Multistage canned pump

Multi-stage cascaded DCMC

Branch: DN25~DN200

Capacity: up to 700 cubic meters per hour

Head: up to 700 meters

Rotational speed: 1,450 to 3,500 rpm

Operating temperature: up to 160°C

Viscosity: maximum 100 mm ²/s

Pressure rating: 2.5–16 MPa

Structural Features ：

● BB5, barrel casing, multi-stage, annular cross-section design

● Based on the multi-stage standard design, a pressure vessel shell has been added to reduce the number of sealing points and enhance safety.

● A non-self-priming pump with up to 12 stages.

● Enables internal high-pressure circulation, with the conveyed medium cooling the motor and lubricating the sliding bearings.

● Series pressurization.

● This pump features low flow rate, high head, and an extremely low net positive suction head.

Working Principle

A canned pump is an integrated unit comprising a centrifugal pump and a three-phase AC motor, with the hydraulic components directly coupled to the motor’s drive shaft to form the rotor assembly. The stator housing is fitted inside the stator, separating the rotor chamber from the stator chamber and thereby enabling completely leak-free operation of the pump.

Characteristics of canned pumps

● Adopts advanced European hydraulic modeling for high efficiency.

● The stator housing is made of imported Hastelloy C276, which offers high magnetic permeability and outstanding corrosion resistance.

● The sliding bearing is made of silicon carbide (SSIC), which offers high strength, excellent wear resistance, and superior corrosion resistance, resulting in a service life ten times that of graphite bearings.

● This shielded motor is a three-phase squirrel-cage induction motor, featuring high efficiency, an IP55 protection rating, and an explosion-proof classification of II CT3–T5.

● Axial force is automatically balanced hydraulically.

● Adopts a simple, compact modular design for easy installation and maintenance.

● Compared with pumps equipped with mechanical seals, it offers longer mean time between failures, reduced wear and lower maintenance frequency, resulting in lower overall operating costs.

● Low noise.

Standardized chemical process pumps:
Flow rate: up to approximately 600 cubic meters per hour
Head: up to 200 meters
Small magnetic drive pumps:
Flow rate: typically less than 50 cubic meters per hour
Head: typically less than 100 meters
Multistage canned pump:
Flow rate: Common range up to 400 cubic meters per hour
Lift: Its maximum lift can exceed 2,000 meters, which is the primary series that enables it to achieve ultra-high-altitude lift.
Ultra-low-temperature canned pumps for liquefied natural gas:
Flow rate: Depending on the specifications, it can be very high (used for large-scale LNG transportation).
Pump head: Can be designed to meet specific requirements and can also achieve high pressure.

Working Principle

The hermetically sealed canned motor pump is an integrated unit comprising a centrifugal pump and a three-phase AC motor, with the hydraulic section directly connected to the motor’s drive shaft to form the rotor assembly. The stator housing is embedded in…

The inner side of the stator is used to isolate the rotor chamber from the stator chamber, thereby enabling the sealless pump to achieve complete leak-free operation.

Characteristics of canned pumps

1. Adopts an outstanding European hydraulic model for high efficiency.
2. The stator is manufactured from German-imported Hastelloy C4, which is rolled and formed using a specialized process, resulting in high precision, superior quality with no welding defects, high magnetic permeability, and excellent corrosion resistance.
3. The sliding bearings are made of silicon carbide (SSIC, SIC30), which offers high strength, excellent wear resistance, and superior corrosion resistance, with a service life ten times that of graphite bearings.
4. This canned motor is a three-phase squirrel-cage induction motor with high efficiency and an IP55 protection rating.

Explosion-proof rating: II CT3–T5
4. Axial force is automatically balanced hydraulically.
5. Adopts a simple, compact, modular structure for easy installation and maintenance.
6. Compared with pumps equipped with mechanical seals, it boasts a longer mean time between failures (MTBF) and reduced wear.

Moreover, it boasts a lower maintenance rate and lower total operating costs.
7. Low Noise

The core feature of a canned pump is its integrated design, which combines the motor and the pump casing into a fully sealed, pressurized vessel. In this configuration, the motor rotor is in direct contact with the conveyed fluid, while the stator windings are electrically insulated from the fluid by a magnetic shield. This design achieves static sealing, ensuring zero leakage during operation.

