Laboratory apparatus to determine the particle size distribution in mineral soils in accordance with DIN ISO 11277 using 12 samples with 4 fractions (optionally 2 fractions according to the US nomenclature)
The determination of the particle size distribution is fundamental for natural science as well as engineering. The composition of the fine soil defines the predominant soil type. Measuring apparatus and method are based on the German DIN ISO 11277 and thus, the Sedimat is the only automatic measuring device providing comparable measurement results according to the standardized Köhn analysis.
Before the actual measurement starts the sand fraction must be determined by sieving of coarse, medium and fine sand. The remaining soil sample is now homogenized and organic substances are separated.
The sedimat determines four remaining fractions: coarse silt, medium silt, fine silt and clay. Due to the different sizes and shapes the individual soil particles have different sedimentation rates in a water column. By means of pipetting the fractions are now separated. The Köhn analysis defines setting times as well as setting depth in the suspension to take the defined sample volumes. Subsequently the samples are dried and weighed. Using the four mass fractions determined by sedimentation together with the sand fractions it is possible to define the grain-size distribution curve as well as the soil type.
Compared to the manual analysis the sedimat guarantees preciseness for each measuring process in adjustment of depth as well as extraction volume. This applies also to other measuring conditions such as temperature (25 °C). Thus, statistically verified results are guaranteed. With respect to the weighed samples the variation of the measurement results based on repeating the test with the same samples is < 1 %.
The sedimat operates fully automatically. Since the work is reduced to the test preparation and the evaluation of the results, a complete Köhn analysis on 12 samples lasts only one day.
Using the ku-pF-Apparatus the automatic determination of the unsaturated hydraulic conductivity and Retention curve on up to 10 soil samples is possible. Retention curve and unsaturated hydraulic conductivity are decisive parameters in soil science. They describe for instance the water holding capacity and the drainage ability of soils. The user gets important information which plants and trees are more resistant to changed climatic conditions etc.
By means of the UGT soil sample rings with 250 cm3 volume soil samples are taken undisturbed in the field. Having the samples saturated in the laboratory the total weight is determined gravimetrically. Subsequently from the side 2 Tensiometers (see below: Tensio 130 – lab tensiometer for ku-pF) are installed in a vertical distance of 3 cm. Finally, having put the soil samples into the sample holders they are mounted on a star-shaped carrier.
By natural evaporation the soil constantly loses weight and the tension inside the soil samples increases. By weighing the ku-pF Apparatus step by step determines the weight loss of each sample. Simultaneous the Tensiometers measure the increase of the tension as well as the gradient.
Due to the automatic measuring system the necessary working time is minimized. By means of the integrated data logger and microcomputer the ku-pF runs independently. The user will need a computer merely for configuration, measurement start and data export.
Hood permeameter according to HARTGE
The hood permeameter by Hartge is a laboratory meassurement instrument for the determination of the saturated conductivity using undisturbed soil samples. The saturated conductivity is an important parameter in soil physics, hydrology, agriculture, forestry, civil engineering etc. It describes the propagation behaviour of water in a soil where the pores are saturated with water.
The water movement is physically characterized by the law of Darcy. Besides the saturated conductivity the volumetric flow rate also depends on the potential gradient (pressure gradient between two points) in the soil. Determining the conductivity in laboratury often high pressure gradients are applied. The soil scientist Prof. Dr. Karl-Heinrich Hartge (former president of the International Soil Association) pointed out that high pressure differences are rarely be found in natural soils. Thus, it is more plausible to measure with small potential gradients.
The hood permeameter of the UGT meets this requirements. The device makes it possible to easily adjust an appropriate pressure gradient in order to determine the flow rate. Using the Darcy-law the saturated conductivity can be calculated.
Up to 10 sample rings are placed on a sieve plate inside the spacious tub, gradually saturated and finally covered completely with water. The measuring is performed by means of a water filled hood which is step by step placed over the soil sample rings. At the top of the soil sample the pressure gradient is applied and the water flow through the soil starts. For stationary flow conditions the discharge is determined gravimetrically. The geome try of the sample ring define flow area and length. By means of the standpipes the potential gradient is shown as height diffenrence.
