components depending on the purpose of the pump as well as the installation. For example, wastewater submersible pumps may have graining teeth on the impeller that help to chop up or grind waste.
However, there are general features that are usually found in all submersible pumps. These include the following:
- Pump discharge head: this is a separate component on the top of the pump section and is a measure of the pump’s power. The bigger the pump head, the great the pressure that it can generate.
- Pump body: the pump body is similar to multi-stage centrifugal pumps with either a single or multi-pump design.
- Pump intake: this is the entrance through which fluid enters the pump.
- The seal: this is located between the pump intake and motor. Its purpose is to protect the electric motor by keeping out water.
- The motor: connected to the bottom of the pump seal, this can be a single motor or made up of multiple motors joined together in tandem. The motor is airtight sealed and close-coupled to the pump body.
- Motor base: this is an integral base located at the bottom of the motor.
- Power cable: this supplies electricity to the pump to keep it working.
- Production tubing: this is important in the delivery of fluid from the pump body to the surface. The water is pushed through this tube.
- Control box: protects the pump from high or low voltage, clogged well screens, low yield wells and rapid cycling.
How Does a Submersible Pump Work?
Submersible pumps operate in a simple way. Unlike shallow well pumps, the submersible pump doesn’t rely on suction to extract water from the source. Instead, it converts rotary energy to kinetic energy. Finally, it converts it into pressure energy to push the water toward the surface.
When the pump is switched on, the impellers begin to spin, drawing water into the pump housing. This water is called ‘drive water’. As the pump then draws additional water in, the drive water combines with it and is pushed through the diffuser. From there, it’s driven up the pipe to the storage tank.
Types of Submersible Pumps
Now for a brief look at the different types of submersible pumps available on the market.
- Stainless Steel Pumps
Stainless steel submersible pumps have a far better appearance than the typical cast iron pumps and they’re also highly resistant to acidity. They are used for irrigation systems, industrial applications, dewatering systems and for raw water supply.
- Deep Well Pumps
Deep well submersible pumps are the most popular and extensively used for residential, industrial and commercial purposes. They are used in wells up to 300ft in depth and are very powerful devices that perform excellently.
- Oil-Filled Pumps
The oil-filled submersible pump utilizes oil that’s filled into its motor. It’s used mostly for water lifting from wells, farmland irrigation, delivering water supply to mountain regions and also as a drainage system for industrial water supply.
- Bladder Pumps
These are pneumatic devices that utilize and generate compressed air to extract water. The bladder pump comes with a flexible bladder made of PTFE or polyethylene and a screen that filters out any unwanted materials that could get in the way of its check valves. It’s mainly used for groundwater analysis and fluid sampling applications.
- Grinder Pumps
Designed specially with cutting blades, grinder pumps have the ability to grind sewage into a fine slurry before pumping it on to the central sewer system. They pump low amounts of sewage over very long distances, making them very efficient. However, if they don’t have the required head pressure to function correctly, they can burn out quickly.
- Borehole Pumps
This pump is specially made to extract water or other types of liquid from boreholes. It’s made of corrosion-resistant materials and is designed to fit perfectly inside boreholes, with little clearance on all sides. It’s used for irrigation, mining, industrial and construction purposes.
- Utility Pumps
These electric pumps are used for multiple purposes including the removal of standing water from basement floors, water beds and even draining aquariums. Available in both manual and automatic configurations, utility pumps have the capacity to handle large applications as it stays under water for very long periods of time.
- Fountain Pumps
Fountain Pumps are devices that are designed to serve aesthetic purposes as well as aeration. They circulate water and have the ability to control the outflow of the water. Maintenance-free and easy to install, these pumps can operate 24/7 as long as they continue to be submerged in water.
- Sump Pumps
Sump pumps are installed in the lowest part of crawlspaces and basements which are areas that prone to flooding. Their main function is to keep such areas dry by pumping out floodwater as it accumulates. Usually these pumps are installed in specially made sump pits and their job is to pump water out of the pit, away from the crawlspace or the basement so that it stays dry.
