CDOM/fDOM (Dissolved Organic Material)
Dissolved Organic Material originates from many forms including secretions from organisms and humic acids. Concentrations of CDOM can have significant effect on many different biological activities in water systems such as rivers, reservoirs, bays. Very high concentrations of CDOM will have a limiting effect on photosynthesis and inhibit the growth of phytoplankton. Variations in CDOM levels are primarily the results of natural processes such as precipitation levels due to rain, human activities such as agriculture and effluent discharge.
Fluorescent dissolved organic matter, or fDOM, is the fraction of CDOM that fluoresces. Not all the components of CDOM fluoresce so fDOM measurements are used instead of CDOM directly.
The ARGES CDOM/fDOM Sensor by Keynes Controls is a single-channel instrument that can detect and report CDOM levels in the range of 0 - 1000 QSU and temperature in Degrees Celsius. The sensor has been designed to be used as a stand-alone laboratory instrument, as part of a multi-parameter device inside a Keynes Controls SONDE, and can be connected directly into a plant-wide SCADA system using the in-built MODBUS protocol. The SDI12 and RS485 digital networks enable the sensors to be directly connected to Web based data loggers, Wi-Fi and Local Area Networks.
In-situ measurement, no sampling, no reagents
• Direct SI Unit output of parameters
• Optical window with coating to minimize clogging
• Real time measurement
• Automatic compensation for temperature effects
Measurement Integrity
All of the ARGEs sensor range 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.
Why Measure CDOM
Dissolved Organic Material originates from many forms including secretions from organisms, humic and fulvic acids. Concentrations of CDOM can have significant effect on many different biological activities in water systems such as rivers, reservoirs, bays. Very high concentrations of CDOM will have a limiting effect on photosynthesis and inhibit the growth of phytoplankton. Variations in CDOM levels are primarily the results of natural processes such as precipitation levels due to rain, human activities such as agriculture and effluent discharge.
Application
The Continuous monitoring of wastewater CDOM levels is used as is an indicator of discharge water quality.
Along with turbidity and chlorophyll, CDOM is an important consideration in determining light attenuation water bodies.
Commonly Used With
The ARGES CDOM/FDOM Sensor by Keynes Controls is commonly deployed with the Tryptophan, Chlorophyll , pH, Conductivity and Turbidity Sensors.
Application Software
The ARGES CDOM/fDOM fluorometer is supplied with free applications software that can be used Configure, Calibrate, make test measurements, store and display results. The Q-LOG software can be used with single sensors as well as the multi-parameter sensor systems.
The user can observe the real-time measurements in charts and panel meters as shown below.
Calibration Period
All of the ARGES sensors are Factory-calibrated before shipment. Keynes Controls recommends a check calibration every year and a full calibration every 2 years.
Calibration Solution
Keynes Controls offers Quinine Sulphate calibration solutions for The ARGES CDOM/fDOM Sensor by Keynes Controls on the online shop. The Quinine Sulphate solution fluoresces similar to CDOM. A minimum of a single point calibration can be used, however superior results will be achieved with a multiple point calibration at the temperature for which the sensor is to deployed.
Custom Calibration Range
In order to optimise the performance of The ARGES CDOM/fDOM Sensor by Keynes Controls then the calibration range can be adjusted to suit the range of the application required. The Applications software allows new calibration parameters to be written directly into the sensor.
Optional Accessories
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-SDI12-AG1 media converter can be used to connect any of the ARGES chemical sensors and multiparameter housings directly to a Windows PC without the use of any external power supply. The USB-SDI12-AGI media converter powers all the sensors directly from the PC USB port, making testing and configuration operational simple to undertake. All the ARGES chemical sensors come with the free QLOG application software.
Product Features
| TYPE | RANGE (Typical levels) |
| Fluorometer | |
| Concentration range: | 0.- 100 QSU / 0 - 100 ppb - other range on request |
| Resolution: | Five auto range scales: 0.00 - 999.9mg/l. |
| Accuracy: | +/- 1% of reading. |
| Stand-alone and SONDE Multi-parameter operations |
|
| Sensor Warranty | 2 year |
| Optional Analog Output | 0-2 Volts DC |
| pH Range | 0-14 |
| Response Time | 1 Sec |
| Built-in Digital Communications | SDI12 / RS485 / MODBUS Digital Communications |
| Sensor Information | User interrogation Serial Number and Last Calibration date |
| Simple Calibration | Multi point Calibration Point Option |
| SI Units |
Raw / QSU / ppb |
| Analogue Output |
0-2 V DC - proportional to concentration |
Factors adversely affecting measurement accuracy using fluorescence include:
- Interference from compounds which fluoresce at similar wavelengths.
- Differences in the fluorescent response caused by temperature effects.
- Differences in the fluorescent response caused by ambient light.
