Guiyang.bai@honno-auto. com
86-13840589744
Tuning fork level switch with piezoelectric vibration for liquids and flowable solids. No calibration needed, relay / PNP, up to 40 bar, Ex d IIC T6, IP65, PTFE coating option.
The HNL120-A tuning fork level switch vibrates the fork at resonance through a pair of piezoelectric crystals mounted on the fork base. When the fork contacts the measured medium, the vibration amplitude and frequency change abruptly; the intelligent circuit detects this change and converts it into a switch signal. The detection is completed by electronic circuits with no moving parts, so the switch needs no calibration on site and little maintenance after commissioning.
The switch suits tap water and mineral water plants, pulp and paper, glue and dye production, mud and sludge handling, alkaline and acid solution tanks, beer and beverage lines, gas-producing liquids, flowable powder and granular solids, pipelines and tanks level alarm, chemical and pharmaceutical vessels, water treatment and pumping stations, and plants needing maintenance-free point-level detection.
Good fit: tap water and mineral water plants, pulp and paper, glue and dye production, mud and sludge handling, alkaline and acid solution tanks, beer and beverage lines, gas-producing liquids, flowable powder and granular solids, pipelines and tanks level alarm, chemical and pharmaceutical vessels, water treatment and pumping stations, maintenance-free point level detection.
Choose HNL120-A when:
You need a reliable point-level alarm for water, oil, pulp, glue, dye, mud, alkaline or acid solutions, beer, beverages, gas-producing liquids, or flowable powder and granules.
You want no on-site calibration and no moving parts, with detection independent of conductivity, dielectric constant, viscosity, pressure and temperature.
Relay or PNP output, 24 VDC or 220 VAC supply, matches the control system.
Confirm with us first when: density is below 0.5 g/cm³, particle size exceeds 10 mm, viscosity exceeds 10,000 mm²/s, pipeline flow exceeds 5 m/s, or the required pressure / temperature exceeds the selected version.
Different electrical parameters and densities of the tested material do not affect the measurement. Switch operation is independent of medium conductivity, dielectric constant, viscosity, pressure and temperature; different probe lengths adapt to media of various densities.
Because detection is not affected by the medium's electrical parameters or density, no on-site calibration is required for any liquid type. High-frequency excitation gives excellent anti-noise interference capability. Once installed and put into operation, the electronic detection needs no maintenance.
Standard type or anti-corrosion type with PTFE coating; thread, flange or clamp process connection; aluminum shell. Pressure ratings 10, 25 or 40 bar; three temperature ranges up to 200 °C.
| Model | HNL120-A — Tuning fork level switch |
|---|---|
| Measurement medium | Water, oil, flowable powder or granular media; liquids, slurries and flowable solids |
| Repeatability | 1 mm typical; 2 mm maximum |
| Response time | 0.5 s when fork covered by medium; adjustable 0.5…60 s |
| Max switching frequency | 150 times/min; 1 switch signal |
| Allowable pressure | 10 bar / 25 bar / 40 bar |
| Density / particle size | Density >0.5 g/cm³; solid particle diameter <10 mm |
| Viscosity | Maximum 10,000 mm²/s |
| Service life | >1 million cycles |
| Signal output | Relay or PNP; max voltage 48 VDC / 220 VAC; current 6 A; power consumption ≤2 W |
| Working temperature | –40…80 °C; –40…150 °C; –40…200 °C |
| Transport / storage | –40…85 °C |
| Vibration / shock | Sine 20 g, 25 Hz–2 kHz; piston 4.4 g, 25–200; impact 50 g/6 ms; free fall 1 m |
| Protection level | IP65 (IEC 529), with matching connectors |
| Explosion-proof grade | Exd IIC T6 |
| Mechanical connection | Thread, flange or clamp; terminal wiring |
| Wetted parts / shell | 304 / 316 / PTFE coating; aluminum shell; weight 3.5 kg |
| Terminal | Function |
|---|---|
| 1, 2 | AC 220 V supply |
| 3 | Ground |
| 4, 5 | DC 24 V supply |
| 6–11 | Relay output terminals |
Red light: tuning fork working status; green light: SSR relay output status. PNP normally open: terminals 4, 5, 6; PNP normally closed: terminals 4, 5, 8; dip code at the H end.
