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IV-
ON-SITE
CHECKS AND
MAINTENANCE
PROCEDURES
We
recommend that
the following
checks
be
performed before initial use, after
reloca~ion,
and
after
each
filter
change. They should
also be
carried
out
at
regular
intervals, usually six
months or one
year,
as
specified
by an i.rldustrial
hygienist, safety officer
or
other qualified person.
The tests
described below meet recommended
minimum
requirements.
They
must
be
performed
by an
experienced technic.km using
p roper
procedures and
instruments.
Our
representatives
can
tell you about
other tests
which you may consider desirable.
As
reported earlier
in
this
manual, each
individ-
ual
cabinet made
by
The
Baker
Company is care-
fully
tested
before it leaves
the
factory.
Your
copy
of
the test report,
which you will find a!' the
back
of this manual,
gives
the factory test
results
for
your
own
SteriiGARD~'II
cabinet. Use
it
as your
record
of
the
original
testing, and as
your
guide to
testing in the future.
To gain
many years of satis-
factory
service, please be sure that your mainte-
.)
nance
personnel come as
close
as
possible to du-
plicating these
original test
figures.
2.
Usc
one
of the following methods:
I)
Primary
method using
a
Direct
Instrument
Measurement
Device
(DE'vl) sealed lo the fronl
access
opening. Taking the av-
erage
of
five reading, divided
by
the front access
opening
square
footage lo
calculate
inflow
velocity.
Sash areas
arc
noted
below. The calculated inflow
velocity
required
is
I
00
to
1
10
FPM.
2) Secondary method using
a
thermal anemometer mounted
on
a
ring
stand S inches above
the
exhaust filler, lake
reading on
a grid
as
shown
on
the
cabinet
air flow
data
plate.
Average
these reading and
multiply
lhc average by the
open
area of the
exhaust
collar
installed over the exhaust filter. SG400 1.72
square
feel
and
SG600
2.37 square feel.
Divide
this
value
(CFM)
by
the sash
open area
lo determine the
inflow
velocity.
The
calculated
inflow
velocities
required are, SG400
125
to
135
FPM
and
SG
600
liS
to
125 FPM
Sash areas
SG
400
SG600
8 Inch
sash
2.56 ft
2
3.89 ft
2
10
loch sash
3.19 ft
2
4.86
ft
2
3.
Using
the
same
instrument
mounted on
a
ring
stand
within the
work
area,
take readings
with
the anemometer probe
set
in
plane
of
the bouom of
the sash
with
the
supply
air diffuser
in-
stalled. TI1e
location and
average
of
these
readings
should
be
the
same as shown
in the factory test
report
and the table below.
Uniform
Downflow
Zone
Downflow
Sin
Sash
lOin
Sash
SG400
60
to
70 FPM Zone I
62-72
FJ>M
60-70
FP.\1
Zone
2
110-120
FPM 110-120 FPM
Your
test procedures should be identical
to ours
so
that
comparing
test results will have meaning.
Please
correspond directly with us to
request
detailed
procedures
for
your
particular
cabinet
model.
Alternate testing
procedures
can
be
found
in
the
NSF International Standard No. 49.
SG600 60
to
70 FPM*Zone
I
60-70 FPM
62-72
FPi'vl
The Airflow
Balance
Warning! This
procedure
should be
performed
by
4.
qualified
technicians
only.
The
airflow
balance which is
set
at the factory provides
5.
your unit
with air
volume
and
vclocit
y
control
to minimize
leakage
of
airborne
contamination
either
in or out of
the work
area.
In
order
lo duplicate as
closely
as possible
the
aiflow
char-
acteristics described in
lhe
original factory
lest
report. please
follow
these
steps:
I.
Adjust
the
viewscrecn
to its
connerct 8-inch
operating
bcigbl.
If
the
viewscreen
is
scllo any
other bcighl an alarm
will sound.
19
Zone
2
105-11
5
FPM
100-110
FPM
*SG600
10" sash
is
only
zone downflow.
Alter you have compared your figures with
those
origin.aUy
recorded
at
the
factory,
make
whatever
adjttstments
may
be
necessary.
As the
HEP A
(High Efficiency
Particulate
Air) filters load
up
with particulates, airflow
wiJI be maintained automatically, at
least
until
the
filter
resistance
i:rtcreases 50
percent
or
more. When airflow eventually diminishes,
an
alarm wi.ll
sound.
fiNe explained the
alarm
function
at the
beginning of Section
3.) You
will
have
to increase the blower
speed in or-
der
to maintain
the
original volume of
recir-
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