Counter calibration
Requires reference particles and a controlled metrology setup appropriate to the counter and ISO 21501-4.
System view
From suspension to detected pulse
- Select the certified PSL node and compatible suspension.
- Generate an aerosol without creating unacceptable residues or agglomerates.
- Condition and dilute the aerosol into the counter’s useful concentration range.
- Control sampling flow, transport loss and reference measurement.
- Evaluate size response, counting efficiency and other required parameters.
Particle choices
What must be confirmed
| Requirement | Why it matters |
|---|---|
| Certified diameter | Defines the reference node for size response |
| Distribution / CV | Influences peak width and resolution evaluation |
| Concentration / solids | Affects aerosol-generation strategy and dilution |
| Suspension additives | Can alter aerosol residue or generator behavior |
| Refractive index | Affects light-scattering response |
| Bottle volume | Affects practical test consumption and repeatability |
Calibration vs filter challenge
Do not conflate two aerosol jobs
Filter challenge
Requires a challenge population and test method to evaluate penetration or leakage; the AP HEPA Test family is not presented as instrument-calibration material.
Key boundary: a particle that aerosolizes well is not automatically a calibration standard, and a calibration standard is not automatically approved for every filter-test method.
Failure modes
Why the observed peak moves
- Agglomeration creates apparent larger particles.
- Evaporation residue changes the aerosol population.
- Transport losses remove particles selectively.
- Coincidence causes undercounting or altered size response.
- Flow error changes count concentration and sampling.
- Optical contamination changes sensitivity.
Applied Physics technical pathway
Match the standard to the measurement—not the other way around.
Send the instrument, medium, target size, concentration, certificate and packaging requirements to Applied Physics for a technical recommendation.