Suction probes are used for the non-destructive removal of soil water from the pore system of the soil. The essential part of the suction probe is the porous suction cup that has to be brought into direct contact with the surrounding soil to remove water from the pore system. By applying a vacuum, the water is sucked from the surrounding soil through the pores of the cup into the interior of the suction probe and then into a sample vessel. As long as the pores of the porous cup are water filled, they are airtight and thus only water can be transported via the pores.
Since some groups of substances of the soil solution are prone to adsorption on certain materials, the choice of a suitable material of the porous candle is of immense importance for authentic examination results. Porous ceramic cups are usually more favorable and are suitable for the investigation of poorly adsorbing substances such as chloride, sodium, sulfate or nitrates. Other materials such as glass (sintered glass) and plastic (nylon membrane, sintered plastic) may also be considered for these materials. Glass cups, on the other hand, should be used in the investigation of substances with strong adsorption properties. These include organic substances (DOC), phosphates and pesticides. For examining heavy metals in the soil solution, however, plastic cups should be used.
Suction probes are available in various designs. Depending on the type of application and installation option, the design of the suction cup is defined by the user. The installation depth and accessibility of the installation point play a central role when selecting the type of construction. When selecting the right type, you can choose between a suction cup with a shaft or without a shaft. In the case of suction cups with a shaft, the option of a storage volume integrated into the shaft for the removed soil solution can also be considered.
Cups with shafts facilitate the installation of the probe at greater depths if the application of a trench for installation or a destruction of the soil material during the final removal of the probe is undesirable. The possibility of storage within the shaft should be taken into account when storage of the sample is desired under ambient conditions (temperature and light), or the depth of installation is so high that it is not possible to apply a suitable vacuum to extract and transport the water to the soil surface at the same time.
In addition to the suction probes, UGT offers a broad range of suction probe technologies for a trouble-free measurement campaign. This includes technologies to apply a vacuum to extract the water from the soil pore system and to transport the water to the soil surface. To conduct special investigation plans, the vacuum technology can be supplemented by a control system.Various methods for collecting, storing and transporting samples are also offered.