Biosystems MultiPro Reference Manual - 1. Description
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1. Description
The MultiPro is
a multi-sensor
gas detector
that can be
configured to
meet a wide
variety of user
requirements.
This chapter
provides an
overview of many of the features of the
MultiPro. More detailed descriptions of the
specific features of the MultiPro are
contained in the subsequent chapters of this
manual.
1.1
Methods of sampling
The MultiPro may be
used in either
diffusion or sample-
draw mode. In
either mode, the gas
sample must reach
the sensors for the
instrument to
register a gas
reading. The
sensors are located at the bottom of the
instrument. There are three distinct sensor
ports that allow air to reach the individual
sensors.
The sensor ports must
be kept free of obstruction. Blocked
sensor ports can lead to inaccurate and
potentially dangerous readings.
In diffusion mode, the atmosphere being
measured reaches the sensors by diffusing
through the vents at the bottom of the
instrument. Normal air movements are
enough to carry the sample to the sensors.
The sensors react quickly to changes in the
concentrations of the gases being measured.
Diffusion-style operation monitors only the
atmosphere that immediately surrounds the
detector.
The MultiPro can also be used to sample
remote locations with the hand-aspirated
sample-draw kit or with the motorized,
continuous sample draw pump. During
remote sampling, the gas sample is drawn
into the sensor compartment through the
probe assembly and a length of tubing.
Remote sampling operations only monitor the
atmosphere at the end of the sample draw
probe.
Use of the hand-aspirated sample draw
kits is covered in section 3.1.
Use of the motorized sample draw pump
is covered in section 3.2.
A detailed description of the MultiPro
probe assembly is given in section 5.5.
1.2 Multi-sensor
capability
The MultiPro can be configured to
simultaneously monitor oxygen, carbon
monoxide, hydrogen sulfide and combustible
gases and vapors. All sensors are
replaceable in the field. Each of the
MultiPro’s sensor channels is configured for
a specific type of sensor.
Note: It is necessary to verify the
accuracy of the MultiPro by calibration
with known concentration test gas
whenever a change is made to the
sensors installed in the instrument.
Calibration procedures are discussed in
detail in Chapter 4.
The MultiPro uses electrochemical toxic gas
sensors that have been designed to minimize
the effects of common interfering gases.
These sensors provide accurate, dependable
readings for toxic gases commonly
encountered during confined space entry and
other industrial applications.
Different measurement units are used
depending on the gas being measured.
Type of Hazard
Measurement unit
Oxygen (O2)
Percentage by
volume
Combustible gas
Percentage of lower
explosive limit
(%LEL)
Carbon Monoxide,
Hydrogen Sulfide
Parts per million
(PPM)
Table 1.2. MultiPro Units of Measurement.
1.3 Calibration
The MultiPro detector features fully automatic
fresh air and span calibration.
The accuracy of the
MultiPro should be checked periodically
with known concentration calibration gas.
Failure to check accuracy can lead to
inaccurate and potentially dangerous
readings. (The Canadian Standards
Association (CSA) requires an accuracy
check using known concentration
calibration gas prior to each day’s use.)
Calibration procedures are discussed in
detail in Chapter 4.