Eye protection

Question 1

What features does eye protection need to have?

Answer 1

Comfort
Protection from hazard
Non-flammable
Non-irritant
Not steam up
Not impair vision
Lightweight
Good optical quality
Compatible with other safety equipment
Easy to clean
Can be readily replaced
Cosmetically ok
Durable
Inexpensive

Question 2

What types of safety specs are available in a glazed rx?

Answer 2

Safety specs
Cup goggles

Question 3

What are some disadvantages of afocal one piece safety specs?

Answer 3

FOV restricted
Slight magnification
Reflections
Peripheral displacement

Question 4

What are some disadvantages of cup goggles?

Answer 4

Poor ventilation
Uncomfortable
Poor peripheral vision
Can’t wear over specs

Question 5

What are some disadvantages of box goggles?

Answer 5

No nasal fitting
Difficult to replace lens

Question 6

What are some advantages of box goggles?

Answer 6

Well ventilated
Lightweight
Good FOV
Can wear over specs
Good fit

Question 7

What are some advantages of face shields?

Answer 7

Can wear over specs
V good FOV
Can be handheld

Question 8

How is heat-toughened glass made?

Answer 8

Heated to 637 degrees for 50-300 secs and rapidly cooled, creating compression envelope

Question 9

How is chemically toughened glass made?

Answer 9

Lens preheated and immersed in bath of KNO3 @470 degrees for 16 hours. Compression envelope formed by exchange of large K+ and small Na+ ions.

Question 10

How is laminated glass made?

Answer 10

A layer of plastic is sandwiched between two layers of crown glass.

Question 11

What are the advantages of chemically toughened glass?

Answer 11

Thinner than heat-toughened
Better impact resistance than heat-toughened
No warping

Question 12

What are the disadvantages of heat-toughened glass?

Answer 12

Thicker than crown glass
High plus lenses need longer heating
Scratches reduce impact resistance
Reactions don’t work well
Strain pattern created (maltese cross)

Question 13

What is the advantage of laminated glass?

Answer 13

Higher impact resistance than crown glass (slightly)

Question 14

What is the disadvantage of laminated glass?

Answer 14

Doesn’t always stick to plastic layer on breakage as it should (so not suitable for safety specs)

Question 15

What pattern does heat-toughened glass make on impact?

Answer 15

Radial

Question 16

What pattern does chemically toughened glass make on impact?

Answer 16

Crazing

Question 17

What pattern does laminated glass make on impact?

Answer 17

Cobweb

Question 18

What are the advantages of plastic lenses over glass?

Answer 18

Better impact resistance
Fragments are larger and more blunt
Thinner than glass
Less condensation
Better UV protection
Better for molten metal/hot sparks (won’t fuse to surface)

Question 19

What are the disadvantages of plastic lenses over glass?

Answer 19

Softer - easily scratched
Impact resistance reduced by hardcoat

Question 19

Why is CR39 better than PMMA?

Answer 19

Better impact resistance
Can be tinted

Question 20

What are the advantages of polycarb lenses?

Answer 20

Very lightweight
No warping or chipping
High impact resistance (good for kids)
Absorbs UV

Question 21

What are the disadvantages of polycarb lenses?

Answer 21

V soft - easily scratched
Higher v-value causes peripheral TCA (colour fringing)

Question 22

What are the advantages of trivex lenses?

Answer 22

100% UV protection
V high impact resistance
Resistant to most common chemicals/solvents
V lightweight and thin
High tensile strength

Question 23

What factors influence a lens’ impact resistance?

Answer 23

Scratches
Lens thickness, curvature and material
Toughening method
Speed and size of missile

Question 24

What do the PPE regs 1992/2002 cover?

Answer 24

Protective clothing and equipment

Question 25

What does Part 1 of PPE 1992/2002 regs cover?

Answer 25

13 regulations

Question 26

What does Part 2 of PPE 1992/2002 regs cover?

Answer 26

Selection, use and maintenance of PPE Lists hazards to eyes and types of eye protection

Question 27

What does regulation 4 of PPE 1992/2002 cover?