Vertical CZF-V Type: Flow rate: approximately 800 m³/h; Head: up to 260 m; Operating temperature: –100 °C to +100 °C; Viscosity: up to 100 mm²/s; Pressure rating: approximately 6.3 MPa. Structural features: ● Single-stage vertical pump. ● Internal high-pressure circulation can be achieved without external piping, and both motor cooling and sliding bearing lubrication are provided by the conveyed medium. ● Suitable for conveying low-viscosity media that do not contain solid particles, have a melting point below the maximum allowable inlet temperature of the motor, and operate within the specified temperature range. Operating principle: The canned motor pump is a combined unit consisting of a centrifugal pump and a three-phase AC motor. The hydraulic section is directly connected to the motor drive shaft, together forming the rotor assembly. The stator housing is embedded inside the stator, completely isolating the rotor chamber from the stator chamber and thereby ensuring zero leakage. Key features of the canned motor pump: ● Adopts an advanced European hydraulic model with high efficiency. ● The stator housing is made of imported Hastelloy C-276, which offers high magnetic permeability and excellent corrosion resistance. ● The sliding bearings are made of silicon carbide (SSIC), providing high strength, outstanding wear resistance, and superior corrosion resistance; their service life is ten times that of graphite bearings. ● The canned motor is a three-phase squirrel-cage induction motor with high efficiency, IP55 protection rating, and explosion-proof classification of II CT3–T5. ● Axial thrust is automatically balanced hydraulically. ● Simple, compact structure with modular design, facilitating installation and maintenance. ● Compared with pumps equipped with mechanical seals, it boasts longer mean time between failures, lower wear and maintenance frequency, and lower overall operating costs. ● Low noise level.

HERMETIC is a world-leading brand in the field of leak-free pumps. Its magnetically driven pumps are renowned for zero leakage and superior safety, primarily serving high-end industrial sectors that demand exceptional reliability, environmental protection, and performance under extreme operating conditions.

According to search results, Haimitek magnetic drive pumps are used in a wide range of applications, with their core advantage lying in providing critical fluid-handling solutions for strategic industries such as chemicals, petrochemicals, and nuclear power.

The following is a detailed overview of its primary application industries:

Applications Industry-Specific Applications/Features Key Customers/Notes
🏭 Core application areas in the chemical and petrochemical industries. The conveyance of flammable, explosive, highly toxic, or strongly corrosive media—such as acids, bases, solvents, and hydrocarbons—is essential to prevent leaks at the source, thereby ensuring production safety and environmental protection. Major domestic and international players include Sinopec, PetroChina, BASF, Bayer, Dow Chemical, DuPont, and others.
☢️ Nuclear-grade fluid systems demand exceptionally high sealing performance, which is why nuclear power technology is widely employed. The company has obtained a design and manufacturing license for civil nuclear pressure equipment issued by the National Nuclear Safety Administration, and its products serve nuclear power plants across China, providing critical equipment for these facilities.
❄️ Refrigeration and cryogenic technologies are employed to convey low-temperature or low-boiling-point media such as refrigerants, liquid ammonia, and fluorocarbons, ensuring the efficient operation of refrigeration systems while preventing leaks. This technology is widely applied across various fields, including industrial refrigeration and air-conditioning systems.
🌱 New energy technologies have been deployed in emerging fields such as photovoltaics and energy storage, delivering reliable, leak-free fluid solutions for manufacturing processes. In 2024, the company will make its debut at the International Photovoltaic and Energy Storage Conference to further expand its presence in the new energy market.
💊 The pharmaceutical and textile industries require the transportation of solvents, intermediates, and other materials during production to meet GMP requirements for cleanliness and safety; additionally, this product is used for conveying acid, alkali, and salt solutions in the textile and synthetic fiber industries.
🚆 Railway locomotives are equipped with fluid systems for cooling, lubrication, and other functions in rail transit vehicles, meeting stringent requirements for high reliability and safety.
💡 Core Advantages and Customer Base
Himeitike magnetic drive pumps have gained entry into these high-end industries thanks to their German-origin technology and more than 20 years of manufacturing expertise as a Sino-German joint venture. With a product portfolio spanning 21 series and 440 models, Himeitike has become a trusted long-term partner to global chemical giants such as BASF, Bayer, and Sinopec.

If you require further information on the specific applications of any of the aforementioned industries, or if you would like to receive more detailed selection recommendations and technical specification descriptions, please do not hesitate to let us know. We will be delighted to provide you with more in-depth answers.

Operating principle description:

The company holds a leading position in the high-end and specialized application markets. Its product portfolio spans national strategic industries such as aerospace and nuclear power, as well as foundational sectors like petrochemicals and clean energy.

Based on the product’s characteristics and publicly available market information, its primary application industries can be categorized into the following three major sectors:

🚀 National Strategy and High-End Manufacturing
Leveraging its outstanding market reputation and extensive track record in the field, it maintains an undisputed leading position in the domestic market share.

Aerospace: The company has long supplied shielded pumps to China’s Xichang, Taiyuan, and Jiuquan Satellite Launch Centers, providing critical support for the launch of the Shenzhou series of crewed spacecraft.

Nuclear power sector: The company holds a design and manufacturing license for nuclear-grade canned motor pumps and is a leading domestic manufacturer of Class 3 nuclear-grade canned motor pumps for civilian nuclear power plants.

