Overview
EN ISO 18526-4:2020 - "Eye and face protection - Test methods - Part 4: Headforms" (CEN adoption of ISO 18526-4:2020) specifies the geometry, reference distances and tolerances for physical headforms used to test eye and face protectors (safety glasses, goggles, face shields). The standard provides anthropometric background, CAD reference data and guidance for assembling test headforms that represent adult and child populations for laboratory testing and product development.
Key topics and technical requirements
- Headform classification: Six adult headform sizes are defined - 1-S, 1-M, 1-L and 2-S, 2-M, 2-L - intended to statistically cover ≈95% of the measured population.
- Reference distances and dimensions: Detailed facial and cranial dimensions (interpupillary distance, canthal distances, bizygomatic breadth, nasal measurements, corneal apex positions, etc.) are provided and illustrated (Figure 3). CAD files with nominal dimensions are available from ISO.
- Tolerances and manufacturing:
- Tabulated values and annex data use a dimensional tolerance of ±0.1 mm (engineering drawing practice).
- Tolerance for manufactured headforms is ±2% relative to CAD data.
- Specific fixtures: pupil diameter = 5 mm, ear pinhole diameter = 2.0 mm.
- Children headforms and types: Dimensions and classifications for child headforms (Type 1 and Type 2) are included.
- Anthropometry and test panels: Informative annexes (A and B) detail anthropometric measurement methods, data sources (including NIOSH datasets) and considerations for human test panels used in fit and usability assessments.
- Normative references: Cross-references include ISO 4007 (vocabulary) and CSA Z262.6:2014.
Applications and who uses this standard
EN ISO 18526-4:2020 is essential for:
- PPE manufacturers and product designers - to design and verify the fit, coverage and compatibility of safety spectacles, goggles and face shields against standardized headform geometries.
- Test laboratories and certification bodies - to build and use compliant headforms for reproducible performance and regulatory testing.
- Standards committees and regulatory agencies - to harmonize test methods used in the ISO 18526 series and ISO 16321 family for occupational eye and face protectors.
- R&D and ergonomics teams - to evaluate human factors, comfort and anthropometric coverage during prototyping.
Practical benefits include consistent lab testing, improved international conformity of eye/face protectors, and reliable fit assessment across user populations.
Related standards
- ISO 18526 series (other test methods for eye/face protection)
- ISO 16321 series (requirements for occupational eye and face protectors)
- ISO 4007 (terminology for eye and face protection)
- CSA Z262.6:2014 (facially featured headforms)
