8
Introduction
SWT4 User Manual v3.1
1.7 Quick Start
This section does not replace the rest of the user manual. It is only a
summary. Please read the complete manual carefully before using the
instrument, particularly Chapter 3 and 5!
1.
Drilling
the borehole
Mark the required drilling depth both on auger
and
on Tensiometer
shaft. Note: Installation depth = drilling depth / cos .
For SWT4R: For installation from the soil surface, an installation angle
of 25° to 65° from the vertical line is ideal for the optimal removal of air
from the cup (Fig. 1
a). For “horizontal” installation from a manhole the
borehole should point upwards in an angle of 5° (Fig. 1b).
2.
Slurrying
the cup is only reasonable in clayey soils and only if the
bore hole is larger than the ceramic cup (24 mm). In coarse sand or
pebbly soils, a fine-pored slurry might create a water reservoir which
slows down the response. With the special Tensiometer gouge auger
type
SWT4-AUG
slurrying is unnecessary because of the accurate fit
of the Tensiometer into the hole.
3.
Take off
the protective plastic bottle from the Tensiometer cup. Tilt
and pull the bottle off carefully. If necessary, carefully turn it counter-
clockwise only! (as marked on the bottle)
Turn the bottle counter-clockwise only when you remove the bottle
but also when you reassemble the bottle (see arrow on bottle
label).
4.
Insert
the SWT4 or SWT4R into the hole to the depth mark with
constant gentle pressure and without using force.
In clayey soils a dangerous overpressure might develop. So
monitor the Tensiometers pressure with a type SWT-MR
(INFIELD7) Manual Readout Unit or a data logger.
Do not exceed -2 bar ( -200 kPa, -2000 hPa) during insertion.
Do not turn the Tensiometer after it is inserted into the ground -
this might loosen the cup.
