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Where is it found?
Ammonia (NH3) is a colourless gas with a pungent odour that can be detected by humans at 0.4–1 ppm. The source lists an exposure limit of 50 ppm.
NH3 originates from both natural and anthropogenic sources, the main ones being agriculture (fertiliser application and fabrication) and livestock (manure management), followed by waste and water management (slurries, composting and landfills). Other sources are household and industrial cleaners, which can directly affect humans exposed to them.
Why is it harmful?
NH3 is a volatile gas that is poisonous if inhaled at high concentrations, causing respiratory tract and eye irritation, while causing throat and skin irritation in lesser amounts. It is highly soluble in water, so it is associated with acid deposition and eutrophication, affecting land and water ecosystems by reducing biodiversity.
Besides, it is explosive when mixed with air or oxygen at very high concentrations. NH3 also contributes to the formation of particulate aerosols in the atmosphere as a secondary particulate precursor.
NH3 cartridge
The NH3 cartridges contain electrochemical sensors that accurately measure NH3 in different ranges. The following cartridge types are shown for different applications:
- Type A: Used to detect low concentrations up to 50 ppm, with a typical noise of less than 0.3 ppm when the ambient temperature is below 25 °C. This sensor is responsive to H2S when present at high concentrations (ppm level), which is relevant since the two substances can coexist in the same environment. Therefore, to accurately measure NH3, it is necessary to have the H2S cartridge installed in the same device when high H2S concentrations are present. Kunak's algorithm considers both concentrations to correct H2S interference and obtain precise NH3 measurements.
- Type B: A higher range version used to carry out continuous measurements of concentrations up to 1,500 ppm, with lower precision at low concentrations.
Type A and Type B sensors are specially designed for industrial leak detection and are not intended for environments with continuous background NH3 concentrations, such as livestock facilities.
Technical specifications
| Type | Electrochemical |
| Unit of measurement | mg/m3, ppm |
| Measurement range (1) |
0–50 ppm (A) 0–1,500 ppm (B) |
| Resolution (2) | 0.01 ppm |
| Operating temperature range (3) |
-10 to 50 °C (A) -20 to 43 °C (B) |
| Operating RH range (4) | 0 to 99 %RH |
| Recommended RH range (5) | 15 to 90 %RH |
| Operating life (6) | > 24 months |
| Guarantee range (7) |
100 ppm (A) 5,000 ppm (B) |
| Limit of Detection (LOD) (8) |
0.02 ppm (A) 0.15 ppm (B) |
| Repeatability (9) |
0.03 ppm (A) 0.5 ppm (B) |
| Response time (10) |
< 45 sec (A) < 45 sec (B) |
| Typical accuracy (12) |
± 0.3 ppm (A) ± 1.5 ppm (B) |
| Typical precision R2 (11) | — |
A and B: Superscripts identify the cartridge types described above.
