DurOx 325 DISSOLVED OXYGENELECTRODES
Galvanic oxygen electrodes for DO meters
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? Dissolved Oxygen Electrodes Product Description
? Dissolved Oxygen Electrodes Specifications
? Dissolved Oxygen Electrodes Options & Prices
? Dissolved Oxygen Electrodes Brochure
? Dissolved Oxygen Electrodes Manual*
The DurOx 325 dissolved oxygen electrodes areeasy to use and maintain electrodes for taking dissolved oxygen measurements inthe field. The dissolved oxygen electrodes are temperature compensated andwaterproof to the IP 68 standard or up to 2 bar. The dissolved oxygenelectrodes have a long working life of up to six months from one electrolyterefill. An easy to use calibration vessel is included with each dissolvedoxygen electrode as well as a protective hood for field use. The dissolvedoxygen electrodes can be easily cleaned with warm water for many applications.
The DurOx 325 dissolved oxygen electrode is ideal for monitoring oxygen levelson fish farms, in control measurements, and at wastewater treatment plants,specifically in the aeration basin. With the Oxi3205 handheld field meters the dissolved oxygen electrodes are ideal forroutine field measurements. The Oxi3210 meter raises the performance level of the dissolved oxygen electrodesto a point where they are recommended for highly precise control and qualityassurance measurements.
What is Dissolved Oxygen?
Some oxygen is dissolved in practically every liquid. For example, at atemperature of 68 øF (20 øC) and an atmospheric pressure of 1013 mbarsaturated water contains about 9 mg/l oxygen. Ethanol can contain up to 40mg/l whereas glycerol only has about 2 mg/l.
Each liquid takes up oxygen until the partialpressure of oxygen in the liquid is in equilibrium with the air or gas phase incontact with it. The actual oxygen concentration depends on a number offactors, such as temperature, air pressure, oxygen consumption by microorganismsin a biodegradation process or oxygen production by algae, etc.
The oxygen concentration is important for the:
- Living conditions for fish and microorganisms in waters
- Degradation processes in wastewater treatment
- Corrosion processes in pipelines
- Shelf life of beverages, etc.
The determination of the dissolved oxygenconcentration was formerly carried out by the WINKLER titration method. Today electrochemical measurement is a recognized method in numerous standardprocedures.
In its simplest form a dissolved oxygen electrodecontains a working electrode and a counterelectrode. Both dissolved oxygenelectrodes are located in an electrolyte system which is separated from thesample by a gas-permeable membrane. The working dissolved oxygen electrodereduces the oxygen molecules to hydroxide ions. In this electrochemicalreaction a current flows from the counterelectrode to the working dissolvedoxygen electrode. The more dissolved oxygen present in the sample, thelarger the current signal generated by the dissolved oxygen electrode. Ameter connected to the dissolved oxygen electrode calculates the oxygenconcentration in the sample from this signal.
Why Measure DO?
Dissolved oxygen (DO) is the amount of oxygen (O2) dissolved inwater. Dissolved oxygen measurements provide one of the best indicators ofthe health of a water ecosystem, as oxygen is a necessary element for all formsof life, including aquatic life. Oxygen enters water at the water surfacethrough direct exchanges with the atmosphere. It is also produced as abyproduct of plant and phytoplankton photosynthesis. A decrease indissolved oxygen levels is typically associated with an organic pollutant. Dissolved oxygen is used by plants and animals for respiration, and by aerobicbacteria in the process of decomposition. When organic matter (such asanimal waste or improperly treated wastewater) enters a body of water, algaegrowth increases. As the plant material dies off and decomposes, dissolvedoxygen levels decrease. If the water at the surface is not mixed withdeeper water layers, the water?s dissolved oxygen levels can becomestratified. Dissolved oxygen levels can also vary according to the time ofday, weather, and temperature. Dissolved oxygen in water can range from0-18 parts per million (ppm), but most natural water systems require 5-6 ppm tosupport a diverse population. As dissolved oxygen levels drop below 5.0mg/L, aquatic life is put under stress. As dissolved oxygen levelsdecrease, pollution-intolerant organisms are replaced by pollution-tolerantworms and fly larvae. If dissolved oxygen levels fall below 1-2 mg/L for afew hours, large fish kills can result.
Measuring Principle:Membrane covered galvanic sensor
Temperature Compensation: IMT
Measurement Range (68øF (20øC), 1013 hPa): 0 – 50 mg/L O2
Temperature Range: 32 to +104øF (0 to +40øC)
Maximum Pressure: 14.5 psi (105 Pa (1 bar))
Immersion Depth: 1.6 inches min/19.7 ft max (4 cm min/6 m max)
Operating Position: Any
0.08 ft/s (2.5 cm/s) at 10% measeasurementaccuracy
0.16 ft/s (5 cm/s) at 5% measeasurement accuracy
Zero Signal: <1% from saturation value
Response Time at 68øF (20øC):
t90 (90 % of indication of end valueafter) < 25 s
t95 (95 % of indication of end valueafter) < 40 s
t99 (99 % of indication of end valueafter) < 125 s
Self Consumption at 68øF (20øC): 0.006 ug h-1 (mg/L)-1
Drift: Approximately 3%/month in operation conditions
Working Life: Approximately 6 months per electrolyte refill
Cable Length: Varies
Cable Plug: 8 pin socket
Membrane Head: POM
Thermistor Housing: VA-steel 1.4571
Cable Screw Joint: POM
Size of Probe:
Electrode Shaft: 4.3 inches L x 0.7 inchesDia. (110 mm L x 17.5 mm Dia.)
Membrane thickness: 0.98 mil (25 um)
Weight: 0.5 lb. (220 g) w/9.9 ft (3 m) of cable