One of the first challenges for choosing a gas detecting product is to determine which gas sensor technology you need. Gas detection sensor technologies have differing functionality and their limitations depend on the conditions they’re exposed to.
Understanding the properties of gas detecting sensors will boost your product selection decision. Choosing the right sensor type for gas monitoring involves an assessment of many factors: Atmospheric Conditions, Environmental Conditions (Temperature/Humidity), Oxygen Content, Poisons and Interferences.
| Sensor Type | Catalytic | Electrochemical | Point IR | Open Path | PID | Semiconductor | Paper Tape |
| Works in inert atmosphere | No (requires presence of Oxygen) | No (requires presence of Oxygen) | Yes | Yes | Yes | No (requires presence of Oxygen) | No (requires presence of Oxygen) |
| Resistant to poison | Susceptible to poisons like Lead and Sulphur containing compounds, silicones vapours and phosphates | Yes | Yes | Yes | Yes | Susceptible to poisons like Halide compounds, Silicone vapours, caustic and acid liquids and concentrated vapours | Yes |
| Detects Hydrogen | Yes | Yes | No | No | No | No | No |
| Performance in 100% humidity | Yes | Yes | Yes | Yes | No | Yes | No |
| Performance in typical pressure conditions | Yes | Yes | Yes | Yes | Yes | Yes | Yes |
| Performs in all temperatures | Yes | No (some sensors can be unstable in low and high temperatures) | Yes | Yes | Yes | No, some sensors can be compromised below -40C and above 90C | No, some sensors can be compromised below -40C and above 90C |
| Immune to dust/dirt | Yes, with adequate weather and dust protection | Yes, with adequate weather and dust protection | Yes, with adequate weather and dust protection | Yes, with adequate weather and dust protection | Yes, with adequate weather and dust protection | Yes, with adequate weather and dust protection | Yes, with adequate weather and dust protection |
| Immune to sunlight | Yes | Yes | Yes | Yes | Yes | Yes | No (decays tape) |
| Performance in O2 enriched atmosphere | Yes | No (can alter readings and response) | Yes | Yes | Yes | No (can alter readings and response) | No (detection of mineral acids is compromised in Oxygen enriched atmospheres) |
| Immune to human interference | No | No | No | No, e.g. poor alignment | No | No | No |
| Speed of response | <20 secs | <30 secs (typical) | <6.5 secs | <3-5 secs | <5 secs | <60 secs | <10-30 secs |
| Maintenance requirement | High | High | Low | Low | High | High | High |
For more, in-depth analysis, read our Gas Detection Sensor Selection guide
