NKGF Series Explosion-Proof Micro Gear Flow Meter

Brand: NOIKE-AH
Model:‌ NKGF Series

Specification

High-Precision Positive Displacement Flow Measurement for Low-Flow Applications

When liquid flow rates are extremely low, conventional flow measurement technologies may not provide the accuracy, repeatability, or stability required by precision industrial processes. For applications that also require hazardous-area protection, the selection of a suitable flow meter becomes even more critical.

The NKGF Series Explosion-Proof Micro Gear Flow Meter is a positive displacement (PD) flow meter developed for high-precision measurement of ultra-low clean liquid flow rates.

Based on a precision elliptical gear measuring mechanism, the NKGF Series measures liquid volumetrically by continuously displacing a defined volume of fluid with each gear rotation. The meter supports a minimum detectable flow rate of 0.5 mL/min and measurement accuracy of up to ±0.2% FS, depending on the selected configuration.

An Ex ia IIC T5 intrinsically safe explosion-proof configuration is available for applications where hazardous-area protection is required.

What Is the NKGF Series Micro Gear Flow Meter?

The NKGF Series is a positive displacement micro flow meter designed specifically for low-flow liquid measurement.

Unlike flow meters that calculate flow from velocity, differential pressure, or other indirect parameters, a positive displacement flow meter measures flow by physically dividing the flowing liquid into defined volumes.

The NKGF Series uses a pair of precision elliptical gears installed inside a sealed measuring chamber. As liquid passes through the meter, the pressure difference between the inlet and outlet causes the gears to rotate.

Each rotation displaces a defined volume of liquid.

Therefore:

Total Flow Volume = Number of Gear Rotations × Displacement per Rotation

The rotation of the gears is converted into a corresponding flow signal, allowing the system to determine the volumetric flow rate.

This measuring principle makes the NKGF Series particularly suitable for applications requiring stable and repeatable measurement of very small liquid flow rates.

Key Specifications of the NKGF Series

Parameter	Specification
Measurement Principle	Positive Displacement (Volumetric)
Accuracy	±0.5% FS or ±0.2% FS
Minimum Detectable Flow	0.5 mL/min
Fluid Viscosity	2–200 mPa·s
Higher Viscosity	Available upon request
Standard Fluid Temperature	-20°C to +80°C
High-Temperature Version	Up to 200°C with heat sink
Cast Iron Maximum Pressure	1.6 MPa
Stainless Steel Maximum Pressure	1.6 MPa
Cast Steel Maximum Pressure	2.5 MPa or 6.4 MPa
Power Supply	24 VDC
Output Signal	Pulse or 4–20 mA
Explosion-Proof Rating	Ex ia IIC T5
Optional Configuration	Insulated Jacket

Note: Actual operating conditions, selected materials, pressure rating, temperature configuration, and output configuration should be confirmed according to the specific NKGF model and application requirements.

Why Use a Gear-Type Positive Displacement Flow Meter for Micro Flow Measurement?

1. Direct Volumetric Measurement

The NKGF Series uses a positive displacement measuring principle. Instead of relying primarily on fluid velocity calculations, the measuring chamber repeatedly separates and displaces a defined volume of liquid.

This provides a direct volumetric measurement principle that is well suited to low-flow applications.

2. Minimum Detectable Flow of 0.5 mL/min

The NKGF Series can detect liquid flow rates as low as:

0.5 mL/min

This makes it suitable for applications where the required flow rate is significantly lower than that of conventional industrial flow measurement systems.

Typical applications include precision dosing, laboratory equipment, lubrication monitoring, chemical dosing, and OEM fluid-control systems.

3. High Measurement Accuracy

Depending on the selected configuration, the NKGF Series is available with accuracy options of:

±0.5% FS
±0.2% FS

The actual achievable accuracy depends on the meter configuration and operating conditions. For engineering applications, the selected accuracy class should be confirmed during model selection.

4. Suitable for a Wide Viscosity Range

The standard applicable fluid viscosity range is:

2–200 mPa·s

Higher-viscosity applications can be considered upon request.

For positive displacement gear meters, higher fluid viscosity can reduce internal leakage within the measuring chamber. Under suitable operating conditions, this can contribute to improved measurement stability.

NKGF Explosion-Proof Configuration

For applications involving hazardous environments, the NKGF Series can be supplied in an intrinsically safe configuration with an explosion-proof rating of:

Ex ia IIC T5

The explosion-proof configuration is intended for applications where the instrumentation system requires an intrinsically safe design.

However, explosion-proof equipment selection should not be based solely on the product marking. The complete installation must be evaluated according to the hazardous-area classification, gas or vapor characteristics, temperature requirements, electrical parameters, and applicable installation regulations.

