Magnetic pump is a centrifugal pump that uses the principle of magnetic coupling (magnetic transmission) to transmit torque and achieve complete static sealing.

Magnetic pump is a centrifugal pump that uses the principle of magnetic coupling (magnetic transmission) to transmit torque and achieve complete static sealing.

Revolutionary feature: It uses the magnetic force of a set of permanent magnets (or electromagnets) to penetrate the isolation sleeve in a non-contact manner, transmitting the torque of the motor to the impeller on the pump shaft. It completely eliminates the traditional pump shaft dynamic seal (packing seal or mechanical seal) and structurally eliminates the possibility of leakage.

Design standards:

Industrial grade: API 685 "Unscented Centrifugal Pumps for Petroleum, Petrochemical, and Natural Gas Industries" is the highest standard with extremely strict requirements for reliability and safety.

General industrial grade: ASME B73.3M is the most widely used magnetic pump standard for the chemical industry.

ISO 2858/ISO 5199: International General Standards.

2、 Detailed explanation of structure and working principle
The core of a magnetic pump lies in "magnetic transmission" and "passive lubrication cooling cycle".
Functional description of key components:

Magnetic coupler:

External magnetic cylinder: connected to the motor shaft, usually containing a rare earth permanent magnet (such as neodymium iron boron NdFeB) with low temperature resistance but strong magnetic force; Or samarium cobalt SmCo, with high temperature resistance.

Internal magnetic cylinder: connected to the pump shaft, also containing a permanent magnet ring, enclosed in an isolation sleeve.

Working principle: The motor drives the outer magnetic cylinder to rotate, and its magnetic field penetrates the air gap and isolation sleeve, driving the inner magnetic cylinder to rotate synchronously, thereby achieving non-contact transmission of torque.

Isolation sleeve: This is the core static sealing barrier of the pump, usually made of high resistivity corrosion-resistant metals (such as Hastelloy, titanium) or ceramics. It must be thin enough to reduce eddy current losses and strong enough to withstand system pressure.

Bearing system:

Location: There are two sets of sliding bearings at the pump end, located on the impeller side (front bearing) and the inner magnetic cylinder side (rear bearing).

Material: It must rely on the lubrication of the conveyed medium, commonly using silicon carbide (SiC), which is recommended as the first choice by API standards due to its extremely high hardness, wear resistance, and good self-lubricating properties. Carbon graphite, hard alloy, etc. are also used.

Circulation and cooling system:

Internal circulation: A small stream of medium (about 1-5% flow rate) is introduced from the high-pressure area of the pump, which flows through the rear bearing, rotor chamber (cooling the inner magnetic cylinder and isolation sleeve), front bearing, and finally returns to the low-pressure suction port of the pump. This cycle lubricates the bearings, cools the magnetic steel, and isolates the sleeve.

External cooling: For high-temperature, easily vaporized, or low lubricious media, it is usually necessary to install a cooling jacket on the outside of the isolation sleeve or pump cover, and pass cooling water to enhance heat dissipation and prevent the media from vaporizing in the rotor cavity.

3、 Core advantages
100% leak free: The static sealing design fundamentally solves the problem of leakage of toxic, harmful, flammable, explosive, and expensive media, ensuring safety and environmental protection.

Easy maintenance: No need to maintain or replace mechanical seals, avoiding complex alignment work. The replacement of vulnerable parts such as bearings is relatively easier for shielded pumps (usually on-site).

High reliability: The transmission components have a relatively simple structure and no mechanical wear (magnetic transmission is non-contact).

Overload protection: When the pump end is overloaded or stuck, the inner and outer magnetic cylinders will "slip", protecting the motor from being burned out.

Modular design: usually a pullback design, which eliminates the need to disassemble pipelines when repairing internal components.

4、 Main drawbacks and limitations