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* H2S co-location field study *
Where is it found?
Most of this gas in the atmosphere has a natural origin from organic matter decomposition. From human activities, it occurs in processes involving sulphur compounds and organic matter at high temperatures.
Some industrial activities that emit this gas are paper pulp manufacturing, oil refining, water treatment plants and the viscose manufacturing textile industry.
Why is it harmful?
Hydrogen sulfide (H2S) mainly affects the respiratory system, with the first symptoms being nose, throat and eye irritation.
This compound begins to be detected by human smell at concentrations much lower than those that can harm health. Short-term exposures to high concentrations can cause headaches, dizziness and vomiting.
H2S cartridge
The H2S cartridge has a built-in electrochemical sensor very sensitive to its target pollutant, allowing it to detect small changes in H2S concentration. This cartridge also responds to methyl mercaptan (CH4S) and other total reduced sulphur compounds (TRS).
To cover different applications, there are two measurement ranges:
- Type A: Detects low ppb concentrations in real environments. Although the Kunak algorithm corrects temperature variations well, it is not recommended to use this cartridge to measure levels below 15 ppb.
- Type B: A higher range version that can measure up to 20 ppm, with lower precision at low concentrations.
Technical specifications
| Type | Electrochemical |
| Unit of measurement |
µg/m3, ppb (A) mg/m3, ppm (B) |
| Measurement range (1) |
0–2,000 ppb (A) 0–20 ppm (B) |
| Resolution (2) |
1 ppb (A) 0.01 ppm (B) |
| Operating temperature range (3) | -30 to 50 °C |
| Operating RH range (4) | 0 to 99 %RH |
| Recommended temp. & RH range (5) |
-30 to 45 °C 15 to 90 %RH |
| Operating life (6) | > 24 months |
| Guarantee range (7) | 100 ppm |
| Limit of Detection (LOD) (8) |
2 ppb (A) 0.01 ppm (B) |
| Repeatability (9) |
4 ppb (A) 0.01 ppm (B) |
| Response time (10) | < 60 sec |
| Typical accuracy (12) |
± 10 ppb (A) ± 0.05 ppm (B) |
| Typical precision R2 (11) | > 0.8 |
| Typical slope (11) | 0.78–1.29 |
| Typical intercept (a) (11) |
-5 ppb ≤ a ≤ +5 ppb (A) -0.05 ppm ≤ a ≤ +0.05 ppm (B) |
| DQO - Typical U(exp) (13) | — |
| Typical intra-model variability (14) |
< 2 ppb (A) < 0.02 ppm (B) |
- 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.
