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delicate and the filter media should never be
touched.
Proven efficiency of all HEPA filters used in
Baker cabinets is 99.99% for particles 0.3 microns
iJl diameter. The 0.3 micron particle is used as the
basis for filter definition because theoretical
studies have shown that filtration efficiency
should be at a minimum for particles of this
diameter, with efficiency increasing for particles
either larger or smaller. (Model SG400ULT comes
with ULP A, Ultra Low Penetration Air, filters
which have a proven efficiency of 99.999% for
particles 0.12 microns in diameter.) Experiments
with various viruses and microbial agents have
proven the effectiveness of HEPA (and ULP A)
filters. Contact Baker for more information.
It must be pointed out that HEPA (and liLPA)
filters are
not
intended to filter gasses or vapors.
Since most Baker cabinets are partially
recirculating, there will be gaseous bttildup to the
point of equilibrium. Before any chemicals are
used in the cabinet it is necessary to consider
these points:
,
1.
2.
Are these chemicals, either singly or in
combination, able to attack filter components?
Are these chemicals potentially toxic to the
operator? Is there any combination of two or
more which could be toxic? If the cabinet is
being used correctly and only the operator's
hands and arms are inside the work area,
then toxicity or irritation could occur through
skin penetration. A proper evaluation of
toxicity must deal not only with onetime
exposure, but also with the effect of many
small exposures over a period of time.
3.
Are these cllemicals explosive or flammable?
If
so, they should never be used in your
cabinet. With a buildup caused bv
recircHlation of air, an explosion can be the
result of a motor spark or a burner operating
in the 1Nork area.
In cases vvhere dternical carcinogens! mutagens
or teratogens are to be used, the risks should be
carefulJv \veis;hed in choosing a cabinet \Vhere
the exh:1lJSt effluent
contains~
contaminant it
may need treatment.
18
The life of a filter is determined by how it is
used and how often. Under normal laboratory
conditions, you can expect at least five years ~f
use. However, misuse or a heavy dust load
within the cabinet will shorten
any
filter's lifefime.
Bunsen burners and misuse of chemicals will also
shorten the useful life.
Operating procedures
After many years of seeing our equipment used
and misused, we have made up this list of
suggestions:
•
•
•
•
Store equipment and supplies outside of the
cabinet.
Always tum on the blower.
Set the view screen at the proper height.
When possible, use pipetting aids.
•
Avoid use of zm open flame within the
cabinet unless the use has been specifically
approved by a safety professional.
•
•
•
•
•
•
Always keep the air intake grills clear and
unobstructed.
Only use toxic, explosive or flammable
substances if a safety professional has
approved them for work in your cabinet.
The control system will adjust automatically
for small changes in the load on the blower:
Adjustments for larger changes should only
be made by a qualified technician. Don't
change the cabinet or blower speed unless the
change is required by a decrease in measured
air velocity.
1,Alu,..,.,..'k-
~"~tih ,..,..,..,1~,
1"""'- ,...,.,..
Trln..-io-r::'l-!-a_r-icl. ::'lcre>nh::.
•
J..~,
¥> J.
I
\ • .JJ.UJ
<V>>
V..l
.L.LOV,_._.._..._U<...._,
...__,_,_..._,_-.
'-e>'--'-L~~
in this cabinet.
Always close the drain valve after each use .
1f the tmit presents a warning signal, don't
operate the unit until the warn'""lg ceases.
If
b'1e operators are well trained and use good
common sense 'ivhen operating your cabinet, you
should have very
fe'l>"
problems.
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