Many instruments available for measuring dissolved oxygen are old-fashioned, complex to use, expensive, and require a high degree of proficiency to operate. These instruments may also require expensive additional housings and accessories before they can be deployed for any monitoring task. End users who are looking for a simple to use instrument to make dissolved oxygen measurements need look no further than that of The ARGES Dissolved Oxygen by Keynes Controls.
The ARGES Dissolved Oxygen Sensor by Keynes Controls is a single-channel instrument that can detect and report dissolved oxygen levels in the range of 0 - 250 %. The dissolved oxygen level in the water sample is calculated based on the Stern- Volmer equation. The sensor has been designed to be used as a stand-alone laboratory instrument, or as part of a multi-parameter system. The instrument and can be connected directly into a plant-wide SCADA system using the in-built MODBUS and RS485 protocols. The RS485 network enables the sensors to be put onto local area and Wi-Fi networks. The SDI12 digital network connection is ideal for low power remote solutions.
In-situ measurement, no sampling, no reagents
• Direct SI Unit output of parameters
• Optical window with coating to minimise clogging
• Real time measurement
• Automatic compensation for temperature effects
When measuring concentrations of metals and minerals in water:
1 milligram per liter
(mg/L) = 1 part per million (ppm)
1 microgram per liter
(ug/L) = 1 part per billion (ppb) and 1 ppm = 1,000 ppb
Measurement Integrity
All of the ARGEs sensor range including the ARGES Dissolved Oxygen Sensor by Keynes Controls have the serial numbers and the last calibration date stored internally. The user can access this information for reporting purposes. The sensors can be redeployed at any time with the calibration and serial number records are retained in the sensor.
Product Calibration
The ARGES Dissolved Oxygen Fluorescence Sensor by Keynes Controls is factory calibrated before shipment.
The sensor is calibrated using an environmental test chamber. The images opposite show the calibration software in operation, and the bubble system used to maintain the 100% saturation of the over the calibrated temperature range.
The calibration factors are stored directly into the sensor.
The advanced design of the sensors means that the time between re-calibration of an instrument is minimised. Keynes Controls recommends a check calibration every year. The User can adjust the calibration for a specified range to improve accuracy for dedicated tasks.
Multiparameter Measurements
The ARGES Dissolved Oxygen Sensor by Keynes Controls can be fitted into any of the Keynes Controls ARGEs multiparameter housings. The optional USB-SDI12-AG1 media converter shown below can be used to connect a multiparameter system, or single sensor directly to a Windows PC USB Port. The media converter powers the sensor directly and no external power supply is required.
Setup and Configuration
The ARGES Dissolved Oxygen Sensor by Keynes Controls is simple to use and configure. It is supplied with the free QLOG Windows application software that can be used to:
- Sensor Configuration
- Calibration
- Range setting
- Make and display real-time measurements
- Assign Engineering Units automatically.
The software operates for sensors using the SDI12 and RS485 digital networks.
Product Features
| TYPE | RANGE (Typical levels) |
| Solid state Fluorometer | Optical Fluoresecent |
| Concentration range: | 0. to 16.5 mg/L 0-200% - at 25 Deg C |
| Resolution: | 0.001 mg/L |
| Accuracy: | +/- 2 % of reading - Typical |
| Multi-parameter Housings |
7 / 3 Port Options - others on request |
| Calibration Period: | Approximately 2 year between Calibration - |
| Sensor Material | Stainless-steel body - Gold plated Connector pins |
| pH Range | 0 - 14 |
| SDI12 V1.4 | Automatically assigned SI Units - %DO, Temperature Deg C |
| Digital Communications | SDI12 / RS485 / MODBUS Digital Communications - 0-2 V DC Optional |
| Temperature Sensor | NTC 0 - 50 Deg C / 0.2 % accuracy |
| Simple Calibration | Two points - Multipoint Calibration Point Option |
| SI Units |
mg/L / % Dissolved H20 - Degrees Celsius - User adjustable |
| Analogue Output |
Optional - 0-2 V DC - proportional to concentration and temperature |
Optional USB Interface
Keynes Controls manufactures a range of accessories that can be used to connect the ARGES range of sensors to a Windows computer system and enable the sensors to be used in laboratory applications, multi-parameter instruments and calibration operations.
