Ultrasonic Level Sensors: Reliable Non-Contact Measurement

The cost-effective standard for water, wastewater, and industrial fluid management. Longvista Ultrasonic Level Sensors deliver accurate, continuous, non-contact liquid level monitoring across industrial tanks, open channels, sumps, and remote reservoirs.

By utilizing high-frequency acoustic sound waves, non-contact ultrasonic sensors calculate fluid distance without ever coming into contact with the medium. This eliminates physical sensor wear, chemical corrosion, and media buildup, drastically reducing lifetime maintenance costs.

From compact OEM sensors (SUL801A) and chemical-resistant PTFE housings (SUL801), to hazardous-area explosion-proof models (SUL805H) and long-range 60-meter transmitters (SUL806), our portfolio covers every environmental and installation constraint.

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Key Category Advantages

  • Non-Contact Reliability: Ideal for aggressive chemicals, wastewater sumps, or hygienic food-grade applications where fluid contact must be avoided.

  • Built-In Echo Intelligence: Automatic temperature compensation algorithms and digital false-echo filtering come standard across all models.

  • Universal System Integration: Flexible output options including 4-20mA analog, RS485 Modbus RTU, and wireless IoT networks (LoRaWAN, NB-IoT, 4G).

Quick Selection Guide

Application & Requirement Recommended Series / Model Key Feature & Capability Max Range
Aggressive Acids & Chemicals SUL801 Pure PTFE / PVDF corrosion-proof housing Up to 15m
General Industrial & Precision SUL801A High precision (±0.2%) with compact dead zone Up to 15m
Harsh Sumps & Industrial Washdown UL106 Rugged M30 compact thread for enclosed spaces Up to 10m
Hazardous & High-Temp Zones SUL805H Explosion-Proof (Ex) rated up to 110°C Up to 10m
Non-Intrusive Tank Measurement SUL814 External bottom/side mount; zero wall drilling Custom
Deep Storage Silos & Reservoirs SUL806 Extended high-power acoustic beam transmitter Up to 60m
Remote IoT & Smart City Telemetry SUL650 Wireless LoRaWAN, 4G, and NB-IoT connectivity Up to 10m
Remote Field Depth Surveys SUL811 Portable hand-held acoustic depth sounder Portable
Separated Display / Control Panel SUL807 Split-body meter with remote display console Up to 30m
Submerged Sludge & Sediment SUL812 Underwater acoustic sludge interface profiling Submerged
Standard Water & Tank Level SUL804A Universal digital display water transmitter Up to 15m

Engineering Essentials: Accuracy & Environmental Control

To maintain accurate readings, an ultrasonic level transmitter must compensate for the atmospheric conditions within the tank or vessel:

1. Speed-of-Sound Temperature Compensation

The speed of sound in air varies with temperature by approximately 0.17% per degree Celsius. In outdoor vessels subject to extreme daily temperature swings, uncompensated acoustic measurements can drift by more than 7%.

  • The Longvista Solution: Transmitters like the UL105, SUL801A, and SUL806 incorporate integrated temperature sensors to continuously adjust time-of-flight distance calculations in real time.

2. Managing the Transducer Dead Zone (Blind Area)

The “Dead Zone” is the minimum clearance distance required directly below the transducer face while the crystal dampens its transmission vibration.

  • Compact Vessels: Sensors such as the UL106 and SUL801A feature short dead zones (down to 0.2m–0.3m) to maximize usable tank volume.

  • Deep Reservoirs: Extended-range transmitters like the SUL806 require larger dead zones (up to 1.0m) to generate the acoustic energy necessary to measure depths up to 60 meters.

  • Installation Rule: Mount the sensor high enough so the maximum high-water mark never enters the dead zone, preventing signal lock-up.

Application-Specific Technology Matching

Corrosive & Aggressive Media

In chemical processing, sulfuric acid, hydrochloric acid, and solvent vapors can ruin standard plastic faces.

  • SUL801 Series: Sealed with PTFE or PVDF materials to resist chemical attack and vapor saturation.

  • SUL814 Series: Measures externally through the outer shell of plastic or steel tanks—eliminating contact with toxic fluids.

Explosion-Prone Environments

In fuel storage, oil processing, and chemical mixing facilities, flammable gases may be present.

  • SUL805H Series: Built with flameproof/explosion-proof enclosures (Ex rating) and high-temperature tolerance up to 110°C.

Remote IoT & Off-Grid Infrastructure

For flood early-warning networks, irrigation channels, and remote municipal sumps without grid power:

  • SUL650 Series: Integrates battery-powered electronics with LoRaWAN, 4G, or NB-IoT telemetry to transmit level alarms directly to central SCADA or cloud dashboards.

Technology Comparison: Selecting the Right Sensing Principle

Operational Feature Ultrasonic (SUL / UL Series) Radar Level (MQ / FRM Series) Submerged Hydrostatic
Primary Benefit Cost-Effective Non-Contact High Heat, Vapor & Foam Immune Deep Wells & Turbulent Basins
Vapor & Steam Tolerance Moderate (Requires Filtering) Excellent (Unmodified by Gas) Unaffected (Measures Pressure)
Heavy Surface Foam Poor (Foam Absorbs Sound) Moderate to High Unaffected (Submerged)
Physical Maintenance Zero (Mounted Above Liquid) Zero (Mounted Above Liquid) Periodic (Sensor in Fluid)
Relative Investment Budget to Mid-Range Mid to High-End Budget to Mid-Range

FAQ

Q: Can ultrasonic level meters be used for dry bulk solids or powders?

A: While possible in light applications, dry powders (such as cement, flour, or sand) absorb sound waves and form irregular angle slopes, which reflect acoustic energy away from the receiver. For dry bulk solids, we recommend exploring our high-frequency Radar Level Sensors.

Q: How do I select between a non-contact ultrasonic sensor and an external non-intrusive sensor?

  • Choose a top-mounted non-contact sensor (e.g., UL105 / SUL801) when measuring open sumps, vented storage tanks, or basins from above.

  • Choose an external non-intrusive sensor (SUL814) when working with sealed, high-pressure, or toxic chemical vessels where drilling mounting holes into the tank wall is prohibited.

Q: What installation precautions prevent false-echo reflections?

Ensure the sensor’s acoustic beam cone (typically 8° to 12°) is clear of internal ladders, pipes, inlet streams, and agitator blades. Mount the transducer perfectly vertical to the liquid surface—a tilt greater than 3° can cause signal loss.

Ready to find your solution?

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Need an alternative sensing principle for extreme process conditions?

  • Radar Level Sensors: Explore non-contact radar transmitters engineered for high-temperature steam, vacuum pressures, and heavy surface foam.

  • Open Channel Radar Flow Meters: Browse dual velocity and level radar units (such as the FRM Series) designed for unlined rivers and concrete canals.

  • Submerged Hydrostatic Level Transmitters: Explore pressure-based level probes for deep wells, boreholes, and high-agitation tanks.

  • Pressure & Flow Instrumentation: Complete your process loop with Longvista inline flow meters and pressure transmitters.

 

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