Alco
‐
Sensor
FST®
Operator’s Manual
PROTECTED
A
Alco
‐
Sensor
FST®
Operator’s
Manual
6
of
30
2018
‐
12
‐
18
2.5
Science
of
Breath
Testing
When
a
person
consumes
an
alcoholic
beverage,
it
passes
from
the
mouth
and
esophagus
to
the
stomach
and
small
intestine,
where
it
is
absorbed
into
the
blood
stream.
The
absorption
of
alcohol
is
quite
rapid,
generally
taking
20
to
30
minutes
after
consumption
to
reach
the
maximum
reading.
Absorption
time
may
be
affected
by
the
type
and
amount
of
food
in
the
stomach,
the
rate
of
alcohol
consumption,
the
type
of
beverage
consumed
as
well
as
some
drugs,
disease
and
emotional
states.
Once
in
the
blood
stream,
the
alcohol
is
distributed
to
all
parts
of
the
body
including
the
lungs,
brain
and
liver.
It
is
the
depressant
action
of
alcohol
in
the
brain
that
causes
impairment
and
intoxication.
Elimination
of
alcohol
begins
immediately
after
it
has
entered
the
blood.
Most
of
the
alcohol
(approximately
95%)
is
eliminated
by
metabolism
in
the
liver.
The
remainder
(approximately
5%)
is
excreted
unchanged
through
breath
and
other
body
fluids.
Unlike
absorption,
the
elimination
process
is
slow.
The
elimination
rate
ranges
between
10
‐
20
mg%
per
hour
for
most
of
the
population.
The
basis
for
all
breath
test
equipment
is
that
alcohol
is
eliminated
unchanged
in
the
breath.
There
is
a
fixed
and
known
relationship
between
the
amount
of
alcohol
in
the
breath
and
the
amount
of
alcohol
in
the
blood.
This
relationship
(essentially
the
principle
of
breath
testing)
is:
At
34
o
C,
2100
parts
of
deep
lung
air
contains
the
same
amount
of
alcohol
as
one
part
of
blood.
Using
this
ratio,
it
is
possible
to
collect
a
measured
volume
of
breath,
analyze
it
for
alcohol
and
convert
the
result
to
a
blood
alcohol
concentration.
This
principle
is
used
in
all
breath
test
instruments
and
screening
devices
operated
in
North
America,
including
the
Alco
‐
Sensor
FST®.
It
should
be
noted
that
this
ratio
is
lower
than
the
actual
ratio
(2300:1)
and
so
the
results
obtained
through
breath
testing
tend
to
underestimate
the
actual
blood
alcohol
concentration.
2.6
Theory
of
Fuel
Cells
The
Alco
‐
Sensor
FST®
analyzes
the
amount
of
alcohol
in
a
sample
of
breath
by
means
of
a
fuel
cell.
A
fuel
cell
is
similar
to
a
battery
except
that
it
requires
a
fuel
(like
alcohol)
to
make
it
produce
a
current.
The
current
is
produced
by
a
chemical
reaction
that
occurs
when
alcohol
comes
in
contact
with
the
fuel
cell:
Alcohol
‐‐‐‐‐‐‐‐‐
>
Acetic
Acid
+
Electrons
‐‐‐‐‐‐‐‐‐‐‐‐
>
CO
2
+
O
2
+
H
2
O
The
current
is
produced
when
electrons
are
generated
in
the
above
reaction.
The
more
alcohol
there
is
in
a
breath
sample,
the
more
electrons
are
produced
causing
a
stronger
current
and
subsequently,
a
higher
reading.
