Hyprop Tensiometer Shafts Application User Guide

September 26, 2024
METER

Hyprop Tensiometer Shafts Application

Product Information

Specifications

  • Manufacturer: METER Group, Inc.
  • Model: Hyprop Tensiometer Shafts
  • Available Ceramic Types: 8.8-bars and 5-bars
  • Color Options: Black (8.8-bars ceramic) and Blue (5-bars ceramic)
  • Software Compatibility: LABROS SoilView-Analysis
  • Software Version Requirement: 5.3.0 or higher

Product Usage Instructions

Introduction
The Hyprop Tensiometer Shafts are designed to measure soil tension with the option to utilize the air-entry value of the ceramic tensiometer cup for extended measurements.

Differentiation
There are two types of tensiometer shafts based on the air entry point of the ceramics:

  • 8.8-bars ceramic (Black color)
  • 5-bars ceramic (Blue color)

Settings in LABROS SoilView-Analysis Software for Power User
Power Users can manually adjust the Air entry point value to 5 bars in the Information tab.

Settings in LABROS SoilView-Analysis Software for Public User
Public Users can select the Air entry point value from a drop-down menu available in software version 5.3.0 and above.

Consequences for the Results and Potential Error
Incorrect selection of the air entry point value may lead to inaccurate tension measurements, impacting the results obtained.

FAQ

  • Q: How can I determine the correct air entry point for my Hyprop Tensiometer Shaft?
    A: Power Users can manually set the value to 5 bars, while Public Users can select it from the drop-down menu in the LABROS SoilView-Analysis software.

  • Q: What are the color options for the Hyprop Tensiometer Shafts?
    A: Shafts with a black color have an air entry point of 8.8 bars, and those with a blue color have an air entry point of 5 bars.

INTRODUCTION

Using the air-entry value of the ceramic tensiometer cup as an additional measurement point can extend the range of the tensiometric measurements (Schindler et al., 2010b). The LABROS SoilView-Analysis includes this option for Power Users. The air-entry point occurs when the pressure of the tensions drops quickly to zero. This option is only viable if the sharp drop towards zero tension is recorded, i.e. if the measurement campaign was performed long enough to capture this data. Clicking on the Use Air Entry Point button adds an extra measurement point for each tensiometer that has reached the point where air passes the tensiometer cup. At that point in time a tension that is specified in the Information register as HYPROP Parameters is used to measure tension of the respective tensiometer (see Figure 3 below).

When the Use Air Entry Point option is active, dashed lines are shown that interpolate the tensiometric data between the last reliably measured points (stop point) and the air entry points of both tensiometers.

DIFFERENTIATION

There are two kinds of tensiometer shafts that differ in the air entry point of the ceramics: 8.8-bars ceramic (Figure 1A) and 5-bars ceramic (Figure 1B). Shafts with a black color have an air entry point of 8.8 bars (Figure 1A) Shafts with a blue color have an air entry point of 5 bars (Figure 1B).

SETTINGS IN LABROS SOILVIEW

ANALYSIS SOFTWARE FOR POWER USER
For evaluation, the correct Air entry point of the used tensiometer shaft must be selected in the Information tab. There are two ways to adapt the Air entry point value. The first option is to change the user mode to Power User (see Figure 2) and adapt the value manually to 5 bars (see Figure 3).

ANALYSIS SOFTWARE FOR PUBLIC USER
The second option is to select the Air entry point value with the offered drop-down menu (see Figure 4) in Public User mode. This drop-down menu is available from software version 5.3.0 upwards. LABROS SoilViewAnalysis can be downloaded here.

The displayed default value can be defined in the Settings menu. Access the Settings menu by clicking the green gear in the upper right corner of the LABROS SoilView-Analysis software window.

CONSEQUENCES FOR THE RESULTS AND POTENTIAL ERROR

Using a 5-bars ceramic, the measurement duration is shorter as the air entry point is reached faster. This causes a smaller measurement range. The time for refilling and degassing the 5-bar tensiometer shaft is approximately 20 % shorter than the 8.8-bar tensiometer shaft.
NOTE: Verify that the correct air entry point is selected for type of tensiometer shaft used. Selecting the wrong value will cause an error of +/- 3.8 bar at this base point. Interpolating further, e.g. up to the permanent wilting point of 15 bar, the error may be even higher.

REFERENCES
Schindler, U., W. Durner, G. von Unold, and L. Muller. “Evaporation Method for Measuring Unsaturated Hydraulic

METER Group, Inc.
2365 NE Hopkins Court, Pullman, WA 99163
T: +1.509.332.2756 F +1.509.332.5158
E: info@metergroup.com
W: metergroup.com

References

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