|
|
|
|
|
|
|
|
|
|
|
|
In recent CSIRO field trials at Walla Walla
in New South Wales and Warwick in
Queensland, the Dräger X-am 7000 was
used to monitor fumigant gas concentrations
during an experimental fumigation in sealed,
welded-steel grain silos. The X-am 7000
multigas detector is designed for
applications where reliable monitoring of
oxygen, toxic and combustible gases and
vapours in air is necessary, and has common
use in monitoring entry to confined or
closed spaces. |
|
|
|
|
|
Greg Dojchinov (CSIRO Entomology) organised
and supervised the fumigation trials
at both sites. These trials were the first
time that Vapormate™, a new cylindered
formulation of ethyl formate in carbon dioxide,
had been evaluated in farm type silos
using a fan-forced distribution system.
Vapormate™ is the product developed by
BOC Limited following several years of
close collaboration with CSIRO. Peter Richards and George Opasinis (Dräger
Australia) joined Greg at the trial in New
South Wales to check on the performance
of the Dräger X-am 7000 and observe the
overall fumigation process.
During the fumigation it was important to
obtain a reliable measure of both ethyl formate
vapour and carbon dioxide gas levels.
To be an effective treatment, Vapormate™
needs to be rapidly and uniformly distributed
throughout the grain. Determining the
success of the fan-forced delivery system to distribute the fumigant evenly throughout
the grain silo was therefore a very important
part of the trial work. Normally, two measuring
devices would be needed to determine
accurate gas levels, which can be a cumbersome
and slow process. The Dräger X-am
7000 provided the versatility to continuously
measure both gases, simultaneously.
Gas samples from the grain silo were drawn
via sampling lines positioned at different depths and locations within the silo. The
fumigant was drawn down from the silo
using a small vacuum pump and then
across the two infra-red sensors of the
X-am 7000 using the internal pump fitted
to the instrument. One sensor was calibrated
for carbon dioxide, the other for
propane. A laboratory determined calibration
curve for converting propane response of
the X-am 7000 to ethyl formate concentration
was used to convert propane readings
to ethyl formate in the field. |
|
|
|
|
|
Ethyl formate concentrations measured
during the trials ranged from 10 to 120 milligram
per litre, and concentrations of carbon
dioxide in air ranged up to 30 percent. The
versatility of Dräger X-am 7000 to continuously
monitor gas levels in a stored grain
environment is likely to lead to its greater
use in an industry that is striving for safe and
effective fumigation monitoring procedures. |
|
|
|
|
|
It is often the case with new grain fumigants
that the development of technologies used
for rapid and accurate measurement follows
the commercialisation of the gas. However,
the X-am 7000 precedes the arrival of the
new Vapormate™ formulation, and this has
immediate benefits to the future use of the
gas for pest control in the Australian grain
and horticultural industries |
|
|
|
|
|
Greg Dojchinov
Investigative Scientist
CSIRO Entomology
|
|
|
|
|
|
|
|
|
|
|
|
|
|
 |
|
|
|
|
|
Dräger Safety AG & Co. KGaA |
|
|
Revalstrasse 1 |
|
|
23560 Luebeck, Germany |
|
|
|
Tel +49 451 882 0
Fax +49 451 882 2080
|
|
|
|
