Solution Summary: Auto-darkening Welding Helmets with PAPR
An auto-darkening welding helmet with powered air-purifying respirator (PAPR) is PPE that reduces the repetitive, quick neck motions required to position the face screen before welding and to shield the face. These helmets have light sensors that detect the bright spark when beginning to weld and darken the screen in a fraction of a second. The PAPR’s blower draws air through a filter and reduces welding fume concentration before supplying air to the user.
Auto-darkening welding helmets have light sensors that pick up the bright spark when beginning to weld. In a fraction of a second, they darken the welder’s front screen to avoid eye strain and eye damage from infrared (IR) and ultraviolet (UV) radiation. Auto-darkening helmets either have 2, 3, or 4 light sensors. More sensors allow quicker switching times at any angle. Switching times vary from 1/20,000 to 1/3,600 of a second.
There are many shades of screens available depending on the job and the amperage used. Shades start at #8 for low amperage and go up to #13 for high amperage uses. Some high-end helmets have additional setting down to #3 for applications like cutting or grinding. Passive helmets typically have a permanent #10 shade.
3M Adflo PAPRs with Speedglas Auto-Darkening Filter
(Photo courtesy of 3M)
- Costs: $1,100 to $1,500 (depending on model and options)
- Shades: 10 or 11 (shade 5 off state for torch work)
- Number of Sensors: 2
- Weight: 7 pounds
- Airflow Rate: >6 cubic feet per minute
- Assigned Protection Factor: 1,000
- Battery: nickel metal hydride
Traditional or “passive” welding helmets require the user to quickly tilt or tip their head forward so that the front screen will move into place. Repeated, quick neck motions can cause neck pain and injury such as neck strain. More serious musculoskeletal disorders (MSDs), such as neck disc syndrome, are also possible. Repeated forward bending of the neck can cause the interior gel part of the disc to protrude towards the back, ultimately causing arm pain or weakness. An auto-darkening welding helmet eliminates the tipping motion since the shield remains stationary before and after welding. Furthermore, the shaded face screen can prevent eye trauma by shielding the eyes from foreign material and ocular burns induced by ultraviolet rays.
Exposure to welding fumes from mild steel is associated with the development of a benign lung disease, "arc welder's siderosis." This is a reversible condition and no associated respiratory signs may be present at the time the disease is discovered (Rom, 1992).
Employees exposed to hexavalent chromium, which is often notated as Cr(VI), face an increased risk of significant health effects. OSHA notes that lung cancer, asthma, nasal septum ulcerations and perforations, skin ulcerations (“chrome holes”), and allergic and irritant contact dermatitis are associated with hexavalent chromium.
Recent studies indicate neurological and neurobehavioral deficits may occur when workers are exposed to low levels of manganese (<0.2 mg/m3) in welding fumes. These effects include changes in mood and short-term memory, altered reaction time, and reduced hand-eye coordination.
In the Construction Industry, OSHA requires that when welding, cutting or heating is performed in an enclosed space on metal coated with lead-containing paint employers must: (a) provide local exhaust ventilation or protect employees with airline respirators, and (b) ensure that the paint is stripped back at least 4 inches from the area of heat application or protect the employees with airline respirators.
How Risks are Reduced:
Auto-darkening welding helmets eliminate the tipping motion required to snap passive helmets into place. The shaded lens eliminates the harmful rays from infrared and ultraviolet radiation. The PAPR’s battery-powered blower draws air through a filter, pushes it into the helmet, past the user’s face and out the bottom of the helmet. The blower maintains a positive pressure inside the helmet, preventing hazardous fumes and particles from entering the user’s breathing zone.
Welding helmets with auto-darkening shades meeting the ANSI Z87.1 standard ensure the equipment provides 100 percent infrared and ultraviolet protection regardless of shade setting. Once the rays from the welding arc strike the sensor(s) on the helmet, the lens darkens up (Sommers, 2009).
Miller Electrical Manufacturing states on its website that, “A lighter weight helmet minimizes strain on the user's neck reducing fatigue and increasing comfort,” and that passive helmets “may lead to repetitive stress injuries.” Welding Design and Fabrication magazine states, “The repetitive task of flipping up and down [a helmet] causes neck discomfort after a day of welding.”
Health and safety experts believe that welders, especially new employees, should be using auto-darkening welding helmets more. They believe that auto-darkening helmets reduce musculoskeletal disorders of the neck caused by tipping or snapping passive helmets into place.
The American Welding Society states on their website “Use of lighter weight welding helmets and adopting the practice of never nodding a helmet down may help to prevent neck fatigue, strain, and degenerative disc disease.”
Depending on the welding job, flipping down a welding helmet can become a repetitive task. Palmer et al. (2007) state that evidence for neck pain “is strongest for repetition, by itself or in combination with neck flexion or static loading of the neck–shoulder musculature.” According to Bernard et al. (1997), there is a strong association between repetitive neck movements and MSDs.
Exposures to metals in welding fume have been found to be highly variable between similar types of welding while nitrogen dioxide and ozone exposures were less variable. Welding fume exposures were significantly higher, 474 μg/m3, for production welders than for non-welders working in the same facility, 60 μg/m3. The average nitrogen dioxide and ozone exposure for welders was higher than for non-welders but the differences were not statistically significant [Schoonover]. In a 2010 review of over 300 samples in three datasets, Meeker et al. found median hexavalent chromium exposures of 0.06, 0.20 and 1.18 μg/m3. In a 2007 field study Meeker et al. found uncontrolled manganese exposures averaged 0.124 mg/m3.
OSHA has given powered air-purifying respirator helmets and hoods an assigned protection factor (APF) of 25, meaning that they can be expected to protect workers at concentrations up to 25 times the occupational exposure limit. An employer may use an APF of up to 1,000 when supporting evidence from the PAPR’s manufacturer is available.
The use of respirators and other PPE is less desirable than using elimination, substitution or engineering controls to reduce health hazards. The effectiveness of respirators is dependent on proper and consistent selection, maintenance and use. Respirator users must participate in a respiratory protection program and undergo medical evaluation, training and, for some types of respirators, fit testing.
Effects on Productivity:
Use of a welding helmet with an auto-darkening lens and a powered air-purifying respirator has been shown to increase productivity.
Be sure that the welding helmet you purchase meets the 2010 ANSI standard. You will be able to tell because the helmet will say ANSI Z87.1 or Z87+ approved. Some of the previous ANSI standards are from 1989 and do not have temperature testing as part of the standard tests. Helmets not temperature tested can have much slower switching times in low temperatures. If the switching time is slower, the welder’s eyes can be exposed to the arc flash and eye injury can result.
Things to consider when purchasing and auto-darkening welding helmet:
- Choose a helmet that is as light as possible. A 1 lb difference in weight makes a considerable difference in the forces placed on the neck.
- Make sure the helmet meets the ANSI Z87.1-2010 standard.
- A fixed shade helmet is reasonable if welding on the same material with the same arc welding process. However, if using a variety of welders, consider using a variable shade helmet that can adjust to different amperages and can be used for jobs like grinding.
- Select a switching time that is as fast as possible. Good industrial grade helmets will have 1/20,000 second switching times.
- Helmets are available with 2, 3, or 4 light sensors, and having more sensors ensures better switching times regardless of helmet position.
Jean Christophe Le, MPH. - CPWR - The Center for Construction Research and Training. Dan Anton, PT, PhD, ATC and Zack Sinner, SPT – Eastern Washington University. Mike Cooper, CIH, MPH - The Lippy Group.
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