Troxler 3430-M, Manual Of Operation And Instruction

Page: 54 / 142

4-6
TRENCH OFFSETS
If the Model 3430 gauge is to be used for moisture or density
measurements in a trench or within two feet (0.6 m) of a large
vertical structure, a trench offset may be required. If used, the trench
offset adjusts all moisture measurements but only the density
measurements from backscatter through four inches (10 cm).
To perform a trench offset:
✓
Take the daily standard count (outside the trench) and record the
density count (
DS ) and moisture count ( MS )values.
✓
Place the gauge on the reference standard block in the trench the
same distance from the wall as the anticipated readings.
Do not
take another standard count.
✓
Set the count time to four minutes.
✓
With the source rod in the SAFE (standard count) position, take
a four-minute count. To start the count, press the
〈
START/ENTER
〉
key.
✓
Record the trench density count ( DC
Trench
) and moisture count
( MC
Trench
.).
✓
Subtract the daily standard count values from the trench count
values:
Dens Const = (DC
Trench
) – DS
Moist Const = (MC
Trench
) – MS
To enable a trench offset, choose Trench from the Offset options
under the Special functions. The gauge requests the Dens Const and
Moist Const values determined above. The procedure for entering
the values is the same as for moisture and density offsets, ignoring
the
±
sign on the display.