Vaisala DM70 - Manual (Page 64)

USER'S GUIDE____________________________________________________________________
0405-011
Figure 29 Gas Collection Option
The following numbers refer to Figure 29 above.
1 = Gas from GIE
2 = Gas to the collecting system
Operating Environment
A typical dewpoint of pure SF
6
is usually around -60 °C. The
recommendations for the moisture limit of the equipment insulated
with gas (GIE) vary between
70 ... 810 ppm
v
, which corresponds to -45 ... -22 °C T
d/f
in the
atmospheric pressure, or -29 ... -3 °C T
d/f
in 5 bar
g
pressure. DM70 is
able to measure the dewpoint directly in the GIE pressure (usually 3 ...
8 bar
g
), or the gas can be sampled and measured in the atmospheric
pressure. If there is a need to measure high-pressure gas (>10 bar), for
example in the recycling bottle, a regulator should be used to drop the
pressure before the measurement.
High-voltage equipment can locate either indoors or outdoors. The
operational temperature range of DM70 is between -10 ... +60 °C.
Measuring
CAUTION Before measuring moisture, make sure that hydrofluoric (HF) acid is
not present in the GIE.
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