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The Haver CPA measures or examines particles as they free-fall in front
of a light source, with a sophisticated camera capable of making 10,000
scans per second.
The finalized data is stored and sorted into 250 classes. In other
words, analysis equivalent to 250 test sieve measurements. The
information is then finally presented in the size analysis fractions or
shape calculations chosen by the user. This is all accomplished in a
matter of minutes. The CPA is operated by a Windows based system.
Simple point-and-click functions operate the entire analysis.
Files can be setup for each test application, including any related notes and comments.
Analysis data is presented as you request. Custom presentation is one easy setup for any or every product application.
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You may select any sieve size classification in either ASTM or ISO
designations. This would allow analysis equal to a select stack of test
sieves. Also, there is a selection of shape analysis presentations to
fit your individual needs.
The CPA particle size distribution analysis differs from the
traditional sieving process in one major aspect. Analyzing data from
sieving is based on weight distribution of a given sample, i.e. 20% of
a sample retained on a No. 50 test sieve would then represent 20% of
the bulk material at a particle size of 300 micron.
However, the CPA actually counts the number of particles in each
chosen size class. Particle size distribution, therefore, is based on
the actual particle count in a given/chosen size class.
Therefore, a difference between the two methods will exist, as
finer particles would be of greater volume and of a lesser weight
percentage of any given sample.
Given that difference, the Haver CPA can be applied in two ways.
First, raw data. Raw data, or pure particle counts can be used for
analysis when "traditional" sieving data is not required to meet
specifications or past results. In-line applications generally can be
monitored using raw data.
Secondly, in applications where "traditional" sieving data has been
used for analysis, CPA technology can provide meaningful data. A
featured benefit is the capability to "correlate" CPA raw data to
traditional test sieving weight distribution results.
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The Haver CPA presents results formatted graphically and tabular,
immediately following examination of the last particles. Results can be
viewed individually or as comparison graphs/tables with up to 6 tests
being displayed on the monitor simultaneously. Most tests, run with 50
or 100-gram samples, are generally processed in two to six minutes.
The CPA process has been researched, developed and continuously
tested throughout the 1990's. The repeatability of the machine is
remarkable and the variances from traditional sieving data versus CPA
correlated results are minimal. The correlation feature is important
because, as it is designed, the CPA is not meant to replace test
sieving in every application.
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