Link to USGS home page.
Coastal and Marine Geology Program

Skip menu and go to content. OFR 2005-1001 Home  /   Procedures  /   East-Coast Database  /   GIS Data Catalog

U.S. Geological Survey Open-File Report 2005-1001
USGS East-Coast Sediment Analysis: Procedures, Database, and GIS Data
skip menu



radio button - current selection Coulter Counter

Coulter Counter

Video Length: 1 minute, 53 seconds
Get RealPlayerŠ
Browse Video Directory

Image shows view of the entire coulter counter system.
The Coulter Counter Multisizer IIe determines distributions of silt and clay-sized particles suspended in a conductive liquid by forcing the suspension to flow through a small aperture.
Image shows close-up view of  sample stand (tube and electrodes).
As a particle passes through the aperture, it changes the resistance between the internal and external electrodes. This produces a current pulse of short duration having a magnitude proportional to the particle volume.
Image shows operator introducing the sample with pipette.
To minimize coincidence, or measuring more than one particle at a time, the concentration of the suspension may be adjusted. Acceptable concentrations limit the number of particles passing through the aperture to less than 1,000 per second.
Image shows close-up view of  the control panel and pulses.
During analysis of a sample, the series of pulses is electronically classified by size and counted.
Image shows close-up view of loggine computer.
After an analysis is completed, the data is logged on a computer.
Image shows silt and clay fractions of sample.
The silt and clay fractions of geological samples usually have a large particle diameter range. If this diameter range exceeds 20:1, more than one size aperture tube must be used.
Image shows the 200- and 30-micron aperture tubes.
The first analysis is performed with a 200-micron aperture tube; a 30-micron aperture tube is used during the second analysis. The analyst first performs all of the 200-micron aperture analyses, then swaps aperture tubes and changes the machine settings.
Image shows analyst splitting sample with a 20-micron sieve.
Before the 30-micron aperture analyses are run, the analyst must split each sample with a 20-micron sieve. When an individual sample is run as part of a group, a typical time for each multi-aperture analysis is approximately 5 minutes.
skip menu

skip footer

U.S. Geological Survey
Coastal and Marine Geology Program
Woods Hole Science Center