SONO VARIO LD Radar Moisture Meter

The SONO VARIO LD is a universal radar moisture meter from IMKO designed for highly accurate measurement of moisture and conductivity in agricultural grain crops (corn, wheat, barley, soybeans) and other low-density bulk solids. It features an adjustable probe (up to 2 m long) for flexible installation in silos, hoppers or conveyors. Using patented 1 GHz TRIME® TDR technology with 1-picosecond resolution, it delivers accuracy of ±0.1 % without recalibration for many grain types. Ideal for continuous inline monitoring in storage and processing.

Operating Principle

The SONO VARIO LD uses patented TRIME® TDR (Time Domain Reflectometry): a 1 GHz electromagnetic pulse is sent along the probe into the material. Water strongly changes the dielectric constant (εr), affecting signal propagation speed and reflection time. The sensor calculates moisture and conductivity from the runtime with 1 ps resolution. An integrated temperature sensor compensates for fluctuations, and averaging modes (up to 10 kHz) ensure stable readings. Optional ultrasonic integration for density measurement is available.

Specifications

• Materials: Housing – high-grade stainless steel V2A (1.4301); probe surface – stainless steel with highly abrasion-resistant special ceramic

• Temperature: 0…+70 °C (standard); up to +120 °C with high-temperature version and external SONO-ES converter (on request)

• Analogue outputs: 2 × 0(4)…20 mA (output 1: moisture 0…20 %, adjustable; output 2: conductivity 0…20 dS/m, optionally temperature or standard deviation; cycles 4…11 mA / 12…20 mA every 5 s); optional 0…10 V DC with 500 Ω resistor

• Power supply: +12…+24 V DC, 3 W (stabilised)

• Protection: IP65 (with MIL connector); gas- and water-tight mounting with SONO-FLANGE

• Interfaces: RS485 (data bus protocol); IMP-Bus (galvanically isolated); optional Profibus/Ethernet via modules

• Dimensions: Standard – 108 × 71 mm (Ø × length); with flange – 150 × 71 mm

• Measurement range: 0 % to saturation (up to 100 % with calibration); conductivity 0…12 dS/m

• Accuracy: ±0.1 %

• Measurement field: 70–100 mm

• Up to 15 material calibration curves (polynomials up to 5th order); integrated temperature sensor (3 mm from surface)

Main Application Areas

Continuous moisture monitoring of grain crops (corn, wheat, barley, soybeans) in silos, hoppers, conveyors and dryers. Perfect for agriculture where precise moisture control is essential for storage, drying and processing. Also suitable for other low-density bulk solids such as wood pellets and animal feed in the food and energy sectors.

Advantages of the SONO VARIO LD Radar Moisture Meter

• Exceptional accuracy (±0.1 %) and 1-picosecond resolution

• No recalibration required for most grains; automatic temperature and density compensation

• Extremely robust – abrasion-resistant ceramic surface, ignores salts and contamination

• Adjustable probe length for flexible installation

• Up to 15 material curves, various averaging modes for dynamic conditions

• Easy integration into industrial networks (RS485, Profibus, etc.)

• Low power consumption, minimal maintenance, long service life even in aggressive environments

• Significantly reduces spoilage and energy costs through precise moisture control