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General Purpose Water-based Condensation Particle Counter 3787

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This is the cost effective, entry level model of the family of three Water-based CPCs. Since this CPC uses water as its working fluid, it is easy to keep it supplied using water purchased locally. Additionally, it does not emit organic solvent fumes, and it can be operated safely in sensitive environments. Most commonly used in laboratory environments, model 3787 is a useful tool for ambient air monitoring, basic aerosol research, inhalation studies, among other applications.

Product Details

TSI W-CPCs are the most comprehensive, characterized set of solutions for measuring concentrations of airborne nanoparticles operating with water. The model 3787 and the ultrafine WCPC model 3788 are fully integrated into the SMPS™ family model series 3938 enabling particle size and number concentration measurement. The Environmental Particle Counter model 3783 is the best fit for 24/7 monitoring.

SMPS stands for Scanning Mobility Sizer, another reference system by TSI to measure nanoparticle size distributions.

Features and Benefits

  • Concentration range up to 250,000 particles/cm³ - applicable for most environments
  • Size range down to 5 nm (D50) - good fit to measure size distribution with SMPS
  • Data rate up to 10 Hz - capture dynamic processes
  • Fast response to rapid changes in aerosol concentration (T10-90 < 300 ms)
  • Reliable diagnostics with Pulse Height Monitoring
  • Distilled water as working fluid - no smell, no VOC emissions, no supply issues
  • High aerosol counting flow rate of 0.6 L/min - high accuracy at low concentrations


  • Indoor aerosol research environments sensitive to VOC emissions, such as hospitals and schools
  • Inhalation or exposure chamber studies
  • Health effects studies
  • Basic aerosol research


  • Can the CPC be operated with different carrier gases?
    Yes, but only inert gases.
  • How does the water CPC performance compare to CPCs that use butanol?
    Laboratory and field tests show excellent agreement and correlation between the water CPC (Model 3785) and butanol CPCs (Models 3010, 3025A and 3022A) for particles larger than about 20–30 nm. Preliminary test results can be viewed in a poster presentation by S. Hering, M. Stolzenburg, F. Quant and D. Oberreit (2003 AAAR Annual Conference, Anaheim, CA) at Additional test data will soon be submitted for publication.
  • How frequently should I have the CPC serviced?
    We recommend the CPC be returned for annual maintenance service. Your company’s Quality Management System may specify a more or less frequent service interval based on history, use and criticality of the measurement. The Standard Annual Service includes:Perform an ‘AS FOUND’ operational and calibration check.Replace tubing, o-rings and water wick.Clean optics, flow path and all wetted parts.Update firmware/software.Perform operational check.Calibrate flows.Calibrate photometric mode using sodium chloride aerosol.
  • How pure does the water need to be?
    We recommend using water that is distilled or purer. 
  • How sensitive is the instrument to flooding?
    While fairly insensitive to flooding, several precautionary measures will help avoid this condition. Do not tip the instrument more than 10 degrees in any direction. Avoid large pressure fluctuations or restrictions in flow at the sample inlet (>25 cm water at 1.0 liter/minute). When accessing the reservoir for cleaning or drying, always lay the instrument on its side with the Fill and Drain connectors on the bottom. 
  • Is the counting efficiency for each CPC determined individually?
    No. The CPC efficiency curve has been determined by testing a statistically valid number of CPCs and averaging the results to obtain the curve published in the product literature. Variation between units is very small. 
  • What is the final droplet size after growth by condensation?
    This question has been investigated, theoretically, by Ahn and Liu (1990). For the initial particle diameters of 5 and 20 nm, the computation results show a final droplet size of 11.3 and 12.3 micrometers, respectively (Ahn and Liu, 1990). Similar experimental results have also been determined.

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