Magnetic Drive Recycle Pump
Magnetic Drive Recycle Pump
What is a magnetic drive recycle pump?
A magnetic drive recycle pump, also called a magnetically coupled recycle pump, is a hermetically sealed pump that uses the force of magnetism to move fluid through the pump. The pump manufacturer design it with a set of magnets, a drive magnet on the outside, and a driven magnet on the inner side of a hermetically sealed pump chamber, to create a magnetic field that helps to turn the impeller and to pump the fluid. A magnetic drive recycle pump features a robust design with a hermetically sealed pump chamber that makes the pump airtight. The airtight design reduces the risk of fluid or vapor leakage during operation. Magnetic drive recycle pumps are widely used in the chemical industry to handle highly corrosive products, acids, alkalis, pollutants, and toxic materials. They are also ideal for pumping expensive and dangerous chemical products for which even the slightest leakage cannot be tolerated. Hermetic seals save day-to-day operating costs because they require less maintenance.
Figure: Magnetic drive recycle pump.
Components of a magnetic drive recycle pump
Pump magnetic drive
A magnetic drive recycle pump uses a magnetic drive to rotate the impeller and to move the fluid. Unlike conventional pumps with direct coupling between the shaft and the impeller, the magnetic drive recycle pump uses a magnetic drive instead of traditional coupling. The magnetic drive consists of a drive magnet and impeller magnetic that are magnetically coupled. The drive magnet is mounted on the end of the motor shaft and aligned outside the pump chamber. The impeller magnet is connected to the impeller and located inside the pump chamber and within the center of the magnetic field of the drive magnet. Magnetic drive recycle pump manufacturers create magnets from rare earth metals such as neodymium or samarium alloyed with other metals. The most common combinations include Neodymium-Iron-Boron and Samarium-Cobalt. These complex alloys offer the advantages of low weight and excellent temperature stability.
The pump chamber separates the drive Magnet and impeller magnet and keeps the pumped medium contained. The magnetic drive recycles pump’s chamber is hermetically sealed, meaning it can operate without mechanical seals and does not experience leakage of transfer liquid during operation.
The impeller is the component that moves the liquid through the pump into the piping network. The magnetic drive recycles pump’s impeller can be directly integrated into the internal magnet or may be assembled using a variety of methods. The impeller is operated by the magnetically coupled impeller magnet and drive magnet. It also rides on an internal shaft and bushing assembly to ensure concentric rotation with the drive shaft and inside the pump chamber.
The impeller shaft is the component of a magnetic drive recycle pump that carries the impeller and the impeller magnet. The impeller shaft rotates the impeller due to the magnetic force generated by the drive and impeller magnet. The magnetic drive recycle pump manufacturers design shafts using ceramic materials because they provide a performance-bearing surface on which the impeller can rotate. Magnetic pump manufacturer usually fit the impeller shaft ends with O-rings or gaskets to prevent fluid leakage.
A magnetic drive recycle pump also consists of an electric motor to power the pump. It uses electrical energy from electricity mains and converts it into mechanical energy to rotate the drive magnet to generate a magnetic field. When the motor is started, the drive magnet spins, generating a magnetic field that causes the impeller magnet aligned with it to begin rotating. As the impeller magnet rotates, the impeller turns, causing fluid transfer through the pump and piping network.
How does a magnetic drive recycle pump work?
A magnetic drive recycle pump operates using a set of magnets working in tandem to move the fluid through the pump. The first magnet is called the external or drive magnet and is mounted to the motor shaft using grub screws or a particular type of adhesive. The second magnet, internal or impeller magnet, is inside the pump and usually encapsulates in metal or high-grade thermoplastic. The two magnets are separated by a hermetically sealed pump casing that helps to keep the pumped medium contained. When the power is supplied to the motor, the motor shaft rotation causes the drive magnet to turn. Because of the different polarities of the magnets, the strong magnetic field penetrates through the pump casing allowing the torque generated to be transferred from the drive magnet to the impeller magnet. This transfer of torque using magnetic fields is called magnetic coupling. As a result, the impeller, which is directly coupled with the impeller magnet inside the pump, rotates in unison with the drive magnet, thereby pumping the fluid through the pump system.
When the impeller rotates, a vacuum is created, and the atmospheric pressure forces the fluid into the center of the impeller via the inlet connection. As the impeller continues to rotate, the vanes catch the fluid, increasing its velocity and kinetic energy and forcing it toward the pump’s discharge port. The mechanical movement of the fluid generates the discharge pressure that moves the liquid to the required destination through the pipes. The discharge pressure and fluid flow depend on several variables, such as the impeller diameter, motor horsepower, fluid supply pressure, etc.
Figure: working of a magnetic drive recycle pump
Types of magnetic drive recycle pump
Magnetic drive recycle pumps have two broad types: rotating shaft and stationary shaft
Rotating shaft magnetic drive recycle pump
Rotating shaft magnetic drive recycle pumps are meant for heavy-duty applications. They feature a rotating shaft and metallic construction. The metallic structure offers the best strength, pressure, and temperature ratings. Their rotating shaft increases the pump complexity as more parts are required. They thus have higher construction and maintenance costs.
Stationary shaft magnetic drive recycle pumps
These types of magnetic drive recycle pumps have a fixed shaft and are designed for medium-duty applications. Stationary shaft magnetic drive recycle pump manufacturers produce these pumps from non-metallic materials (such as ceramics and plastics), which generally provide good corrosion resistance. However, they have a limited temperature range between 200- and 250-degree Fahrenheit. Stationary shaft magnetic drive recycle pumps are less complex and have few parts, reducing construction and maintenance costs.
