LP/p - Soil Capillary Pressure Laboratory Probe

LP/p is a laboratory miniprobe designed for monitoring instantaneous profiles of soil water capillary pressure (matric potential, suction force) in soil columns or in undisturbed soil cores sampled with standard sampling equipment. LP/p is pushed into the soil core and fixed with a clamp nut. Several LP/p probes can be inserted through the wall of a soil column or a steel sampling cylinder, thus allowing for vertical scanning of the instantaneous water potential profiles. Such an array, when combined with similarly installed miniprobes for soil moisture (LP/ms probes), enables collecting a set of corresponding water content and matric potential data from drying or wetting front transition. From the collected data set, after further processing, one can obtain a complete set of the unsaturated water flow characteristics of the soil, that is: water retention (PF-curve), unsaturated water conductivity (k-function), differential water capacity and unsaturated water diffusivity.
Features:
  • Operates with a TDR/MUX/mpts unit.
  • Relative error: ±15%. 
  • Resolution: 1 mbar.
  • Offset drift: ±20 mbar/month.
  • Delay: 0 to 800 mbar in about 120 s, 800 to 0 mbar in about 3 s.
  • Available custom cable lenghts.
  • Up to eight LP/p probes can be connected to one TDR/MUX/mpts device at the same time with the use of BNC T-splitters.
Technical characteristics:
  • Pressure diaphragm: a ceramic cup 15 mm long with 3 mm in diameter. 
  • Air-entry pressure: about 900 mbar.
  • Replaceable ceramic cup element.
  • Pressure transducer: an integrated, fully active Wheatstone bridge with four piezoresistive strain gauge resistors diffused into a silicon diaphragm.
  • Available probe clamps for securing the probe in a sample cylinder.
See also:
  • TDR/MUX/mpts laboratory meter.
  • Laboratory probes for soil moisture and salinity: LP/ms and for temperature: LP/t.