Laser Safety Manual

24 Laser Safety Manual E. Equipment Use of Engineering Controls Engineering controls must be implemented where possible to reduce hazards associated with the use of lasers and laser systems. Engineering controls should be considered in the following order: • substitution of less hazardous equipment or processes • physical isolation of the operator or process • local and general exhaust ventilation and/or filtration Specific Engineering Controls • All lasers require a protective housing. • Beams must be enclosed as much as is operationally practical. Items to consider for enclosing the beam may include curtains, side shields, partitions, or entryway mazes. • All Class 3B and Class 4 lasers must be equipped with protective housing interlock systems to prevent emission of laser radiation when the protective housing is open. • Viewing portals in the protective housing must be equipped with filters and attenuators that keep escaping light below the MPE limit. • Optical instruments for viewing laser systems must be equipped with filters, attenuators and interlocks to keep exposures below the MPE limit for all conditions of operation and maintenance. • All Class 3B and Class 4 lasers must adhere to the following engineering controls guidelines: ¤¤ Lasersmust be equipped with removablemaster key switches and must not be operable when the keys are removed. ¤¤ Lasers must be equipped with electrical connections allowing the lasers to be controlled by area interlock systems and remote shut-off devices. ¤¤ When terminals are open-circuited, lasers must not emit any radiation in excess of the MPE. ¤¤ Class 4 laser systems must have an integral and permanently attached beam stop or attenuator, capable of preventing the emission of laser light in excess of the MPE limit when the laser system output is not required (such as during warm-up procedure).