The lens shading is shown by a number. Different lens shades are suitable for different types of work. It is important to consider where the work is being conducted, and how bright the environment is. Safety Glasses with high levels of light transmission should be used in good visibility conditions, whereas eye protection with low levels of light transmission should be used in very bright environments, or places where there is likely to be glare.
Here are the lens shades and their corresponding letters:
|1.2||74.4% – 100%|
|1.7||43.2% – 58.1%|
|2.5||17.8% – 29.1%|
|3.1||8.0% – 17.8%|
The lens shading is the most easily identifiable part of the safety glasses rating, as it is shown as a number with a decimal point. Normally the lens shading is proceeded by the glasses’ level of radiation protection. This is shown as a single number followed by a dash, so that together with the lens shading the rating will appear as 2-1.2, for instance. The level of radiation protection you need will depend on the environment in which you work.
Here are the ratings for radiation protection:
|2||UV Protection (EN170). May affect colour recognition|
|2C or 3||UV Protection (EN170). The number 2C (previously 3) indicates the filter allows good colour recognition|
|4||Infrared Protection (EN171)|
|5||Solar Protection (EN172) – 100% UV protection with no infrared protection|
|6||Solar Protection (EN172) -. 100% UV protection – with infrared protection|
The strength of the lens for safety glasses is indicated by a letter. Different letters indicate that the lenses are able to resist different types of hazards.
You may find that safety glasses have a strength rating with two letters, for instance FT. The letters are as follows:
|Letter||Strength of Lens|
|F||Withstand small objects travelling up to 45 meters per second|
|B||Withstand small objects travelling up to 120 meters per second|
|A||Withstand small objects travelling up to 190 meters per second|
|T||Withstand impacts at extreme temperatures.|
Combining these together, you will see a rating that tells you what you need to know about eye protection.
Here are some examples of what a full rating might look like:
|2C-1.2 F||UV protection with good colour recognition. 74.4% – 100% light transmission and able to withstand small objects travelling up to 45 meters per second.||Ideal for factory or warehouse work where flying particles may be a hazard.||M9800 Panoview Specs|
|5-3.1||Solar Protection (EN172) – 100% UV protection with no infrared protection. 8.0% – 17.8% light transmission.||Outdoor workers who are exposed to bright sunshine||Bolle Hustler Safety Glasses|
To find the right safety glasses it is essential to do a proper risk assessment. Once you know what type of glasses you need, you can check the rating to ensure that the eye protection you need with be right for your workplace.