The hood permeameter by Hartge and the used sample rings are fully compatible with the ku-pF-Apparatus. Thus, the soil samples after determining the saturated conductivity may be directly taken to measure the unsaturated conductivity using the ku-pF.
The lab lysimeter is a small-sized lysimeter. It was designed to investigate natural soil processes under defined and controlled conditions (temperature, air humidity, light etc.) in the laboratory. The lysimeter vessel encloses a soil column weather excavated undisturbed in the field or filled by hand in the lab. Using appropriate measuring devices (Tensiometers, soil moisture sensors, temperature sensor, suction probes etc.) it is possible to analyze the physical processes driving the water balance. Lab lysimeters can also be used to investigate conservative or reactive transport.
The lab provides many possibilities to control boundary conditions. A special rainmaker for lab lysimeters simulates rain events. The natural process of evaporation is measured by weighing. Seepage water is collected at the vessel bottom. By means of suction probes, suction plates and tension control the internal water balance may be changed. Thus, the processes are accelerated resulting in shorter test times.
Collected seepage water as well as soil water solution extracted by suction probes can be analyzed in the laboratory for its various constituents. Each lab lysimeter is specifically customized according to the project by the UGT. This includes measurement technology (balance, weighing monitor, sensors), data logger and additional control units for the boundary conditions.
The air pycnomoter is used to determine the solid and pore volume of undisturbed or disturbed soil samples. The air pycnomoter is primarily suitable for skeletally poor soils such as sands, gravels or plant granules. It is a quick and less expensive method than the use of glass pycnometers. The measurement method is based on the fact that only the solids volume of a soil sample acts gas displacement, while the pore and void volume is filled with gas.
The air pycnometer consists of a measuring chamber and an additional chamber, which presents the additional volume. The known additional volume is filled with compressed air and connected via a shut-off valve to the measuring chamber containing the soil sample. Opening the valve will equalize the pressure within the two volumes. A digital pressure gauge displays the pressure values. In addition to the use of room air, which is fed by an integrated compressor, another measuring gas can optionally be used.
The evaluation of the data is based on the isothermal gas equation according to BOYLE-MARIOTTE. The measuring chamber has a volume of 2120 cm³. Therefore, the examination of different sample volumes is possible with the device.
The air pycnometer was developed in accordance with the guidelines of the FLL (Landscape Development and Landscaping Research Society).
With the overhead shaker, several samples can be homogenized at the same time. Homogeneous mixing of a sample is a prerequisite for many chemical analyzes or for sedimentation analysis according to KÖHN in order to determine the particle size distribution of the fine grain fraction of a soil sample.
The sample containers are securely clamped in the overhead shaker. The speed can be adjusted continuously and is displayed in a digital display. The maximum speed is 50 rotations per minute. The overhead shaker can accommodate 60 sample bottles of 100 ml or 72 sample bottles of 250 ml each.
FOGII Plus Digital Soil Calcimeter™ with UMP-1
The mobile soil calcimeter is suitable for determining the carbonate content of soil samples in the field and in the laboratory. The measurement is based on the Scheibler method. Here, after the addition of hydrochloric acid to the soil sample, the temperature-compensated pressure increase is determined.
The soil calcimeter is also available as a set with the UMP-1
water content probe. By measuring the water content the results can be referred to the dry matter, whereby a drying of the sample in the laboratory is no longer necessary. A big advantage of the soil calcimeter is the ease of use and the robust design, which makes direct measurement in the field possible.
Tensio 130 - laboratory tensiometer for ku-pF-Apparatus
This tensiometer is a pure accessory for the ku-pF-apparatus!
Laboratory tensiometers are used to measure the pressure head of a soil sample under laboratory conditions. Compared to field tensiometers, laboratory tensiometers are significantly smaller and thus provide pinpoint accuracy with minimal disturbance of the soil. The ceramic cup of the laboratory tensiometer is 20 mm long and has a diameter of 6.5 mm. The laboratory tensiometer is therefore ideal for examining the soil on the sample scale.
For a reliable laboratory application, the laboratory tensiometer has a vent screw in the acrylic head with which air bubbles can be quickly detected and removed from the tensiometer. For easy and small-disturbance installation of the tensiometers, a drill set is available as an accessory. The tensiometer can be installed both horizontally and vertically. The sensor head of the laboratory tensiometer is available in both elongated and round versions.