12
5. Wait for the readings to stabilize. (Forty-
five seconds to one minute is usually
sufficient.)
6. Note the readings. Readings are
considered accurate if they are between
90% and 120% of the expected value. If
the readings are considered accurate,
then the instrument may be used without
further adjustment. If readings are
considered inaccurate, the instrument
must be adjusted using the “span”
calibration procedures discussed in
section 3.5 before further use.
3.5
Span Calibration (toxic sensor
versions)
Span calibration should be performed when a
functional (bump) test has shown that the
instrument’s gas readings are not between
90% and 120% of the expected values as
given on the calibration gas cylinder
(as
discussed in section 3.4). Prior to performing
a span calibration, perform a fresh air/zero
calibration as discussed in section 3.3. After
successful completion of the fresh air/zero
calibration, the
instrument will begin a
second five-second
countdown with the
calibration gas bottle
icon highlighted.
1. Press the MODE button before the
countdown is complete to initiate the span
calibration. The display will alternate
between “GAS” and the expected
concentration of calibration gas.
↔
2. Apply calibration gas as shown above in
figure 3.4. Once calibration gas is
detected, the readout will change to show
the gas reading. Note that the negated
horn symbol is shown at lower left to
indicate that the
alarms are not
operating because
the instrument is in
calibration mode.
Note: ToxiPro instruments equipped with
a chlorine dioxide (ClO
2
) sensor require a
chlorine dioxide generator as a calibration
gas source.
3. The calibration is fully automatic from this
point on. Once the instrument
successfully completes the span
calibration, it will emit three short beeps
and display the maximum span calibration
adjustment value for
two seconds.
Note: The maximum
span calibration adjustment value shown
is an indication of the relative health of the
sensor. As a sensor loses sensitivity, the
maximum adjustment level will approach
the calibration gas concentration, letting
you know when the sensor is losing
sensitivity. Once the maximum span
adjustment descends to within 10% of the
calibration gas concentration, it is time to
order a new sensor.
4. Following
successful
calibration, the
instrument will display
the gas reading with
the negated horn icon
until the reading drops
below the alarm threshold.
Disconnect the calibration assembly
immediately after calibration.
Use of non-standard
calibration gas and/or calibration kit
components when calibrating the ToxiPro
can lead to inaccurate and potentially
dangerous readings, and may void the
standard Sperian Instrumentation Gas
Detection Warranty.
3.6
Failure to calibrate
3.6.1 Fresh air/zero calibration failure
In the event of fresh air/zero calibration
failure, the “no” and “CAL” screens will be
alternately displayed as shown below with the
“0-CAL” segment lit. The instrument will then
return to the gas reading screen.
↔
Following a fresh air/zero calibration failure,
the triangular warning
symbol will be lit and the
“0-CAL” indicator will flash
until a successful fresh
air/zero calibration is
performed.
3.6.1.1 Causes of fresh air/zero calibration
failures
Fresh air/zero calibration failures often result
from the attempt to calibrate the instrument in
a contaminated atmosphere.
Fresh air/zero calibration failures in the
ToxiPro O
2
can also result from an oxygen
sensor that has failed.
