Biosystems MultiPro Reference Manual - ↔
17
center of the LCD display. Low flow or other
pump fault conditions activate audible and
visible alarms and cause the display of the
appropriate explanatory message.
The pressure sensor in the sample draw
pump is designed to detect pressure
changes while the sample-draw probe is
being held in a vertical position. If the probe
is held horizontally or at a low angle while
inserted into a fluid, a pressure drop
sufficient to cause the pump to shut down
may not be generated, and water could be
drawn into the pump assembly causing
damage to the pump, sensors and internal
components of the MultiPro.
CAUTION: Insertion of the sample draw
tube into a fluid horizontally or at a low
angle may lead to water ingress and may
cause damage to the sensors and internal
components of the MultiPro.
If the MultiPro determines that a significant
pressure change has occurred, it will go into
alarm and notify the user that there is a
blockage of the pump. The display will
alternate between the following two screens.
↔
Remove the blockage and press the MODE
button to acknowledge the alarm and resume
sampling.
3.3
Sample draw probe
The MultiPro’s sample draw probe is the
standard probe assembly from Biosystems.
The sample probe handle contains moisture
barrier and particulate filters designed to
remove contaminants that might otherwise
harm the instrument.
Particulate contaminants are removed by
means of a cellulose filter. The hydrophobic
filter includes a Teflon
™ barrier which blocks
the flow of moisture as well as any remaining
particulate contaminants.
Sample probe filters should be replaced
whenever visibly discolored due to
contamination. See section 5.5.1 for a probe
diagram and a list of available sample probe
filter replacement kits.
4. Calibration
The accuracy of the MultiPro should be
verified on a regular basis*. Verification can
be as simple as performing a bump test,
which is described below in section 4.1.
*
The Canadian
Standards Association (CSA) requires the
LEL sensor to be bump tested prior to
each day’s use with calibration gas
containing between 25% and 50% LEL.
The functional (bump) test procedure is
covered in section 4.1.
If exposure to fresh air yields an oxygen
reading of less than 20.7% or greater than
21.1% or a toxic or LEL sensor reading of
anything other than 0, then a Fresh Air/Zero
Calibration should be performed as
described in section 4.2.
If exposure to a known concentration
calibration gas (as described in section 4.1)
shows that LEL or toxic sensor readings are
not between 90%** and 120% of the value
given on the calibration gas cylinder, then the
Span Calibration should be performed as
described in section 4.3.
**
The Canadian
Standards Association (CSA) requires the
instrument to undergo calibration when
the displayed value during a bump test
fails to fall between 100% and 120% of the
expected value for the gas.
For Biosystems’ official
recommendations concerning calibration
frequency, see Appendix B.
4.1
Functional (Bump) testing
The accuracy of the MultiPro may be verified
at any time by a simple functional (bump)
test.
To perform a functional (bump) test, do the
following:
1. Turn the MultiPro on and wait at least
three minutes to allow the readings to
fully stabilize. If any of the sensors have
just been replaced, the new sensor(s)
must be allowed to stabilize prior to use.
See section 5.4 for further details on
sensor stabilization requirements.
2. Make sure the instrument is located in
fresh air.
3. Verify that the current gas readings
match the concentrations present in fresh
air. The oxygen (O
2
) sensor should read
20.9% (+/-0.5%/vol.). The readings for
the LEL sensor should be 0% LEL and
toxic sensors should read 0 parts-per-
million (PPM) in fresh air. If the readings
deviate from the expected levels in a
fresh air environment, proceed to section