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Magnetic-bearing and air-bearing compressors are increasingly used in high-efficiency refrigeration, data center cooling, industrial temperature control, and other applications where low friction, compact integration, and reliable continuous operation are essential.
Although the auxiliary refrigeration pump is much smaller than the compressor itself, it plays an important role in maintaining refrigerant circulation and thermal management.
The challenge is that refrigerant delivery is not the same as conventional liquid pumping. A cooling pump may need to handle low-viscosity refrigerants, high differential pressure, wide temperature ranges, limited installation space, and changing gas-liquid conditions while maintaining stable flow.
For these applications, a micro magnetic gear pump can provide a compact positive-displacement solution with magnetic-drive sealing, precise flow control, and flexible motor configurations.
This article explains the main engineering requirements for compressor cooling pumps, how Suofu's NP Series addresses them, and how to select a suitable model for magnetic-bearing and air-bearing compressor systems.
Magnetic-bearing compressors use magnetic forces to support the rotating shaft without conventional mechanical contact. Air-bearing compressors use a thin gas film to support the high-speed rotor.
Both technologies reduce mechanical friction, but they also place strict requirements on the supporting thermal management system.
The cooling pump must deliver refrigerant or cooling media under well-defined pressure, temperature, and flow conditions. In particular, unstable circulation can affect the thermal balance of the compressor system and the operating conditions of temperature-sensitive components.
A suitable compressor cooling pump should therefore be evaluated according to the complete system rather than by flow rate alone.
Key requirements normally include:
Stable flow under changing system pressure
Compatibility with the specified refrigerant or cooling medium
Reliable sealing to minimize leakage risk
Compact dimensions for integrated installation
Resistance to low and high operating temperatures
Long-term continuous operation
Appropriate motor and speed-control options
Compatibility with the system's inlet and outlet connections
For equipment manufacturers, the pump should also be considered as part of the overall refrigeration circuit rather than as an isolated component.
Many refrigeration systems use fluids with much lower viscosity than conventional oils or water.
Low-viscosity media can increase internal leakage within a positive-displacement pump because the fluid can pass through the small clearances between internal components.
This means that selecting a pump only according to its theoretical displacement can result in insufficient actual flow at the required differential pressure.
For this reason, engineers should evaluate:
Required operating flow
Differential pressure
Pump displacement per revolution
Operating speed
Fluid viscosity
Actual performance curve
A micro magnetic gear pump should therefore be selected according to the actual operating point, not simply its maximum rated flow.
Refrigeration circuits can experience changes in fluid state and local gas-liquid conditions.
Depending on system design and operating conditions, the pump may encounter entrained gas, flashing, or temporary changes in inlet conditions.
This makes inlet pressure and suction conditions important selection factors.
Suofu's NP Series includes configurations designed for demanding fluid-transfer applications, but dry-running capability and allowable dry-running conditions are model- and configuration-dependent. Engineers should therefore confirm the actual operating limits with Suofu before applying a specific model to a refrigerant system.
Magnetic-bearing and air-bearing compressor systems often integrate the compressor, heat exchanger, valves, sensors, electrical components, and auxiliary circulation components into a compact package.
The cooling pump therefore needs to provide sufficient performance without creating unnecessary installation volume.
A compact magnetic-drive structure can simplify system integration while keeping the fluid chamber separated from the motor drive.
For OEM applications, the pump can also be configured with different motors, connections, control methods, and structural arrangements according to system requirements.
A micro magnetic gear pump combines two important technologies:
Positive-displacement gear pumping + magnetic-drive transmission.
The gears generate fluid displacement as they rotate, while the magnetic coupling transfers motor torque without requiring a conventional rotating shaft to pass through the pump housing.
This structure offers several potential advantages for refrigeration and liquid-cooling systems.
Traditional shaft-driven pumps normally require a dynamic shaft seal where the rotating shaft passes through the pump housing.
A magnetic-drive pump transfers torque through magnetic coupling instead.
This allows the fluid chamber to remain isolated from the motor-side drive system and reduces dependence on a dynamic shaft seal.
For refrigerant systems, where leakage control can be an important design consideration, this structure can provide an additional layer of sealing reliability.
Unlike a centrifugal pump, a gear pump moves a defined volume of fluid through each gear rotation.
As a result, pump speed and displacement can be used to establish a predictable relationship between rotational speed and theoretical flow.
The actual flow still depends on operating pressure, viscosity, internal clearance, temperature, and other system conditions.
This makes a micro magnetic gear pump particularly useful when the compressor cooling system requires controlled and relatively low flow rather than simply maximum flow capacity.
The following table provides a quick engineering reference for several NP Series families. These are general product ranges rather than guaranteed operating points for every refrigerant application. Final selection should be based on the actual medium, pressure, temperature, speed, motor configuration, and performance curve.
