HNL10-A Magnetic Float Liquid Level Switch for Small Tanks

The HNL10-A is a compact magnetic float level switch for point-level control and alarm on small containers. A sealed non-magnetic tube holds one or more magnetic reed switches; a hollow float with an internal ring permanent magnet rides up and down on the rod. As the float moves, its magnet closes the reed switch to generate a switching action for level control. The normally open (NO) or normally closed (NC) state is defined with no liquid present and can be specified by the user.

INQUIRY

Low-Cost Point-Level Switching for Tanks and Trays

With a low price, reliable reed-switch action, flexible mounting and a choice of body materials, the HNL10-A suits machinery, electronics, chemicals and household-equipment small tanks. The compact rod-and-float design needs only a small opening in the tank wall, giving a dependable on/off signal for pump control, high/low level alarm and interlock duty. Materials cover water, oil and mildly aggressive media.

Good fit: small-container level control and alarm, machine-tool coolant tanks, electronics manufacturing equipment, chemical dosing and storage tanks, household appliance water tanks, water and oil tank switching, pump on/off control and dry-run protection, HVAC condensate and drainage trays, medical and laboratory fluid containers, food and beverage utility tanks, OEM equipment level interlocks, low-cost point-level detection.

Is HNL10-A Suitable for Your Application?

Choose HNL10-A when:

• You need a point-level on/off signal — high/low alarm, pump start-stop or interlock — not a continuous level measurement.

• The container is small to medium, with a G1/2 or R1/2 mounting opening (or a customized fitting).

• The medium is water, oil or mildly aggressive, matched to SUS304, SUS316, PP, PVDF or PTFE construction, within the –20…80 °C or 0…60 °C range.

Confirm with us first when: you need a continuous analog/Modbus level signal, the medium is strongly corrosive or high-temperature, the foam or coating is heavy enough to restrict float movement, or the tank needs multi-point monitoring at several levels.

How the Reed-Switch Float Works

Magnetic actuation, no contact wear

The float magnet actuates the sealed reed switch magnetically; there is no sliding electrical contact to wear out. NO and NC are the switch states before liquid enters; the contact logic can be switched to match your control circuit.

Five body materials, three connection options

SUS304, SUS316, PP, PVDF or PTFE wetted construction; G1/2, R1/2 or customized thread. Match the material to the medium, and confirm the material-temperature range with our engineers on aggressive duties.

DC24V switch signal

Power supply DC24V; output NO or NC per order. The switch feeds a relay, PLC digital input or alarm circuit rather than a 4–20 m analog level loop.

Technical Specifications

Ordering Code

Mechanical Dimensions

Side-mounted compact float switch: threaded body with side float bulb and outgoing cable; DIN-plug and cable versions available by material.

Installation and Wiring

Mount through the G1/2 or R1/2 opening so the float travels freely up and down without touching the tank wall, baffle or heating element. Keep the float path clear of foam buildup and sludge. Wire the NO or NC contact to your PLC input, relay or alarm; confirm whether the circuit needs the contact closed on rising level or on falling level before choosing NO/NC. For pump dry-run protection, position the switch at the minimum safe level.

Typical Applications

• Coolant and hydraulic tanks: machine-tool sump and reservoir level switching.

• Dosing and chemical tanks: mildly aggressive liquid level alarm and pump control.

• HVAC and drainage: condensate trays and drain pan high-level alarm.

• Appliance and OEM: small water tanks, medical/lab containers and packaged equipment interlocks.

What to Send Us for Selection

Send: medium and concentration, operating temperature, tank size and mounting opening, required NO/NC logic, function (pump control, alarm or interlock), and whether the medium contains foam or buildup. We will confirm the material and temperature class before quoting.

Frequently Asked Questions

Can this float switch detect oil levels?

Yes. Choose a body material compatible with the oil; the float responds to the liquid level in the oil tank and switches the reed contact for pump control or alarm.

How should float material be selected for corrosive liquids in compact tanks?

Use PP, PVDF or PTFE for chemically aggressive media; SUS304/SUS316 for water, oil and mild conditions. Send the exact medium and concentration so we match the material to the fluid and temperature range.

Does foam affect magnetic float switching reliability?

Heavy foam or sticky buildup can restrict the float or delay its rise. Keep the switch in a clear liquid zone, away from aeration and foaming, and schedule periodic cleaning if buildup occurs.

Can NO or NC contacts provide pump dry-run and overflow interlocks?

Yes. Position one switch at the minimum safe level for dry-run protection and another at the high level for overflow alarm; choose NO or NC to match the safety logic of your control circuit.

What maintenance prevents the float sticking after product buildup?

Periodically check that the float slides freely, wipe off sludge and residue, and inspect the cable seal. Avoid mounting the switch where heavy deposits or crystallizing fluids collect on the rod.

Datasheet Download

HNL10-A Magnetic Float Level Switch Datasheet (PDF) — view all product manuals on our Download page »

Need Us to Check the Application?

Send us the medium, temperature, tank size and mounting thread. We will confirm the material, NO/NC logic and ordering code before we quote.

Send us your application details »