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Where are they found?
Chlorine (Cl2) is a greenish-yellow gas with a strong, irritating odour. It is highly reactive and classified as a toxic gas. Cl2 is not flammable, but it is an oxidising agent, meaning it can intensify fires when in contact with combustible materials.
Chlorine dioxide (ClO2) is a reddish-yellow gas with a pungent chlorine-like odour. It is a strong oxidising agent. Though effective in microbial control, it is also a toxic air pollutant and regulated due to its potential health and environmental impacts.
Neither Cl2 nor ClO2 are naturally present, but they are widely present in industrial processes. Their presence in the environment is mainly due to human activity in the paper and textile industry, wastewater treatment plants (WWTP) and chemical manufacturing.
Why are they harmful?
Both Cl2 and ClO2 are highly toxic and pose serious health and environmental hazards.
Their inhalation can cause severe irritation of the respiratory tract, coughing and pulmonary edema, while contact with the skin or eyes leads to painful burns and tissue damage. Chronic exposure may result in long-term respiratory conditions.
Environmentally, they are extremely harmful to aquatic organisms.
Cl2 – ClO2 cartridge
The Cl2 – ClO2 cartridge has a built-in electrochemical sensor capable of measuring both Cl2 and ClO2 pollutants, from low concentrations (ppb level) to high concentrations. The cartridge is calibrated against Cl2, while the response to ClO2 is higher than 70%.
This dual cartridge is an excellent option for measuring chlorine compounds when coexisting in the same applications (WWTP, disinfection applications, etc.), offering high stability, fast response and recovery, and robustness under environmental conditions, making it an excellent cartridge for industrial monitoring.
Technical specifications
| Type | Electrochemical |
| Unit of measurement | mg/m3, ppm |
| Measurement range (1) | 0–20 ppm |
| Resolution (2) | 0.01 ppm |
| Operating temperature range (3) | -20 to 50 °C |
| Operating RH range (4) | 0 to 99 %RH |
| Recommended RH range (5) | 15 to 90 %RH |
| Operating life (6) | > 24 months |
| Guarantee range (7) | 250 ppm |
| Limit of Detection (LOD) (8) | 0.01 ppm |
| Repeatability (9) | — |
| Response time (10) | < 60 sec |
| Typical accuracy (12) | ± 0.03 ppm |
| Typical precision R2 (11) | — |
| Typical slope (11) | — |
| Typical intercept (a) (11) | — |
| DQO - Typical U(exp) (13) | — |
| Typical intra-model variability (14) | < 0.01 ppm |
- Measurement range: Concentration range measured by the sensor.
- Resolution: Smallest unit of measurement that can be indicated by the sensor.
- Operating temperature range: Temperature interval at which the sensor is rated to operate safely and provide measurements. In the PM sensor Type A: -40 to 50 °C with heater (more information on this version on request).
- Operating RH range: Humidity interval at which the sensor is rated to operate safely and provide measurements.
- Recommended RH range: Recommended relative humidity range for optimal sensor performance. Continuous exposure outside the recommended range may damage the cartridge.
- Operating life: Time period during which the sensor can operate effectively and accurately under normal conditions.
- Guarantee range: Concentration range covered by Kunak's guarantee.
- LOD (Limit of Detection): Measured at laboratory conditions at 20 °C and 50% RH. The limit of detection is the minimum concentration that can be detected as significantly different to zero gas concentration, calculated according to the Technical Specification CEN/TS 17660.
- Repeatability: Measured at laboratory conditions at 20 °C and 50% RH. Closeness of the agreement between the results of successive measurements of the same measurand carried out under the same conditions of measurement, calculated according to the Technical Specification CEN/TS 17660.
- Response time: Time needed by the sensor to reach 90% of the final stable value.
- Typical precision – R2, slope and intercept: Statistics obtained between the device hourly measurements and reference instruments in field tests between -10 to +30 °C at different locations. For the type B PM sensor, the expected error for PM10 is higher in the presence of coarse particles.
- Typical accuracy: For criteria pollutants, this is the average Mean Absolute Error (MAE) obtained between the device hourly measurements and reference instruments for 1 to 8 months of field tests between -10 to +30 °C in different countries. For other pollutants, it is the expected error of the measurement at the reading.
- DQO - Typical U(exp): Data Quality Objective expressed as the Expanded Uncertainty in the Limit Value obtained between the device hourly measurements and reference instruments for 1 to 8 months of field tests between -10 to +30 °C in different countries, calculated according to the European Air Quality Directive 2024/2881 and the Technical Specification CEN/TS 17660. For the type B PM sensor, the expected error for PM10 is higher in the presence of coarse particles.
- Typical intra-model variability: Calculated as the standard deviation of the three sensor means in 1 to 8 months of field tests between -10 to +30 °C in different countries.
A, B, C, D superindex: The super indexes refer to different types of cartridges related to the same target pollutant but with different technical specifications.
