Performance
• Resolution: 1 mm
• Read rate: ~2 Hz
• Transducer frequency: 42 kHz
• Maximum range: 5,000 mm (5 m / 196 in)
• Minimum reported distance: 50 mm (near-field readings below 50 mm are clamped to 50 mm)
• Detection profile: long range, narrow detection zone
Electrical / Power
• Supply (standard): 3.0–5.5 VDC
• Average current: ~1.8 mA
Outputs and interfaces
• Select one by wiring: RS232 or TTL serial; scaled analog voltage; analog envelope
• Optional at purchase: 4–20 mA output (replaces standard modes; requires 9–36 VDC)
Signal processing and stability
• Real-time automatic calibration (supply voltage, humidity, ambient noise)
• Firmware filtering for noise tolerance and clutter rejection
• Additional stability filter to reject occasional anomalous readings
• Detects the largest signal return in the field of view; uses full dynamic range and selects the next largest target when appropriate
• Analog envelope output for troubleshooting and custom signal processing
Environmental, compliance, reliability
• Operating temperature: –40 °C to +65 °C (–40 °F to +149 °F)
• Weather resistant IP67; optional chemical-resistant F-Option
• RoHS compliant
Mechanical / mounting
• Connection end fits standard PVC pipe fittings: 3/4″ National Pipe Thread Straight (NPS)
• Horn opening fits standard PVC pipe fittings: 2″ National Pipe Thread Straight (NPS)
• Lightweight module; designed for easy integration
Why MB7851 for tank level?
MB7851 is a weather-resistant, non-contact ultrasonic tank-level sensor designed for stable liquid level measurement in process tanks, reservoirs, barrels, and bins. It helps minimize the influence of internal structures for more consistent readings.
Key operating details
Provides 1 mm resolution, a ~2 Hz read rate, and a 5 m maximum range. For very close targets, a 50 mm reporting floor is applied (objects closer than 50 mm are returned as 50 mm) for predictable near-field behavior.
Integration options (select one by wiring)
• Serial — RS232 or TTL
• Scaled analog voltage
• Analog voltage envelope (real-time signal profile)
• Optional 4–20 mA A purchase-time configuration is available for 4–20 mA output. This option replaces the standard serial/analog modes and requires a 9–36 VDC supply.
Power
Standard operation: 3.0–5.5 VDC. Optional 4–20 mA configuration: 9–36 VDC.
Responsiveness & best-fit use cases
With a ~2 Hz read rate and typical filtering, MB7851 is ideal for applications with reaction times of ~3 seconds or longer and for periodic monitoring (e.g., polling every few seconds to minutes). It is not intended for high-speed closed-loop control of fast-changing surfaces.
Teach & calibration tools
When wired for serial, a “teach” feature lets the sensor learn what an empty container looks like, improving performance in vessels with internal features. Each unit is factory calibrated for consistent beam patterns and dependable detection zones.
Stable readings in noisy environments
To maintain low-noise distance data around acoustic or electrical interference, MB7851 combines high-output acoustic power, continuously variable gain, waveform signature analysis, and advanced noise-rejection algorithms.
Installation tips
Mount with a clear path to the liquid surface. Avoid aiming directly at sidewalls, fittings, or ladders. For best results, provide a short stilling area or aim at the quietest region of the tank surface.
Implementation Guide
Typical applications
Industrial tank level monitoring • water and wastewater reservoirs • chemical totes and IBCs • process tanks • farm and utility tanks.
TankSensor CAD Files
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