pF pressure step module

Vacuum control

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Vacuum setting to determine water retention curves of soil samples (soil water characteristic curves). Needs external vacuum source.

  • Precise vacuum setting (control accuracy 1 hPa)
  • Adjustable limit values
  • Integrated vacuum reservoir buffers against pressure surges between vacuum source and suction plate
  • Operation via key buttons, permanent display of current vacuum as well as upper and lower limit values
  • Up to 3 pF suction plate modules directly connectable
Vacuum control: Microprocessor, pressure sensor, magnetic valve
Display: 3 separate displays for system pressure, upper and lower limit values
Connection option: 3 suction plate modules via ball valves
Buffer capacity: ca. 7 l
Operating voltage: 12 V DC
Dimensions (L x W x H): 160 mm x 400 mm x 580 x mm
Frequently asked questions about "Soil water retention (pF) curves"

According to the Geological Survey of North Rhine-Westphalia in Krefeld, 3-4 working days are usually sufficient for dewatering of sample rings with a capacity of 100 ccm for samples of medium grain size and pressure levels up to 300 hPa. The equilibrium adjustment is delayed with

a) larger sample volume,
b) increased clay content and
c) higher pressure values

and can then take up to several weeks. At the Institute of Soil Science of the Christian-Albrechts-Universität Kiel, the following drainage periods are observed:

60 hPa 1-2 weeks
150 hPa 2-3 weeks
300 hPa 3-4 weeks
500 hPa 2-4 weeks

The total drainage period is between 10 and 13 weeks.
If you have any further questions about these specifications, we will be happy to put you in touch with the respective contact persons