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 content by simply inserting the probe, connected to an HH2 portable instant readout meter or data logger, into soil.
Image Credit: Delta-T Devices Ltd
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-1 and it boasts a broad operating temperature range—tests have shown that the ML3 can 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
Image Credit: Delta-T Devices Ltd
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 beneficial testing 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.
Image Credit: Delta-T Devices Ltd
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.