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In-Situ RDO Sensor |
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Announcement of new Optical
Dissolved Oxygen Sensor |
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The new RDO sensor utilizes recent advances
in lifetime-based optical fluorescence sensor technology to provide an
extremely stable, precise and low maintenance dissolved oxygen senor.
This technology stands to revolutionize the current methods of water quality
monitoring by eliminating the need for membranes, stirring, and cleaning
while allowing deployment for many months without need for recalibration.
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Features: |
- High precision and accuracy. Measure
absolute oxygen concentrations without field calibrations
- Integrates directly into the TROLL 9000
with Smart Sensor technology - "Plug & Play"
- No membranes / No electrolyte
- 5 years / 5 Million readings before
lumiphore is exhausted
- Up to 1 year between calibrations
- Minimal maintenance / no hazardous
cleaning solutions
- No flow requirements
- Fast and stable response
- Low drift
- Excellent performance in anoxic conditions
(0 ppm)
- Not "poisoned" by Sulfides
- Not subject to "thermal shocking"
- No cross sensitivity to: H2S, pH, CO2,
NH3, SO4-, Cl-, Cl2, ClO2, MeOH, EtOH, various ionic species
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Two options are available:
Titanium or Delrin
30 Day no risk guarantee!! If you don't like it after 30 days just return,
for full credit. |
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When making critical decisions based on D.O., which
data would
you rather see? |
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The data on the left is from a traditional
Clark-electrode, while the one on the right is from an RDO sensor.
Surprisingly, this data is from the same sample. So why the difference? The
truth is that so many factors can influence the readings of a
Clark-electrode and without good experience, it is had to get good data.
Optical D.O. can obtain the correct results without all the hassle. This
is why this new technology is so exciting! |
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RDO Sensor
Installation |
Rugged Construction with Flexible
Installation
The powerful Rugged Dissolved Oxygen sensor ("RDO") with optical technology
means peace of mind with dissolved oxygen monitoring. It is available as an
optional sensor that plugs right into new and existing TROLL 9000s and TROLL
9500s. The design makes it easy to add or remove and can be used any time
you require high quality D.O. readings without the hassle. |
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Technology
addresses the age-old problem with D.O. |
Dissolved Oxygen (DO) is one of the single most important parameters
monitored when examining aquatic biology and related processes. Until
recently the ability to accurately monitor dissolved oxygen levels over long
periods of time was limited. Existing electrochemical sensors (Clark,
Galvanic) require sample stirring and are functionally limited by the
durability of their membrane and electrode, while galvanic diffusion types
offer characteristically slow response.
The new RDO sensor provides superior performance to traditional DO sensing
technology currently on the market.
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The micro-optical technology incorporated in the RDO sensor centers around
the extensively field-proven methodology of Lifetime-based Luminescent
Dissolved Oxygen detection.
This solid-state method uses LEDs to excite a fluorescent material, while an
optical receptor gauges the duration, or lifetime, of the event. The
duration of fluorescence is inversely proportional to the ambient amount of
dissolved oxygen in the water.
Environmental Industry interest in the RDO sensor is centered around the
fact that in many instances it can remain deployed through entire testing
seasons - spanning months without |
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calibration; at the same time
retaining its accuracy in even the harshest of fouling environments, without
the need for stirring.
All dissolved oxygen sensors are
affected by active bio-fouling. Optical D.O. technology is also affected by
fouling in the sense that the actual D.O. levels may be increased or
decreased around the sensing element. However, the difference is that an
optical D.O. sensor can simply be cleaned and redeployed with NO need for
recalibration.When viewed from
the bottom line, benefits of this sensor are not only the time/money saved
with freedom from calibration, but also notably reliable and accurate test
data. |
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Compare the old and the new: |
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Why Optical D.O.? |
The new RDO sensor is to the Clark cell what the
computer was to the typewriter.
Now you can:
- Reliably measure oxygen concentration with
accuracy and precision
- Eliminate the need for flow/stirring
- Eliminate the need for changing membranes
and electrolyte
- Eliminates unwanted temperature effects
- Eliminate the need for complex sensor
storage and conditioning
ANSWER: Higher quality data at a
lower cost of ownership |
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Old Clark - style DO sensor
New Rugged DO sensor |
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Optical D.O. Technology - how does it work? |
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- The sensing element (luminophore) is
activated, or excited when illuminated with a blue light
- When activated, the sensor emits red light
in an intensity that is inversely proportional to the amount of oxygen
present in the water
- There is also a time delay between the
peak emission of blue light and peak response of fluoresced red light. The
amount of delay is inversely proportional to the amount of oxygen present.
- This time delay can be expressed as a
phase shift between the wave patterns of incident blue light and the
fluoresced red light
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3 ways to
measure using optics: |
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1. Magnitude -- Not very good. Interference from
ambient light.
2. Time Domain -- Good, but subject to errors due to problems with peak
detection. Signal to noise ratio
limits range.
3. Phase Domain -- Best. Lock-in amplifier determines phase angle based on
entire signal and reference
wave forms. Magnitude is not important, greater operating
range. This is the method used by RDO! |
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RDO does not require stirring |
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Graph shows test of Clark electrode vs. an RDO
sensor with and without stirring. Notice how the Clark-electrode is
adversely affected when stirring is turned off while the RDO is continue to
display the correct reading. |
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How does photo bleaching affect optical D.O. sensors? |
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After two days of direct sunlight exposure, the
RDO sensor still measures accurately. Though this cannot be said for some of
the other optical D.O. technologies on the market. |
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7 RDO sensor match precisely with Winkler Titrations
and other lab methods |
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Testing Results |
Extensively Field Proven
Successfully tested and deployed over 300 sensors in the following
environments:
Deployments/Usages:
Harsh environments:
- Fresh water applications
- Brackish water
- Dirty water
- Ground-water
- Waste streams
Oceanic application:
- Depths of up to 6000 meters
- High salinity
- Low temperature
- Long-term deployment (greater than 6
months)
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3rd Party Testing - RDO
shows superior accuracy & stability: |
