Tricolor Absorption Photometer Model 2901


Easy-to-use and cost-effective aerosol black carbon and light absorption measurement in a very compact package.

Perform real-time light absorption and black carbon measurements using light transmission through a filter with the Tricolor Absorption Photometer (TAP). Based on a decades-proven design that is simple to use and maintain, the TAP measures light absorption at three wavelengths by particles deposited on a filter. By assuming a mass extinction efficiency, the ambient mass loadings of black carbon can also be determined. The TAP has been deployed at Global Aerosol Watch sites around the world for many years, demonstrating good agreement with other simultaneously deployed filter-based light absorption methods.

Learn About Product

All Features
• Eight sample channels and two reference channels
• Easy to operate and install (external computer and vacuum pump required)
• Multiple-wavelength light source (Red, Green and Blue, or Red, Green and UV)
• Data logging software included
• Up to 84 days of unattended operation on one filter at a PM2.5 loading of 10µg/m3 and an aerosol single scatter albedo of 0.95
• Internal heater eliminates RH filter artifact
• Fully characterized and field tested
• Low maintenance
• High sensitivity – detection limit of 0.02 µg/m3 black carbon mass
• Extremely compact – fits inside a 6.3 inch (16 cm) cube!
• Only 5 minutes required to change filter
Technical Specs

Copyright ©2023 All specifications are subject to change without notice. BMI assumes no responsibility for inaccuracies in this document or for any obligation to update information in this document. BMI reserves the right to change, modify, transfer or otherwise revise this publication without prior notice.

*Some products may be shown with optional accessories, which are sold separately. Items shown may not be to scale.

Applications and Solutions
  • Aerosol-Cloud interaction studies
  • Laboratory smog chamber studies
  • Visibility reduction studies
  • Aerosol health impacts
  • Long-term climate and air quality monitoring
  • Wildfires, Climate & Health studies
The TAP comes with the TAP Reader software, a Graphical User Interface (GUI) for Windows™ PC (not included) to allow easy configuration and operation of the instrument. The TAP Reader allows you to set the sample average time, a fixed or variable sample time for each spot, start and end filter spots, as well as the transmittance threshold values to switch to a new spot. Published corrections are applied internally by the software and all raw and processed data are written to a data file on the PC so raw data may be reprocessed if desired. A data processing tool written in the Igor™ software language is provided to read and plot all TAP data for easy analysis.
The TAP Reader also automatically allows white filter checks to be performed when new filters are installed. Timelines of transmittance, absorption coefficients, black carbon mass concentrations, temperatures and sample flow rate are provided to easily monitor instrument performance. Indicators are provided of expected spot and filter life so you can plan for upcoming filter changes. The software is very flexible and uses a configuration file to remember the settings that best suit your needs.
What's Included
  • Model 2901 or 2901-UV TAP
  • TAP Reader software for Windows™ PC
  • Pack of 20 sample filters
  • Zero-air filter for white filter check
  • External 24 VDC power supply
  • Communication and power cables
  • Operator’s manual
  • Weatherproof shipping case
  • Torque wrench for TAP clamping bolts
The following optional accessories are available:

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