Rail Transit: Since 2007, its products have been widely adopted in China’s high-speed locomotive sector.

🏭 Petrochemical and Energy Industries
Possesses a large number of engineering application cases.

Petrochemical industry: Products are widely used for medium transportation in various units, including oil refining, ethylene production, caprolactam production, polyoxymethylene production, and polycarbonate production.

Coal chemical industry: This technology has also been successfully applied in projects such as hydrogen production and urea-based compound fertilizers.

Clean Energy: We offer LNG (liquefied natural gas) cryogenic tank-bag pumps, which are widely used in critical applications such as LNG receiving terminals and liquefaction plants.

🏗️ General Industry and People’s Livelihood Sectors
In addition to the aforementioned high-end sectors, Dalian Empire’s products are also widely favored in conventional industrial and residential applications.

Water Treatment: In collaboration with companies such as Blue Water Technology, we provide specialized pumps for seawater desalination, industrial wastewater treatment, and wastewater treatment in the new energy sector.

Refrigeration and Air Conditioning: As a traditional application area for canned motors, this product is widely used in refrigeration and air-conditioning systems.

Chemical engineering, shipbuilding, and other fields: It is also widely used in general chemical processing, pharmaceuticals, textiles, shipbuilding, and other industries.

Are you conducting preliminary research for a specific project, such as in the chemical industry or water treatment? Please provide details about the application scenario, and I will help you analyze the advantages and disadvantages of selecting a canned pump for that operating condition.

Summary of Extreme Parameters
Parameter values can be numeric; applicable to product/remark source.
Maximum flow rate of 1,000 cubic meters per hour for low-boiling-point liquid transfer series [10]
Propane Transfer Pump with Maximum Head of 300 Meters (RW84 Series) [8]
The maximum working pressure is 35 MPa, and the company’s overall design capability is [4].
20 MPa Hydrodesulfurization Unit Series [7]
The design pressure of the caprolactam-specific pump is 8.0 MPa [4].
Hydrodesulfurization Unit Series with a Maximum Operating Temperature of 450°C [7]
Cryogenic LNG canned motor pump with a minimum operating temperature of −160°C [6]
Ultra-large canned pump with a maximum power of 560 kW, compliant with API 685 standards (2-pole water-cooled motor) [6]
Special monitoring items for pumps used in hydrodesulfurization units: THG (bearing monitoring), vibration, winding temperature, and shield sleeve damage monitoring [7].
4. Nuclear-Grade Product Certification
Dalian Imperial has obtained a license for the design and manufacture of nuclear-grade canned motor pumps, supplying such pumps to domestic civilian nuclear power plants and satellite launch bases, and making significant contributions to satellite launch missions, including those involving the Shenzhou spacecraft.

5. Summary of Technical Parameters
Core parameter boundaries at the application level; typical products
Heavy-duty high-pressure pump for the petrochemical industry, with a pressure rating of 20–35 MPa, operating temperature of 450°C, and power output of 560 kW; part of the hydrodesulfurization series, specifically designed for caprolactam applications.
LNG-specific pumps, ammonia canned pumps, and L-type air-conditioning pumps with cryogenic refrigeration temperatures ranging from -35°C to -160°C and flow rates of 1,000 cubic meters per hour.
Design and manufacturing license for nuclear-grade pumps for nuclear power and aerospace applications, applicable to pumps used in nuclear power plants and satellite launch bases.

Power transmission: When the motor stator is energized, a rotating magnetic field is generated, which drives the rotor—enclosed in a shielding sleeve—to rotate. The rotor shaft directly powers the impeller to convey the working medium.

Zero-leakage guarantee: The stator windings and the rotor core are individually sealed and protected by a stator shield sleeve and a rotor shield sleeve, respectively, ensuring complete isolation from the conveyed medium. Both shield sleeves employ a stationary, welded metal-seal design, fundamentally eliminating any dynamic sealing points.

Cooling and Lubrication: These are critical to the operation of a canned motor pump. A small high-pressure fluid stream is tapped from the pump discharge, filtered, and then sequentially passes through the rear bearing, the air gap between the motor rotor and stator, and the front bearing, providing lubrication to the bearings and cooling the motor. The fluid is finally returned to the low-pressure region at the pump inlet, thereby forming a closed, self-circulating system.

2. Detailed Classification
There are numerous ways to classify canned motors pumps; the following are the mainstream classification methods:

1. Classification based on the arrangement of the motor and pump (the most basic classification)
Basic type: the most common configuration. The motor is located at the rear of the pump casing, with bearings mounted at both ends of the rotor; axial thrust is balanced by either impeller balance holes or a thrust disc. This design is compact and widely used.

