AUTO DARKENING FILTER LENS (ADF)

Today, there are two types of filter lenses: passive and auto darkening. Space does not allow a full scale analysis of auto darkening filter lenses (ADF) in a blog format but we will detail the main points. A welder needs to do some prep and positioning work before welding, and some weld cleaning after the weld. With a passive filter lens, he needs to push his welding helmet up into a rest position so he can see to perform those tasks.

 The Bureau of Labor Statistics disclosed that 67% of welding and cutting injuries are face and eye injuries. Most of those injuries occurred when welders had their helmets in an up position between welds and were injured by others welding, chipping or grinding in the area. OSHA estimates that up to 90% of those injuries could be eliminated if welders wore their helmets in the down, protective position all shift long. The only way that is possible is with the use of an ADF.

An ADF uses complex electronics and LCD’s to automatically adjust the filter shade to the various stages in the welding process. When the lens is not activated, it usually is a shade 3 or 4 which are relatively easy to see through, similar to sunglasses. A welder can see to do his prep work and position his MIG gun, TIG torch or stick electrode.

 When an arc is struck, light sensors mounted near the lens detect it and simultaneously darken the filter lens to its welding shade 10, 11, 12 or 13 in a fraction of a second. When the arc is extinguished, the lens automatically reverts to its shade 3 or 4 inactive shade so the welder can see to clean the weld without having to lift his helmet. Protection from ultra-violet radiation (UV) and infrared radiation (IR) is continuous, whether the ADF is in the light or the dark state.

Because an ADF equipped helmet always stays in its protective position, another safety related benefit is the fact that it does not have to be “nodded down” before each weld. That eliminates a leading cause of repetitive motion injuries to the neck and back of welders. That not only reduces the cost of injuries, it also contributes to lowering workers comp premiums and costs.

When face and eye injuries and the strains, sprains and muscle fatigue caused by the repetitive nodding motion are eliminated, the quality of work life is enhanced and moral improves as welders enjoy rising expectations that welding does not have to result in daily aches and pains.

Beyond an ADF helmets basic protective function is its contribution to productivity. It is well documented that a reasonably comfortable, well protected welder will stay on the job longer, concentrate better, and produce more welds with fewer rejects, rework and delays. When an ADF is selected carefully, and used properly in an appropriate application, productivity gains from 30% to 50% are common.

But how do you carefully select an ADF welding helmet? The Fibre-Metal Products Company introduced ADF’s to the domestic market more than 20 years ago when it partnered with Hornell Speedglass of Sweden, the founder and pioneer of the ADF, to incorporate its highly successful European ADF technology in lenses specifically designed for Fibre-Metal brand helmets. Today there are many competitors with a bewildering array of models and price points. Because most of them could not improve on the original technology, they sought market entry with faster “switching speeds”, gadgets and gimmicks and lower selling prices.

As with any other PPE, do your homework in the selection process. Look at different brands and different technologies. Ask lots of questions. Most importantly, ask for samples or “loaners” to try on your job under your working conditions. Many of the inferior brands cite impress performance statistics achieved in a test lab. But they don’t hold up in a harsh welding environment. When evaluating an ADF equipped welding helmet there are some things to consider. There are 3 basic performance characteristics that determine the performance quality of an ADF lens. Anything else is superfluous:


1. Optical quality


2. Switching speed


3. Electronic reliability

Many suppliers have tried to establish switching speed, the amount of time it takes the lens to switch from its light to dark shade, as the most important performance characteristic because that is all they have to offer. The reality is most, if not all ADF’s that meet current standards, switch many times faster than International Standards require. Moreover ADF’s switch too fast for the human eye to see. If you watched 3 brands switch from light to dark you could not tell which one switched faster. And switching from light to dark occurs before welding begins, so what real affect could it have on a welders performance?

You must always consider switching speed in conjunction with switching reliability. The electronic packages utilized to maximize switching speed make those types of ADF’s very unstable. It is important for the lens to switch to its dark shade only in response to a welding arc. Top quality ADF’s use an “intelligent” technology that allows the lens to ignore other light sources and only recognize a welding arc. The high switching speed technology is so sensitive, it results in “nervous” or “trigger happy” lenses that often react to over-head lights, sunlight, other welder’s arcs and switch at inappropriate times.
.
Optical quality is by far the most important performance characteristic for an ADF lens. A welder must look through his ADF all day long. The optical quality determines his ability to see his work clearly in all stages of the welding process. The top quality brands of ADF’s have superior optical quality that is easy to see while testing a lens. Just as the inferior technology, built for switching speed, is unstable, it also has numerous optical quality problems.