The optional USB media converters can be used to connect a multi-parameter instrument to a PC.
The media converter powers the ARGEs sensor range directly from the PC USB port.
Sensor Connections
The ARGES Dissolved Oxygen Sensor by Keynes Controls is easy to use. Simply connect the sensor to the network type of choice. The sensor will detect the network traffic and automatically start communications. It is now possible to make configuration changes and measurements.
All of the ARGES sensors have the same Pin-out as shown in the image opposite. Any ARGES sensor can be used in any port in the multi-parameter housing. The sensor interface cable connects to the top of the sensor to a PC or suitable digital network.
1 = +RS485 2 = -RS485 3 = SDI12 4 = Gnd 5 = 12V DC
Sensor Pin-out
Specifications
| ENVIRONMENTAL CHARACTERISTICS | ||||
| DO | MDL 0 % | Range 0 - 200 % | Non freeze | |
| User set range | Ambient Range: 0 - 50 Degree Celsius | |||
| Water Temperature: 0 to 50 Degree Celsius | ||||
| Accuracy | +/- 5 % of Reading | |||
| PHYSICAL DIMENSIONS | ||||
| Resolution | 0.01 % | |||
| Length x Diameter: 22 x 205 mm | ||||
| Sample Period |
|
Weight: 108 g | ||
| Wiper Trigger | SDI12 Command | aM! | Maximum Depth : 50 m - 500 m optional | |
| Excitation | UV | Built-in Network Types: | ||
| Housing | 316 Stainless Steel | MODBUS / SDI12 / RS485 / Analogue Output | ||
| Focal Point | In-front of sensor faceplate | |||
| Data Output | SI Units - %DO / Degrees C | Supply Voltage: 10 - 18 V DC Standby Current 0.3 mA 30 mA Active measurement |
Supported Commands
| Most commonly used commands | ||
| Start measurement | aM! | a05\r\n where 05 = time delay before measurement sent |
| Send ID | aI! | a14KEYNESCOISO000014\r\n Part description assigned by Keynes |
| Address Query | ?! | Where a = ID number - 0 - 9 (standard) / (a..z) Enhanced SDI-12 |
| 0 - 9 / a - z for RS485 | ||
| Change Address | aAb! | where a = Initial address and b = Final address |
| Start Measurement | aM! | Make a measurement - a = address of sensor |
| Example 1M! starts a measurement for sensor with ID=1 | ||
| Set Output Variables | XCSTR0! | Sets the parameter order for measurements sent from the sensor - factory set BCKL |
| Read Serial Number | aXSN! | Instrument Response a+Serial-number |
| Calibration Date | aXCD! | Instrument Response a+date |
| | | ||
| Calibration Commands | ||
| First Calibration point (ppb) | XCA0 | Typical value = 1000 (ppb) - High value |
| First Calibration - uncompensated (ppb) | XCA1 | Typical Value = 1000 as prepared from calibration standard |
| Second Calibration point (ppb) | XCA0 | Typical value = 20 (ppb) |
| Second Calibration - uncompensated (ppb) | XCA1 | Typical Value = 20 as prepared from calibration standard |
Built-in Communication Options
The ARGES Dissolved Oxygen Sensor by Keynes Controls supports SDI-12, RS485 and MODBUS digital communications as standard enabling the sensors to be directly connected to Data Logger for remote web based reporting, onto Wi-Fi and Local Area Networks using the RS485 option, and directly into SCADA applications using the MODBUS.
Additional Information:
Related Products by Keynes Controls: ARGES pH, ARGES Tryptophan, ARGES Conductivity, ARGES Nitrate, ARGES Turbidity, ARGES Hydrocarbon, ARGES CDOM, Dissolved Oxygen, ARGES Chloride, MODBUS, SDI12,RS485 , USB-SDI12-AG1, USB-485-Pro, QLOG, Turbidity, Conductivity, ARGES PAH, ARGES Hydrocarbon, Ammonia, Ammonium, ARGES Brush, SONDE. Cryptospiridium, Kathryn Thomas
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