The MTN02 - Multi-purpose Thermal Needle System allows fast measurements of the thermal resistivity or conductivity of soils. It is specifically designed to be robust, as well as accurate. It is therefore, for laboratory as well as field measurements of soil thermal properties. The sensor is a Non-Steady-State Probe (NSSP), TP07, which is mounted on the Insertion Tool, IT03. The system is operated using a hand-held Control and Readout Unit CRU02.
Suitability for laboratory measurements:
MTN’s primary focus has been on the capability to perform laboratory measurements. The needle of TP07 is relatively thin, so that common samples can be used. The IT03 can be mounted on the levers that are commonly used in machine shops so that the needle can be vertically inserted into the sample.
Suitability for field measurements:
MTN02’s can, provided that soils are relatively soft, also be used for field measurements. In case of harder soils or measurements at greater depths (up to 1.5m) the use of stronger needles (like TP09) and a lance (like in the system FTN01) is recommended. MTN02 is able to perform measurements without external power source. The system is sufficiently robust to survive manual insertion into most common soils. The system runs as a stand-alone unit, powered by the batteries in the CRU. Recharging can be done by a 12VDC source or a car battery using the CA01 car adapter, or on 220/110 VAC using the WSA01 wall socket adapter.
CRU02 automatically processes the measurement data, and gives both an end-result and a quality indication of the measurement. CRU02 can archive 50 measurements. In case of review, the end result is preferably checked and recalculated by analysis of the measured data in a spreadsheet (like Excel) or a mathematical program.
Verification of the stability of the total system can be done by repeated testing in glycerol. This test can also be performed in the field.