Do I Need a Check Valve on My Sump Pump?

Most water pumps are usually equipped with check valves, which play a vital role in water pump systems. Today, let’s introduce in detail:

The universality of check valve installation

In various water pump application scenarios, the installation of check valves is very common. This is because the working characteristics of water pumps and the safety and stability of system operation require check valves to ensure. Whether in industrial fields such as chemicals, petroleum, and electricity, or in civil fields such as water supply and drainage, HVAC systems, etc., it is common to install check valves at the outlet of water pumps.

For example, in urban water supply systems, from water intake pumps at water sources to booster pumps in urban pipe networks, almost every water pump is equipped with a check valve to ensure that water flows in the prescribed direction and prevent water backflow from damaging the water pump and system.

Function of check valve

Preventing water hammer phenomenon: When the water pump stops running suddenly, such as in the case of power failure or fault shutdown, the water flow will not stop immediately due to inertia, but will continue to flow forward for a distance. At this time, the water flow speed in the pipeline changes sharply, causing the pressure to rise instantly, forming a water hammer pressure wave. This pressure wave reflects back and forth in the pipeline, which will produce extremely high pressure peaks, which may cause serious damage to the pipeline, water pump and other equipment, such as pipeline rupture, water pump impeller damage, valve seal failure, etc. The protective role of the check valve: The check valve can be quickly closed at the moment the water pump stops running, preventing the backflow of water, thereby effectively avoiding the occurrence of water hammer. It is like a “one-way door”, allowing water to pass through during normal water supply, and immediately closing the channel when the water pump stops working to prevent water backflow and protect the safety of the entire system. For example, in the water supply system of some high-rise buildings, if there is no check valve, when the water pump fails and stops, the water hammer pressure may cause the water tank on the roof to rupture, or cause water leakage at the pipe connection on the ground floor, causing great inconvenience and loss to the building and residents’ lives.

Protect the water pump

· Prevent the impeller from reversing: When the water flows backward, it will drive the water pump impeller to rotate in the opposite direction. The impeller of the water pump is usually designed for forward rotation. Reverse rotation may cause the connection between the impeller and the shaft to loosen, or even damage the impeller.

The check valve can prevent the water from flowing backward, prevent the impeller from being damaged by reversal, and extend the service life of the water pump. For example, in the circulating water pump system in some industrial production, the damage of the impeller will cause the entire production process to be interrupted, causing huge economic losses, and the installation of the check valve can effectively prevent this from happening.

· Avoid motor overload caused by water pump reversal: If the water pump impeller reverses, the load of the motor will increase, which may cause the motor to overload and heat, or even burn the motor. The check valve prevents water from flowing back and avoids the pump from reversing, thereby protecting the motor and enabling it to operate under normal working conditions.

For example, in the pump system of some sewage treatment plants, the maintenance and replacement costs of the motor are high. The reasonable installation of the check valve can reduce the risk of motor failure and ensure the stable operation of the sewage treatment system.

Maintaining stable system pressure

Preventing pressure fluctuations: In some complex water supply systems or hydraulic systems, check valves can prevent pressure fluctuations in the system due to backflow of water. When the water pump is working normally, it pressurizes water and delivers it to the system to keep the system at a certain pressure. Without a check valve, when the water pump stops running or a pressure change occurs in a certain part of the system, water may flow back, causing the system pressure to drop and affecting the normal operation of the system. The existence of a check valve ensures that the pressure in the system can remain relatively stable and provides stable working pressure for various equipment in the system. For example, in some industrial automation production lines, stable hydraulic system pressure is essential for the precise movement of equipment and the control of product quality, and check valves play an indispensable role in this. Ensure pressure buildup: When starting the water pump, the check valve can prevent the water in the pipeline from flowing back to the water pump inlet, allowing the water pump to smoothly pressurize the water and build up system pressure. Without a check valve, it may take longer to build pressure when the water pump starts, and it may not even be able to build up enough pressure, affecting the normal startup and operation of the system. For example, in some fire water supply systems, quickly building up sufficient water pressure is essential for fire fighting. The installation of check valves can ensure that the fire pump can quickly provide the required pressure for the fire pipe network after starting. Application of preventing medium backflow pollution in special medium transportation: In some systems that transport special media, such as chemical raw materials, food and beverage, pharmaceutical and other industries, it is very important to prevent medium backflow pollution. If the medium flows back, it may cause different types of media to mix, resulting in product quality degradation, production accidents and even harm to human health. Check valves can effectively prevent this from happening, ensure that the medium flows in the prescribed direction, and protect product quality and production safety. For example, on a beverage production line, a check valve can prevent beverages of different flavors from mixing and ensure the pure taste of the product; in the pharmaceutical industry, a check valve can prevent cross-contamination during the production process of drugs and ensure the quality and safety of drugs. Role in sewage treatment systems: In sewage treatment systems, check valves can prevent treated water from flowing back to the treatment pool and prevent treated water from being contaminated by untreated sewage. At the same time, it can also prevent sewage from flowing back in the system, affecting the process and effect of sewage treatment. For example, in the activated sludge wastewater treatment process, the check valve can ensure that the mixed liquid in the aeration tank flows in the correct direction, prevent the sludge from flowing back to the front-end pretreatment unit, and ensure the normal operation of the wastewater treatment system.

