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186 Ophthalmic Lenses

Helmets
Helmets are commonly worn during welding. They provide protection of
the face and neck from intense radiation and spatter. The filters can also be
attached which can also be so designed that it can be flipped up to expose.

REGULATIONS AND STANDARDS RELATING TO EYE PROTECTION
The British and European Standards for eye protectors BS EN 166:2000
Personal Eye Protection Specification is at the heart of the strategy for eye
protectors, but other standards like USA …. ANSI Z 87.1, Canada …. CSA
Z 94 etc are also linked to it.
BS EN 165 – specifies personal eye protection vocabulary.
BS EN 166 – personal eye protection – specification.
BS EN 167 –specifies optical test methods.
BS EN 168 – specifies non optical test methods.
BS EN 169 – specifies tints for welding protection and similar operation.
BS EN 170 – specifies for UV filters.
BS EN 171 – specifies for IR filters.
BS EN 172 – specifies for sun glare filters.
BS EN 175 – specifies for ski-goggles.
BS EN 207 – specifies for filters and eye protectors against laser radiation.
BS EN 208 –Laser adjustment eye protectors.
BS 7930 – 1:1998 – Eye protectors for racket sports. Part 1 Squash.
BS 4110 – Eye visors for vehicle users.

Table 12.2: 1 BS EN 166 Code numbers for filters
Filter Code No. Filter Property
No code no. Welding filters.
2. UV filter where colour recognition may be affected.
3. UV filter with good colour recognition.
4. IR filter.
5. Sun glare filter without IR specification.
6. Sun glare filter with IR specification

Table 12.3: BS EN 166 – Optical Class – Tolerances

Number Sph & Cyl Horizontal Prism Vertical Prism
1. +, – 0.06D 0.75 deg out 0.25 deg in 0.25 deg up & down
2. +, – 0.12D 1.0 deg out 0.25 deg in 0.25 deg up & down
3. + 0.12D-0.25D 1.00 deg out 0.25 deg in 0.25 deg up & down