Is HNF10-A the right choice for your application?

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

• The measured medium is water, sewage, deionized water, weak acids/alkalis, mineral oil, hydraulic oil, lubricating oil or similar single-phase liquids.

• Pipe diameter is between DN8 and DN300, and threaded plug-in installation (G1/2 or G1/4) is acceptable.

• Only flow / no-flow detection is required for on-off alarming, interlock protection or pump control – continuous flow reading is not needed.

• NPN or PNP switching output is required to interface with a PLC, relay or equipment control circuit.

• The installation site is damp or exposed to water splash, requiring IP67 waterproof housing and all-stainless wetted parts.

• Installation space is limited and a small, low pressure-loss, non-mechanical solution is preferred.

Please consult us first if: the medium contains large amounts of solids or fibres, medium temperature is outside −10…60 °C, line pressure exceeds 1.6 MPa, analogue or communication output is required, or the fluid is highly corrosive.

Why choose an electronic flow switch

No moving parts, longer service life

Thermal detection principle means no baffles, no vanes and no pistons inside. There is no mechanical wear or jamming, making it ideal for continuous long-term operation with much lower maintenance than mechanical switches.

Low-resistance probe, negligible pressure loss

The small-diameter all-stainless probe protrudes only slightly into the flow stream, causing minimal flow disturbance and almost no pressure drop – well suited for cooling and lubrication circuits sensitive to head loss.

Dual-colour LED for instant status

Green indicates flowing, red indicates no flow or empty pipe. On-site status can be read at a glance without additional instruments, simplifying commissioning and troubleshooting.

Fully waterproof, wide pipe coverage

IP67 housing with 304 body and 316L wetted parts covers pipe sizes from DN8 to DN300, delivering reliable performance in machine tools, environmental systems, water treatment and semiconductor applications.

Technical Specifications

Installation & Commissioning

Confirm 4 items before ordering:

1. Pipe nominal diameter and thread size – to select standard, long or small probe version.

2. Medium type and operating temperature – to verify compatibility with 316L wetted parts.

3. Output type – NPN or PNP, matching the control system.

4. Line operating pressure – must not exceed 1.6 MPa rated pressure.

Install the switch on a straight pipe section with fully developed flow, avoiding valves, elbows and pump outlets where flow is disturbed. The probe should face the flow direction for good media contact. After wiring, first verify the indicator and output level at zero flow, then confirm the switch point at normal flow before putting the circuit into automatic operation.

Outputs & System Integration

• NPN / PNP switching output: connects directly to PLC digital inputs, relays or contactors for flow-present / flow-absent detection, no-flow alarm and interlock shutdown.

• Green / red LED indication: provides on-site visual status of flow and no-flow conditions for commissioning and routine inspection.

• 3-wire DC connection: brown = DC 24 V+, blue = 0 V, black = signal output, compatible with standard industrial wiring practice.

For OEM volume projects, please specify controller input type, thread specification, probe length and medium temperature range with your enquiry so we can match the correct configuration.

Typical Applications

Machine-tool & machining coolant circuits

Monitors cutting fluid and cooling water flow, triggering alarm or shutdown on flow interruption to protect spindles, tools and heat-treatment equipment from overheating.

Pump dry-run & dry-running protection

Installed on the pump discharge to verify that effective flow is established, triggering a protection signal on suction loss or empty suction to prevent pump seizure.

Environmental & water treatment equipment

Used in environmental systems, circulating water loops and water treatment plants to monitor branch-line flow and ensure dosing, filtration and aeration processes run as intended.

Semiconductor & photovoltaic equipment

Cooling water monitoring for etching, grinding, slicing and CVD processes, with 316L wetted parts meeting cleanliness and corrosion-resistance requirements.

Food, pharma & metallurgy

Provides flow abnormality detection in process water lines, mineral furnace cooling and powder metallurgy equipment, improving equipment reliability and process stability.

Information Required for Selection

To confirm the correct HNF10-A configuration, please provide: pipe diameter & thread size, medium name & temperature range, normal operating flow rate, output type (NPN or PNP) and required probe length. If necessary we will request additional details on line pressure and mounting orientation to ensure the switch point matches your operating conditions.

Frequently Asked Questions

Can it detect both water and oil flow?

Yes. The HNF10-A operates on the thermal principle and detects flow / no-flow conditions for water, aqueous solutions and various oils including mineral, hydraulic and lubricating oils.

Which probe fits DN8 to DN10 pipes?

For DN8–DN10 lines we recommend the G1/4 small-probe version. Standard G1/2 probe covers DN15–DN100, and the long-probe G1/2 version is used for DN100–DN300.

Does the red LED indicate a no-flow alarm?

Yes. A red LED means no flow or an empty pipe, and the switch output is active. This signal can be used for pump protection or shutdown interlock.

How does the stainless probe minimize pressure loss in coolant circuits?

The probe has a small diameter and smooth profile, so it introduces very little flow disturbance. Pressure drop is negligible, making it suitable for low-resistance cooling and lubrication loops.

What output should be selected for NPN or PNP pump protection logic?

Choose according to your PLC or control circuit input type. PNP (sourcing) is common in European and Japanese systems, while NPN (sinking) is often used on domestic and older equipment. Match the logic of your control loop.

Downloads

HNF10-A Electronic Flow Switch Datasheet (PDF)

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