What is the Number of Samples Locations Calculations Readings for ISO14644?

What is the Number of Samples Locations Calculations Readings for ISO14644?

By Ashraf Almuhtaseb | Data Center Technical Cleaning Expert | idata.center

The number of sample locations required to verify compliance with ISO 14644-1 (Air Cleanliness Classification by Particle Concentration) is determined by the size of the cleanroom or controlled area. ISO 14644 specifies a formula and provides tables to calculate the number of sampling locations based on the room’s area.

Calculation for the Number of Sample Locations

The number of sample locations is calculated using the formula:

𝑁𝐿=27× (𝐴 𝑚² ÷ 1000)

Where:

NL = Number of sample locations (rounded up to the next whole number)

A = Area of the cleanroom or zone in square meters (m²)

Simplified Table of Sample Locations

Below is a quick reference for typical cleanroom sizes:

Room Area (m²)

Minimum Sample Locations

2𝑚² = 2 readings

4𝑚² = 2 readings

10𝑚² = 3 readings

20𝑚² = 5 readings

50𝑚² = 8 readings

100𝑚² = 10 readings

500𝑚² = 23 readings

1000𝑚² = 32 readings

Larger than 1000 𝑚² = Use this formula (𝑁𝐿=27× (𝐴 𝑚² ÷ 1000) )

This table is a suggested number of samples per area; you can take more samples than suggested, and taking fewer is not recommended.

Sampling Procedure

A- Particle Measurement:

Measure particle concentration at each sampling location for the required particle sizes (e.g., 0.1 µm, 0.5 µm).

Use particle counters that comply with ISO 21501-4 standards.

B- Duration of Sampling:

The volume of air sampled at each location must be sufficient to detect the required number of particles based on the cleanroom classification.

C- Uniform Distribution:

Sampling points should be evenly distributed across the room, avoiding clustered locations unless local contamination sources are expected.

About the Author

Ashraf Almuhtaseb is a Data Center Technical Cleaning Expert with over 9 years of specialized experience since 2017. He is the only independent professional in the MENA region — and one of very few globally — publishing dedicated, in-depth technical knowledge on data center cleaning standards, contamination control, and ISO 14644 compliance. Visit idata.center for more articles, guides, and resources.

© Ashraf Almuhtaseb | idata.center | All rights reserved