When comparing flammability analyzers and catalytic sensors for process applications, we've already talked about speed of response and failsafe performance. Our next topic is response factors.
Catalytic sensors have a broad response range and will react to many different combustible vapors. But they react differently to different substances and do not have the ability to selectively measure just one substance in the presence of others.
When a sample contains vapors from more than one substance, safety codes require that the sensor be calibrated for the vapor to which it is least sensitive. This causes the sensor to overreact to the other components of the sample, generating false high alarms. Sensors safely calibrated for the vapors in a specific process often require recalibration when changing process set-ups.
Catalytic sensors are expendable devices. As they react with combustible vapors, some of the catalyst is depleted causing a shift in their response. When used to measure typical vapor concentrations in process applications, frequent recalibration will be required to assure proper performance.
Over time, catalytic sensors will lose sensitivity to some vapors while still being able to react to others. That is why a catalytic sensor can test good when calibration gas is injected even though it is unable to sense the presence of one or more of the process vapors.
A flammability analyzer gives consistent and reliable readings even when faced with multiple or changing solvent concentrations. This technology provides the ability to accurately measure solvent concentrations for an array of solvents, even though it was calibrated on only one specific solvent. There is no need for recalibration, giving you excellent cross-calibration accuracy and ultimately eliminating incorrect readings.