Applications of magnetic-drive recycle pump
- Magnetic drive pumps are used in chemical industries to transfer all chemicals, including acids, alkalis, and alcohol.
- They are also used for surface conditioning- for example, to transfer from circulating and treatment baths and tanks and containers.
- They are also used in the food and beverage industries to pump CIP detergents for cleaning processing equipment.
- Magnetic drive recycle pumps are also used in photo processing to transfer photo development chemicals.
- They are used for the mechanical handling of oil, fats, lubricants, cooling liquids, solvents, and solid-free products.
- In water treatment plants to magnetic pump samples and for dosing acid and alkalis for PH control
- Magnetic drive recycle pumps are used to transfer hazardous and corrosive chemicals.
- They are also used in cryogenics to pump liquid for cooling equipment and air conditioning.
- They are also used for pressure boosting.
- Magnetic drive recycle pumps also apply in loading, offloading, metering, and batching operations.
- They also pump liquid that may crystallize on seal surfaces, which may cause seal failures.
- Magnetic drive recycle pumps transfer expensive fluid, mitigating the risk of losing products.
Advantages of magnetic drive recycle pump
- Magnetic drive recycle pumps have low maintenance, operation, and installation cost hence reducing customer life cycle cost (LCC)
- They also have a low risk of fluid or vapor emission leakage
- Magnetic drive recycle pumps are leak-free and suitable for handling corrosive, hazardous, costly, flammable, and toxic chemicals, thanks to the leak-proof design.
- Their magnetic coupling eliminates procedural pump alignment.
- Magnetic drive recycle pumps are highly reliable.
- The magnetic drive recycles pump’s design complies with many strict environmental and safety objectives typically required by many regulations.
- They have a simple design with fewer working parts, which allows longer service life and easier pump stripping.
- Magnetic drive recycle pumps are also available in different materials, including metal and non-metals.
- Magnetic drive recycles pumps have low operational costs as there aren’t any mechanical seals, seal-fluid pots, or cooling lines that may break during pumping.
Disadvantages of magnetic drive recycle pump
- Magnetic drive recycles pumps have a limited solid handling capacity. As such, they are only perfect for transferring clean fluids and are not recommended for fluid with any size of particles. They can’t handle liquids containing ferromagnetic particles because they may collect on the magnet, causing it to break down over time.
- Magnetic drive recycles pumps are unsuitable for high-temperature applications because exposure of magnets to temperatures above their threshold can cause loss of magnetism.
- In a magnetic drive recycle pump, some energy may be lost in the magnetic coupling due to magnetic resistances.
- They also have limitations in power rating as robust magnetic coupling may not be feasible or cost-effective.
- Magnetic drive recycles pumps are susceptible to transient cases such as low flows and operation near shutoff head conditions.
- Magnetic drive recycle pumps consume more power as compared with centrifugal pumps.
Troubleshooting a magnetic drive recycle pump
- Low motor speed. Check the motor speed against the speed ranges recommend by the magnetic drive recycle pump manufacturer and correct it as necessary.
- The impeller diameter is too small. Confirm that the impeller diameter is the required size.
- The system head is too low. Check whether t the system head is lower than anticipated. Raise the liquid level or pressure level in the tank.
Pump losses prime
- Leakage in the suction piping. Check the suction line for leakage and repair it as necessary
- Air or gas is present within the fluid. Remove air or gas from the fluid by priming.
- Impeller clogged with foreign matter. Inspect the impeller and remove any foreign matter
- The foot valve or suction opening is not sufficiently submerged. Inspect the foot valve and suction opening and correct their positions as required.
- The suction lift is too high, or NPSHa (net positive suction head available) is insufficient. Reduce the suction lift by raising the liquid level in the suction pipe to the level recommended by the pump manufacturers.
Insufficient fluid discharge
- Air leakage in the suction line. Inspect the suction line for air leakage and perform necessary repairs.
- The discharge valve is partially closed. Open it fully.
- The impeller vanes or suction lines might be clogged. Inspect and clean the vanes and suction line from any deposits and debris.
- Incorrect motor rotation. Verify that the motor rotation is correct or change the direction of motor rotation if necessary.
Noise and vibrations
- Foreign objects in the impeller. Disassemble the impeller and remove the clogged materials.
- The motor and piping are loosely mounted. Ensure the motor and piping are adequately secured with the torque recommended by the magnet drive recycle pump manufacture.
- Cavitation is present due to improper suction or feed. Ensure that the suction or feed is proper according to the pump manufacturer’s guidelines.
A magnetic drive recycle pump uses the magnetism force to move fluid through the pump. Unlike conventional pumps with direct coupling between the shaft and the impeller, the magnetic drive recycle pump uses a magnetic drive instead of traditional coupling.
A magnetic drive recycle pump consists of a drive magnet outside the pump casing and an impeller magnet inside the case. The driver magnet is run using an electric motor to generate a magnetic field that penetrates through the motor casing creating a magnetic coupling with the impeller magnet and causing it to spin synchronously with the driver magnet. As the impeller magnet spins, it rotates the pump impeller attached to it, displacing the fluid through the pump system.
Magnetic drive recycle pump manufacturers design the pump to fit many applications, including water treatment, food and beverage industries, surface treatment, and corrosive mechanical transfer. Significant advantages include high reliability, simple design, and low installation, operation, and maintenance costs.