PAHSC コンピューター制御土壌水分吸引砂装置




The Computer Controlled Soil Moisture Suction Sand Unit "PAHSC" has been designed to study and understand the water retentivity principles in terms of soil suction, the relationship between water retentivity and soil and the derivation of soil moisture characteristic curves.

The unit is large enough to permit the simultaneous evaluation of several samples and consists of a suction system and a soils container:

  • Suction system: It consists of a water circuit that includes a water tank, a computer controlled pump, a water jet pump, a pressure sensor and a flow sensor. The pump propels water from the water tank and circulates through the water jet pump, which sucks the water of the soils container.
  • Soils container: It consists of a cylindrical tank filled with saturated sand (not supplied) that contains three soil sample retaining rings. Inside of the sand the soil samples are placed as well as the water volume sensors. A cover is provided to prevent evaporative water loss during the practical exercises and several filters avoid sand transport to the water tank. The soils container includes a pressure sensor and an air inlet (pressure inlet) to study of the effect of the atmospheric pressure.

Soil samples placed on the sand are subjected to suction. This suction is applied by means of the water jet pump and the water pump. In order to maintain the suction, a volume water supply is required.



  1. Understanding of the relationship between water retentivity and soil.
  2. Understanding of the basic principles of water retentivity in terms of soil suction.
  3. Study of the effect of the atmospheric pressure.
  4. Determination of the retentivity of different soil samples.


  1. Sensors calibration.
  2. Derivation of the soil moisture characteristic curves for several soils.

Other possibilities to be done with this Unit:

  1. Many students view results simultaneously. To view all results in real time in the classroom by means of a projector or an electronic whiteboard.
  2. Open Control, Multicontrol and Real Time Control. This unit allows intrinsically and/or extrinsically to change the span, gains, proportional, integral, derivative parameters, etc, in real time.
  3. The Computer Control System with SCADA allows a real industrial simulation.
  4. This unit is totally safe as uses mechanical, electrical/electronic, and software safety devices.
  5. This unit can be used for doing applied research.
  6. This unit can be used for giving training courses to Industries even to other Technical Education Institutions.
  7. Control of the PAHSC unit process through the control interface box without the computer.
  8. Visualization of all the sensors values used in the PAHSC unit process.
  9. By using PLC-PI additional 19 more exercises can be done.
  10. Several other exercises can be done and designed by the user.