A Guide to Laser Welding Safety & Laser Controlled Areas
When working with lasers, it is of utmost importance to understand the potential hazards and take necessary measures to ensure worker safety. Required and recommended laser safety measures include PPE, training, and Laser Controlled Areas (LCA).
Whether you are considering adding laser welding capabilities to your operation or are trying to make sure your current laser welding workspace is up to snuff, this article will take you through everything you need to know about Laser Controlled Areas.
What is a Laser Controlled Area?
Put simply, a Laser Controlled Area is a designated space where precautions are taken to protect individuals from potential hazards associated with laser light.
The steps required to ensure operator and bystander safety depend on laser characteristics like power, power density (power divided by beam area), and wavelength. The necessary measures also depend on conditions like expected duration of exposure and how the beam is impacted by optical aids like microscopes and binoculars.
In the United States, the Food and Drug Administration (FDA) regulates the safety of lasers through its Center for Devices and Radiological Health (CDRH). The FDA laser classification system categorizes lasers based on their potential hazards into classes.
Class 1 Lasers: Considered the least hazardous, Class 1 lasers do not emit light that is capable of causing harm under normal circumstances. Class 1 lasers may be capable of causing eye damage if viewed directly without protection for very long periods of time.
Devices can also be referred to as “Class 1 Laser Systems” – this means that the laser inside may be a higher class but the laser is integrated with an enclosure and safety interlocks that prevent users from viewing the beam without protection.
Common examples of Class 1 laser devices include laser printers, CD players, some lab equipment, and fully integrated systems.
Class 2 Lasers: Class 2 refers to low power lasers that pose a low risk of injury. Class 2 lasers are capable of causing eye damage if viewed directly for an extended period of time. These lasers can also be used without special training or qualification.
Common examples of Class 2 laser devices include laser pointers, barcode scanners, and range finding equipment.
Class 3a Lasers: Class 3a lasers are medium power lasers that are safe under normal conditions but that are likely to cause eye damage when viewed through optical instruments. Class 3a lasers can be used without special training or qualification but a Laser Safety Officer should be consulted if there is any chance of viewing through secondary optics.
Class 3a laser devices include higher power laser pointers, barcode scanners, and laser sights.
Class 3b Lasers: Class 3b lasers are medium power lasers that can cause eye damage if the beam or its reflections are viewed without protection. These lasers can cause burns or irritation if directly exposed to bare skin.
Spectrometry, 3D printing, and light shows are common applications of Class 3b lasers.
Class 4 Lasers: This is the classification under which handheld laser welding devices fall. Class 4 lasers are high-power lasers that present the most potential safety concerns, including eye damage, skin burns, and fire hazards.
Direct or indirect exposure of unprotected eyes to Class 4 laser beams and their reflections should be avoided at all costs. When in close proximity to Class 4 laser light, exposed skin should be covered with appropriate PPE. Read our full guide to laser welding PPE here.
Common examples of devices and applications that use Class 4 lasers are handheld devices used for welding, cleaning, and cutting and their heavier duty industrial equivalents as well as laser surgery machines.
Legal requirements dictate that Class 4 laser devices must be used within a Laser Controlled Area.
Laser Controlled Areas for Handheld Laser Welding
How you implement a Laser Controlled Area for laser welding depends upon your workspace and welding environment. Here are the considerations, requirements, and best practices to keep in mind.
Laser Welding Enclosures
A laser safety enclosure is essentially a series of walls or other barriers that block direct and reflected laser light. The point of an enclosure is to prevent unprotected workers and passersby from being exposed to harmful laser light. For laser welding, these enclosures are often referred to as laser welding rooms or laser welding booths.
The first step is to understand what effectively blocks Class 4 laser light. Different laser wavelengths all interact with various materials in unique ways. In the case of handheld laser welders, which utilize lasers with an infrared wavelength of approximately 1070 nanometers, sturdier, darker materials are best.
This means that light-colored or transparent plastic is not effective unless treated specifically to block infrared wavelengths (as is the case with laser-safe viewing windows and laser safety glasses). Regardless of color, things like normal curtains and cloth or cloth-like materials are not recommended.
Existing structural walls are often sufficient, particularly if they are made of concrete, brick, or some metals (brushed or anodized is best). Certain wall materials – wood, plaster, or otherwise – are enough to protect what’s on the other side but extra care should be taken to ensure that they are not exposed to laser light reflected at close range to avoid fire hazards.
Of course, not everyone has access to a spare or unused room. For many, the best answer is some kind of barrier or full enclosure purpose-built for containing harmful laser light. Choices include standalone barriers, various types of durable curtains, and anodized aluminum walls. These barriers can be used to create a full “welding booth” or can supplement existing structural walls.
It is worth noting that the final enclosure should be as “light tight” as possible. It should not be easy for individuals outside the enclosure to look inside, accidentally or intentionally, except through appropriately rated viewing windows. However, enclosures do not usually need dedicated ceilings or to reach all the way to the ground as long as workers and passersby are not likely to have line of sight into the welding area from above or below.
Laser Welding Safety Interlocks
Safety interlocks ensure that potentially harmful lasers cannot be on while an enclosure is open. This means that the laser will not start if the enclosure is open and that it will turn off immediately if the enclosure is opened while the laser is in use.
Reputable brands of handheld laser welders are built with safety interlock device interfaces. The FDA requires that all Class 4 laser products are provided with a safety interlock connection. Integration is as simple as wiring the laser welder with a separate safety interlock switch installed by the enclosure’s entrance.
Locks & Restricted Access
Only welders and other essential personnel should enter the laser welding area. To help enforce this, enclosures can utilize physical locks or keypads with keys and codes only given to the appropriate individuals. Locked doors are often paired with safety interlocks to maximize the safety of the Laser Controlled Area.
Technically, end users are not legally required to implement locks or safety interlocks when using Class 4 laser products. However, we very strongly recommend utilizing at least one or the other at a minimum.
Laser Welding Safety Signs
Facilities using Class 4 laser devices require laser safety signs to meet ANSI Z136.1 requirements for safe operation. These signs must be visible both outside and inside the area in which the laser is being used.
There is no single exact design for laser safety signs but there are some legal requirements. Signs must include the word “Danger” or “Warning” as well as a laser safety symbol. They must also be labeled with the laser classification and include language like “avoid eye or skin exposure to direct or scattered radiation” or “do not enter without protective eyewear.”
Signs can also include additional information including laser output power and wavelength as well as the name and contact information of the Laser Safety Officer.
Dedicated laser safety products often include the required laser safety signage. If not, signs are inexpensive and easy to purchase from a variety of sources. Additional measures can also be taken, such as implementing illuminated “laser in use” signs or other warning lights for when laser welding is in progress.
Other Considerations
Reflective materials in the area (such as mirrors and metals like copper) should be considered and relocated or covered if necessary. Flammable materials should always be as far from the welding area as possible, particularly if they are directly across from where the laser welding torch is pointing. This includes wall posters and things that might be resting on the welding surface like cloths and non-laser PPE. In the event of a fire, a fire extinguisher should be kept nearby.
Although not strictly necessary, we recommend providing an easily accessible area in which to store laser welding PPE like laser safety glasses and laser welding helmets.
Laser Safety Officers
A Laser Safety Officer (LSO) plays a crucial role in ensuring the safe and responsible use of lasers. They are responsible for providing safety training to personnel who work with or around the lasers as well as implementing and maintaining Laser Controlled Areas.
There is usually no need to hire a dedicated LSO – instead, you may designate an employee as the LSO and make them aware of the role and responsibilities. LSOs do not legally require specific training or certification but training programs are available if desired.