Biosystems MultiPro Reference Manual - ↔
19
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 Manual 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
standard fresh air /zero calibration, the
MultiPro will alternate between the
following two screens:
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3. 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.
If the MultiPro still fails to calibrate after
attempting the manual fresh air / zero
calibration, contact Biosystems.
4.3 Span
Calibration
Once the fresh air / zero calibration has been
successfully completed, the MultiPro will
automatically proceed to the automatic span
calibration countdown screen.
Press the MODE button before the
countdown is complete to initiate the span
calibration. The screen will immediately
show “APPLY GAS” and then list the sensors
for calibration and the expected levels of
calibration gas.
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Note: Biosystems recommends the use
of multi-component calibration gas for
calibrating the MultiPro.
Apply calibration gas as
shown above in figure
4.1. The readout will
change to a numerical
display almost
immediately and will
continue to display the
current readings.
The actual calibration of the oxygen sensor
to 20.9% occurs during the fresh air
calibration, but the oxygen sensor is tested
for response to diminished oxygen levels
during span calibration. Biosystems
calibration gas cylinders contain
approximately 18.0% oxygen. In order to
pass the span calibration, the MultiVision
must register an oxygen reading below
19.5% during span calibration.
See section 4.3.2 below if the oxygen sensor
does not detect the drop in oxygen level and
fails the span calibration.
The calibration is fully automatic from this
point on. Upon successful calibration of a
sensor, the MultiVision will beep, show the
adjusted reading for the calibrated sensor
and then move on to the next sensor.