Dust particle counter measured by dust particle counter UCL - Database & Sql Blog Articles

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1. Average particle concentration at the sampling point

C₁ + C₂ + ... + Cₙ

A = ————————

N

Where: A represents the average particle concentration at a specific sampling point (in grains per cubic meter). C₁ is the particle concentration measured at that point, and N is the number of samples taken at that location.

2. Overall Average (Mean)

A₁ + A₂ + ... + Aᴸ

M = ——————————

L

Where: M is the average particle concentration in the clean zone, representing the mean of all individual averages. L is the total number of sampling points within the clean room.

3. Standard Error (SE)

SE represents the standard error of the mean, indicating the variability of the average values across different sampling points (in grains per cubic meter).

4. Upper Confidence Limit (UCL)

UCL = M + t × SE

Where: UCL is the 95% confidence limit for the mean value, t is the t-distribution coefficient corresponding to a 95% confidence level, which varies based on the number of sampling points.

T-Distribution Coefficient for 95% Confidence Level

Sampling Point (L) | T-value

2 | 6.31

3 | 2.92

4 | 2.35

5 | 2.13

6 | 2.02

7 | 1.94

8 | 1.90

9 | 1.86

≥9 | No need to calculate UCL

Note: When there are more than 9 sampling points, calculating the UCL is not necessary as the data becomes statistically reliable enough.