Nedenfor er vist en oversigt over målemetoder til måling af partikelstørrelse og partikel størrelsesfordeling.
| Diesel Particle Sizing Instruments |
| Instrument |
Size Range |
Comments |
| Cascade Impactors (Aerodynamic Method) |
| Micro-orifice uniform deposit impactor (MOUDI) |
0.056 - 10 µm |
• Not real-time, gravimetric and chemical analysis performed after collection. |
| Nano-MOUDI |
0.010 - 10 µm |
• Same as MOUDI
• Low pressure may cause volatile particles evaporate. |
| Electrical low pressure impactor (ELPI) |
0.032† - 10 µm |
• Near real-time with time resolution from 2 - 15 s
• Can measure ambient concentrations, but low pressure may cause volatile particles to evaporate. |
| Electrical Mobility Analyzers |
| Differential mobility particle sizer (DMPS) |
0.01 - 0.5 µm |
• Discrete changes in electric field of DMPS makes sampling for entire range slower than for SMPS.
• Biased results if concentration and size change during scan.
• Pre-classification stage must be used to remove particles larger than 1.0 µm for diesel aerosol measurements. |
| Scanning mobility particle sizer (SMPS) |
0.010 - 0.7 µm |
• 2 - 4 min scan time for 100 size intervals—can ramp DMA electric field to reduce scan time.
• Time resolution of a few seconds for a single channel.
• Scan times as short as 30 s may be used with reduced resolution.
• Biased results if concentration and size change during scan.
• Pre-classification stage must be used to remove particles larger than 1.0 µm for diesel aerosol measurements. |
| Engine Exhaust Particle Sizer (EEPS) |
5.6 - 560 nm |
• Time resolution of 0.1 s allows for transient testing.
• Newer instrument, little experience available. |
| Fast Particulate Spectrometer DMS500 |
5 - 2500 nm |
• Time response (T10-90) 0.2 s, suitable for real-time transient testing.
• Same working principle as EEPS
• Newer instrument, little experience available. |
| Nano-differential mobility analyzer (nano-DMA) |
3 - 50 nm |
• Time resolution of about 10 s required to scan all intervals.
• Not fully characterized and developed. |
| Diffusion Batteries |
| Diffusion battery (DB) |
0.01 - 0.5 µm |
• Slow sampling time requires steady-state conditions.
• Strongly distorted results if concentration and size change during scan. |
| Electrical diffusion battery (EDB) |
5 - 300 nm |
• Fast and simple instrument, but size resolution not very good.
• Not fully characterized and developed. |
| † - Lower detection limit of 0.007 µm with added electrical filter stage |