Therefore, users should confirm the required explosion-proof configuration with the manufacturer before ordering.

How Does the NKGF Micro Gear Flow Meter Work?

The NKGF Series contains two precision elliptical gears installed inside a precision-machined measuring chamber.

Step 1: Liquid Enters the Meter

The liquid enters through the inlet of the flow meter and creates a pressure differential between the inlet and outlet.

Step 2: The Gears Rotate

The pressure difference causes the elliptical gears to rotate.

Step 3: Fixed Volumes Are Displaced

As the gears rotate, liquid is captured in the spaces between the gears and the meter housing.

These cavities form defined measuring volumes.

Step 4: Rotation Is Converted Into Flow

The number of gear rotations corresponds to the amount of liquid displaced.

The measurement system therefore determines the total volume or flow rate based on gear rotation.

This positive displacement principle provides the foundation for the NKGF Series’ low-flow measurement capability.

Fluid Compatibility and Application Conditions

The NKGF Series is designed primarily for clean liquids.

The standard viscosity range is:

2–200 mPa·s

Applications involving higher viscosity liquids can be evaluated separately.

The flow meter is not recommended for liquids containing solid particles, because particles may interfere with the precision gear mechanism, cause gear blockage, or affect measurement performance.

The NKGF Series is also designed for liquid measurement rather than gas measurement. Gas measurement can result in measurement errors because the operating principle and displacement characteristics are intended for liquids.

For this reason, the medium condition should be confirmed before selecting the flow meter.

Temperature Capability

The standard fluid temperature range is:

-20°C to +80°C

For higher-temperature applications, an optional configuration with an insulated jacket and heat sink can support temperatures up to:

200°C

The high-temperature configuration should be selected according to the actual process temperature and installation conditions.

Users should confirm the complete temperature specification of the selected model before applying the meter to a high-temperature process.

Pressure Rating

The maximum operating pressure depends on the housing material.

Housing Material	Maximum Pressure
Cast Iron	1.6 MPa
Stainless Steel	1.6 MPa
Cast Steel	2.5 MPa or 6.4 MPa

Higher-pressure configurations may be available upon request.

The pressure rating must be considered together with the actual operating temperature, medium, connection configuration, and selected meter construction. The applicable pressure rating for a specific project should be confirmed before installation.

Available Housing Materials

The NKGF Series can be configured with different housing materials according to application requirements.

Available material options include:

Cast Iron

Suitable for applications where cast iron construction meets the process medium and pressure requirements.

Stainless Steel

Stainless steel construction can be selected for applications requiring a different level of material compatibility or corrosion resistance.

Cast Steel

Cast steel configurations are available for applications requiring higher pressure capability, including configurations rated at 2.5 MPa or 6.4 MPa.

The correct material should be selected according to the measured medium, operating pressure, temperature, and process requirements.

Output and Electrical Configuration

The NKGF Series can be configured with different signal-output options.

Available outputs include:

Pulse output
4–20 mA output

For remote and intelligent digital display configurations, the specified power supply is:

24 VDC

The appropriate output configuration should be selected according to the control system, PLC, display instrument, or data-acquisition system used by the customer.

Typical Applications

The NKGF Series is designed for applications where accurate measurement of low liquid flow is required.

Typical applications include:

Chemical Dosing

Used for monitoring and controlling low-volume chemical liquid delivery where stable volumetric measurement is required.

Laboratory Equipment

Suitable for laboratory systems requiring repeatable measurement of small liquid flow rates.

Pharmaceutical Production

Can be considered for clean-liquid measurement applications where the material and process requirements are compatible with the selected flow meter configuration.

Precision Dispensing

The positive displacement principle makes the meter suitable for applications requiring controlled and repeatable liquid delivery.

Lubrication Systems

The NKGF Series can be used for monitoring low-flow lubrication oil and other compatible liquids.

Hydraulic Oil Monitoring

Suitable for monitoring compatible hydraulic oils within the specified viscosity, temperature, and pressure ranges.

Fuel Measurement

Can be considered for compatible clean liquid fuels when the required material, temperature, pressure, and hazardous-area conditions are satisfied.

Ink and Coating Systems

Suitable for compatible low-flow liquid applications involving inks, coatings, and similar fluids.

Resin and Adhesive Metering

Can be applied to compatible resin and adhesive systems, particularly where viscosity falls within the applicable range.

OEM Fluid-Control Equipment

The compact positive displacement measuring principle makes the NKGF Series suitable for integration into OEM equipment requiring precise low-flow liquid measurement.