Counterflow type: The flow direction of the cooling circulating fluid is opposite to that of the basic type (from the front bearing to the rear bearing). This configuration is suitable for media that are prone to vaporization, such as liquefied gases, as it ensures that the pressure inside the pump remains consistently above the medium’s vapor pressure, thereby effectively preventing cavitation.

Reverse configuration: the motor is located at the front end of the pump casing (on the inlet side). This design effectively prevents gas from accumulating in the pump chamber, making it particularly suitable for conveying gas containing liquid or for handling media prone to crystallization.

High-Temperature Type: A cooling jacket or an external cooler is added to the exterior of the standard canned pump to forcibly cool the circulating fluid, thereby accommodating high-temperature media (typically >150°C).

2. Classification by Bearing Type and Monitoring
Sliding-bearing type: the absolute mainstream. Sliding bearings made from self-lubricating materials such as graphite, silicon carbide, and cemented carbides operate by being lubricated by the process fluid.

Monitoring method:

Built-in bearing wear monitor: Uses electrodes to detect the degree of bearing wear and automatically triggers an alarm or shuts down the pump when wear reaches its limit. This is a standard feature on high-end canned motors pumps.

Non-monitoring type: low cost, but requires regular maintenance and inspection.

Rolling-bearing type (rare): Found only in specially designed or ultra-low-power canned pumps, with extremely limited applications.

3. Classification by Shielding Sleeve Material
Hastelloy shielding sleeve: Exhibits outstanding corrosion resistance, particularly in chloride-ion corrosive environments, making it the preferred choice for high-specification chemical applications.

Stainless steel shielding sleeves: the most widely used (e.g., 304, 316L), with low cost, suitable for most applications involving non-strongly corrosive media.

Special metal shielding sleeves, such as those made of titanium and tantalum, are used for specific highly corrosive media and are relatively expensive.

Double-layer shielded casing: A double-layer shielded casing is employed on the stator or rotor, with a leak detection port provided in the intermediate layer. Should the inner layer rupture, the process fluid will escape through the detection port and trigger an alarm, thereby providing dual safety protection for extremely hazardous media.

4. Classification Based on the Characteristics of the Conveyed Medium
Standard type: Conveys clean, low-temperature liquids with good lubricity (such as water and light oils).

Types of easily vaporizable media: Special designs, such as reverse circulation, are employed for the transportation of liquefied gases, propylene, liquid ammonia, and similar substances.

High-melting-point medium type: Equipped with an insulated jacket or trace-heating system, designed for conveying media such as sulfur, asphalt, and resins that solidify at ambient temperatures.

Mud/particle type: By using special bearing materials (such as cemented carbide to silicon carbide), increasing the clearance, and equipping the system with a filter, it is possible to convey media containing a small amount of particles (though this is not recommended as the primary application).

4. Key Considerations for Application Selection
Media-first principle: The media must be clean, exhibit good lubricating properties, and possess a certain degree of electrical conductivity (to form a bearing lubrication film). Dry running, no-load operation, and flow interruptions are strictly prohibited.

Bearing monitoring is critical: for mission-critical applications, it is essential to select models with built-in bearing wear monitoring, as this is the core safeguard that prevents “small issues (bearing wear)” from escalating into “major disasters (motor burnout).”

Pay attention to cavitation: when conveying media that are prone to vaporization, select canned pumps with special designs such as reverse circulation, and ensure that the equipment has sufficient net positive suction head.

Power limitation: Due to the thickness of the magnetic shield and thermal management requirements, the single-unit power rating of conventional canned motors is limited (typically below 400 kW); however, high-power technologies have been steadily advancing in recent years.

In summary, canned motors pumps are meticulously engineered, highly integrated, and leak-free. Owing to their high efficiency, low noise levels, and exceptional operational stability, they occupy a unique position in applications such as refrigeration, heating, certain chemical processes, and aerospace. The key to their proper selection and application lies in a thorough understanding of their operating characteristics: namely, that they rely on the self-lubricating cooling effect of the process fluid for operation, coupled with real-time monitoring of bearing condition.

Detailed Description of Application Industries
1. Heating, Ventilation, Air Conditioning, and Refrigeration Industry
This is the largest and most established application market for canned motors, and it has virtually become the industry standard configuration.

Chillers/Heat Pump Units: Designed for the conveyance of refrigerants (such as R134a and R1234ze), secondary coolants (ethylene glycol solutions or brines), and cooling water. Their zero-leakage design completely eliminates refrigerant leaks and losses, ensuring long-term, high-efficiency system operation.

Absorption chillers: The core power equipment is the pump that circulates the lithium bromide solution, which requires high-vacuum sealing; therefore, a canned motor pump is the only suitable choice.

District Cooling/Heating Stations: Widely used in primary and secondary loop systems of large-scale energy plants, these stations are ideally installed indoors due to their quiet operation and maintenance-free design.

