Specifications; How The Sensor Works - Vernier Go Direct GDX-ODO Instruction Manual

Specifications

Range (mg/L) 0 to 20 mg/L
Range (%) 0 to 300%
Accuracy (mg/L) ±0.2 mg/L below 10 mg/L
±0.4 mg/L above 10 mg/L
Accuracy (%) ±2% below 100%
±5% above 100%
Accuracy with calibration reset ±0.1 mg/L below 10 mg/L
(mg/L)
±0.2 mg/L above 10 mg/L
Accuracy with calibration reset ±1% below 100%
(%)
±5% above 100%
Type Luminescent
Response time 90% of final reading in 40 seconds
Temperature range 0 to 50°C
Pressure range 228 mmHg to 1519 mmHg
Minimum sample flow none required
Wireless specification Bluetooth 4.2
Maximum wireless range 30 m
Battery 650 mA Li-Poly
Battery life (single full charge) ~24 hours
Battery life (long term) ~500 full charge cycles (several years
depending on usage)
Care and Maintenance
Battery Information
Go Direct Optical Dissolved Oxygen contains a small lithium-ion battery. The
system is designed to consume very little power and not put heavy demands on the
battery. Although the battery is warranted for one year, the expected battery life
should be several years. Replacement batteries are available from Vernier (order
code: GDX-BAT-650).
Storage and Maintenance
When you have finished using Go Direct Optical Dissolved Oxygen, rinse it off
with distilled water and blot it dry using a paper towel or lab wipe. Insert the
probe back into the storage bottle containing the sponge, dampened with distilled
water.
The tip of the probe is a replaceable screw-on cap called the Go Direct Optical
Dissolved Oxygen Replacement Cap. This cap is warranted to be free from defects
of a period of two years from the date of purchase; it is possible that you can get
longer use than the warranty period. If you notice a reduced response, it is
probably time to replace the cap (order code GDX-ODO-CAP). To extend the
lifetime of the cap, do not expose it to direct sunlight for an extended period of
time.
To store Go Direct Optical Dissolved Oxygen for extended periods of time, put
the device in sleep mode by holding the button down for at least three seconds.
The red LED will stop flashing to show that the unit is in sleep mode. Over
several months, the battery will discharge but will not be damaged. After such
storage, charge the device for a few hours, and the unit will be ready to go.
Exposing the battery to temperatures over 35°C (95°F) will reduce its lifespan. If
possible, store the device in an area that is not exposed to temperature extremes.
This probe should be used in aqueous solutions only. Do not place the probe in
viscous, organic liquids, such as heavy oils, glycerin (glycerol), ethylene glycol, or
alcohols. Do not place the probe in acetone or non-polar solvents, such as pentane
or hexane.
Water Resistance
Go Direct Optical Dissolved Oxygen is designed so that the tip of the probe can be
submerged in an aquatic environment for extended periods of time. For best
results keep the pressure-sensing element out of water so as not to interfere with
the active pressure readings. This probe is not designed for long-term
immersion applications.
The included micro USB cable is not waterproof.

How the Sensor Works

Go Direct Optical Dissolved Oxygen operates on the principle of reversible
luminescence quenching of a luminophore by oxygen as it passes through the cap.
The cap is coated with a luminescent compound encased in a matrix for
protection. Blue light from an LED is transmitted to the cap and excites the
luminophore.
A collision of an oxygen molecule with the luminophore in its electronic excited
state results in energy transfer from the luminophore to oxygen. As the
luminophore relaxes it emits red light. The time from when the blue light is
transmitted and the red light is emitted is measured by a photodiode. The more
oxygen that is present, the shorter the time it takes for the red light to be emitted.
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