Almost all of the brands that focus on high switching speed technology suffer from “flickering” and “fluttering”. Flickering looks like wavy lines similar to interference in a TV or bad tracking in your VCR. Fluttering is continual and unpredictable switching back and forth from light to dark. Both conditions are very distracting to a welder and result in downtime to try to remedy the condition. These flaws are very obvious during on the job evaluations.

Other optical flaws present in nearly all inferior ADF technologies are mottling (measles like spots when first turned on); tracers (impressions of sparks); shadows (like ghosts on a TV). They cause a great deal of annoyance, discomfort and downtime for a welder. Again these flaws will be very obvious during testing and evaluation. In fact, one ADF supplier provided an instruction that if when you turned the lens on it had a mottled appearance, turn it off and wait a half hour. Built in downtime.

All brands of ADF’s have an optical flaw, called angle dependency, in varying degrees. It usually manifests as light spots in the corners of the lens when viewed from an angle. Recently the Fibre-Metal by Honeywell brand of ADF has introduced an upgraded technology that virtually eliminates the problem with angle dependency no matter the viewing angle.

Only consider ADF helmet brands that come from the factory fully assembled. You do not want to have to spend the time or assume the responsibility for proper assembly. ADF’s are either battery or solar powered. The solar powered lenses draw their energy from the arc. Both power sources work fine but the advantage of the solar powered lenses is that you do not have to replace batteries. ADF’s come in a fixed lens shade, or with the ability to select one of multiple shades. If a welder is a production welder, who uses the same process to weld the same materials, a fixed shade is the proper choice. But if a welder works on various materials, using different processes in the course of his work, the ability to change lens shades without having to change lenses is a huge productivity gain and a selectable shade model is the right one.

Only consider ADF equipped helmets that have all controls inside of the helmet. Many of the low price, low technology brands mount some of the functional controls on the outside of the helmet where they are exposed to harmful sparks and spatter. It only takes a small amount of spatter in a control to render the ADF useless.

The number of light sensors is something that is frequently debated. The notion that “more is better” is a myth. The reality is the number of sensors is electronic technology dependant. If the technology is such that all it needs is one sensor to function, that is fine. If the technology is such that it needs 4 sensors to function, that is fine also. On the job performance is what is important. Not the number of light sensors.

There is value in simplicity. Look for a simple, but functional ADF design with user friendly controls. A light sensitivity control is necessary to adjust for the sensitivity to other sources of light in the work area and a dark to light delay control is useful for some materials and high amperage applications where the weld puddle is still very bright after the welding arc has ceased and for situations where the filter sensors may be temporarily blocked from seeing the welding arc.



Beyond that, additional features are superfluous, a drain on the electronics package and something else to break down. Make sure any ADF’s you consider will be able to function across a wide range of welding applications and processes and can detect low amp TIG arcs. Be leery of any application limitations such as “cannot be used for overhead welding”

A problem with ADF’s is that many are installed in cheap, inferior welding helmets to try to keep the purchase price down. They use things like attractive graphics to mask tissue thin shells made from ordinary materials. But the function of an ADF requires a high quality, robust helmet made from a high performance material. Because an ADF equipped helmet stays in the down position longer, buying decision makers must consider a number of factors. The welding helmet must be sturdy enough to withstand the extra burden put upon it by increased exposure to heat, sparks and spatter for an extended period of time.

The headgear must be capable of anchoring, balancing, and stabilizing the added weight of the ADF in the front of the helmet. The headgears overhead band and position stop adjustments must allow a welder to properly align the ADF with his field of vision to minimize awkward or uncomfortable working positions in order to see through the lens.

Because the helmet remains down longer, smoke and fumes can accumulate within the shell. The helmet design should allow sufficient air circulation to move them out of the welders face. If the air circulation is not sufficient or hazardous fumes are present, the helmet must comfortably accommodate a respirator with appropriate filter. OSHA requires that a welder wear protective spectacles at all times. The helmet design must not interfere with the use of primary eye protection.

 

The two ADF manufacturers with the highest quality ADF technology are Balder and 3M SPEEDGLASS. Between them they are responsible for most technical advances in ADF design and performance. But because they are primarily lens manufacturers, their welding helmets leave a lot to be desired. However, both produce ADF lenses for top quality Fibre-Metal by Honeywell brand helmets. And that combination of ADF and helmet quality and performance is the one all other ADF equipped welding helmets are compared with and measured by.


