DustScan Sentinel Model 3030

The DustScan Sentinel Aerosol Monitor is a flexible tool for generating particulate matter (PM) trending information. The unit's weatherproof enclosure permits its use in a variety of challenging outdoor environments, and its battery operation permits siting independent of a mains power source.

Applications for the monitor include land fills, material handling facilities, and hazardous waste clean-up sites. Space-constrained urban sites and traffic corridors are other locations that can benefit from the monitor's features.

Features for Outdoor Measurements

The DustScan Sentinel unit builds upon by the DustScan Scout Model 3020 Aerosol Monitor. It houses the hand-held unit in an outdoor enclosure, and adds a number of features:

• A built-in humidity sensor monitors the air stream flowing out of the DustScan Scout unit. The monitor also contains a heated air inlet that operates under microprocessor control. When the exit humidity level exceeds the value entered by the user in the monitor's firmware, the sample tube heater turns on. This feature is designed to minimize the effect that changing outdoor relative humidity levels exert upon the mass concentration readings from the monitor.
  
• A wind vane/anemometer connection permits the capture of meteorological information. These data are stored in the monitor's internal buffer along with the mass concentration readings. This can provide a convenient means of determining whether relationships exist between wind speed/direction and ambient PM loading.
  
• Size-selective inlets developed by the Harvard School of Public Health provide PM-2.5 and PM-10 cut point characteristics similar to those of the USEPA rererence inlets. A rain cap is available for applications that do not require size-selective sampling.
  
• An optional modem with a wide temperature range permits bi-directional data transmission.
  
• The DustScan Sentinel unit provides convenient, weatherprotected access to connection points for contact closure and 0-5 VDC outputs.
  
• The unit includes mounting hardware for flexible installation.
  
• The waterproof enclosure permits consitent operations in the ambient temperature range of -15 to 60 degrees C. For indoor installations, optional sample tube extensions can bridge the distance between the monitor and the outdoor-mounted sample inlet.

Operating Principle

At the heart of the DustScan Sentinel unit is a transducer that uses near-forward light scattering to assess the concentration of particulate matter in ambient air. The light source is a safety-interlocked laser that operates at a wave length of 670 nm. The scattered light received by a sensor forms the basis of the particle loading results (in milligrams per cubic meter) generated by the monitor. The sensor is located at a 180 degree angle from the light source.

Data Generation

Users can select the data averaging/storage interval to be between 2 seconds and 30 minutes. In each record, the monitor stores the minimum and maximum concentrations with time stamps, along with the average for the period. With an optional wind vane/anemometer attached to the monitor, the DustScan Sentinel unit includes meteorological information along with PM concentration in each stored record.