Current challenge particles
Review the current AP HEPA Test product page.
Intended use
Filter challenge particles are not automatically calibration standards
Current Applied Physics HEPA Test PSL pages describe a higher-solids aqueous particle family for HEPA/ULPA efficiency, leakage, aerosol generation and related research. The same page states that the family is not intended for instrument calibration or diagnostic reagents.
Selection rule: use the family that matches the filter-test method. Do not substitute a size-calibration bottle or challenge material solely because the nominal diameter matches.
Current family profile
Applied Physics HEPA Test pathway
| Published attribute | Current family-level description |
|---|---|
| Material | Polystyrene microspheres in aqueous suspension |
| Range | Approximately 30 nm–3.1 µm on current AP pages |
| Solids | 10% by weight on current AP pages |
| Bottle formats | 15 mL, 100 mL and 1,000 mL pathways are described |
| Use boundary | Filter challenge and research; not intended for instrument calibration |
Test planning
The procedure controls the challenge
- Identify the governing filter-test method and required challenge material.
- Confirm target aerosol size distribution and concentration.
- Select and qualify the aerosol generator.
- Control dilution, transport and spatial uniformity.
- Measure upstream and downstream under the approved procedure.
- Document safety, cleaning and waste handling.
- Do not make health or regulatory superiority claims without evidence.
HEPA Check legacy
Separate replacement status from current product selection
Applied Physics currently labels an older HEPA-Check product as replaced by the AP5000-series HEPA Test particles. Legacy pages may still appear in search. Route current purchasing decisions through the live product family and technical confirmation.
Calibration standards
Use a calibration-grade size family when the objective is instrument calibration.
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.