2. Chemical and Process Industries
Primarily used for circulating process media that are relatively clean, valuable, or hazardous.

Fine chemicals and pharmaceutical industries: conveying high-purity solvents, monomers, intermediates, and other materials to prevent contamination and leakage losses. Particularly suitable for thermal medium circulation (heat transfer oil) in the jackets of closed reaction vessels.

Low-temperature liquid transfer: For conveying media that are prone to vaporization, such as liquefied petroleum gas, liquid ammonia, and liquid carbon dioxide, reverse-circulation canned pumps should be used to prevent cavitation.

High-temperature heat transfer medium system: transports high-temperature heat-transfer oils such as biphenyl ether for heating reactors, molds, and other equipment. It requires the use of high-temperature canned pumps equipped with external cooling jackets.

Light Oil Transportation: Transporting light, highly volatile, and flammable materials such as benzene, toluene, and gasoline within the plant.

3. New Energy and the Power Industry
Nuclear power plants: Nuclear-grade canned motor pumps are critical equipment used to convey primary- and secondary-loop cooling water, boric acid solution, and other fluids, requiring absolute reliability, zero leakage, and the ability to withstand extreme operating conditions such as earthquakes. They are typically equipped with multiple monitoring and protection systems.

Polysilicon/photovoltaic industry: In the reduction and hydrogenation stages of silicon material production, it is used for the recirculating conveyance of chlorosilanes such as trichlorosilane and tetrachlorosilane. The process medium is highly flammable and explosive and commands a high value, thus placing stringent requirements on sealing integrity.

Geothermal/water-source heat pump systems: designed for water circulation on the underground heat-exchange side, with stringent requirements for quiet operation and maintenance-free performance.

4. National Defense and Aerospace
Naval nuclear power plants: Similar to civilian nuclear power stations, they are used for main coolant circulation pumps and place extremely high demands on reliability and compactness.

Aerospace: Used in environmental control systems for aircraft and spacecraft—such as fuel, hydraulic, and lubricating-oil heat-exchange circuits—as well as in critical fluid-handling applications in ground support equipment.

5. Other Specialized Fields
Ultrapure water systems: Used as the final polishing stage in ultrapure water systems for semiconductors or pharmaceuticals, requiring zero contamination and no desorption.

Experimental and testing equipment: A small, quiet, vibration-free, and leak-proof fluid circulation system must be provided.

Food and beverage industry: Used for conveying clean liquids such as edible oil, syrups, and alcohol on hygienic production lines; however, it should be noted that this type of product is not suitable for media containing particulates.

Taboos and Limitations in the Selection of Magnetic Drive Pumps
Understanding the “non-applicable” scenarios for canned motors pumps is just as important as understanding their application areas:

The conveyance of media containing solid particles is strictly prohibited: such particles will rapidly abrade the graphite/silicon carbide bearings, leading to pump failure. This is the most critical limitation.

Dry running and interruptions are strictly prohibited: bearings rely on the process fluid for lubrication and cooling, and even brief dry running can result in catastrophic damage.

Exercise caution when using high-viscosity media: such media can impair the self-circulating cooling performance and may lead to motor overheating.

Not suitable for highly corrosive but poorly lubricated media: Even if the material is corrosion-resistant, poor lubrication will still lead to rapid bearing wear.

Relatively limited power output: In high-power applications, the design flexibility of conventional pump configurations is inferior to that of magnetic drive pumps—except in specialized operating conditions such as nuclear primary pumps.

Comparison of Application Selection for Magnetic Drive Pumps

Comparison of Application Selection for Magnetic Drive Pumps
Select shielded pumps and magnetic drive pumps as the priority based on operating conditions.
The medium is classified as clean-grade, with no particulates; however, it may contain trace amounts of particles (to be specified separately).
Relatively low lubricity is required for the medium (e.g., water, light hydrocarbons).
Operating mode: long-term continuous operation, which can be either continuous or intermittent.
Ease of maintenance: This motor is a specialized type, making on-site maintenance more challenging; in contrast, standard motors are relatively easier to maintain.
Typical industries include HVAC and refrigeration, nuclear energy, certain chemical processes, general chemicals, pharmaceuticals, semiconductors, and electroplating.
In summary, canned motors pumps serve as the silent guardians of closed-loop systems and clean-process applications, having established an unshakable position in fields such as air-conditioning and refrigeration, nuclear energy, and specific chemical processes. The key to their successful application lies in ensuring that the conveyed medium flows like pure blood—smoothly and quietly through a closed “vascular” network (piping)—driven by this highly integrated, leak-free “heart.” Should the medium’s conditions deteriorate, the “heart” becomes exceedingly vulnerable. Therefore, proper selection and strict adherence to operating procedures are the cornerstones of long-term, stable performance.

