Causes Of Fresh Air/Zero Calibration Failures; Forced Fresh Air/Zero Calibration; Span Calibration Failure; Sensor Out Of Range (No Cal) - Honeywell ToxiPro CO Reference Manual

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
also result from an oxygen sensor that has failed.
3.6.1.2

Forced fresh air/zero calibration

If a fresh air/zero calibration fails in an atmosphere
known to be fresh, the ToxiPro can be forced to fresh air
calibrate as follows.
1. Follow instructions 1 and 2 in section 3.3 to begin
the fresh air/zero calibration sequence.
As soon as the alternating right and left 0's are
2.
shown on the screen, press and hold the MODE
button.
3. The forced fresh air/zero calibration is complete
when the instrument emits three short beeps and
then moves on to the span calibration procedure.
Performing the forced fresh
air calibration in a contaminated atmosphere will
lead to inaccurate and potentially dangerous
readings.
3.6.2

Span calibration failure

The ToxiPro is designed to recognize two distinct types
of span calibration failures: failures that occur due to
sensor response outside the sensor's normal range for
calibration and failures that occur when the instrument
fails to recognize any calibration gas whatsoever.
3.6.2.1

Sensor out of range (no CAL)

If the instrument recognizes calibration gas, but the
sensor response is not within the range to calibrate the
instrument, span calibration will fail and the "no" and
"CAL" screens will be alternately displayed.
After displaying "no" and "CAL" times, the instrument will
return to the current gas readings screen and the
warning symbol and the calibration bottle icon will be
shown, which signifies that the instrument failed the last
attempt to span calibrate.
↔
↔
Note: If the Calibration Due Lockout is enabled, the
ToxiPro will turn itself off following a failed
calibration attempt.
3.6.2.2
Span calibration failures can be caused by:
can
1.
2
2.
3.
4.
3.7
To perform a fresh air calibration in a contaminated
atmosphere, it is necessary to use special calibration
gas, whose composition is identical to that of fresh air.
Honeywell Analytics offers the "Zero Air" calibration gas
cylinder as part number 54-9039, which contains 0 PPM
toxic gas and 20.9% oxygen.
1.
2.
3.
18

Causes for span cal failure

Expired calibration gas.
Calibration gas whose concentration fails to
match the concentration expected by the
instrument.
Inappropriate regulator. The ToxiPro must be
calibrated using a 1.0 liter/minute fixed flow
regulator.
Sensor failure.
Fresh air/zero calibration in a
contaminated atmosphere
Apply "Zero Air" calibration gas to the instrument
as shown above in figure 3.4 for at least 15
seconds or until the readings fully stabilize.
Perform the fresh air/zero calibration procedure
as described in section 3.3 while continuing to
flow gas to the sensor.
Once the fresh air/zero calibration is complete,
disconnect the calibration assembly. If the
ToxiPro is equipped with a toxic gas sensor,
proceed to the span calibration procedure if
necessary as described in section 3.5.