Arc Flash – These faceshields are used for protection against an arc flash. The requirements for arc flash protection are given in the National Fire Protection Association (NFPA) 70E standard. Faceshields are included in this standard and must provide protection based on an Arc Thermal Performance Value (ATPV), which is measured in calories per square centimeter (cal/cm 2 ). The calorie rating must be determined first in order to select the shield that will provide the best protection. Refer to Quick Tips #263 NFPA 70E: Electrical Safety Summary for more information on the proper selection of PPE.
Corrective lenses can be produced in many different shapes from a circular lens called a lens blank. Lens blanks are cut to fit the shape of the frame that will hold them. Frame styles vary and fashion trends change over time, resulting in a multitude of lens shapes. For lower power lenses, there are few restrictions which allows for many trendy and fashionable shapes. Higher power lenses can cause distortion of peripheral vision and may become thick and heavy if a large lens shape is used. However, if the lens becomes too small, the field of view can be drastically reduced.