Many conductivity sensors on the market are big and bulky or probes with separate evaluation units that require matching and calibration in the field. ifm's LDL conductivity sensor is an all-in-one transmitter and does not require calibration in the field prior to use.
Each conductivity sensor is factory calibrated during production to offer good performance out of the box.
ifm conductivity sensors come ready to use out of the box but can also be adjusted in the field for specific media, reference temperatures, or to match known concentration curves. The two main parameters that can be adjusted to match a known value or reference sensor are the Calibration gain [CGA] and Temperature compensation [T.Cmp].
Calibration gain [CGA] adjusts the measurement curve of the sensor to match the conductivity of a known value at a given reference temperature.
Temperature compensation [T.Cmp] adjusts the rate of change the conductivity changes as medium temperature changes.
Adjusting the CGA and T.Cmp provides the highest accuracy of the measured conductivity. Depending on your application, these adjustments may not be necessary.
1 | Maintain calibration solution at the reference temperature. |
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2 | Set sensor temperature compensation [T.Cmp] parameter to 0% and dAP = 0. Download settings to sensor. |
3 | Insert sensor into calibration fluid** and make sure media temp is stable at reference temperature. |
4 | Adjust calibration gain [CGA] percentage up/down from 80…120% to match conductivity of calibration solution. CGA = known conductivity of calibration solution / measured value * 100. Enter this new % value for the calibration gain [CGA] parameter. |
5 | Enter reference temperature [rEF.T] of the process media if known, otherwise use default. |
6 | Return temperature compensation [T.Cmp] parameter to desired % (default 2%) and dAP = 1 |
7 | Download the changes to the sensor. |
**Alternatively, the sensor can be adjusted while installed using the above process to match the measurement to that of an existing device which has recently been calibrated.
LDL100 sensors
Since the LDL100 is not a traditional conductivity with a fixed cell constant, the measured conductivity is influenced by the installed environment. The sensor accuracy stated on our datasheets include variability from sensor to sensor as well as variabilty due to installation. By eliminating the variability due to the installed environment, adjusting the CGA will significantly improve measurement accuracy.
Installed pipe size | Calibration gain (CGA) |
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1-1/2" | 96% |
2" | 97% |
3" | 100% |
> 3" / tank | 107% |
1 | Install the sensor in the application or in same size pipe section to replicate the installation environment. Sensor accuracy is highly influenced by installation. |
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2 | Maintain calibration solution at the reference temperature (typically 25 °C. |
3 | Set sensor temperature compensation [T.Cmp] parameter to 0% and dAP = 0. Download settings to sensor. |
4 | Flow calibration medium through the system or insert pipe section into the medium. |
5 | Adjust calibration gain [CGA] percentage up/down from 80…120% to match conductivity of calibration solution. CGA = known conductivity of calibration solution / measured value * 100. Enter this new % value for the calibration gain [CGA] parameter. |
6 | Enter reference temperature [rEF.T] of the process media if known, otherwise use default. |
7 | Return temperature compensation [T.Cmp] parameter to desired % (default 2%) and dAP = 1 |
8 | Download the changes to the sensor. |
1 | Set [T.Cmp] to 0% and [dAP] to 0 and download the change to the sensor. |
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2 | Measure conductivity (C1) at temperature (T1), making sure temperature is stable. |
3 | Change the medium temperature, wait until it is stable, and measure conductivity (C2) at new temperature (T2). |
4 | [T.Cmp] = (C2 - C1) ÷ C1 (T2 - T1) x 100 . Enter this new value for [T.Cmp}. |
5 | Return temperature compensation [T.Cmp] parameter to ON and dAP = 1 and download the change to the sensor. |