FAAM NON-CORE TSI Modified Water Filled TSI 3786 Condensation Particle Counter
 
The 3786 CPC measures particles as small as 2.5 nm and operates on the principle of enlarging small particles using a condensation technique until they are large enough to be optically detected. A sample is drawn through a cooled saturator block and then into a heated condenser, where water vapour diffuses into the sample stream. Supersaturated conditions are created as water vapour diffuese to the center line of the condenser faster than heat. Particles greater than a critical radius in this region will serve as condensation nuclei for the water vapour and will quickly grow. These droplets are then counted by optical methods.
 

System Components

The 3786 samples at 0.6 LPM from a Rosemount inlet, two sections of conductive tubing is used to deliver the sample. The first section is 1/2 " with a length of 1.96 meters, this is shared by the DMT dual column CCN and the TSI 3025a when flown. The second section is 1.41 meters of 1/4" tubing.
 
3786

 

Documentation

CPC  pdf 3786 Manual (5.92 MB) (5.92 MB)
Added literature for the low pressure model   pdf Manual Addendum (400.35 kB) (400 KB)
Troubleshooting documentation for the  pdf 3786 WCPC(1.17 MB) (1.17 MB)
CCN Rack  pdf technical specification.9 MB) (2.90 MB)
 

Data

The 3786 reports CN concentrations at 1 Hz, this signal is recorded over USB on the CCN rack computer using AIM software. The data recorded is subsequently written to a Nasa Ames format and stored at the BADC in the faam-non-core folder. FAAM are currently working on integrating this measurement into it's core data set.
 
The instrument's particle measurement size range is a D50 of 2.5 nm to > 3 µm with a concentration range of 0 to 1*106 particles per cubic centimeter. The instrument has a measurement uncertainty of ±12% at less than 1*10 particles per cubic centimeter and a resposne time of less than 2 seconds for a 95% resposnse to a step change. 
 
The residence time in the sample tubing is 11.5 seconds, this is increased to 33.3 seconds if the CCN is not operated. These residence times are not reflected in the data product. The nominal D50 and D90 transmission efficiencies at four different standard atmosphere altitudes and STP can be seen on their equivalent hyperlinks above. These documents have two flow regimes, one for CPC (0.6 lpm) with no CCN operated and one when the CPC and CCN are operated together (1.76 lpm).
 
This instrument has been modified by Quant Technologies  to enable the operation down to 180 hPa.
  
 

Publications

 
 
 

Further Details