Is HNF10-D the right choice for your application?

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

• The medium is water, oil, air or inert gas, and only flow / no-flow detection is needed – continuous flow reading is not required.

• Flow rate falls within 0.3–70 L/min (water, calibrated at 20 °C, horizontal mounting), suitable for small-bore low-flow applications.

• A purely mechanical principle is preferred for simple structure, high reliability and minimum electronic maintenance.

• Reed-switch contact output is acceptable for relay, contactor or PLC digital input circuits.

• The pipeline uses female thread connections from G1/4 to G1, with horizontal installation possible.

• Cost-sensitive high-volume deployment on machinery is planned, with stable switching repeatability required.

Please consult us first if: the medium contains many particles or is highly viscous, medium temperature exceeds 90 °C, line pressure is above 100 bar, installation is vertical or upward flow, analogue or communication output is needed, or corrosive fluids require special materials.

Why choose a mechanical piston flow switch

Truly mechanical, full electrical isolation

Flow moves the piston and an internal magnet actuates the reed switch. Mechanical and electrical parts are completely separated; the fluid never touches the electronics, delivering high reliability and long service life for typical industrial water, oil and gas circuits.

Printed scale, no field calibration needed

The housing is marked with a switching scale so the trip point can be read and set directly. No field calibration and no electronic programming are required; the switch is ready to use after installation with very low commissioning effort.

Low pressure loss, dirt-tolerant design

The optimised piston flow path produces very low pressure drop – about 0.3 bar at 25 L/min – while offering good tolerance to dirt and particles, so it resists jamming in typical cooling water and lubrication circuits.

Multiple housings for different pressure ratings

Three housing options – POM plastic, anodised aluminium and stainless steel – offer 10 bar, 50 bar and 100 bar pressure ratings respectively, allowing economical selection matched to actual medium and pressure conditions.

Technical Specifications

Installation & Commissioning

Confirm 4 items before ordering:

1. Pipe thread size and medium type – to select the correct connection and material option.

2. Normal flow and required trip point – to match the appropriate range scale.

3. Supply type and number of switch points – choose DC or AC, single or dual set points.

4. Medium pressure and temperature – to verify the housing material and seal compatibility.

Horizontal installation is recommended, with flow direction matching the arrow on the body. Avoid disturbed flow locations such as pump outlets and downstream of valves. After installation, preset the trip point via the scale ring, then fine-tune under actual flow conditions until switch-on and switch-off are correct. Check seal integrity and wiring insulation before commissioning.

Outputs & System Integration

• Reed switch output: passive contact signal for direct connection to relays, contactors or PLC digital inputs, enabling flow/no-flow alarming and equipment interlocking.

• Single / dual switch points: single set point for basic on-off alarm; dual set points allow separate high and low thresholds for two-stage control.

• LED status indication: the DC version includes a switching-status LED for instant on-site visual feedback during commissioning and routine inspection.

• 2-wire connection: simple wiring with 2-wire normally-open circuit for both DC and AC versions, compatible with standard industrial control wiring practice.

For OEM volume projects, please specify thread size, flow trip point, supply type, number of switch points and housing material with your enquiry so we can match the optimal configuration.

Typical Applications

Pneumatic & hydraulic systems

Flow/no-flow monitoring in hydraulic power units, lubrication systems and pneumatic circuits, triggering protection on abnormal flow to prevent actuator damage from oil or air starvation.

Machine-tool coolant & lubrication

Installed in coolant and lubrication lines of machine tools to detect cutting fluid and oil flow, protecting spindles, guideways and tools from dry-running damage.

Refrigeration, air conditioning & compressed air

Used with chillers, HVAC water systems and compressor pipelines to monitor cooling water and compressed air flow, ensuring heat-exchange performance and reliable equipment operation.

Water treatment & low-flow dosing

Reliable on-off detection in water treatment plants, dosing units and small chemical lines at low flow rates, supporting dosing interlock and dry-line alarm functions.

Industrial automation & general machinery

An economical flow detection component for high-volume integration into automation equipment, packaging machinery and general industrial devices.

Information Required for Selection

To confirm the correct HNF10-D configuration, please provide: medium name & temperature range, pipe thread size, trip-point flow or flow range, supply type (DC/AC), number of switch points, housing material preference and electrical connection style (M12 / direct cable). If necessary we will request additional details on mounting orientation and line pressure to ensure the trip point matches operating conditions.

Frequently Asked Questions

What is the lowest adjustable water set point?

The smallest range is 0.3–7 L/min, with a minimum trip point of 0.3 L/min under calibrated conditions: clean water, horizontal mounting and 20 °C.

Can it switch gas as well as liquid flow?

Yes. The HNF10-D is a gas-liquid dual-use model, suitable for both water and oil liquids as well as air and inert gas flow / no-flow detection.

Which housing material supports 100 bar pressure?

The stainless steel housing version offers the highest pressure rating of up to 100 bar. Aluminium is rated 50 bar and plastic 10 bar; choose according to actual operating pressure.

How does the printed scale simplify setting the trip point without field calibration?

The housing has a printed switching scale so the trip point can be read and adjusted directly. Factory-calibrated on clean water, it requires no additional calibration tools on site – just turn the scale ring.

Does the piston design tolerate dirt while maintaining low pressure loss?

Yes. The optimised piston flow path produces very low pressure drop at rated flow while offering good dirt and particle tolerance, so jamming is uncommon in typical cooling water and lubrication circuits.

Downloads

HNF10-D Piston Flow Switch Datasheet (PDF)

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