Safety Tip of the Month by Tim Bambrick
All Falls Are Arrested
About the year 1687 Isaac Newton discovered and published that a body in motion will remain in motion until acted on by an outside force. Fast forward 330 years and I would like to explain how a body in motion comes to a stop using Energy Absorbing Lanyards (EAL) or Self Retracting Lifelines. Last month we talked about practicing 100% tie off when using energy absorbing lanyards and self-retracting lifelines. This month I want to discuss the differences between the two different types of products so you can have better understanding of how these pieces of equipment work. All falls arrested. Think about that and let it sink in. During a fall at some point the person will come to a stop. Either safely through proper fall protection or in an unsafe manner, striking the lower level or ground using improper fall protection or no fall protection at all. Both energy absorbing lanyards and self-retracting lifelines arrest falls. They are the pieces of equipment that connect your full body harness to the anchorage and ease the blow of g-forces to your body during a fall event. Energy absorbing lanyards are designed with stitching that rips as the fall forces are being applied to the lanyard. As the lanyard gets taut, the forces start to rip the stitching to absorb the energy. These engineered stiches rip at predetermined locations, allowing the falling worker to come to a controlled arrest. Think about that time when your jeans got caught while trying to jump a chain link fence as a kid. You could feel the jeans slowly ripping thread by thread as gravity brought you closer to the ground. This same thing happens with energy absorbing lanyards. ANSI rated energy absorbing lanyards are designed for 6 feet or 12 feet free falls meaning they are designed for the worker to either fall 6ft or 12ft before the equipment is deployed. This allows the user to be connected to anchor points that are not always directly overhead. Below is a chart showing the differences between the 6ft and 12ft free fall lanyards. