Magnetic Peripheral Centrifugal Pump
Magnetic Peripheral Centrifugal Pump
What is a magnetic peripheral centrifugal pump?
A magnetic peripheral centrifugal pump is a type of centrifugal pump consisting of a periphery impeller and using magnetic technology to move fluid through the pump. The magnetic technology that helps to run the pump impeller consists of a drive magnet and an inner magnet separated by seal-less housing. Magnetic peripheral centrifugal pump manufacturers design the two magnets such that their magnetic fields are aligned to create a magnetic coupling that helps the impeller rotate when the motor is started. The impeller rotates inside a concentric casing, and the liquid flows between the vanes and casing, transmitting a large amount of energy and building high pressure within the pump. As such, the fluid flows along the circumference from the inlets to the outlet with increasing pressure.
Magnetic peripheral centrifugal pump manufacturers design the pump for handling clean fluids because of the narrow clearance between impeller vanes and pump casing. Any solid particle presents in the fluid may stop the impeller. They find uses in medium to high-pressure liquid transfer applications such as hydro cyclone feed, jetting, filtration, transfer of fluids across large distances, and display fountains. The seal-less housing design prevents fluid leakage making the pump perfect for transferring potentially dangerous and costly liquids.
Figure: (a) Front view of magnet peripheral centrifugal pump (b) Magnetic peripheral centrifugal pump
Components of magnetic peripheral centrifugal pump
A magnetic peripheral centrifugal pump consists of two magnets that forms the pump’s magnetic drive. One magnet is attached to the motor shaft, called the outer or driver magnet, and is located outside the pump housing. The other, called the driven magnet or inner magnet, is located inside the pump, attached to the pump impeller, and rides on the internal shaft. Pump manufacturers mount the inner magnet within the center of the magnetic field of the outer magnet. When the drive magnet rotates due to the rotation of the motor, the internal magnet rotates synchronously due to the magnetic coupling created between it and the drive magnet, forcing the impeller to turn.
The electric motor is the prime mover in the magnetic peripheral centrifugal pump, providing all the power required to run the pump. The electric motor is an electromechanical device that converts electrical energy from the main electricity supply into mechanical energy. In a magnetic peripheral centrifugal pump, the electric motor works with the magnetic drive to facilitate the rotation of the impeller via a magnetic coupling instead of the direct connection between the electric motor and the impeller, as with conventional centrifugal pumps. An electric motor can be either an AC motor or a DC motor. Ac motors work with alternating current, while Dc motors operate with direct current.
The periphery impeller is the component comprising a series of radial vanes on the outside edge. It is usually mounted on a shaft supported by bearing and housed in a water-tight casing. The primary function of an impeller is to displace the fluid through the pump by increasing the kinetic energy and pressure of the liquid. Magnetic peripheral pumps use enclosed impeller types in which the vanes are closed from both ends with shroud plates. In a magnetic peripheral centrifugal pump, the impeller is connected to the internal magnet, whose rotation due to magnetic coupling with the outer magnetic causes the impeller to rotate and displace fluid through the pump.
Figure: Periphery impeller
The shaft is a rotary mechanical component supported on bearings. The pump shaft carries the impeller and inner magnets in a magnetic peripheral centrifugal pump. The whole assembly connects to the electric motor through magnetic coupling created between the drive magnet and internal magnet when the electric motor is started. Magnetic peripheral pump manufacturers design the shaft using solid metals such as stainless steel and carbon steel to transmit the torque required to turn the impeller.
Like in any other type of pump, the suction pipe of a peripheral magnetic pump comprises two ends. One end is connected to the suction flange while the other dips into the water. The lower end of the suction pipe is designed with a foot valve to inhibit the backward flow of water and a filter to prevent foreign bodies from entering the suction pipe.
The delivery pipe also consists of two ends. One end is connected to the discharge flange of the pump, while the other delivers the water at a designed height. The primary purpose of the suction pipe is to lift fluid to the required destination.
Figure: suction and delivery flanges where suction and delivery pipes are mounted
How does a magnetic peripheral centrifugal pump work?
The pump operates based on magnetic technology. Magnetic technology comprises outer and inner magnets arranged so that their magnet poles align. The outer magnet (driver magnet) is connected to the motor shaft, while the inner magnet (driven magnet) is connected to the pump impeller. The electric motor is powered with electricity from the main supply during operation. As the electric motor begins to run, it rotates the outer magnet generating a rotating magnetic field. The magnetic field so created affects the inner magnet and begins to turn synchronously with the external magnet due to the magnet coupling. As the internal magnet rotates, it causes the periphery impeller to rotate and displace the fluid through the pump.
When the periphery impeller starts rotating, a vacuum is created inside the pump casing and causes fluid to enter the annular channel through the suction flange. Once the liquid strikes the impeller’s blades, the centrifugal force acting on the edges rotates and transforms the liquid in a centrifugal motion. The fluid is rotated at the same speed as the periphery impeller at the annular channel. Water’s kinetic energy is converted into a pressure head before it leaves the pump via the discharge flange.
Figure: working of magnetic periphery centrifugal pump
Applications of magnetic peripheral centrifugal pump
Magnetic periphery centrifugal pumps are preferred for most fluid transfer activities in various industries. Some industries where the Magnetic periphery centrifugal pumps are most widely applied include water treatment plants, petroleum, chemical and petrochemical, energy and oil, and power plants. The most common uses of magnetic periphery centrifugal pumps include the following:
- They are used to transfer environmentally hazardous liquids, toxic media, flammable materials, acids and alkalis, high-purity media, and active ingredients.
- They are also used for dosing applications.
- They are used for Hygienic and sterile applications.
- They are also used in potentially explosive areas because they are leak free and can transfer inflammable liquids.
- Magnetic periphery centrifugal pumps are used in high-pressure liquid transfer applications such as hydro cyclone feed, jetting, filtration, transfer of fluids across large distances, and display fountains.
- They are used as boiler feed pumps for small boilers
- Magnetic periphery centrifugal pumps can be used as pressure-boosting pumps
Advantages of magnetic peripheral centrifugal pump
Magnetic periphery centrifugal pumps offer numerous benefits, including the following
- Magnetic periphery centrifugal pumps have a robust design that is easy to maintain.
- They are free of external pressure. The presence of magnetic coupling helps to prevent the occurrence of external pressure.
- They have a low net positive head requirement (NPSH)
- They can provide a low flow rate at high pressure
- They have a compact design and low axial thrust; hence their lifespan is long
- They have a silent operation and are easy to clean.
- They have a Leak-proof design because the pump housing is hermetically sealed.
- They are perfect for large discharge and trimmer heads.
- They are highly reliable.
- They have incredible energy and operation efficiency.
- They provide steady and consistent output.
Disadvantages of magnetic peripheral centrifugal pump
- Magnetic peripheral centrifugal pump can overheat.
- The magnetic coupling can lead to a significant loss of energy
- They may fail due to intense load.
- Peripheral pumps have lower efficiencies compared to radial pumps.
- Magnetic peripheral centrifugal pump cannot handle contaminated fluids as any solid particle in the pump would stop the impeller.
- Magnetic peripheral centrifugal pumps are unfit for high-temperature environments because overheating can cause loss of magnetism.
Troubleshooting magnetic peripheral centrifugal pump
The pump does not deliver fluid
- The motor is not operational. Check Motor windings and phases and replace them if necessary.
- The inlet or Discharge valve is closed. Open all valves
- Low NPSH. Confirm that the pump NPSH meets the magnet peripheral pump’s manufacturer’s specifications
- Wrong motor rotation direction. Confirm that the motor direction of rotation is right according to the pump manufacturer guide
- The filter is blocked with sediments. Backwash the filter, or remove, clean, and refit it.
Excessive power consumption
- There are particles in the discharge. Disconnect the discharge flange, flush and refit it.
- The pump pressure, fluid viscosity, or temperature are outside the magnetic periphery pump manufacturers’ specifications. Check pump design, fluid characteristics, and system requirements from the magnetic pump manufacturer guide.
- Use of collapsed hose. Fit rigid hoses according to the pump manufacturer’s recommendations
- End of Service life or adverse pumping conditions. Counter-check the pump’s installation and maintenance history.
- Some parts are severely worn out. Inspect the pump for worn-out components such as the shaft, bearing, and periphery impeller. Replace such components with parts recommended by the pump manufacturer.
Low pressure/ flow output
- The pump speed is incorrect. Confirm the pump’s VDFD setting according to the pump manufacturer’s guide.
- Faulty motor. Inspect the motor winding and phases for errors and replace them if required.
- There is a foreign object in the suction line. Inspect the filter, and Flush inlet pipework is necessary.
- End of pump’s service life. Check the service life of the pump from the pump manufacturer’s guide and replace it if necessary.
- Wrong motor speed. Ensure that the motor operates within the speed range specified by the pump manufacturer. Inspect the motor bearing and consult a licensed electrical engineer to inspect the motor condition.
- The pump components are worn out. Inspect the pump for worn-out parts and replace them.
- The particles inside the pump. Check the vane for damages, and clean the pump and filter.
Pump is leaking
- Damaged O rings. Check for particles or seals trapped/twisted in the pump casing
- The pump shaft is worn out. Wearing can cause the pump shaft to be undersized, resulting in leakage around the shaft ends. Inspect the shaft for wear and Replace the shaft and O-rings if necessary.
- Loose flange fasteners. Check that torque of bolts meets the pump manufacturer’s requirement.
- Thermal expansion. High-temperature mays cause the fluid to expand within the pump as it is being circulated. Ensure the pump manufacturers design the system to prevent such from happening.
A magnetic periphery centrifugal pump uses magnetic technology to run the periphery impeller, which moves fluid through the pump and piping network. Pump manufacturers design magnetic periphery centrifugal pumps with several components such as a motor, periphery impellor, magnets, shaft and suction, and delivery flanges. The magnetic technology used for the pump consists of a drive, and driven magnets arranged such that their magnetic fields are aligned to create a magnetic coupling. When the motor is started, it turns the drive magnet making a rotating magnetic field in the outer magnet. This rotating magnetic field interacts with the magnetic fields of the driven magnet creating a magnetic coupling that leads to torque transfer from the outer magnet to the inner magnet, sets the periphery impeller in rotary motion, and causes fluid displacement in the pump.
Magnetic periphery centrifugal pumps have many applications across many industries, including water treatment plants, petroleum, chemical and petrochemical, energy and oil, and power plants. Although magnetic periphery centrifugal pumps are limited by low solid handling capacity and energy loss due to magnetic coupling, they offer many advantages, such as low maintenance cost, excellent performance efficiency, and silent and leak-free operation.