Unidirectional flow

An airflow moving in a single direction, in a robust and uniform manner, and at sufficient speed, to reproducibly sweep particles away from the critical processing or testing area.

Source: GMP Draft Annex 1

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Unidirectional Airflow and Laminar Flow Units

In a laminar flow unit, clean air has a unidirectional down flow from the face of the fan filter unit. The accurate terms to describe these units are unidirectional airflow cabinet and down flow booth - however laminar flow cabinet or laminar flow booth is the cleanroom industry's preferred term.

A unidirectional down-flow of clean air ensures that only extremely clean air passes down over the process, protecting sensitive products and processes from airborne particulate.

This means that the environment will be free from any particles shed from operatives, and any particles generated from the process.

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