Iso 14644-3.pdf |link| -

Particle counters: provide size-resolved counts for required cut-offs; flow-checked and calibrated within manufacturer/standards intervals.
Anemometers and flow hoods: calibrated and suitable for low velocities typical in cleanrooms.
Pressure gauges: differential range and resolution appropriate for expected ΔP.
Aerosol/photometer for filter testing: use accepted challenge aerosols and photometer setup; follow manufacture and standard procedures.

Use Annex A (General requirements). Verify: