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In early 2004, Dräger introduced the latest
addition to the Polytron stationary gas detector
family - the Dräger Polytron 7000.
Built on a modular platform, the Dräger
Polytron 7000 offers a wide range of specification
features that can be added at any
time, creating a truly flexible transmitter.
In the beginning
For over a decade the Polytron 1 and Polytron
2 have formed the foundation for
Dräger’s success, with a current worldwide
installed base of over 100,000 transmitters
solidifying Dräger’s position as a market
leader in stationary toxic gas detection. In
order to maintain this position and further
our growth in the future, Dräger invested in
new technologies and concepts to create a
new generation of detectors.
In collaboration with key customers from
various industries and using input from our
sales team, we derived a comprehensive list
of design criteria for the ideal gas detector.
This list was long and diverse, though not
every element was needed by everyone.
Dräger’s answer to this challenge was to
design a modular gas detector with the
flexibility to satisfy current and adapt to
changing application requirements.
The first step – Dräger Polytron 3000
The development project was split into two
phases, the first phase being the development
of the Dräger Polytron 3000 to replace
the Polytron 1. This was successfully
launched in the beginning of 2003 and in
the first year exceeded all sales expectations.
It was designed to satisfy the basic requirements
of an intrinsically safe gas detector
for toxic gas and oxygen detection. An
analogue 4 to 20 mA detector for selected
gases and ranges, the Dräger Polytron
3000 is also able to accept pre-calibrated
sensors. This can cut down maintenance
time and cost considerably.
Polytron Docking Station
Usually, installation and commissioning are
done by different people at different times
and makes up a significant cost component
of a detection system. Dräger's solution was
to develop an easy to install approach consisting
of two components. This will avoid
exposing the sensitive measuring equipment
to construction hazards.
The Polytron Docking Station is easily premounted,
wired and protected from the elements
by a ‘rain cover’. When the site is
ready for commissioning, the Dräger Polytron
7000 slides into the docking station
and is secured by a fast-lock mechanism.
No special tools or keys are required and
the process takes just seconds.
Dräger Polytron 7000 & modules
One year later we were able to launch the
Dräger Polytron 7000 onto the market.
Choices between different modules such
as communication field buses, software features,
pump, relay and remote sensor modules
provide the ability to customise and
upgrade the Dräger Polytron 7000 to individual
specifications.
A lot of development and investigation time
was also spent on making the navigation
and operation of the system as simple as
possible. A simple three button navigation
intuitively guides you through the menu
driven functions. The large graphic display
shows both descriptive icons as well as
plain text information to help with any diagnosis
of the gas detector.
Communication mode
With the Polytron 7000, communication to
the central control system is selectable,
either 4 – 20mA, digital HART or LONBUS.
With HART up to eight transmitters can be
daisy-chained on a single twisted pair. For
the future, a Profibus and Foundation Fieldbus
will also be developed.
Enhanced software options
Different applications require unique and
specialised software functions, so specialised,
optional software dongle modules
tailor the transmitter to fit specific applications:
- Sensor Self Test Function continuously
performs patented sensor tests to ensure
reliability and integrity of the gas detection
system.
- Sensor Diagnostic Function continuously
evaluates the ‘health’ of the sensor. Now
predictive sensor maintenance is possible
- Datalogger and Eventlogger Function for
continuous recording of gas concentrations
and events which can be downloaded and
evaluated on a PC. As requested by many
operators, a 15 minute online concentration
graph can be shown on the transmitter display
at the push of a button.
Measuring point
If the point of measurement is hard to access
or impossible to mount, it may be necessary
to pump the gas to the transmitter.
Without additional wiring or extra mounting
space a pump is able to fit inside the
Dräger Polytron 7000.
Alternatively, the sensor can be mounted
up to 30 m / 100 ft away from the transmitter.
To measure gas inside the air stream of
a duct, different duct mount kits are available.
Relay module
With the optional alarm relay module, the
transmitter is able to operate as a standalone
unit. This allows installation of alarm
devices at the point of detection, without
having to run signal wires to a central controller
and power wires back to strobes or
horns. However when the pump or relay
modules are installed the transmitter cannot
be used in explosion hazard areas.
Approvals
For use in classified, hazardous areas the
Dräger Polytron 7000 has worldwide ATEX,
UL and CSA* approvals. To considerably
cut down the cost of the gas detection system
it is also approved for installation in
Zone 2 areas without a safety barrier (Division
2 UL approval without safety barrier is
pending).
In the design and planning of a safety system
more focus is being placed on the Life
Cycle Safety reliability of the whole system.
The EN 61508 standard provides guidelines
to classify theses systems by Safety
Integrity Levels (SIL). To classify the
Dräger Polytron 7000 as SIL 2, safety-relevant factors needed to be considered during
the development phase. A complex risk
analysis and documentation process is used
to ensure that failures are recognised and
indicated. Designed and verified to SIL
standards, the Dräger Polytron 7000 is suitable
for SIL 2 applications, thus leaving sufficient
margin for other safety relevant devices
needed to complete the system.
In the past, radio frequency interference
(RFI) from portable radio devices has been
a concern for all gas detection systems.
Through new technological advancements
in electronic design, Dräger Safety was able
to provide both the Dräger Polytron 3000
and 7000 with unsurpassed RFI resistance.
Looking to the future
Future industry requirements, expectations
and trends were considered throughout the
development process. Not only does the
Dräger Polytron 7000 fulfil today’s customer
requirements, but its flexible, modular design
also leaves options open for additional
module development in the future - firmly
putting the choice back into our customers’
hands.
Kathleen Leahy
Dräger Safety AG & Co. KGaA |
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Dräger Safety AG & Co. KGaA |
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Revalstrasse 1 |
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23560 Luebeck, Germany |
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Tel +49 451 882 0
Fax +49 451 882 2080
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