Product Overview

The NOIKE-AH Electronic Flow Switch NK300B is a high-precision intelligent thermal dispersion flow sensor designed for reliable flow monitoring of liquids and gases. Featuring a maintenance-free design with no moving parts, the NK300B delivers stable and accurate flow detection for industrial automation systems.

Designed for circulating water, cooling systems, cutting fluids, lubricating oils, hydraulic systems, and compressed air applications, the NK300B helps prevent pump dry running, monitor flow conditions, and improve equipment reliability.

---

Working Principle

The NK300B operates using the thermal dispersion (thermal mass flow) principle.

Inside the stainless-steel probe are two precision temperature-sensitive resistors:

• One resistor is continuously heated.
• The second resistor measures the actual medium temperature.

When there is no flow, a stable temperature difference exists between the two resistors.

As the medium begins to flow, heat is transferred away from the heated resistor. The faster the flow velocity, the greater the heat loss and the smaller the temperature difference.

The internal electronics continuously calculate this temperature difference to determine the flow velocity. When the preset switching point is reached, the sensor outputs a switching signal for monitoring or equipment protection.

Because the NK300B contains no mechanical moving components, it offers high reliability, excellent repeatability, and long-term maintenance-free operation.

---

Key Features

• Thermal dispersion sensing technology
• Suitable for both liquids and gases
• No moving parts for maintenance-free operation
• High sensitivity with excellent repeatability
• Adjustable switching point via potentiometer
• Real-time 6-LED flow indication
• Multiple output options: PNP, NPN, Relay (SPDT)
• Reverse polarity, overload and short-circuit protection
• High pressure resistance up to 100 bar
• IP67 protection for harsh industrial environments
• Compact stainless-steel probe with durable PBT housing
• Fast response time with simple installation

---

Technical Specifications

---

Industrial Applications

The Electronic Flow Switch NK300B is suitable for a wide variety of industrial flow monitoring applications, including:

• Industrial circulating water systems
• Cooling water monitoring
• Pump dry-run (idling) protection
• Hydraulic systems
• Pneumatic systems
• Lubrication systems
• Cutting fluid monitoring
• Industrial machinery
• HVAC systems
• Air compressor systems
• Water treatment equipment
• Process automation
• Filter monitoring
• Heat exchangers

---

Installation Recommendations

For optimal performance:

• Install the sensor where the pipeline remains completely filled with the process medium.
• Avoid installation immediately downstream of pumps, valves, or elbows where turbulence is excessive.
• Ensure the probe is fully inserted into the flow stream.
• Verify the flow direction before commissioning.
• Allow approximately 8 seconds after power-up for initialization.
• Periodically clean the probe if the medium contains deposits or contaminants.

---

Advantages of the Electronic Flow Switch NK300B

Compared with traditional paddle or mechanical flow switches, the NK300B offers:

• No moving mechanical components
• Longer service life
• High measurement stability
• Excellent repeatability
• Low maintenance costs
• Suitable for liquids and gases
• Fast response
• Easy installation
• Visual LED flow indication
• Reliable pump protection

---

Industries Served

The NK300B is widely used in:

• Industrial Automation
• Machinery Manufacturing
• Chemical Processing
• Water Treatment
• Food & Beverage
• Pharmaceutical
• HVAC
• Power Generation
• Steel Industry
• Paper Mills
• Textile Industry
• Electronics Manufacturing
• Air Compressor Systems

---

Frequently Asked Questions (FAQ)

1. What is the working principle of the NK300B?

The NK300B uses thermal dispersion technology, measuring heat transfer between a heated sensor and a reference sensor to detect fluid flow accurately.

2. Can the NK300B measure both liquids and gases?

Yes. The NK300B is designed for water, oil, and compressed air, making it suitable for both liquid and gas applications.

3. Does the NK300B require regular maintenance?

No. Its no-moving-parts design minimizes wear and typically only requires occasional probe cleaning in contaminated media.

4. What output options are available?

The NK300B supports:

• PNP output
• NPN output
• Relay output (SPDT Normally Open + Normally Closed)

5. What is the maximum operating pressure?

The standard NK300B supports operating pressures up to 100 bar.

6. Is the switching point adjustable?

Yes. Users can easily adjust the switching threshold using the built-in potentiometer.

7. What protection level does the NK300B provide?

The sensor is rated IP67, offering excellent protection against dust and water ingress in demanding industrial environments.

8. What are the typical applications of the NK300B?

Typical applications include pump protection, circulating water systems, cooling systems, hydraulic equipment, lubrication systems, HVAC equipment, compressed air systems, machinery automation, and industrial process monitoring.

---

Why Choose the NOIKE-AH NK300B?

The NOIKE-AH Electronic Flow Switch NK300B combines thermal dispersion sensing, maintenance-free reliability, and high industrial durability into one compact device. With gas and liquid compatibility, 100-bar pressure resistance, IP67 protection, and flexible output options, it provides a dependable solution for industrial flow monitoring and pump protection across a wide range of applications.

---

The Wiring Diagram

The wiring method can be customized with a 4-wire system

---

Size Chart（mm）