Unmatched Accuracy in Soil Moisture Monitoring with ML3 ThetaProbe

Few sensors can compete with the ML3 ThetaProbe sensor for soil moisture research where absolute precision is needed.

Its ±1% accuracy, build quality, reliability, and stability have made it the go-to option for thousands of scientific researchers worldwide for over a decade.

The ML3 is a user-friendly, robust solution. In just a few seconds, users can precisely measure the soil's moisture contentby simply inserting the probe, connected to an HH2 portable instant readout meter or data logger, into soil.

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The ML3 has a built-in thermistor that allows it to measure soil temperature while the probe is buried.

Its salinity response has been identified at EC values as high as 2000 mS.m^-1and it boasts a broad operating temperature range—tests have shown that the ML3can function at –40 °C (non-flexing cables).

The ML3’s Rigorous Testing Regime

Environmental testing regimes include:

Ultraviolet exposure

Solar gain testing

Water vapor diffusion testing

Ice heave

Cable fatigue

Submergence (4 m)

Hot water leak testing

Thermal shock testing

Drop testing

Thermal cycling

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EMC testing involves:

Surge testing

Electrostatic discharge

Fast transient electrical testing

Miscellaneous testing involves:

Usability testing

Field trials

Calibration traceability

Highly Accelerated Life Testing (HALT) the ML3 Sensor

HALT is a highly beneficialtesting technique used across the soil sensor range.

It is a method of effectively simulating rigorous use over time by subjecting an instrument to sustained high temperatures for a short period of time.

This type of testing not only assesses an instrument's longevity and consistent accuracy, but also demonstrates its ability to function beyond its stated specifications.

ML3 ThetaProbes have undergone 149 days of HALT testing at 90 °C, which is comparable to 10 years of use at 30 °C.

Following electrical testing, all ML3s were still calibrated and operating flawlessly. The picture below shows that the only indication of degradation was label discoloration.

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Delta-T Devices develops products for field use to exceed all relevant IP standards.

All of Delta-T’s scientific instruments go through the rigorous testing described above and receive attentive, ongoing after-sales technical support.