This standard for welding curtains and screens shall apply to all wielding and cutting operations or processes where harmful radiation (see Section 4) is emitted@ and excludes those sources that emit X-rays@ gamma-rays@ particulate radiation (such as alpha and beta radiation)@ laser light or electron beams. This standard makes use of the International System of Units (SI). Purpose. The purpose of this standard is to provide reasonable and adequate means@ ways@ and methods for the testing@ selection@ and safe use of transparent welding curtains and screens. In order to carry this out@ the function of these transparent welding curtains and screens needs to be understood clearly. These devices are designed to provide outside viewers@ at some distance from the welding arc or operation@ a safe view of the operation and operator. Transparent welding curtains and screens are not meant to replace a welding filter plate or to provide a close-up view of the welding operation. It is recommended that the transparent welding curtain or screen be at least 1 meter from the arc or operation. In establishing safety requirements@ the hazards for a viewer at least 1 meter away were considered@ with an 8 hour viewing time. In addition@ a worst-case welding arc for ultraviolet and blue light emission was used (GMAW on aluminum with an argon shield gas). This represents a conservative approach for eye safety. Because of this philosophy@ curtain or screen grades were not referenced to the welding or cutting operation. The user is free to choose a device of whatever level of visible light transmission for the particular situation. Consequently@ all devices must provide a minimally adequate level of ultraviolet and blue light attenuation. For example@ if a low level of glare attenuation is desired@ a light shade curtain can be selected@ and the user would be assured of adequate levels of attenuation of ultraviolet and blue light radiation.