Answer 27

Selection of PPE

Question 28

What does regulation 7 of PPE 1992/2002 cover?

Answer 28

Maintenance and replacement of PPE

Question 29

What does regulation 10 of PPE 1992/2002 cover?

Answer 29

Use of PPE

Question 30

What is required for the maintenance of safety specs according to PPE regs 1992/2002?

Answer 30

Polycarb/plastic lenses must be wet cleaned with an anti-static and anti-fog lens cleaner. All scratched/pitted lenses must be replaced. All repairs must return to the lab. A suitable storage case must be returned.

Question 31

What does BS EN166 cover?

Answer 31

Specification of PEP

Question 32

What does BS EN 167 cover?

Answer 32

PEP optical test methods

Question 33

What does BS EN 168 cover?

Answer 33

PEP non-optical test methods

Question 34

Give some examples of the tests covered by BS EN 167/168.

Answer 34

Minimum robustness Resistance to corrosion Protection against large particles Resistance of oculars to fogging Resistance to penetration by hot solids

Question 35

What are the engraved markings on a lens?

Answer 35

Scale number (filter/shade no) Manufacturer's mark Optical class (1/2/3) Symbol for mechanical strength (S/F/B/A) Symbol for non-adherence of hot metal/solid (9) Symbol for resistance to surface damage by fine particles (K) Symbol for resistance to fogging (N) Poss kite mark

Question 36

What are the optical classes?

Answer 36

1 - continuous work 2 - intermittent work 3 - occasional work

Question 37

What do the mechanical strength markings mean?

Answer 37

S - increased robustness F - low energy impact (45 m/s) B - medium energy impact (120 m/s) A - high energy impact (190 m/s)

Question 38

What BS EN's deal with filters?

Answer 38

169-172

Question 39

What are shade numbers used for?

Answer 39

Lenses with filters, e.g. for welding, UV/IR protection

Question 40

What are the optical class tolerances?

Answer 40

Tolerances for sph, cyl and prism in safety specs (must also adhere to BS) 1 = +/-0.06D, 0.75^ OUT 2 = +/-0.12D, 1^ OUT 3 = +0.12D, -0.25D, 1^ OUT Vertical prism = 0.25^ UP and DOWN in all classes Horizontal prism = 0.25^ IN in all classes, OUT varies

Question 41

What does 9 mean (lens marking)?

Answer 41

Non-adherence to molten metal and resistance to penetration of hot solids

Question 42

What does K mean (lens marking)?

Answer 42

Resistance to damage by fine particles

Question 43

What does N mean (lens marking)?

Answer 43

Non-fogging properties

Question 44

What is the test for increased robustness (S) (lenses and frame)?

Answer 44

Lenses: 22mm/43g steel ball @ 5.1 m/s Frame: 6mm/0.86g steel ball @ 12 m/s

Question 45

What is the test for low energy impact (F)?

Answer 45

6mm/0.86g steel ball @45m/s

Question 46

What is the test for medium energy impact (B)?

Answer 46

6mm/0.86g steel ball @120 m/s

Question 47

What is the test for high energy impact (A)?

Answer 47

6mm/0.86g steel ball @190 m/s

Question 48

What markings should be on the housing?

Answer 48

Manufacturer's mark EN 166 Field of intended use Resistance to high speed particles (F, B, A) Two scale numbers Small head fitting (H) Can use underwater (W) Resistant to radiant heat (G) CE mark Kite mark

Question 49

Which types of eye protector should have medium energy impact resistance?

Answer 49

Goggles Face shields

Question 50

Which types of eye protector should have high energy impact resistance?

Answer 50

Face shields

Question 51

What BS covers sport eye protection?

Answer 51

7930

Question 52

What are the requirements for squash goggles?

Answer 52

FOV 80 degrees temporal, 60 inferior, 40 nasal, 45 superior Tested at 4 points using similar tests to BS EN 166 (@40 m/s)