Typical Applications; Extended Measuring Range Of The Swt5X - Delta-T Devices SWT5 User Manual

1.6.3 Typical applications

Typical applications of the SWT5 and SWT5x:

Point measurements of water potential

Miniature soil column studies, e. g. in combination with micro
water samplers and soil temperature probes

Determination of drying curves of water content vs tension, or
water conductivity vs tension (pF/wc and K/Psi) in soil
columns, soil cores or soil sampling rings

Determination of leachate and capillary water movements

Controlling irrigation

Pot experiments

Measurements in the upper soil horizons in the field

Monitoring with data loggers

Spot readings with the SWT-MR (INFIELD7)
For field applications it might be better to use SWT4 or SWT4R
Tensiometers.

1.6.4 Extended measuring range of the SWT5x

The special version SWT5x is tested to reach a measuring range of
-160 kPa (-1600 hPa) when delivered. To achieve this, the SWT5x
requires an absolutely bubble-free filling.
You might notice that your SWT5x might even go down to -250 kPa
before running empty, sometimes even to -450 kPa, but this is an
exception and cannot be guaranteed.
The SWT5x is identical with the SWT5 but has a different ceramic. The
extended measuring range is made possible by an effect called boiling
retardation, which requires a special ceramic with smaller pores and an
absolutely gas-free filling process.
Do not allow the SWT5x ceramic to dry out by leaving it unprotected
in air: by drying out the tension might reach the destructive pressure.
Due to the finer pores of the ceramic the water conductivity is lower.
Therefore the response of a SWT5x is slower than with a standard
SWT5.
When the shaft is touched it might warm up. This might cause a
temporary change of the pressure.
SWT5 User Manual v2
Introduction  9