Choosing the Right Gas Detection Technology: A Comparison of Catalytic Bead, NDIR, Electrochemical, and PID Sensors
When selecting a gas detection system for industrial, utility, or commercial applications, understanding the strengths and limitations of each sensor type is critical. Below is a comparison of four widely used gas detection technologies: Catalytic Bead, Non-Dispersive Infrared (NDIR), Electrochemical, and Photoionization Detectors (PID).
Below a comprehensive comparison between different type of gas sensors
Factor | TDLAS (Laser) | NDIR (Infrared) | Catalytic Bead | Electrochemical | Semiconductor (MOS) | Thermal Conductivity |
Detection Sensitivity | Very high (ppb levels detectable) | High (ppm levels detectable) | Moderate (detects %LEL levels, i.e. thousands of ppm) | High (ppm or sub-ppm with new designs) | Moderate (ppm-level detection; typically needs tens of ppm) | Low (detects only high gas concentrations; e.g. percent levels) |
Response Time | Fast (near-instantaneous) | Fast (seconds) | Moderate (seconds to tens of seconds) | Moderate (seconds to ~1 minute) | Moderate (seconds to tens of seconds; slower recovery after exposure) | Fast (seconds, limited by gas diffusion) |
Selectivity | Very high (methane-specific, minimal cross-gas interference) | Moderate (selective to hydrocarbons, some cross-sensitivity to other IR-absorbing gases) | Low (responds to any combustible gas; non-specific) | High (designed for CH₄; minor cross-sensitivity if catalyst is specific) | Low (responds to multiple gases; not methane-specific, high cross-sensitivity) | Low (non-specific; responds to any gas with different thermal conductivity) |
Oxygen Requirement | No (optical detection, works in inert atmosphere) | No (optical detection, works in inert atmosphere) | Yes (requires O₂ for combustion) | No** | Yes (requires O₂ for surface reactions on sensor) | No (works in inert atmosphere; purely physical measurement) |
Maintenance / Lifespan | Low maintenance; stable calibration; long life (laser source ~years) | Low maintenance; minimal drift; sensor life >10 years | High maintenance; frequent calibration; sensor life ~2-5 years (can fail if poisoned) | Moderate maintenance; periodic calibration; sensor life ~2-5 years (electrolyte limited) | Moderate maintenance; periodic calibration needed (some drift over time); sensor life ~5-10 years (resistant to poisoning) | Low maintenance; minimal drift; sensor life >10 years (no catalyst to degrade) |
Relative Cost | Very high (most expensive) | Medium (mid-range cost) | Low (least expensive per unit) | Medium (projected to be low-cost when widely available) | Low (inexpensive per unit; widely used in consumer detectors) | Medium (moderate cost; simple design, niche application) |
