UGT suction probe S30 / S31 / S32 with ceramic tip, acrylic glass standpipe, valves and joint vacuum and sampling line

The S30 to S32 suction probes are equipped with an acrylic glass standpipe that is up to 200 cm long depending on the model. The ceramic tip (P80; Ø20 x 50 mm) is glued directly to the standpipe. The standpipe has a dual function: it facilitates the installation of the suction probe and at the same time serves as a storage volume (shaft collection) for the extracted soil solution. This makes additional sampling vessels unnecessary in many cases. However, such vessels can be connected if necessary. The storage of the sample in the standpipe keeps it largely at soil temperature.

A joint vacuum and sampling line runs inside the standpipe, which is used both to apply the vacuum and to extract the soil water. At the upper end of the standpipe is the suction probe head with two valves: one for the vacuum and sampling line and one for ventilation. Both valves can be opened and closed independently of each other using stopcocks.

The hoses and hose connections used are made of inert PE, which prevents any contamination of the samples. The well-thought-out design of the suction probe allows for autonomous operation, but does not prevent percolate from being sucked back into the soil during dry periods.

How it works

In the initial state, both valves on the suction probe head are closed. To take a sample, the valve of the vacuum and sampling line is opened first. This vents the standpipe and creates a vacuum that draws the soil water through the ceramic tip into the storage volume of the standpipe. Since the ceramic tip is only glued to the standpipe, the percolate can pass back through the ceramic tip into the soil if there is no vacuum.

After closing the valve at the joint vacuum and sampling connection, the vacuum is maintained and gradually decreases as soil water flows in. Further water inflow is not possible if the storage volume of the standpipe is completely filled.

The stored soil solution can be extracted through the joint vacuum and sampling line. After opening the joint vacuum and sampling valve, the venting valve is also opened to allow air to flow in and ensure the free flow of the sample. After the extraction is complete, both valves are closed again.

The process is repeated in the same way for a new sampling.

The suction probe is suitable for operation with a permanently constant vacuum in combination with a suction probe system, as well as for a single application of vacuum. Thanks to the standardized hose connections, the suction probe is compatible with all common hand pumps, electronic pumps and vacuum control units.

Use of a groove auger during installation

For optimal installation of the suction probe in the soil, we recommend using a suitable groove auger. This tool is used to pre-drill a hole with a diameter that is slightly smaller than that of the suction probe. A diameter that is too large can favor preferential flow paths along the suction probe, causing additional water to be directed to the suction cup. This could falsify the measurement results. The appropriate pre-drill not only makes installation easier, but also ensures a proper connection between the suction probe and the surrounding soil, which ensures precise sampling.

Further general information can be found at suction probe.