So when someone tries to sell you an ADF equipped helmet based on low selling price, high switching speed and graphics, tell them you are more interested in optical quality, electronics reliability and improved productivity.

Look at everything that is available. Use the information in this post as your guide. Try any ADF equipped helmet you are considering on your job, under your working conditions. Compare brands. If you can find a better helmet than the ones we ranked as tops, buy it. An ADF equipped welding helmet is a significant investment. But the ROI in terms of lower injury and insurance costs, increased productivity, enhanced quality of welder work life and improved profitability is real and immediate. In most situations, a company pays off the initial investment in a matter of weeks while the value of the benefits goes on throughout the service life of the helmet.

______________________________________________________

Make sure any ADF and helmet considered meets current ANSI or appropriate International standards. Selection should be made by or in consultation with a designated Safety official and welding supervisor. Read and follow all instructions and heed all warnings that come with the ADF helmet. Failure to do so could result in serious injury.

WELDING FILTER LENSES

A few posts ago we talked about welding helmets and how they protect from welding sparks, spatter and radiant heat. But we left protecting the eyes from a welding arc’s harmful radiation for a separate post. Electric arc welding emits IR/UV radiation and intense visible light. Unprotected from these hazards, both eye damage and discomfort can occur. The PPE for protecting welder’s eyes is filter plates and lenses installed in welding helmets. (Traditionally, the 2” X 4 ¼” rectangles used in welding helmets were called “filter plates” and the 50 MM circles used in goggles were called “filter lenses”. But with the advent of auto darkening, both are generally called “filter lenses” today.)

A filter lens serves two purposes. The first is to diminish the intensity of visible light to a point where there is no glare and the welding area can be clearly seen. The second is to block harmful infrared and ultra-violet radiation coming from the arc. Filter lenses come in a variety of shades which are designated by a number. Many people mistakenly think that the lens shade number corresponds to the amount of protection that is provided to the eyes and the higher the number, the better the protection. Actually, the shade number indicates the degree of visible light provided. The lower the number the lighter the shade; the higher the number the darker the shade.

 All filter lenses block 100% of IR/UV regardless of shade number. The filter lens shade number selected depends on the type of work and somewhat on the preference of the welder. Consequently, the filter lens shade number selected must not vary more than two shades from the numbers recommended. A welding filter lens shade should only be selected by a trained welding safety official.

OSHA 29 CFR 1910.133- Eye and face protection, ANSI-Z49-1, and the American Welding Society each publishes a recommended filter shade chart similar to the one below.

Virtually all passive filter lenses are made from polycarbonate. The top quality lenses are injection molded. Molding assures consistency of shading throughout the lens. Avoid filter lenses stamped from sheet stock. Most passive filter lenses cause a welder to see his work in various shades of green. But there are specialty gold plated filter lenses that not only reflect radiant heat and lower the temperature inside a welding helmet, but also allow a welder to see his work in natural colors. They are a good investment in safety and productivity

Always install a clear plastic “cover” plate over top of the filter lens to protect the filter from sparks, spatter and getting scratched. If the welding helmet has a lift-front filter holder, always install an impact resistant, clear, polycarbonate safety lens behind the filter in the body portion of the lens holder as a last line of protection when the filter lens holder lid is lifted. Some welders even install a safety plate behind the filter in helmets with stationary filter holders if there is space to do so.

 Remember to always wear approved protective spectacles under a welding helmet at all times. They are your primary eye protection. Welding helmets are classified as secondary eye protection.

 Like all PPE, there are differences in quality among filter lens brands. Most welding helmets come from the factory with a filter lens installed and you are better off staying with that same supplier’s brand of replacement filter lens. In general, the top brands of welding helmets can be relied on to provide the best quality filter, safety and cover plates and lenses.


And make sure any filter lens you consider meets the test for transmission of radiant energy prescribed in  ANSI/ISEA Z87.1-2010, Practice for Occupational and Educational Eye and Face Protection.


___________________________________________________________
KTF disclaims liability for any injury of any nature whatsoever, whether indirect, consequential or compensatory, directly or indirectly resulting from the use of or reliance on this blog post. KTF also makes no guaranty or warranty as to the accuracy or completeness of any information published herein. The selection of any PPE should only be made by responsible safety officials.