ARGES Fluorescent-pH Sensor by Keynes Controls
ARGES pH Sensor
The Intelligent ARGES Fluoro-pH Sensor By Keynes Controls is a submersible fluorescent based sensor that has been designed to simplify the acquisition of water quality measurement parameters into any platform that supports real-time reporting, data logging operations. Fully compliant with Section 82 of the UK Environment Act 2021, this sensor delivers long-term stable measurements for stand-alone submerged pH monitoring, outperforming traditional glass-bulb devices in reliability and durability.
The ARGES Fluoro-pH sensor does not have a reference cell or require any reagents for operations.
pH in water sources
pH is a measure of the hydrogen ion concentration of the water as ranked on a scale of 1.0 to 14.0. The lower the pH of water, the more acidic it is. The higher the pH of water, the more basic, or alkaline, it is. pH affects many chemical and environmental processes in the water and different organisms have different ranges of pH within which they live and flourish.
The largest variety of aquatic creatures prefer a pH range between 6.5 to 8.0. pH outside of this range reduces the diversity in the water source because it stresses the physiological systems of most organisms and can reduce reproduction. A low pH level can also allow toxic elements and compounds such as heavy metals to become mobile and "available" for uptake by aquatic plants and animals.
The ARGES pH Sensor by Keynes Controls can accurately measure the pH in rivers, lakes and other water sources. Allow the sensor to settle to a steady-state value.
Part Numbers: ARGES-FLRpH-3 range 3.5 to 6.5 pH
ARGES-FLRpH-6 range 6 to 8.5 pH
ARGES-FLRpH-8 range 8-11 pH
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.
Additional Material:
Freshwater lakes, ponds and streams usually have a pH of 6-8 depending on the surrounding soil and bedrock ²¹. In deeper lakes where stratification (layering) occurs, the pH of water is generally higher (7.5-8.5) near the surface and lower (6.5-7.5) at greater depths.
The ARGES sensor covers the range shown above.
Product Features
| TYPE | RANGE (Typical levels) |
| Response | Fastest 1 Sec - Settling from dry 30 mins to be hydrated. |
| Measurement range: 3 models |
3.5 - 6.5 6 - 8 8 - 11 pH |
| Resolution: | 0.1 pH - 4 digits 2 decimal places |
| Accuracy: | +/- 0.02 pH - Typical |
| Temperature |
1-50 Deg C |
| Sensor re-calibration Period | 800-hours continuous use recommended. |
| pH Range | 0 - 14 |
| Operation | Fluorescent |
| Temperature Sensor | NTC 0 - 50 Deg C / 0.2 % accuracy |
| Sensor Type | pH sensitive Hydrogen readings |
| Built-in Digital Networks |
SDI12 / RS485 / MODBUS Digital Communications |
| Calibration Details | 2 Points using Calibration Standards. |
| Operation |
Stand-alone / Multiparameter system |
Calibration Summary
The Intelligent Submersible FLUORO-pH Sensor By Keynes Controls can be used within SONDE multi-parameter housing, or as a stand-alone sensor. The pH sensor should calibrated using the standard solutions available from the on-line shop.
The ARGES FLUORO-pH Sensor by Keynes Controls should be calibrated at 2 points over the defined range. . The overall accuracy of the sensor will depend upon how well has calibrated.
There is a sensor calibration mode in the QLOG software, The user enters the light level for the calibration points. Very simple and fast.
The ARGES pH Sensor by Keynes Controls user calibration Window in the Free QLOG software enables fast calibration and testing of the sensor.
Storage and Handling
When not in use the ARGES pH Sensor By Keynes Controls head should be kept hydrated with the protective cap attached.
Storage temperature range : 2 - 60 Degrees Celsius.
It is safe to store the sensor dry for a considerable time but the sensor must be rehydrated before use.
Using Buffer Solutions
When calibrating the PH sensor, best practice is using buffer solutions that bracket the expected range. For example, if you want test water you expect to be in the 7-8 pH range, using buffer solutions for 6 and 9 pH is advisable.
Buffer solutions have limited shelf life, and their ability to maintain their pH in the face of contamination is limited. As such you shouldn’t reuse buffer solutions, especially not over a long period. Never return used solution to a stock bottle, this will contaminate the stock solution.
There are several internationally recognised pH scales, such as those developed by the United States’ NIST or United Kingdom’s BSI, but all are functionally interchangeable for practical purposes. While buffer solutions recognised by them do vary their pH with temperature, the effect is very limited.
