Is HNF10-B the right choice for your application?

Select this model when all of the following conditions are met:

• The measured medium is a single-phase fluid such as water, hydraulic oil, lubricating oil or compressed air, within the typical velocity range.

• On-site visual flow trend indication is required, and the switch set point needs to be flexibly adjusted to match process thresholds.

• PNP, NPN or relay output is required for PLC input, alarm interlocking or pump start/stop control.

• The pipeline uses standard threaded connections, or hygienic clamp connections for food / pharmaceutical clean lines.

• The site has wide temperature swings and vibration, demanding a non-mechanical, maintenance-free and highly reliable solution.

• High-temperature media or high-pressure hydraulic circuits are present, requiring corresponding high-temp or high-pressure versions.

Please consult us first if: the medium contains large amounts of solids or fibres, is highly corrosive, exceeds available temperature/pressure ratings, or continuous analogue flow measurement is needed.

Why choose a digital thermal flow switch

Dual-sensor thermal principle, no mechanical wear

Based on heat exchange between a heated sensor and a reference sensor, there are no baffles, vanes or pistons inside. This eliminates mechanical wear and jamming, delivering long-term maintenance-free operation.

8-LED bar for instant flow trend

Red LEDs indicate flow below the set point, yellow marks the switch threshold and green shows flow above set point. More green LEDs mean higher velocity, allowing instant on-site assessment without additional instruments.

Field-adjustable set point, high flexibility

The switch threshold can be set locally via capacitive touch buttons or remotely via PC software. No disassembly and no production shutdown are required, making it far more adaptable than fixed-threshold mechanical switches.

All-metal construction for diverse duties

Available in standard threaded, heat-dissipation, high-temperature and hygienic clamp versions with 316L wetted parts option. Pressure ratings up to 300 bar cover general industry, high-pressure hydraulics and food & pharma applications.

Technical Specifications

Installation & Commissioning

Confirm 4 items before ordering:

1. Medium type and operating temperature – to select standard or high-temperature version and wetted material.

2. Pipe connection and diameter – to match thread or hygienic clamp and select the correct probe length.

3. Output type and load requirements – choose PNP, NPN or relay output.

4. Set point threshold and switching logic – specify high-flow or low-flow tripping behaviour.

Install on a straight pipe section with fully developed flow, avoiding valves, elbows and pump outlets where flow is disturbed. Orient the probe facing the flow for good heat exchange. After wiring, verify LED status and output level at zero flow, then set the desired switch point via buttons or software. Validate the switch point and hysteresis at normal flow before putting the circuit into automatic operation.

Outputs & System Integration

• PNP / NPN switching output: connects directly to PLC digital inputs for flow status monitoring, low-flow alarm and pump protection interlocks.

• Relay output: can directly drive contactors, solenoid valves and acoustic/visual alarms, with normally open / normally closed contacts configurable for mixed low-voltage and power circuits.

• 8-LED status indication: provides real-time local flow trend and switch state for on-site commissioning, routine inspection and troubleshooting.

• M12 industrial connector: 5-pin standard interface with reliable protection, suitable for industrial field wiring and quick replacement.

For OEM volume projects, please specify control logic, connection type, probe length and medium temperature/pressure requirements with your enquiry so we can match the optimal configuration.

Typical Applications

Machine-tool coolant & lubrication circuits

Installed in cooling and lubrication lines of machining centres and CNC lathes to monitor flow trend continuously and trigger alarms on low flow, protecting spindles and tools from dry-running damage.

Hydraulic & lubrication system monitoring

Used for oil flow detection in hydraulic power units and lubrication systems. The high-pressure 300 bar option handles demanding hydraulic duties and protects actuators and drives.

Food & beverage and pharmaceutical hygienic lines

Hygienic clamp connections with 316L wetted parts meet clean-process requirements in food, beverage and biopharmaceutical manufacturing, including CIP loop monitoring.

High-temperature processes & cooling systems

The high-temperature version handles elevated media temperatures, suitable for heat-treatment equipment, industrial furnace cooling and high-temperature circulating water applications.

Gas & compressed air systems

Detects flow / no-flow conditions in compressed air, nitrogen and other gas lines, providing reliable switch signals for compressor protection, pneumatic circuits and gas distribution systems.

Information Required for Selection

To confirm the correct HNF10-B configuration, please provide: medium name & temperature range, pipe diameter & connection type, operating velocity or flow rate, output type (PNP/NPN/relay), required probe length, and whether hygienic / high-temperature / high-pressure versions are needed. If necessary we will request additional details on mounting orientation and line pressure to ensure the set point matches operating conditions.

Frequently Asked Questions

What do the eight flow LEDs indicate?

Red LEDs indicate flow below the switch point, yellow marks the switch threshold and green shows flow above the set point. More green LEDs mean higher flow velocity, giving an instant visual trend.

Can the switch point be set from a PC?

Yes. Besides on-site setting via touch buttons, parameters including set point and hysteresis can also be configured via PC software, ideal for batch commissioning and remote parameter management.

Which hygienic connection suits food-grade processing lines?

We recommend the hygienic clamp version, available in 25.4 mm and 50.8 mm clamp sizes with 316L wetted parts, meeting clean-process and food-safety requirements.

How does the dual-temperature-sensor design provide maintenance-free operation?

It operates entirely on the thermal-diffusion principle with no moving mechanical parts inside. There is no wear, jamming or fatigue failure, enabling long-term maintenance-free service with high reliability.

Is a 300 bar pressure option available for demanding hydraulic service?

Yes. Standard rating is 100 bar; for high-pressure hydraulic and other demanding duties a 300 bar version is available. Please specify your actual operating pressure when ordering.

Downloads

HNF10-B Digital Thermal Flow Switch Datasheet (PDF)

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