A canned motor pump, commonly referred to in Chinese as a “shielded pump” or “sealless pump,” is a revolutionary pump design that achieves absolutely zero leakage.

The following is a detailed introduction to canned motors pumps, covering their operating principle, design, advantages and disadvantages, key applications, and comparisons with other pump types.

1. Core Definition and Revolutionary Characteristics
Essence: A canned pump is a specialized centrifugal pump in which the motor and pump casing are integrated into a single unit, eliminating all dynamic seals.

Revolutionary feature: A thin-walled metal sleeve, known as a “shielding sleeve,” completely isolates the motor rotor and stator from the conveyed medium, while simultaneously using the medium itself for circulating lubrication and cooling. This design fundamentally eliminates the primary failure point and source of leakage in conventional pumps—the shaft seal.

Design Standards: In the industrial sector, the most authoritative design and manufacturing standard is API 685, “Sealless Centrifugal Pumps for Petroleum, Petrochemical, and Natural Gas Industries,” which serves as a supplement and refinement to the API 610 standard for sealless pumps. Functional Description of Key Components:

Shielding Sleeve: This is the “heart” of the canned pump. It is typically made from corrosion-resistant materials such as Hastelloy, with an extremely thin wall thickness—approximately 0.1 to 0.3 millimeters—to ensure efficient magnetic coupling. The sleeve must both withstand system pressure and maintain the motor’s electromagnetic efficiency.

Circulation loop: This is the “lifeline” of the canned pump. A small flow rate of process fluid—approximately 1% to 3% of the total flow—is drawn from the high-pressure region at the pump discharge and forcibly routed through the clearance between the rear bearing, the rotor, and the canned sleeve, then through the front bearing, before finally returning to the pump’s low-pressure suction inlet. This loop achieves:

Bearing lubrication: Graphite or silicon carbide bearings shall be lubricated with a medium-grade lubricant.

Cooling of the motor and the cooling medium: removes heat generated by the rotor and bearings.

Eliminate air bubbles: Ensure the bearing area is always completely filled with fluid.

Bearings: Typically made of resin-impregnated graphite or high-performance silicon carbide (SiC). Their lubrication relies on the conveyed fluid, making the fluid’s lubricity and cleanliness critical. The API 685 standard mandates the installation of bearing wear monitors—such as proximity probes—as a vital safety feature.

Heat-exchange device: For media that are prone to vaporization or operate at high temperatures, the temperature of the circulating liquid may exceed acceptable limits. Therefore, canned motors pumps are typically equipped with a built-in heat exchanger (jacket) or are connected to an external cooling system to ensure timely heat removal and prevent vaporization of the process fluid.

3. Core Advantages
Zero-leakage: this is its greatest advantage. With no rotating shaft seals, there is theoretically no possibility of leakage into the atmospheric environment. It is the only safe choice for handling highly toxic, carcinogenic, extremely hazardous, highly radioactive, and high-value media.

High safety: Prevents the risks of fire, explosion, poisoning, and environmental pollution caused by seal failure.

High reliability and low maintenance: compact design, no coupling, and no alignment required. The primary wear component is the bearing, which offers a long service life under optimal operating conditions, significantly reducing maintenance workload.

Suitable for highly volatile media: Because the pump chamber and the motor interior are maintained at the same system pressure, cavitation is unlikely to occur, making this design particularly well suited for handling liquefied gases such as liquefied petroleum gas, liquid ammonia, and propylene.

4. Main Deficiencies and Limitations
Inefficiency:

The shielding sleeve will generate eddy current losses.

This circuit will consume energy.

Friction losses in bearings.

Overall efficiency is typically 5% to 15% lower than that of sealed pumps with the same specifications.

High cost: complex structure, specialized materials (shielding sleeve, bearings), stringent manufacturing requirements, and significantly higher initial procurement costs compared with conventional pumps.

High standards for the media:

Maintain cleanliness at all times: Solid particles can rapidly wear down graphite bearings and the shield sleeve.

Lubricity is essential: Pure water and liquid hydrocarbons (such as propane) exhibit poor lubricity, necessitating the use of specialized bearing designs or lubrication strategies.

Viscosity should not be too high: High-viscosity fluids can impede circulation and cooling, potentially leading to overheating.

Complex maintenance: Once internal damage occurs—such as a seal rupture or bearing seizure—the equipment must be returned to the manufacturer or a specialized repair shop for disassembly and major overhauls; on-site repairs are difficult to perform efficiently.

5. Comparison with Magnetic Drive Pumps
Both are “leak-free pumps,” but they operate on different principles and are often confused with one another.

