Features and characteristics of single pass monitors:
- Suitable for stacks up to 20m diameter
- Requires clean stack gas for calibration
- More suited to higher emissions levels
By comparison, the double pass light transmission measurement technique uses a folded beam transceiver/reflector arrangement. A light beam emitted from the transceiver (TRX) passes across the duct, stack or flue to a reflector. The reflector then returns the light to the transceiver where the intensity of the received light is measured providing either particulate or opacity readings.
![](https://cdn.bfldr.com/Q3Z2TZY7/at/nzxhhg42j887rnrgxc35nn/Environmental_resources_news_1311_ACOEM-single-and-double-pass-diagrams-s11.jpg?auto=webp&format=jpg&auto=webp&width=800)
Features and characteristics of double pass monitors:
- Suited to smaller diameter stacks up to 10m
- Calibration check while process is running
- No power required to passive reflector head
- More suited for lower emission applications
Acoem offer a range of monitoring technologies including both single and double pass light transmission monitors along with options and accessories to create a customised monitoring solution for your emission monitoring application.