Trumen LFV12 & LFV11 compact tuning fork level switches — the most reliable point level detection solution for all liquids. No calibration, no moving parts, universal application. Ideal for high/low level alarm, overflow protection, pump protection and flow detection across process industries.
Based on the piezoelectric tuning fork principle — simple, reliable, and universally applicable to all liquids without any calibration.
Piezoelectric crystals inside the fork are excited by the electronics, causing the two tines to vibrate at their natural resonance frequency (typically ~1400 Hz) in free air.
When the liquid level rises and immerses the fork tines, the vibration frequency drops due to the mass loading effect of the liquid density on the fork.
The onboard electronics continuously monitor the fork vibration frequency. The frequency shift caused by liquid contact is detected instantly within 1 second.
A relay or transistor switching output is triggered — activating alarms, stopping pumps, or signalling the PLC/DCS. LED indicators show status at a glance.
Both models use the same vibrating fork principle and SS316 construction. The key difference is fork size and application suitability.
| Sensor Insertion | 50mm (excl. threads) |
| Min. Process Connection | ½" NPT / BSP |
| Process Connections | ½", ¾", 1" NPT/BSP, Tri-Clamp 1"–1½", SMS Union 1", Flush 1"–1½" |
| Media | All liquids up to 10,000 cP |
| Process Temp (std) | –20°C to +80°C |
| Process Temp (ext) | –30°C to +150°C (T2 option) |
| Process Pressure | Max 15 bar |
| Wetted Material | SS 316 |
| Enclosure | IP65 / IP67 |
| Supply Voltage | 15–80 VDC / 15–260 VAC (universal) |
| Output Options | PNP, NPN, 4–20mA, Relay (AC), NAMUR |
| Response Time | ≤ 1 second |
| LED Indication | Green (Power) + Red (Alarm) |
| External Test | Magnetic key test (no process entry) |
| Best For | Pipelines, small tanks, tight spaces, hygienic applications |
| Sensor Insertion | 128mm (incl. threads) — 100mm 1" entry fork |
| Min. Process Connection | 1" NPT / BSP |
| Process Connections | 1" NPT/BSP, Tri-Clamp 1½"/2", Custom available |
| Media | Liquids up to 10,000 cP + free-flowing solids/powders (max 10mm grain size) |
| Process Temp (std) | –20°C to +80°C |
| Process Temp (ext) | –30°C to +150°C (T2 option) |
| Process Pressure | Max 15 bar |
| Wetted Material | SS 316 |
| Enclosure | IP65 / IP67 |
| Supply Voltage | 15–60 VDC / 15–260 VAC (universal) |
| Output Options | PNP, NPN, 4–20mA, Relay (AC), NAMUR |
| Response Time | ≤ 1 second |
| LED Indication | Green (Power) + Red (Alarm) |
| External Test | Magnetic key test (no process entry) |
| Best For | Larger tanks, vessels, silos, solid/liquid interface |
Engineered to replace float switches, conductive, capacitive and optical sensors — with superior reliability and zero maintenance.
Works on frequency shift principle — completely independent of liquid conductivity, colour, viscosity or dielectric constant. Set once, works forever.
Switching response within 1 second of liquid contact. Fast enough for pump protection, overflow alarms and flow/no-flow detection in pipelines.
Wide range input: 15–80 VDC and 15–260 VAC. Works on any industrial supply without extra power conditioning — ideal for retrofit projects.
Functional test possible without opening the process — a magnetic key simulates the wetted condition externally. Safe and quick commissioning verification.
Fully sealed enclosure rated IP65/67 per IS-13947. Suitable for outdoor, washdown and humid environments — including food, pharma and chemical areas.
Unlike float switches, there are no mechanical moving parts to corrode, seize or fail. Virtually maintenance-free with an extremely long service life.
Unaffected by turbulence, foam, air bubbles, build-up on fork or changes in liquid properties — situations where float and optical switches fail.
High-level or low-level fail-safe mode selectable in the field without rewiring. Minimum and maximum fail-safe configurable as per your safety requirement.
Green LED (power on) and Red LED (alarm state) built into the housing for instant local status indication — no separate indicator panel required.
Widely used across process industries in Tamil Nadu — chemical plants, pharmaceutical facilities, food factories, water treatment plants, power stations and ETP/STP plants.
High/low level alarm in acid, alkali, solvent and chemical storage tanks. Suitable for aggressive media in SS316.
Hygienic tri-clamp connections available. Used in WFI tanks, API tanks, buffer tanks and CIP/SIP systems. Meets GMP requirements.
Hygienic SS316 design for milk, edible oil, juice, brewery and food process tanks. Tri-clamp and SMS union connections for clean-in-place systems.
High level alarm and overflow protection for fuel oil, lube oil, diesel and hydraulic oil storage tanks. Unaffected by oil film or viscosity changes.
Pump start/stop control, sump high-level alarm and ETP/STP tank level monitoring. Suitable for raw water, treated water and chemical dosing tanks.
Coolant tank level monitoring, DM water tank alarm, lube oil high/low level detection and condensate tank level control in thermal and industrial power plants.
Flow / no-flow detection in pipelines, empty pipe detection, interface level in separator vessels, and demand alarm in day tanks and process vessels.
Low-level protection for machine tool coolant tanks and lubrication systems. Prevents dry-run damage to machine tools and protects expensive CNC equipment.
High/low level alarm in fertiliser solution, pesticide and agrochemical storage tanks. Suitable for corrosive fertiliser solutions with SS316 wetted parts.
Why choose vibrating fork over float, conductive or capacitive level switches? Here's a side-by-side comparison for process engineers.
| Parameter | Vibrating Fork (LFV12) | Float Switch | Conductive Switch | Capacitive Switch |
|---|---|---|---|---|
| Moving Parts | ✓ None | ✗ Yes — float, arm | ✓ None | ✓ None |
| Calibration Required | ✓ No | ✓ No | Threshold set | ✗ Yes — per liquid |
| Affected by Conductivity | ✓ Not affected | ✓ Not affected | ✗ Yes — needs conductive liquid | Partially |
| Works in Foam / Turbulence | ✓ Yes | ✗ No — float unstable | ✗ Foam causes false trigger | Partially |
| Build-Up / Coating | ✓ Not affected | ✗ Float may seize | ✗ False reading | ✗ False reading |
| Universal Liquid Compatibility | ✓ All liquids | Material limits | ✗ Conductive only | Most liquids |
| Hygienic Connections | ✓ Tri-clamp, SMS Union | ✗ Limited | ✗ Limited | Some models |
| External Functional Test | ✓ Magnetic key | ✗ Manual only | ✗ Not possible | ✗ Not possible |
| Maintenance | ✓ Zero maintenance | ✗ Regular check needed | Electrode cleaning | Probe cleaning |
Common questions from process engineers and project managers about vibrating fork level switches.
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Official Datasheet
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