A comparative study of high capacity tensiometer designs

Towards the development on new high capacity tensiometers capable of measuring soil matric suction beyond 3 MPa

“…However, as it has been reported by Tarantino and Mongioví (2001), HCTs with this type of ceramic filter are able to measure soil suction well beyond their measuring range where they report measuring suction values in soil specimens in the range of 2.6 MPa. This is in line with observations by Ridley and Burland (1994) and Mendes et al (2020) where HCTs assembled with similar ceramics were able to sustain pressures beyond 2 MPa. This discrepancy in relation to the measuring range in HCTs is not yet fully understood, but it seems that the actual AEV in this type of ceramics varies greatly and inconsistently for each individual ceramic filter and between the nominal value of 1.5 MPa and 2 MPa.…”

“…In the N-HCT design, the ceramic filter used in the assembly was a 10 mm in diameter by 5 mm in height >99.9% alumina ceramic filter with the largest pore size diameter of 75-92 nm (see Figure 3) determined by mercury intrusion porosimetry (MIP) using a Micromeritrics AutoPore IV device. This is about 2 times smaller to the largest pore size diameter of 165 -220 nm (see Figure 3) in the 1.5 MPa AEV ceramic filter (Mendes et al, 2020) commonly used in most HCT designs. A rough estimation of about 3.5 MPa for the AEV of the new ceramic filter was obtained using Young-Laplace equation (Equation 1).…”

“…Since the development of the IC-HCT, various similar HCT designs have emerged from different research groups around the world (Guan and Fredlund, 1997;Meilani et al 2002;Take and Bolton 2003;Lourenco et al, 2008;Cui et al, 2008;Mendes and Buzzi 2014;Bagheri et al, 2018;Jacobsz, 2018;Mendes et al, 2020). Bespoke, or commercially available pressure transducers and the same ceramic filter with an AEV of 1.5 MPa as in the IC-HCT was used in these subsequent HCT designs.…”

Cross-validation of the high-capacity tensiometer and thermocouple psychrometer for continuous monitoring of xylem water potential in saplings

“…The volume of the water reservoir is generally maintained very small (4 mm3) as Ridley and Burland (1993) assumed its small size was key to enable sustained measurement of water tension. However, Mendes et al (2020) have demonstrated that the volume of the reservoir does not play a critical role as generally assumed in the literature.…”

“…The volume of the water reservoir is generally kept very small (~4 mm 3 ), as Ridley and Burland (1993) assumed that its small size was key to enable the sustained measurement of water tension. However, Mendes et al (2020) have demonstrated that the volume of the reservoir does not play a critical role as generally assumed in the literature. The maximum sustainable duration of the measurement can be augmented by imposing cycles of cavitation and resaturation at high water pressure to ‘extract’ cavitation nuclei that remain undissolved upon simple pressurization ( Tarantino and Mongioví, 2001 ).…”