Technical Notes
碳分析仪器比较
Inter-Instrument (Sunset vs. DRI Model 2001 Thermal/Optical Carbon Analyzer) comparison
Comparison of instrument design between Sunset and DRI ECOC analyzer
1 Oven design
The structure is more or less the same. The major difference is that DRI front port is connect to a "auto sampler" and the movement of sample boat is controlled by linear actuator while sample feeding in Sunset is manually. Sunset has one port for thermocouple while the in DRI's design the thermocouple is combined with sample boat. DRI has one port for acid injection but sunset didn't provide this feature.
1 Oven design
The structure is more or less the same. The major difference is that DRI front port is connect to a "auto sampler" and the movement of sample boat is controlled by linear actuator while sample feeding in Sunset is manually. Sunset has one port for thermocouple while the in DRI's design the thermocouple is combined with sample boat. DRI has one port for acid injection but sunset didn't provide this feature.
2 Sample feeding
DRI analyzer sample feeding
The unique feature of DRI analyzer is that it allows sample boat moves after front port sealed. These making acid injection become possible. Since movement is done by linear actuator, the positioning and alignment with laser is expected to be more precise. However, the trade-off is that leaking happens frequently at the fitting part, the user have to tighten the nut every a few days and need to replace the ferrule when tightening didn't help.
DRI analyzer sample feeding
The unique feature of DRI analyzer is that it allows sample boat moves after front port sealed. These making acid injection become possible. Since movement is done by linear actuator, the positioning and alignment with laser is expected to be more precise. However, the trade-off is that leaking happens frequently at the fitting part, the user have to tighten the nut every a few days and need to replace the ferrule when tightening didn't help.
Sunset analyzer sample feeding
There are no moving parts in Sunset's front port so it's more robust. The trade-off is that the positioning of sample to the laser may varied by user operations. And also, there's no port for acid injection.
There are no moving parts in Sunset's front port so it's more robust. The trade-off is that the positioning of sample to the laser may varied by user operations. And also, there's no port for acid injection.
3 Laser configuration
DRI laser configuration
DRI use quartz light pipe to guide the travel of laser, which minimize the mirage effect.
DRI laser configuration
DRI use quartz light pipe to guide the travel of laser, which minimize the mirage effect.
Sunset laser configuration
The laser traveled in carrier gas/ambient air, when heated, the laser signal will expect attenuation due to mirage effect. Correction can be applied using the data during cool down process.
The laser traveled in carrier gas/ambient air, when heated, the laser signal will expect attenuation due to mirage effect. Correction can be applied using the data during cool down process.
4 Miscellaneous
Punch size. Sunset is 1/1.5 cm2 DRI is 0.5 cm2
Punch size. Sunset is 1/1.5 cm2 DRI is 0.5 cm2
The DRI heating coil for sample oven embed modular design, it's not only easier to replace, but also minimize the variability of heating efficiency induced during heating coil installation.
Related Publication: Wu, C., Huang, X. H. H., Ng, W. M., Griffith, S. M., and Yu, J. Z.: Inter-comparison of NIOSH and IMPROVE protocols for OC and EC determination: Implications for inter-protocol data conversion, Atmos. Meas. Tech., doi: 10.5194/amt-9-4547-2016, 2016.
Wu, C., Ng, W. M., Huang, J., Wu, D., and Yu, J. Z.: Determination of Elemental and Organic Carbon in PM2.5 in the Pearl River Delta Region: Inter-Instrument (Sunset vs. DRI Model 2001 Thermal/Optical Carbon Analyzer) and Inter-Protocol Comparisons (IMPROVE vs. ACE-Asia Protocol), Aerosol Sci Tech, 46, 610-621, doi:10.1080/02786826.2011.649313, 2012.
Wu, C., Ng, W. M., Huang, J., Wu, D., and Yu, J. Z.: Determination of Elemental and Organic Carbon in PM2.5 in the Pearl River Delta Region: Inter-Instrument (Sunset vs. DRI Model 2001 Thermal/Optical Carbon Analyzer) and Inter-Protocol Comparisons (IMPROVE vs. ACE-Asia Protocol), Aerosol Sci Tech, 46, 610-621, doi:10.1080/02786826.2011.649313, 2012.