NP Series | Typical Models | Nominal Displacement | Rated Flow Range | Typical Application Direction |
|---|---|---|---|---|
20 Series | NP010 | 0.1 ml/rev | 0-1.5L/min | Small-flow precision cooling |
42 Series | NP020 / NP039 / NP060 / NP070 | 0.2–0.7 ml/rev | 0–2.20 L/min | Small-flow precision cooling |
51 Series | NP100 / NP120 / NP170 / NP190 | 1.0–1.9 ml/rev | 0–6.00 L/min | Small-to-medium cooling circulation |
60 Series | NP240 / NP350 | 2.4–3.5 ml/rev | 0–10.5 L/min | Medium-flow cooling |
98 Series | NP400–NP1700 | 4–17 ml/rev | 0–55.0 L/min | Higher-flow refrigeration systems |
106 Series | NP2600 | 26 ml/rev | 0–65.0 L/min | Large-flow industrial cooling |
*Maximum differential pressure depends on the specific model, medium, speed, motor configuration, and operating conditions. The published NP Series product data lists different pressure limits across the product families.
The NP Series product range covers applications from approximately 0–2.2 L/min to 0–65 L/min, allowing engineers to select a pump according to the required flow range rather than forcing one pump size into every system.
For example:
NP070 / NP190 can be considered for relatively small-flow compressor cooling systems.
NP350 provides a larger flow range for medium-flow applications.
NP1700 is positioned for higher-flow systems.
NP2600 is intended for large-flow applications where the system requires substantially higher circulation capacity.
The actual model should always be determined from the system operating point and pump performance curve.
The magnetic coupling transfers motor torque without a conventional shaft penetrating the fluid chamber.
This design helps reduce leakage risks associated with dynamic shaft seals and is particularly useful when the transferred medium is expensive, environmentally sensitive, or difficult to contain.
Suofu's NP Series can use PEEK gears and high-precision industrial zirconia ceramic shafts.
These materials provide useful wear resistance and low-friction characteristics for demanding continuous-operation applications. Material selection should still be matched to the actual refrigerant, additives, temperature, and pressure conditions.
Published NP Series specifications indicate an operating temperature range of approximately -120°C to 150°C for applicable configurations.
This broad temperature capability gives engineers greater flexibility when designing refrigeration and thermal-management systems.
However, the temperature limit of the complete pump assembly depends on the selected materials, seals, motor, medium, and operating conditions.
Different compressor cooling systems have different control requirements.
Suofu NP Series pumps can be configured with motor options including:
Brushless DC motors
AC motors
Servo motors
Stepper motors
The appropriate motor depends on whether the application requires fixed-speed operation, variable-speed control, closed-loop flow regulation, or integration with an existing controller.
For example, Suofu's published product information lists BLDC configurations with options such as 12–48 V supply, speed control, and different power ranges, while AC and servo configurations are also available.
There is no universal "best" compressor cooling pump.
The correct model depends on the required operating point.
For systems requiring relatively low circulation flow, engineers can consider the NP020–NP190 range.
Typical considerations include:
Compact installation space
Low-flow refrigerant circulation
Precision temperature control
Small or medium compressor packages
Laboratory and test equipment
The NP42 and NP51 series provide rated flow ranges up to approximately 2.2 L/min and 6.0 L/min respectively.
For systems requiring higher circulation capacity, the NP240 or NP350 can be evaluated.
The NP60 Series covers a rated flow range up to approximately 10.5 L/min, with a nominal displacement of 2.4–3.5 mL/rev.
These models can be considered for:
Industrial refrigeration
Precision cooling
Medium-size compressor systems
Liquid-cooling systems
For larger systems, the NP400–NP1700 range provides rated flow capacities up to approximately 55 L/min.
The NP98 Series includes five models from NP400 to NP1700 and supports different flow requirements within the same product family.
For even larger flow requirements, the NP2600 provides a rated flow range up to approximately 65 L/min.
Choosing a pump should start with the system requirements rather than the pump model number.
Specify the exact fluid, including:
Refrigerant type
Lubricant or oil content, if applicable
Chemical additives
Expected gas-liquid conditions
Fluid viscosity
Material compatibility should be confirmed before final selection.
Determine:
Minimum flow
Normal operating flow
Maximum flow
Required flow-control range
Do not select the pump solely according to its maximum rated flow.
The actual operating point should be checked against the pump's performance curve.
Provide:
Inlet pressure
Outlet pressure
Required differential pressure
System pressure
Pressure fluctuations
This is particularly important for positive-displacement pumps because actual flow can change as internal leakage changes with pressure and fluid properties.
Provide:
Minimum fluid temperature
Normal operating temperature
Maximum fluid temperature
Ambient temperature
Start-up temperature
Thermal cycling conditions
For refrigeration systems, the temperature during startup can be just as important as the normal operating temperature.
Specify whether the pump needs:
Fixed-speed operation
Variable-speed control
0–5 V speed control
PWM control
Manual speed adjustment
Servo control
Closed-loop flow control
Motor selection should be made together with pump displacement and operating pressure.