- Water Cooler Pumps
These are used for industrial, residential and farmland irrigation purposes to supply heat exchangers with cooling water. Like oil-filled pumps need to be filled will oil to function, water cooler pump motors need to be filled in with freshwater. These pumps can be used wherever high quality of water is required.
Advantages and Disadvantages of Submersible Pumps
Let’s take a look at the benefits and drawbacks of submersible pumps. The benefits of submersible pumps far outweigh the drawbacks which are not quite problematic as long as you know how to prepare for them and avoid them.
- These pumps never need to be primed since they are always submerged in water.
- They are highly efficient and great for energy conservation since they use less energy than other types of pumps, making them a great choice for those who are on a budget.
- Submersible pumps are highly reliable and durable. They are built to last, performing optimally for up to 25 years. They are built in such a way that repairs are very unlikely to occur.
- They require less maintenance. The pump would need to be serviced about once every 25 years.
- The pumps are safe from cavitation (the formation of small vapor-filled cavities or bubbles that develops in areas of low pressure around the impeller of the pump)
- The body of the submersible pump is well sealed to prevent water from leaking in to the motor and causing it to short circuit.
- Since the pump works under water, it operates very quietly.
- These pumps can draw in not only liquids but also solids.
There are a few drawbacks of this pump that is important to understand clearly before purchasing one. These include the following:
- They are more on the expensive side than most other non-submersible pump models.
- Submersible pumps are quite difficult to access. In case of repair, accessing the pump would be problematic and a hassle since it would have to be pulled all the way up from the bottom of the well.
- If the pump’s gasket loses its integrity, water can leak in and the internal components will be damaged.
- If the pump fails or leaks for any reason, it would be difficult to identify it because it’s submerged under the water.
- Overheating can be an issue if the well or water source runs out of water or if the levels run too low. Being immersed in water controls the temperature of the pump so when there’s no water it can overheat and burn out. In order to function correctly, the pump MUST be totally submerged in water.
Some Key Points to Remember
If you’re interested in getting a submersible pump, whether it’s for industrial or residential use, there are a few things to keep in mind. Knowing how to maintain the pump is useful as it will help prolong the life of the pump and keep it performing optimally. Check out these maintenance tips that will help prevent the pump from failing or being damaged.
- Avoid overheating – the pump must be fully submerged at all times to work or it will overheat and the motor will burn out. To avoid having to deal with costly repairs, check the heating level of the pump frequently.
- Monitor the maintenance frequency – keep an eye out for any unusual sounds or vibrations coming from the pump as it will be helpful to evaluate how often the pump requires maintenance.
- Lubricate the pump – follow the manufacturer’s guidelines and lubricate the pump and its motor. However, don’t overdo it, since extra grease will cause damages.
- Flush the pump after using – dirt can sometimes get trapped under these pumps so doing a clean water flush will help remove it.
- Replace any damaged hoses and seals – if any of the hoses, show wear or seals are damaged, replace them immediately. Don’t prolong this since it could lead to bigger and unnecessary complications in the long run
How to Choose a Submersible Pump
When purchasing a submersible pump, it’s important to consider the following things:
- The size of the well or water source – check the diameter and the depth
- The outlet or delivery size – this is the diameter of the pump tubing through which the water will be ejected to the surface.
- The discharge rate of the pump – this is the measure of the amount of water that’s pumped per minute, also known as gallons per minute (GPM)
- The stage – every pump has an efficiency chart and it’s vital to select the correct stage of pump based on the head and motor rating to maximize its efficiency.
- The construction material – although it doesn’t affect the application or the performance of the pump, it can have an effect on the life span of the device.
The Bottom Line
With all the benefits of submersible pumps, it’s easy to see why this type of pump has become one of the best on the market when it comes to a variety of applications, including pumping water from a well, keeping a fountain running or for commercial purposes like oil-drilling and sewage removal.
The information gives you an overall understanding of submersible pumps. When choosing a pump, make sure to check for its quality and performance. Look for high-quality design and construction.