Specialty canned pump, magnetic drive pump
The underlying principle is to integrate the motor and pump into a single unit and use a magnetic shield to electrically isolate the stator from the rotor. In contrast, conventional motors paired with magnetic couplings rely on magnetic forces between inner and outer magnetic rings to transmit torque across the isolation barrier.
More compact structure with no coupling. Longer length, equipped with both an external magnetic cylinder and a built-in magnetic cylinder.
Relatively low efficiency (due to shield-sleeve eddy-current losses and circulating losses). Relatively high efficiency (though eddy-current losses still exist).
The rotor’s load-carrying capacity is fully immersed in the working medium, and the bearing exhibits a high load rating, making it suitable for high-power applications. In contrast, internal-magnetic-cylinder bearings are constrained by size limitations and are typically used in medium- and low-power applications (generally below 400 kW).
Overall maintainability is good. On-site replacement of the isolation sleeve or bearing components is relatively convenient.
The cost is very high—medium to high.
Applicable standards: API 685 (mainstream). API 685 or ASME B73.3M.
In short, canned motors represent a “deeply integrated” solution that delivers high power output, whereas magnetic drive pumps are a modular coupling solution better suited for small- and medium-power applications.

6. Core Application Areas (Essential Use Cases)
For the following severe operating conditions, canned pumps are the preferred or mandatory choice:

Extremely dangerous medium:

Highly toxic/carcinogenic substances: phosgene, hydrogen cyanide, benzo[a]pyrene, etc.

High-level radioactive liquids: the primary coolant and nuclear waste in nuclear power plants.

Extremely hazardous environmental media: polychlorinated biphenyls, potent pesticides, and the like.

Highly flammable and explosive media: In situations where a leak could result in catastrophic consequences, such as hydrofluoric acid alkylation units and the transportation of ethylene, propylene, and liquefied natural gas.

Valuable media: fragrances, expensive catalysts, platinum solutions, and the like. A leak can result in substantial financial losses.

Highly corrosive or penetrating media: fuming sulfuric acid, liquid chlorine, bromine, and others. These media can rapidly damage any mechanical seal.

Aerospace: Fueling and transfer of rocket propellants, such as dimethylhydrazine.

7. Key Points for Selection and Use
Compliance with Standards: Industrial applications must adhere to API 685, which sets forth mandatory safety requirements, including bearing monitoring, seal cartridge testing, and material selection.

Media analysis: It is essential to have a clear understanding of the medium’s lubricity, cleanliness, corrosivity, and saturated vapor pressure.

Minimum Continuous Flow: Shielded pumps are limited by both the minimum continuous stable flow and the minimum continuous thermal flow. If the operating flow falls below these values, it can result in inadequate circulating cooling, vaporization of the process fluid, and bearing burnout. An automatic recirculation valve is typically required.

Monitoring System: Ensure the installation of bearing wear monitoring devices and sight glasses on the circulation lines, which serve as the “eyes” that safeguard safe operation.

Alternative solution: For critical workstations, even if the shielded pump boasts high reliability, a 100% redundant configuration is typically considered due to the extended downtime required for fault repair.

Abstract
A canned pump is a specialized type of pump designed specifically to address the fundamental issue of leakage. Despite its higher cost and slightly lower efficiency, it delivers unparalleled safety and sealing reliability. Canned pumps are not general-purpose equipment; rather, they are indispensable engineering assets for specific high-risk, high-value, and high-demand operating conditions. In safety- and environmental-sensitive sectors such as chemical processing, petrochemicals, pharmaceuticals, and the nuclear industry, canned pumps play an irreplaceable and critical role.