- Interference caused by turbidity.
- Temperature effects.
The ARGES CDOM/fDOM Sensor by Keynes Controls fluorometer is commonly deployed with with additional sensors that can be used to monitor additional parameters that affect the fluorescent response of the liquid under investigation such as Turbidity and pH. Temperature levels affect the fluorescent measurement. All the ARGES range fluorometers have in built temperature sensors.
Keynes Controls offer a series of multi-parameter SONDE housings for use with the ARGES chemical sensor range.
The ARGES-CDOM sensor can be installed into any of the Keynes Controls SONDE housings and connected to a data acquisition system. This means that any combination of the ARGES sensors can be installed into 3-Sensor and 7-Sensor SONDE housings and connected to a data acquisition system via the gold plated wet mate subsea connector mounted on the top of the housing.
The ARGES fDOM Sensor by Keynes Controls can be used a stand-alone sensor, or part of a multi-parameter package in the SONDE housing. The image below shows the multi-parameter SONDE on test using the Keynes Q-LOG software displaying turbidity results to the screen. The same results can be transmitted via an Internet logger across the internet.
A 7 Port SONDE with fluorometer and selective ion sensors installed
The ARGES CDOM/fDOM Sensor by Keynes Controls can be installed into any of the Keynes Controls SONDE housings and connected to a data acquisition system via the gold plated subsea connector mounted on the top of the housing. A wiper unit is available for use with this sensor and housing.
Specifications
| FDOM | ENVIRONMENTAL CHARACTERISTICS | ||
| Range: | 0..100 ppb (Standard) , 0..500 ppb on request | Ambient Range: 0 - 50 Degree Celsius | |
| MDL | 0.01 ppb | Water Temperature: 2 to 60 Degree Celsius | |
| Light Source | 354 nm | ||
| Measurement Principle: | Fluorescence | ||
| Parameter : | PAH Filter 360 nm | ||
| Resolution | 0.01 QSU / ppb | Built-in Temperature Sensor | |
| Accuracy | ± 0.3 QSU | Water Temperature: 0 to 60 °C | |
| Damage Resist lens | Maximum Depth: 100 m | ||
| Material | 316 Stainless Steel | ||
| Calibration Storage | All factors are stored internally | PHYSICAL DIMENSIONS | |
| Fast Start Time | <0.5 Sec | Length x Diameter: 22 x 220 mm | |
| Isolated Sensor Elements | Weight: 97 g | ||
| Sample Time | 1 sec | Maximum Depth : 60 m | |
| Wiper Trigger | SDI12 Command | ||
| Built-in Network Types: | |||
| Full Digital Operation | SDI12 / RS485 / MODBUS Digital Communications | ||
| Output Units | ppb / QSU / Degrees Celsius | Power Requirement | |
| Simple Calibration | 2 Point Calibration - Option additional points for greater accuracy | Voltage Range: 10-15 V DC | |
| Salinity | SI Units - ppt | Standby Current: 0.8 mA Typical | |
| Measurement 30 mA Typical | |||
| Warranty period: 2 years | |||
| Calibration period 2 years |
Supported Commands
The common commands shown below can be used with the SDI12 and RS485 networks. The MODBUS operations use a different command set to obtain measurements.
Most Used Commands - SDI12
| Description | Master | Instrument Response |
| Start measurement | aM! | a05\r\n where 05 = time delay before measurement sent |
| Send ID | al! | 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 |
| Concurrent measurement: Used for starting a measurement for all the sensors in a SONDE or on a digital network. |
aC! | Start a measurement for sensor on address 'a'. |
| Read Serial Number | aXSN! | Instrument Response a+Serial-number |
| Calibration Date | aXCD! | Instrument Response a+date |
| Row 3 | ||
| Row 4 |
Built-in Communication Options
The ARGES CDOM/fDOM Sensor by Keynes Controls will support 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. H2O, water, H20
All of the ARGES chemical sensors act as MODBUS slave and must be polled from the network master in order to access the measurements.
MODBUS Operations
ALL of the ARGES range of chemical sensors support MODBUS network operations The sensors act as a slave unit only and can communicate to suitable controllers and SCADA systems that support the MODBUS Protocol. The sensors support 16 and 32 bit registers. .
The ARGES sensors can be connected to a PC based system using the optional USB-485-Pro media converter. This device can power the chemical sensor and supports the correct timing protocols for data transmission for MODBUS and standard RS485 network communications
Additional Information:
Related Products by Keynes Controls: ARGES pH, ARGES Tryptophan, ARGES Conductivity, ARGES Turbidity, ARGES Hydrocarbon, ARGES CDOM, Dissolved Oxygen,
Key Words Related to Identifying Our Products or Intended Product Use or Product Outcome: Water, H2O, Water Disinfection, Water Sterilization