Types and features of check valves

·Swing check valve

·Working principle: The valve disc of the swing check valve rotates around the pin outside the valve seat. When the medium flows forward, the medium pressure pushes the valve disc to open and allow the medium to pass; when the medium flows back, the valve disc closes under the action of gravity and medium pressure to prevent the medium from flowing back.

·Features: The swing check valve has the advantages of simple structure and small fluid resistance, and is suitable for large-diameter pipelines. However, its closing speed is relatively slow, and it may not be suitable in some occasions with high requirements for closing speed. For example, in some large industrial water pipelines, swing check valves are widely used because they can meet the requirements of large flow rates and have low resistance to fluids, which can reduce energy consumption.

·Lift check valve

·Working principle: The valve disc of the lift check valve moves up and down along the axis of the valve seat. When the medium flows forward, the medium pressure causes the valve disc to rise and open the channel; when the medium flows back, the valve disc falls under the action of gravity and medium pressure to close the channel.

·Features: The lifting check valve has good sealing performance and fast closing speed, and is suitable for occasions with high sealing requirements. However, its structure is relatively complex and the fluid resistance is large, so it is generally suitable for small and medium-sized pipes. For example, in the water supply or oil supply system of some precision instruments and equipment, the lifting check valve can ensure the sealing of the system, prevent medium leakage, and ensure the normal operation of the equipment.

·Butterfly check valve

·Working principle: The valve disc of the butterfly check valve is similar to a butterfly valve and rotates around the central axis. When the medium flows in the forward direction, the valve disc opens; when the medium flows in the reverse direction, the valve disc closes under the action of the medium pressure.

·Features: The butterfly check valve has the advantages of compact structure, light weight, and easy installation. It is suitable for large-diameter pipes and low-pressure systems. However, its sealing performance is relatively poor, and it needs to be used with caution in some occasions with strict sealing requirements. For example, in the drainage systems of some cities, butterfly check valves are often used in large-diameter drainage pipes because its structural characteristics are easy to install and maintain in the pipes, and can meet the large flow and low pressure requirements of the drainage system.

Installation and maintenance of check valves

Installation location: Check valves are usually installed on the outlet pipe of the water pump, as close to the water pump as possible. This can quickly stop the water from flowing back when the water pump stops running, protecting the water pump and the system. At the same time, the installation location of the check valve should be convenient for inspection and maintenance, and avoid installing it in inaccessible places. For example, in the pump room of some factories, the check valve is generally installed on a horizontal pipe at a certain height from the ground, which is convenient for operators to inspect and repair.

Installation direction: The check valve has a clear installation direction and must be installed in the direction of the medium flow, otherwise the check valve will not work properly. During installation, pay attention to the arrow mark on the check valve body to ensure the correct installation direction. For example, in some complex piping systems, there may be multiple branches and pipes with different flow directions. At this time, it is necessary to carefully identify the flow direction of the medium and correctly install the check valve to ensure the normal operation of the system.

Maintenance points: Regularly check the sealing performance of the check valve, and check whether the valve disc and valve seat are worn, corroded, or debris accumulates. If the seal is not tight or the valve disc is not flexible, it should be repaired or replaced in time. At the same time, the environment around the check valve should be kept clean to prevent debris from entering the valve and affecting its normal operation. For example, in some water supply systems with poor water quality, it is necessary to regularly clean the silt and impurities in the check valve to ensure its sealing performance and the reliability of its action.

Different types of check valves are suitable for different working conditions. In actual applications, it is necessary to select the appropriate check valve according to the specific engineering requirements and system characteristics, and install and maintain it correctly to ensure its optimal performance and ensure the reliable operation of the entire system.