Product Specifications
| Network Type | ENVIRONMENTAL CHARACTERISTICS | |||
| SDI12 | 1.4 / Enhanced address supported. | Temperature Range: 0 to 60 Degree Celsius | ||
| RS485 | Ambient Range: 0 - 50 Degree Celsius | |||
| MODBUS | 16 and 32 Bit Registers | Water Temperature: 0 to 50 Degree Celsius | ||
| Maximum Depth: 50 m | ||||
| Process Electrodes: | Solid State Electrodes | |||
| Glass cell - Solid reference | PHYSICAL DIMENSIONS | |||
| Material | PVC / Stainless Steel | Length x Diameter: 22 x 220 mm | ||
| Weight: 97 g | ||||
| Settling Time |
|
Maximum Depth : 50 m | ||
| Return Parameters Order | User Defined | |||
| Built-in Network Types: | ||||
| Excitation | Galvanic | SDI12 V1.4/ RS485 / MODBUS over 485 | ||
| Housing | 316 Stainless Steel and PVC | |||
| Sensor Connector | Gold Plated | Power Requirement | ||
| SI Units | Automatically Defined | Voltage Range: 10-18 V DC | ||
| Data Output | pH Deg °C | Standby Current: 1 mA Typical | ||
| Temp Compensated | pH Deg °C | Reading: 10 mA Typical |
Please Note: The pH sensors are pre-calibrated at the factory.
Supported Commands
The order for which the measurements are returned from the sensor can be user defined using the sensor configuration settings shown below. Use the free QLOG software to adjust the sensor setup and configuration.
Most Used Commands - SDI12
| Description | Command | 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 |
| Set Output Variables | XCSTR0 | Sets the parameter order for measurements sent from the sensor - factory set BCDM |
| Read Serial Number | aXSN! | Instrument Response a+Serial-number |
| Calibration Date | aXCD! | Instrument Response a+date |
| First Calibration point (pH) | XCA0 | 3.5 pH |
| First point raw light level | XCA1 | Typical Value =127 |
| Second point (pH) | XCA2 | 4.5 pH |
| Second point uncompensated (LUX) | XCA3 | 90.48 Typical background light level |
| - | - | - |
| User Assigned Parameters | ||
| First Calibration point (pH) | First calibration solution concentration in pH | |
| First calibration point (LUX) | Raw light level reading at 1st calibration point | |
| Second Calibration point (ppm) | Second calibration solution concentration in pH - eg 6.5 | |
| Second calibration point (mV) | Raw Sensor light level at 2nd calibration point | |
| SDI12 V1.14 Units | Automatically assigned - pH, Deg °C | |
| Calibration Temperature | Temperature in Deg C at which the calibration was undertaken | |
Commonly used with: Typtophan, Turbidity, Dissolved Oxygen, Ammonium
The pH Sensor by Keynes Controls monitors the levels of pH in water. The ARGES pH Sensor by Keynes Controls readings can be affected by changes in temperature and salinity. This sensor is frequently paired with: Turbidity, Tryptophan, Dissolved Oxygen, Ammonium sensors. All of the ARGES range chemical sensors have temperature sensors built-in.
Turbidity Sensor =The ARGES Turbidity sensor by Keynes Control is a single-channel instrument that can detect and report turbidity levels in the range of 0.5 - 1500 NTU. Read More...
Submersible Tryptophan sensor = The Intelligent Submersible ARGES Tryptophan Sensor by Keynes Controls, is a high performance submersible fluorometer that has been designed to detect the prescence of sewage levels in water souces as part of water quality measurement solution.
Dissolved Oxygen
Oxygen is consumed as ammonia is oxidised (nitrification), and low oxygen levels increase ammonia levels by inhibiting nitrification. The ARGES Dissolved Oxygen sensor is used to monitor the oxygen levels in river water.
Built-in Communication Options
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
Q-LOG Software
The ARGES pH Sensor is integrated into the Keynes Controls free Q-LOG software.
Our Q-LOG software runs on the widely recognised Windows Operating system, and gives the user the ability to calibrate, adjust instrument network operations, and effortlessly display measurements on a series of panel meters and charts. Conveniently store results in text based files for quick analysis in spreadsheets.
Our highly chemical sensors provide chemical concentration and local temperature readings in SI units (Engineering units). Customise the SI units based on your instrument's capabilities, including support for multiple units like turbidity sensors, all easily managed through the device setup.