Imperial canned pumps, Japanese-made modular canned pumps, Hermetic canned pumps, technical features
Certainly. This is a professional review and comparison of the technical characteristics of several mainstream canned motor pump brands. Please note that this overview is compiled based on each brand’s publicly available technical literature and market positioning; in actual applications, model-specific differences may exist.
Below is a comparison of the core technical features of Imperial canned motors pumps, Japanese aircraft canned motors pumps, and Haimitek canned motors pumps:
1. Royal Shield Pump
It typically refers to the product line manufactured by Japan’s Imperial Electric Machinery Manufacturing Co., a pioneer and global leader in the field of canned motors, renowned for its exceptional reliability and durability.
Core technical features:
Timeless, durable design: a classic, robust construction and premium materials ensure exceptionally long service life and virtually maintenance-free operation even under harsh operating conditions. Many pumps that have been in service for over 30 years are still running today.
Outstanding rotor dynamics performance: Leveraging extensive expertise in bearing design—such as the lubrication groove and cooling channel configurations for graphite bearings—and precise control of the rotor–stator clearance, we ensure smooth operation with exceptionally low vibration and noise levels.
Comprehensive materials portfolio: Offers the broadest range of material options, including various specialty alloys, Hastelloy, ceramics, and more, to meet the demands of extreme operating conditions such as severe corrosion, high temperature, and high pressure.
High-precision manufacturing: Extremely stringent precision requirements are imposed on component machining, dynamic balancing, and assembly processes to ensure performance and consistency.
Suitable for critical processes: Dominates in sectors such as petrochemicals, chemicals, and nuclear power, where safety and continuity are of paramount importance.
Market positioning: high-end, mission-critical process-industry applications designed for long-term operation. Although the initial purchase cost is higher, the total cost of ownership (TCO) may be lower over the long term.
2. Daily Installation of Magnetic Drive Pumps
The products of Zhiri Machinery Equipment are renowned worldwide for their technological innovation and modular design.
Core technical features:
Innovative internal design: for example, its renowned “vortex” internal circulation system, which more effectively cools the motor and lubricates the bearings, making it particularly suitable for media that are prone to vaporization, operate at high temperatures, or contain solid particles.
Advanced Monitoring and Diagnosis: Employs early, deeply integrated condition-monitoring technologies—such as bearing wear monitoring and temperature and vibration sensors—to enable predictive maintenance.
Modular and standardized design: High component standardization facilitates maintenance and spare-part replacement. The adoption of a “cartridge-style” core-component packaging design enables rapid replacement of critical components, thereby reducing downtime.
Focusing on high-difficulty media applications: The company boasts significant technological advantages in areas such as liquefied natural gas (LNG), cryogenic media, and the transportation of high-purity chemicals.
Our product portfolio offers extensive coverage, ranging from low-flow, high-head chemical process pumps to high-flow liquefied natural gas transfer pumps.
Market positioning: technology leadership, high adaptability, and a strong focus on maintainability; widely applied in the chemical, liquefied natural gas, electronic chemicals, pharmaceutical, and other industries.
3. Haitetic canned motor pump
German company Hermetic is a leading European manufacturer of canned motors pumps, renowned for their high precision, high efficiency, and ability to provide customized solutions tailored to specific applications.
Core technical features:
Non-contact “torque ring” technology: this is its hallmark innovation. By introducing a “torque ring” between the motor rotor and the pump impeller, torque is transmitted via magnetic fields rather than mechanical connections, achieving complete static sealing and zero leakage. At the same time, dynamic sealing points are eliminated, thereby ensuring an exceptionally high level of safety.
Wear-Free Operation Concept: Thanks to the torque ring and non-contact design, the pump’s internal moving parts experience virtually no wear, resulting in an exceptionally long theoretical service life and minimal maintenance requirements.
High Efficiency: The integrated and optimized design of the motor and pump housing delivers high hydraulic efficiency and outstanding energy-saving performance.
Suitable for high-purity and high-risk media: Particularly adept at handling extremely hazardous, highly toxic, and zero-tolerance-to-contamination high-purity media, such as polysilicon, electronic-grade specialty gases, and hydrofluoric acid.
Precision engineering: Made in Germany, offering high precision, exceptional accuracy, smooth operation, and quiet performance.
Market positioning: The preferred choice for applications demanding ultra-high safety, zero leakage, high purity, and long service life. Widely used in industries with zero-tolerance for leaks, such as polysilicon, electronic semiconductors, specialty chemicals, and pharmaceuticals.

Summary Comparison
Feature size
    
Imperial Shield Pump
    
Japanese-made canned motor pump
    
Haimetik canned motor pump

Core Advantages
    
Classic, reliable, and durable
    
Innovation, intelligence, and robust adaptability
    
Absolute safety, zero leakage, high efficiency

Technical Mark
    
Outstanding Rotor Dynamics and Bearing Technology
    
Eddy Current Cooling System and Condition Monitoring
    
Non-contact “torque ring” technology

Applicable Working Conditions
    
Traditional, rigorous, and time-consuming processes
    
Processes involving liquefied natural gas that are readily vaporizable and require monitoring
    
A process involving high purity, high risk, extreme toxicity, and an absolute prohibition on leakage.

Market Positioning
    
The “Gold Standard” for Process Industries
    
Technology Solutions Provider
    
Experts with Special Safety and Purity Requirements

Cost considerations
    
Initial investment is higher, but the total lifecycle cost may be lower.
    
Balancing Technological Value and Maintenance Costs
    
The initial investment is the highest, but it pays for safety and purity.
Selection recommendations:
For decades of trouble-free operation in traditional petrochemical and chemical key processes, Empire is the first choice.
For LNG and other highly volatile media, the goal is to achieve predictive maintenance: the benefits of routine installation are self-evident.
Polycrystalline silicon, electronic chemicals, highly toxic media, and zero tolerance for leaks—Haimitek is your ideal choice.
The final equipment selection must be based on a comprehensive evaluation of the specific process fluid properties, operating parameters, budget, and project requirements.