Detailed Introduction to EN 168 Standard – Non-Optical Test Methods for Eye Protection
The EN 168 standard specifies non-optical test methods for personal eye protection. It complements EN 166 (General Requirements for Eye Protection) and EN 167 (Optical Test Methods) by defining the mechanical, thermal, and chemical resistance tests that safety glasses, goggles, and face shields must undergo.
This standard ensures that eye protection devices remain durable, resistant to environmental factors, and capable of withstanding impact, heat, and chemical exposure without compromising user safety.
1. Overview of EN 168 Standard
- Full Name: EN 168 – Personal Eye Protection: Non-Optical Test Methods
- Purpose: Defines mechanical, thermal, and chemical resistance tests for protective eyewear.
- Scope: Applies to all types of eye protection, including:
- Safety glasses
- Safety goggles
- Face shields
- Welding visors
- Specialty protective lenses
EN 168 is not a standalone standard; it is used alongside EN 166, which sets the general safety requirements for protective eyewear.
2. Key Testing Methods in EN 168
EN 168 includes multiple test methods to assess the durability, resistance, and reliability of protective eyewear under harsh conditions. The tests include:
- Resistance to Fogging (Anti-Fog Test)
- Resistance to Surface Damage by Fine Particles (Scratch Resistance Test)
- Resistance to Ignition (Flame Resistance Test)
- Resistance to Radiation, Heat, and Humidity (Environmental Testing)
- Resistance to Corrosion (Chemical Exposure Test)
Each test ensures that protective eyewear remains effective in industrial, medical, construction, and hazardous environments.
3. Detailed Testing Methods in EN 168
A. Resistance to Fogging (Anti-Fog Test)
Purpose
- Ensures that protective eyewear does not fog up in humid or high-temperature environments.
- Critical for industries like healthcare, food processing, and firefighting, where clear vision is essential.
Test Procedure
- Preparation:
- The lens is conditioned at 23°C ± 5°C for at least 4 hours before testing.
- A humid environment is created using a water bath at 50°C ± 5°C.
- Fogging Test:
- The eyewear is placed above the water bath to expose the lens to high humidity.
- The lens is observed for fogging duration (how long before fogging occurs).
- Pass/Fail Criteria:
- The lens must remain fog-free for a minimum of 8 seconds to pass.
- Some coatings (anti-fog treatments) can improve this duration.
B. Resistance to Surface Damage by Fine Particles (Scratch Resistance Test)
Purpose
- Evaluates the durability of lenses when exposed to abrasive particles (e.g., dust, sand).
- Ensures that protective eyewear maintains visibility after minor mechanical wear.
Test Procedure
- Abrasion Test:
- The lens is subjected to a controlled flow of fine abrasive particles (typically silica dust) for a set duration.
- Visual Inspection:
- The lens is examined under a light source to check for scratches or loss of transparency.
- Pass/Fail Criteria:
- Lenses must not show significant surface damage that could impair vision.
C. Resistance to Ignition (Flame Resistance Test)
Purpose
- Ensures that protective eyewear does not catch fire or melt when exposed to flames.
- Important for industries such as welding, firefighting, and metalworking.
Test Procedure
- Flame Exposure:
- A small flame (650°C ± 20°C) is applied to the lens or frame for 5 seconds.
- Evaluation Criteria:
- The eyewear must not continue burning after the flame is removed.
- No dripping of molten material should occur.
- Pass/Fail Criteria:
- If the material self-extinguishes within 5 seconds, it passes.
D. Resistance to Radiation, Heat, and Humidity (Environmental Testing)
Purpose
- Assesses how well protective eyewear withstands UV radiation, heat exposure, and high humidity.
- Ensures long-term durability in outdoor environments.
Test Procedure
- UV Exposure Test:
- The eyewear is exposed to ultraviolet radiation (280-400 nm) for 50 hours.
- The lens is checked for yellowing or material degradation.
- Heat Resistance Test:
- Eyewear is placed in an oven at 55°C ± 2°C for 60 minutes.
- The shape and structural integrity must remain unchanged.
- Humidity Test:
- The eyewear is stored in 90% relative humidity for 8 hours to assess potential material breakdown.
Pass/Fail Criteria:
- The eyewear must not show cracks, discoloration, or material deformation.
E. Resistance to Corrosion (Chemical Exposure Test)
Purpose
- Evaluates how well protective eyewear resists chemicals, sweat, and cleaning agents.
- Important for laboratories, chemical industries, and medical fields.
Test Procedure
- Chemical Soak Test:
- Lenses and frames are exposed to sodium chloride (NaCl) and sulfur dioxide (SO₂) vapors for 48 hours.
- Visual Inspection:
- The eyewear is checked for corrosion, discoloration, or weakened structure.
Pass/Fail Criteria:
- The lens must retain optical clarity and structural integrity after chemical exposure.
4. Marking & Certification
Protective eyewear that meets EN 168 standards will receive appropriate markings. These markings are usually combined with EN 166 (General Requirements).
Marking Examples:
- “1” = Highest optical class (minimal distortion)
- “K” = Scratch-resistant coating
- “N” = Anti-fog coating
- “F” = Low-energy impact resistance
- “T” = Resistant to high-temperature impacts
The CE marking confirms compliance with European safety regulations.
5. Applications of EN 168 Protective Eyewear
EN 168-certified eyewear is used in various industries, including:
- Construction & Manufacturing: Protection against dust, sparks, and impact.
- Medical & Laboratory Work: Resistance to chemicals and fogging.
- Welding & Metalwork: High-temperature and scratch-resistant lenses.
- Oil & Gas Industry: Protection from chemical exposure and environmental factors.
- Firefighting & Rescue Operations: Flame resistance and heat protection.
6. Comparison with Related Standards
| Standard | Focus | Key Features |
|---|---|---|
| EN 166 | General eye protection | Covers optical & mechanical requirements |
| EN 167 | Optical test methods | Ensures clarity, transmission, and quality of lenses |
| EN 168 | Non-optical test methods | Evaluates durability, heat, chemical, and impact resistance |
| EN 170 | UV protection | Defines UV filtering requirements |
| EN 172 | Solar protection | Specifies sun glare filters for industrial use |
7. Conclusion
The EN 168 standard is essential for ensuring that protective eyewear remains durable, fog-resistant, scratch-resistant, and heat-resistant under real-world working conditions. The testing methods outlined in EN 168 guarantee that safety glasses, goggles, and face shields offer long-term protection without compromising visibility or structural integrity.
