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Ultra-High Sensitivity Aerosol Spectrometer (UHSAS)
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The UHSAS is an optical-scattering, laser-based aerosol particle spectrometer for sizing particles in the 0.06 – 1 µm range. The instrument counts particles in up to 100 user-specified sizing bins, with a resolution as fine as 1 nm/bin. This high sensitivity makes the UHSAS ideal for aerosol research and filter testing.
Advantages:
Measures aerosols in the 60 nm to 1 µm range
Offers size resolution at 1-2% of particle size
Eliminates sizing uncertainty associated with scattering spectrometers that measure at sizes larger than the excitation wavelength.
Categorizes particles by size in up to 100 bins (user selects number of bins and boundaries)
Counts up to 3,000 particles/second
Uses aerosol spectrometry technique with two detection systems: a primary, highly sensitive APD-based system to size smaller particles, and a secondary PIN photodiode system to size larger particles
Compensates for small drifts in laser power via automatic gain control
Features an on-board computer, built-in monitor, and powerful LabVIEW-designed software for easy, real-time data analysis
Applications:
Aerosol research
HEPA/ULPA filter testing and characterization
Atmospheric and air pollution monitoring and research
Chemical process monitoring and control
Pharmaceutical research and manufacturing
Powders and food products research
Inhalation toxicology research
Combustion and emission source research
Nebulization analysis
Coalescence and nucleation research
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Superior Resolution
UHSAS accurately sizes even the smallest particles. The graph at right shows the results of a test conducted with 95 nm and 104 nm standard PSL particles. Although these particle diameters are only 9 nm apart, the UHSAS has correctly identified two distinct particle peaks.
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Principle of Operation:
A laser illuminates particles, which scatter light that is then collected by two pairs of Mangin optics. One pair of optics images onto a highly sensitive avalanche photodiode (APD) for detecting the smallest particles. The other pair images onto a low-gain PIN photodiode for detecting particles in the larger size range of the instrument. Each detector is amplified in a current-to-voltage stage that feeds into the analog electronics system. The amplification allows the system to detect particles as small as 60 nm.
Calibration:
The UHSAS, with its high resolution and large number of arbitrarily settable bins, requires a complex process to ensure accurate calibration. However, the UHSAS software automates much of this process, making it a simple matter to calibrate the instrument on a daily basis.
Calibration is accomplished by adjusting the instrument’s four gain stages so particles are accurately sized. First, gain stages are adjusted relative to each other, and then the scale is fixed to a known particle size using monodisperse polystyrene latex (PSL) spheres. The combination of relative and absolute gain calibration ensures that the UHSAS is properly measuring particles.
Software:
The UHSAS comes with LabVIEW-designed software that provides a user-friendly virtual instrument panel for the control and data display of the UHSAS. For instance, the program enables the user to do the following tasks:
View a histogram of particles binned by diameter, by transit time, or by peak optical signal
Set boundaries for the histogram bins
Control sample flow and monitor temperature, pressure, and laser current
Calibrate the instrument
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Specifications:
| Measured Parameters |
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Single-particle light scattering
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| Auxiliary Parameters |
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Temperature
Pressure
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| Derived Parameters |
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Particle diameter
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| Number Concentration Range |
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3,000 particles/second
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| Particle Size Range |
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60 nm – 1 µm
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| Aerosol Medium |
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Air, 0 - 30 °C (32 - 86°F)
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| Lasers |
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• Solid-state Nd3+:Y LiF4: ~1054 nm, 1 kW/cm2 intracavity circulating power
• Pump Laser: ~797 nm, 1.6 W
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| Number of size bins |
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100 max:
• 99 standard bins (98 if both overflow and underflow are enabled)
• One overflow bin and one underflow bin
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| Sample Flow |
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• Standard option: 1 – 100 standard cm3/minute (typically 50)
• Other options available
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| Flow Control |
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Controlled from software; can also be manually adjusted via mass or volume flow controller
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| Routine Maintenance |
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Daily:
• Monitor laser power by verifying Laser Reference voltage falls within acceptable levels; if necessary, clean critical optics to restore laser power
• Zero check with high-efficiency filtered air sample
Monthly and around field campaigns:
• Full-scale calibration
Annually
• Flow controller calibration
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| Recommended Service |
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Annual cleaning and calibration at DMT service facility
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| Front Panel Display |
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Built-in monitor, 2 USB 2.0 ports
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| Rear Panel Connections |
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System power switch, system power connection, Ethernet, exhaust vent, exhaust port, serial stream connection
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| Computer System |
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On-board Intel®Celeron™ CPU
504 MB RAM
80 GB hard drive for data storage
User interface via standard keyboard, mouse, and built-in monitor (included)
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| Software |
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Executable program written in LabVIEW
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| Data Recording |
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• Output file written to computer hard drive
• Output data sent to serial port
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| Communications Output |
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Serial, Ethernet, USB
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Power Requirements
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100-240 VAC, 47-63 Hz, 200W
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Dimensions
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56 cm L x 43 cm D x 24 cm H
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Environmental Operating Conditions:
Temp
RH
Altitude
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0 – 30°C (32 - 86°F)
0 – 100% RH non-condensing
Sea level to 4 km
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Specifications are subject to change without notice.The UHSAS is a Class I Laser Product with a Class IV pump laser, U.S. Patent # 5,889,589.
Options and Accessories:
Rack mountable unit (standard 19” instrument rack)
External laptop (for remote applications, replaces flat screen display)
Particle by particle feature (supplies information on individual particles, including inter-particle times)
Bidirectional serial stream communication control
Items Included in Purchase Price:
Instrument
Keyboard with touch pad
Operator manual
Zero-count filter
Domestic and international power supply
One day of training at DMT’s facility
One-year warranty
Email and telephone technical support
Selected Bibliography:
Y. Cai, D. Montague, W. Mooiweer-Bryan, and T. Deshler, “Performance characteristics of the ultra high sensitivity aerosol spectrometer for particles between 55 and 800 nm: Laboratory and field studies,” Journal of Aerosol Science 39 (2008) 759-769. link
R. Yokelson, I. R. Burling, S. P. Urbanski, E. L. Atlas, K. Adachi, P. R. Buseck, C. Wiedinmyer, S. K. Akagi, D. W. Toohey, and C. E. Wold, “Trace gas and particle emissions from open biomass burning in Mexico,” Atmos. Chem. Phys. Discuss. 11, 7321-7374, 2011. doi:10.5194/acpd-11-7321-2011. link
R. Yokelson, S. Urbanski, E. Atlas, D. Toohey, E. Alvarado, J. Crounse, P. Wennberg, M. Fisher, C. Wold, T. Campos, K. Adachi, P. R. Buseck and W. M. Hao. "Emissions from forest fires near Mexico City." Atmos. Chem. Phys. Discuss. 7, 6687–6718, 2007. link
How to Order:
For more information or to obtain a sales quote, contact DMT at +1.303.440.5576,
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Applications
