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Criteria
Used For
Determination
Of Sensor
Integrity |
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Sensors,
whether for
combustible
gases,
oxygen, or
toxic gases,
have a fixed
and finite
life. The
factors
which
determine if
a sensor
should be
replaced are
realized
during the
calibration
process.
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Calibration
is
the
act
of
challenging
an
instrument
to
respond,
by
applying
a
metered
calibration
gas
to a
specific
sensor.
A
functional
sensor
should
yield
readings
in
proportion
to
the
concentration
of
gas
being
applied.
Variances
between
the
known
concentration
of
calibration
gas
and
the
steady
state
reading
of
the
instrument
can
be
changed
by
adjusting
the
span.
Typical
response
time
is
approximately
2
minutes.
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Effects
of Various
H2S
Levels |
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Hydrogen
Sulfide
levels
in
PPM |
Resulting
Condition/Effects
on
Humans |
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0.13 |
Minimal
perceptible
odor |
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4.6 |
0
Easily
detected,
moderate
odor |
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10 |
Beginning
eye
irritation.
Permissible
Exposure
Level,
8
hours
(OSHA,
ACGIH) |
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27 |
Strong,
unpleasant
odor,
but
not
intolerable. |
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100 |
Coughing,
eye
irritation,
loss
of
sense
of
smell
after
2 to
5
minutes. |
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200-300 |
Marked
conjunctivitis
(eye
inflammation)
and
respiratory
tract
irritation
after
one
hour
of
exposure. |
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500-700 |
Loss
of
consciousness,
cessation
(stopping
or
pausing)
of
respiration,
and
death. |
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1000-2000 |
Unconsciousness
at
once,
with
early
cessation
of
respiration
and
death
in a
few
minutes.
Death
may
occur
even
if
individual
is
removed
to
fresh
air
at
once. |
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Source:
Dangerous
Properties
of
Industrial
Materials
(Sixth
Edition) by
N. Irving
Sax. |
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hazardous gases