Setting up the Counter
248083389-1 Rev 4-7
Basic
Requirements
Each of the reports has some basic requirements that, if not met, will
cause the report to FAIL the classification immediately.
Fed Std ft
3
This report requires a minimum of 2 locations measured.
At least 1 sample per location must be taken.
At least 5 samples in total must be taken in the cleanroom.
The minimum sample volume must be at least 0.1 cubic feet.
The 95% Upper Confidence Limit (UCL) must be calculated if the
number of sampled locations is less than or equal to 9.
Air flow (Unidirectional vs. Non-unidirectional) will have an effect on
the minimum locations and minimum samples required. In general, the
Non-unidirectional option requires more of both locations and samples.
For the Fed Std ft
3
report, the classification for a particle size is based
on its samples taken from all locations in the cleanroom. Each particle
size is given one of the following results:
• a classification rating which will be one of the possible
classifications (1, 10, 100, 1000, 10000, 100000)
• “Unable to Classify” if it fails one of the above requirements
• an “Out of Range” if the calculated classification at that particle
count exceeds 100,000
Table 4-3 Shows the minimum volume sizes per channel.
Table 4-3 Minimum volume per channel size
Ch Size (μ)Min Vol (ft
3
)
0.3 0.100
0.5 0.200
1.0 0.917
3.0 10.309
5.0 31.696
10.0 145.985
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