Does in-situ mean maintenance-free?
No. Optics, purging, alignment and signal quality still need checking.
ABB · Analytical measurement
In-situ laser gas analysis
Measuring directly in the duct can reduce sample transport delay. The application must still provide a usable optical path.
Optical measurement in the process
TDLS measures absorption at a gas spectral line. ABB includes LS25 for in-situ measurement in the Advance Optima range; selection depends on the component and the optical and process conditions.
Where it can help
- Processes where extractive sample-line delay is critical.
- Combustion or flue-gas treatment control with available optical access.
- Measurements where sample transport may alter concentration.
Checks before selection
| Aspect | Why it matters |
|---|---|
| Component and range | The laser is selected for the required measurement; it is not a universal analyser. |
| Optical path | Duct distance and geometry influence achievable sensitivity. |
| Dust and windows | Attenuation and fouling can reduce signal quality. |
| Temperature and pressure | Minimum, normal and maximum conditions are needed for application assessment. |
| Purging | Define the purge gas, flow and availability to protect the optics. |
| Accessibility | Alignment and maintenance require access suited to the mounting arrangement. |
Comparison with extractive measurement
A cross-duct measurement represents the optical path, while an extractive probe samples at one point. If the gas is stratified, the readings may differ without either instrument being faulty. Point selection and sample representativeness are part of the design.
ABB documentation
Information for a quotation
To select an in-situ laser analyser, send us the following information, even if preliminary:
- Components to be measured, background gas and expected interferents.
- Normal, minimum and maximum ranges; units and dry or wet basis.
- Pressure and temperature at the sampling point; moisture, dust and condensable components.
- Required response time, number of points and distance from the sampling point.
- Area classification, indoor/outdoor installation, available signals and utilities.
- Duct diameter, usable optical path length, access and purge gas availability.
Frequently asked questions
Can one laser measure all components together?
No. Measurable species and combinations depend on the selected version.