21
oxygen. During the bump test the oxygen
sensor should read /-0.5%
(absolute) of the level given on the
calibration cylinder.
4.2
Fresh Air/Zero Calibration
Fresh air/zero
calibrations may only be performed in an
atmosphere that is known to contain 20.9%
oxygen, 0% LEL and 0 PPM toxic gas.
To initiate the fresh air/zero calibration:
1. Press the MODE button three times within
two seconds to begin the fresh air/zero
calibration sequence. The MultiPro will
briefly display AUTO CAL and then begin
a 5-second countdown.
→
2. Press the MODE button before the end of
the 5-second countdown to begin the
fresh air/zero calibration. The fresh
air/zero calibration has been initiated
when the MultiPro alternates between the
following two screens:
↔
2. The fresh air/zero calibration is complete
when the instrument begins another 5-
second countdown for the span
calibration. If span calibration is not
required, allow the countdown to reach 0
without pressing the MODE button.
4.2.1 Fresh air/zero calibration failure
In the event of a fresh
air/zero calibration failure,
the alarms will be
activated and the
instrument will display the
following screen. Note
that the sensor(s) that fail
the zero calibration are shown (in this case,
CO)
After 3 seconds, the MultiPro will return to the
current gas readings screen and the visual
and audible alarms will cease.
When fresh air/zero calibration is due, the
MultiPro’s display will show the warning
symbol while intermittently displaying the 0-
CAL icon in the gas readings screen until a
successful fresh air calibration is performed.
If a specific sensor has failed the fresh
air/zero calibration, it will be displayed with the
0-Cal icon.
If a successful fresh air / zero calibration is not
performed prior to instrument shut down, the
MultiPro will show that Fresh Air Calibration is
due during instrument start up.
Possible causes and solutions
1. The atmosphere in which the instrument is
located is contaminated (or was
contaminated at the time the instrument
was last fresh air calibrated).
2. A new sensor has just been installed.
3. Instrument has been dropped or banged
since last turned on.
4. There has been a significant change in
temperature since the instrument was last
used.
Recommended action:
Take the instrument to fresh air and allow
readings to stabilize. Perform the fresh
air/zero adjustment again. If the manual fresh
air/zero procedure fails to correct the problem,
perform the manual fresh air / zero calibration
procedure as described in section 4.2.2
below.
4.2.2 Forced fresh air / zero calibration
The MultiPro includes safeguards to prevent
fresh air calibration in contaminated
environments. If the standard fresh air / zero
calibration fails a second time, the instrument
may be “forced” to accept the fresh air
calibration by performing the manual fresh air
/ zero calibration.
Fresh air/zero
calibrations may only be performed in an
atmosphere that is known to contain 20.9%
oxygen, 0.0% LEL and 0 PPM toxic gas.
1. Initiate the standard
fresh air / zero
calibration sequence
by pressing the
MODE button three
times in rapid
succession. The 5-
second countdown will begin.
2. Press the MODE button before the end of
the 5-second countdown and
continue to
hold the MODE button
. As in the
Summary of Contents for MultiPro
Page 1: ......
