ISO 3873:1977

Overview - ISO 3873:1977 (Industrial safety helmets)

ISO 3873:1977 establishes physical and performance requirements, test methods and marking rules for industrial safety helmets intended for general use in industry. The standard sets mandatory tests (shock absorption, penetration resistance, harness performance, flammability) and defines optional performance criteria (low-temperature shock absorption, electrical insulation, lateral rigidity) that apply only where specifically claimed. It also defines headform geometry, conditioning procedures and lab test setups.

Key topics and technical requirements

• Scope and definitions: Covers shell, brim, peak, harness (headband, cradle, cushioning), ventilation holes and accessories.
• Physical construction: Shell must have uniform strength (no highly localized reinforcement), smooth rounded edges and a front profile that does not impede spectacles or goggles.
• Clearances and wearing height:
  • Vertical clearance: 25–50 mm
  • Horizontal clearance: 5–20 mm
  • Minimum wearing heights for different headforms (typical examples): 80 mm (D), 85 mm (G), 90 mm (K).
• Shock absorption: Measured with instrumented impact tests; transmitted force must not exceed 5.0 kN (or equivalent deceleration limits).
• Penetration resistance: Striker must not contact the headform during the prescribed penetration test.
• Flammability: Shell material must not continue to burn with emission of flame more than 5 s after removal of the test flame.
• Electrical insulation (optional): Designed to guard against voltages up to 440 V when claimed; leakage current limits are specified in the standard and verified by salt-solution conditioning and high-voltage testing.
• Lateral rigidity (optional): Maximum lateral deformation and residual deformation limits are defined (e.g., max ~40 mm, residual ≤15 mm).
• Mass labelling: If helmet mass (complete, without accessories) exceeds 400 g, mass must be shown on the label.
• Marking and user information: Mandatory markings include ISO 3873, country of origin, manufacturer ID, year/quarter of manufacture and helmet type; labels must also note optional performance claims and user fit/replacement guidance.

Practical applications and who uses it

• Helmet manufacturers use ISO 3873 to design, test and label industrial helmets for global markets.
• PPE testing laboratories implement the specified conditioning and impact, penetration, flammability and electrical tests.
• Safety managers and procurement officers rely on the standard to select compliant helmets for construction, manufacturing, utilities and maintenance work.
• Certification bodies and compliance officers use the standard as a reference for conformity assessment and marking verification.

Related standards

• Headforms referenced align with ISO/R 1511 (headform geometries).
• Manufacturers and specifiers should compare ISO 3873 with applicable national and regional helmet standards when selecting PPE.

Keywords: ISO 3873:1977, industrial safety helmets, helmet standards, shock absorption, penetration resistance, flammability test, electrical insulation, lateral rigidity, helmet marking, PPE testing.