| Type | Specification |
|---|---|
| Thread | G3/4, G1, NPT3/4, NPT1 (external thread) |
| Clamp | 1-½" = Ø50.5 mm; 2" = Ø64.0 mm |
| Flange | 2", 3", 4" 150 LB / 300 LB; DN50 / DN80 / DN100 at PN2.5 / PN40 |
| Code segment | Code | Description |
|---|---|---|
| Product type | 00 | Standard |
| 01 | Anti-corrosion type (PTFE coating) | |
| Pressure reference | A | 10 bar |
| B | 25 bar | |
| C | 40 bar | |
| Insertion depth | 10–19 / X | 0–128 / 250 / 300 / 400 / 500 / 1000 / 1500 / 2000 / 2500 / 3000 mm; X special custom range |
| Supply voltage | A | 24 VDC |
| B | 220 VAC | |
| Signal output | 1 | Relay output |
| 2 | PNP output | |
| Process connection | A01–A10 / X | G3/4, G1, NPT3/4, NPT1, clamp 1-½", clamp 2", flange DN50, DN80, 2", 3"; X special |
| Electrical connection | 1 | Terminal wiring |
| Temperature range | 1 | Standard –40…80 °C |
| 2 | –40…150 °C | |
| 3 | High-temperature –40…200 °C | |
| Explosion-proof | 1 | Non-explosion-proof |
| 2 | Explosion-proof type |
Compact head or aluminum housing with fork tines at the lower end; thread, flange or clamp fitting. Insertion depth matches the selected range; the PTFE-coated anti-corrosion version protects the wetted fork and fitting.
For high-viscosity media, a perpendicular fork helps the medium detach from the tines. Where there is adhesion to the wall, keep sufficient space between fork and wall. For pipeline installation, flow rate should stay below 5 m/s (viscosity 1 mm²/s, density 1 g/cm³). Both top vertical installation and side-wall flush installation are supported; keep the fork clear of inlet turbulence and agitator action.
Water and beverage: tap water, mineral water, beer, beverage and gas-producing liquid level alarm.
Process industry: pulp, glue, dye, mud, sludge, alkaline and acid solution tanks.
Solids and pipelines: flowable powder and granules, pipeline and tank point-level switching.
Chemical and pharma: vessels needing maintenance-free, no-calibration point detection.
Send: medium and density, particle size, viscosity, temperature and pressure, tank/pipe size and opening, required insertion depth, supply voltage, output preference (relay/PNP, NO/NC), connection type, and any hazardous-area classification. We will confirm the version and selection code before quoting.
Does foam trigger the tuning fork?
Foam or aerated media can affect the fork reading depending on density and stability. The switch is rated for media above 0.5 g/cm³; for foamy or gas-producing service, describe the medium so we can confirm whether a fork or another principle suits the duty.
How reliably does the fork detect viscous liquids or aerated media?
Switching is independent of conductivity, dielectric constant, viscosity, pressure and temperature, but viscosity is capped at 10,000 mm²/s. High-viscosity media should mount the fork perpendicular so the medium detaches; verify detection on site with the actual medium.
Can relay or PNP output stop pumps before dry running?
Yes. Relay or PNP output drives the pump interlock or alarm; set NO/NC for the fail-safe dry-run or overflow logic. Match contact current to the load (6 A max).
Where should the fork be mounted outside inlet turbulence?
Mount the fork away from inlet jets, turbulence pockets and agitator action, with enough clearance from the wall to avoid adhesion. Top vertical or side-wall flush mounting both work; keep the tines in the liquid path.
What cleaning interval prevents heavy buildup between fork tines?
Buildup between the tines can shift detection; clean on a schedule matched to the medium's tendency to coat. In sticky or bridging service, confirm the PTFE-coated version and review the mounting orientation for cleanability.
HNL120-A Tuning Fork Level Switch Datasheet (PDF) — view all product manuals on our Download page »
Send us the medium, density, viscosity, temperature and pressure. We will confirm the version, connection and selection code before we quote.
Send us your application details »
Contact: HongNuo
Phone: 13840589744
Tel: 86-13840589744
Email: Guiyang.bai@honno-auto. com
Add: Zhongguancun Innovation Center, No. 28 Huahai Road, Shenyang Economic and Technological Development Zone, Liaoning Province
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