The final design should confirm:
Pump dimensions
Axial installation space
Inlet/outlet position
Thread specification
Pipe diameter
Electrical interface
Motor mounting
Weight limitations
This prevents a common OEM problem: a pump that meets the hydraulic requirements but cannot be integrated into the equipment.
A micro gear pump contains small internal clearances, so inlet conditions should not be overlooked.
High inlet resistance can reduce available suction pressure and increase the risk of unstable operation.
Engineers should therefore consider:
Inlet pipe diameter
Inlet pipe length
Number of elbows
Filter pressure drop
Inlet pressure
Fluid temperature
Gas-liquid conditions
For applicable NP Series configurations, Suofu recommends a 400-mesh inlet filter. Product specifications also list an inlet vacuum capability of approximately -0.85 bar under speed-dependent conditions.
The actual inlet design should nevertheless be validated against the refrigerant and operating conditions of the complete system.
The choice between a centrifugal pump and a micro magnetic gear pump depends on the system.
Factor | Micro Magnetic Gear Pump | Centrifugal Pump |
|---|---|---|
Pumping principle | Positive displacement | Dynamic |
Low-flow control | Strong | Depends on pump/system curve |
Flow control | Speed-based | Speed and system curve |
Differential pressure | Suitable for higher-pressure applications | Depends strongly on pump design |
Compact integration | Well suited to small systems | Depends on configuration |
Magnetic-drive sealing | Available | Available in some designs |
Precise metering | Strong advantage | Generally less suitable |
Large-flow circulation | Model-dependent | Often advantageous |
For small-flow, pressure-sensitive, compact compressor cooling systems, a micro magnetic gear pump can be an attractive option.
For very large flow rates where precision metering is less important, other pump technologies may be more appropriate.
The correct decision should therefore be based on the actual hydraulic requirements rather than the pump type alone.
To shorten the engineering evaluation process, an OEM should provide the following information:
Cooling medium: refrigerant name and composition
Required flow: minimum / normal / maximum
Differential pressure: normal and maximum
System pressure: inlet and outlet pressure
Temperature: minimum / normal / maximum
Viscosity: operating range
Gas-liquid condition: liquid, gas, or two-phase condition
Operating mode: continuous or intermittent
Motor: voltage, power, speed and control method
Installation: available dimensions and connection requirements
With this information, the pump manufacturer can evaluate the hydraulic operating point, material compatibility, motor selection, and mechanical integration together.
Suofu develops and manufactures micro magnetic gear pumps for precision fluid transfer and cooling applications.
The NP Series covers multiple flow ranges, from small-flow precision transfer to higher-flow industrial circulation. The product platform supports different materials, motor configurations, connection options, and OEM/ODM integration requirements.
For compressor manufacturers and refrigeration-system integrators, Suofu can support:
Pump model selection
Refrigerant compatibility evaluation
Flow and pressure matching
Motor configuration
Speed-control integration
Connection customization
Mechanical integration
OEM/ODM development
The goal is not simply to supply a pump, but to match the pump to the complete compressor cooling circuit.
A micro magnetic gear pump can be suitable when the system requires compact size, controlled low-to-medium flow, stable pressure delivery, and strong leakage control. Final selection depends on refrigerant, flow, pressure, temperature, and inlet conditions.
Potentially, yes, but compatibility must be evaluated for the specific refrigerant, temperature, pressure, seals, gear materials, and operating conditions. A pump should not be selected based on refrigerant name alone.
Magnetic-drive transmission avoids a conventional rotating shaft penetrating the fluid chamber. This reduces dependence on dynamic shaft seals and can help improve containment reliability.
Some NP configurations are designed for demanding gas-liquid fluid-transfer applications, but two-phase operation depends heavily on the actual fluid, gas fraction, pressure, temperature, speed, and pump configuration. The operating conditions should be evaluated with the manufacturer before selection.
As a preliminary guide, NP020–NP190 can be evaluated for lower-flow applications, NP240–NP350 for medium-flow systems, NP400–NP1700 for higher-flow applications, and NP2600 for large-flow requirements. The final model must be selected according to the actual flow-pressure operating point.
Yes. Suofu provides OEM/ODM support covering performance customization, system integration, structural integration, and special product development.
A cooling pump for a magnetic-bearing or air-bearing compressor is a small component with system-level importance.
The correct selection requires more than checking maximum flow. Engineers should evaluate:
Refrigerant compatibility
Flow rate
Differential pressure
Temperature range
Inlet conditions
Gas-liquid behavior
Pump materials
Motor and speed control
Installation dimensions
Continuous operating requirements
A micro magnetic gear pump can be a strong solution when the system requires compact integration, controlled fluid delivery, magnetic-drive sealing, and reliable operation across demanding conditions.
With multiple NP Series flow ranges and OEM/ODM capabilities, Suofu can work with compressor manufacturers and refrigeration-system integrators to develop a pump configuration matched to the actual application.
Looking for a micro magnetic gear pump for magnetic-bearing or air-bearing compressor cooling? Contact Suofu with your required flow, differential pressure, refrigerant, temperature range, and installation requirements for a technical selection recommendation.
