Aeroqual PM Optical Module – Nephelometer
Replacement particle monitor optical module only for Dust Sentry
$4,850.00
Availability: 36 in stock
Product Information
Nephelometer Module (specific PM fraction size)
The PM nephelometer module features in our perimeter air quality monitors: AQS 1 Air Quality Monitor, Dust Sentry, and AQM 65 Monitoring Station.
For projects focused on a particular particle fraction, Aeroqual’s laser nephelometer provides continuous particulate mass concentration measurements. The system is configured for PM1, PM2.5, PM10 or TSP, using the appropriate inlet arrangement rather than measuring all fractions simultaneously.
The PM nephelometer module combines a laser nephelometer with a high-precision sharp cut cyclone to give accurate real-time measurement of ambient particulate matter. By changing the sharp cut cyclone, the particle sensor can be used to measure PM1, PM2.5, PM10 or TSP. The sharp cut cyclone physically selects particles of a target size, ensuring precise measurement of only the size fraction of interest.
Following particle size selection, the sample stream is sent to the nephelometer module. A nephelometer is an optical sensor that uses light scattering to measure particle mass. The light source is a visible laser diode and scattered light is measured in the near forward angle using focusing optics and a photo diode.
The nephelometer has an on-board temperature sensor that corrects for thermal drift, a sheath air filter to keep the optics clean, automatic baseline drift correction, and a fiber optic span system to provide a check of the optical components.
Product Features
| Specification | Details |
| Measurement technology | Laser nephelometer |
| Measurement fractions | PM1, PM2.5, PM10 or TSP – one selected fraction |
| Measurement range | 0-60,000 µg/m³ |
| Display resolution | 0.1 µg/m³ |
| Lower detection limit | <1 µg/m³ |
| Sampling features | Heated inlet and automatic zero checks |
| Accuracy | ±(2 μg/m3 + 5% of reading) |
| Flow Rate | 2L per minute |
| Monitor platforms | Appropriately configured Dust Sentry, AQS 1 and AQM 65 systems |
Performance & Field Data
PM nephelometer field test results PM2.5
An Aeroqual AQM 65 containing an PM2.5 nephelometer module was co-located from December 2016 to March 2017 at an air quality regulatory station in Hartford, Connecticut, and its data compared with reference data downloaded from the USEPA AirNow website. The PM2.5 nephelometer data produced an R2 of 0.79 (24-hour average). The total measurement uncertainty, based on the EU Guide to Demonstration of Equivalence, using an hourly limit value of 50 μg m-3 was calculated as 12.9%. Note that an expanded relative uncertainty of less than 25% is required for a PM2.5 monitor to be considered regulatory grade. The PM2.5 module meets this requirement.
PM nephelometer field test results PM10
An Aeroqual Dust Sentry containing an PM10 nephelometer module was co-located with two BAM reference instruments from July to September 2012 in Nelson, New Zealand. This co-location study was completed as a requirement for MCERTs certification, which this unit has achieved. The PM10 nephelometer data produced an R2 of 0.79 (24-hour average).
Demonstration of equivalence
The total measurement uncertainty, based on the EU Guide to Demonstration of Equivalence, using an hourly limit value of 50 μg m-3, was calculated as 15.3%. Note that an expanded relative uncertainty of less than 25% is required for a PM10 monitor to be considered regulatory grade. The PM10 module meets this requirement.
Directive 2008/50/EC downloaded 10/02/2023 https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:32008L0050&from=en.
Impact of humidity and water vapor
High humidity can lead to inaccurate measurement from an optical particle sensor if not mitigated. This is because high humidity (including fog) causes aerosol particle growth through adsorption of water vapor which can lead to erroneously high measurements by the particle sensor.
However, the nephelometer module contains an inlet heater which reduces the sample air humidity and prevents the particle growth. This maintains the accuracy of the PM measurement even when the water content in the air is very high.
PM nephelometer module expected lifetime
The Aeroqual manufactured electronics module responsible for data analysis does not contain any consumable parts and does not contain any components which might wear out or expire and should last between 3 to 5 years.
The Aeroqual manufactured pump module contains two pumps, both expected to last between 18 months and 2 years of continuous operation.
The MetOne manufactured nephelometer module contains filters which are changed as required, usually between 1 and 3 months. The module also contains a laser and photodetector, requiring factory calibration every 2 years.
Results shown are from the specific manufacturer-reported evaluation described. Performance depends on the monitoring configuration, calibration, site conditions and measurement objectives.
Typical Applications
- Urban and national ambient air quality monitoring
- Roadside and near roadside monitoring
- Industrial perimeter monitoring
- Mine and quarry boundary monitoring
- Checking pollution ‘hotspots’
- Air quality research
Select the right module for your project
Tell Specto what you need to measure, the concentrations you expect and the monitor you plan to use. Our engineers and scientists can help you select the module, configuration and calibration approach for your project.