Advantages of the NKGF Series

High-Precision Low-Flow Measurement

With a minimum detectable flow rate of 0.5 mL/min and accuracy options down to ±0.2% FS, the NKGF Series is designed for demanding micro-flow measurement applications.

Positive Displacement Technology

The gear-based volumetric measuring principle directly relates gear rotation to displaced liquid volume, providing a clear and repeatable measurement mechanism.

Wide Viscosity Capability

The standard viscosity range of 2–200 mPa·s allows the meter to handle a variety of compatible liquid media.

Flexible Material Selection

Cast iron, stainless steel, and cast steel housing options allow the meter to be configured for different pressure and process requirements.

High-Temperature Option

An optional insulated-jacket and heat-sink configuration supports applications with fluid temperatures up to 200°C.

Explosion-Proof Option

The Ex ia IIC T5 configuration provides an intrinsically safe option for applications requiring hazardous-area protection.

Multiple Signal Options

Pulse and 4–20 mA output configurations are available for integration with different industrial control and monitoring systems.

NKGF Series Selection Considerations

Before selecting an NKGF Series micro gear flow meter, engineers should confirm the following operating conditions:

Required flow range and minimum flow rate
Liquid viscosity
Liquid temperature
Operating pressure
Liquid compatibility with the selected housing material
Whether the liquid contains solid particles
Required output signal
Power supply requirements
Whether an explosion-proof configuration is required
Whether a high-temperature configuration is required

Correct selection of these parameters is essential for obtaining reliable measurement performance.

For hazardous-area applications, the explosion-proof requirements should be confirmed before selecting the electrical configuration.

NKGF Series Technical Summary

The NKGF Series Explosion-Proof Micro Gear Flow Meter combines positive displacement technology with precision elliptical gears to provide accurate measurement of ultra-low clean liquid flow.

Its key specifications include:

Minimum detectable flow: 0.5 mL/min
Accuracy: ±0.5% FS or ±0.2% FS
Viscosity range: 2–200 mPa·s
Standard temperature: -20°C to +80°C
High-temperature version: up to 200°C with heat sink
Maximum pressure: up to 6.4 MPa depending on material/configuration
Housing materials: Cast Iron, Stainless Steel, Cast Steel
Output: Pulse or 4–20 mA
Power supply: 24 VDC for remote/intelligent digital display configurations
Explosion-proof rating: Ex ia IIC T5

The NKGF Series is therefore a suitable choice for engineers and OEM manufacturers looking for precision low-flow liquid measurement combined with flexible material, temperature, pressure, output, and intrinsically safe configuration options.

Frequently Asked Questions

What is the minimum flow rate the NKGF Series can detect?

The minimum detectable liquid flow rate is 0.5 mL/min.

What accuracy can the NKGF Series achieve?

The available accuracy options are ±0.5% FS and ±0.2% FS, depending on the selected configuration.

What liquids can the NKGF Series measure?

The NKGF Series is designed for compatible clean liquids. The standard fluid viscosity range is 2–200 mPa·s. Higher-viscosity applications can be evaluated upon request.

Can the NKGF Series measure liquids containing particles?

It is not recommended. Solid particles can interfere with the precision gear mechanism and may cause blockage or measurement problems.

Can the NKGF Series measure gas?

No. The NKGF Series is designed for liquid measurement. Gas measurement is not the intended application of this positive displacement gear flow meter.

Is the NKGF Series available for hazardous-area applications?

Yes. An Ex ia IIC T5 intrinsically safe configuration is available.

Can the NKGF Series be used at high temperatures?

The standard fluid temperature range is -20°C to +80°C. A high-temperature configuration with a heat sink can support fluid temperatures up to 200°C.

What output signals are available?

The NKGF Series supports Pulse and 4–20 mA output configurations. Remote and intelligent digital display configurations use a 24 VDC power supply according to the provided specifications.

Conclusion

For applications requiring accurate measurement of very small liquid flow rates, the NKGF Series Explosion-Proof Micro Gear Flow Meter provides a practical positive displacement solution.

Its precision elliptical gear mechanism, 0.5 mL/min minimum detectable flow, accuracy options down to ±0.2% FS, multiple housing materials, high-temperature configuration, Pulse and 4–20 mA outputs, and Ex ia IIC T5 intrinsically safe option make it suitable for a range of precision liquid measurement and OEM applications.

For engineering projects, the final model should be selected according to the actual flow rate, viscosity, pressure, temperature, medium compatibility, output requirements, and hazardous-area requirements. This ensures that the NKGF Series configuration matches the real process conditions and provides reliable long-term measurement performance.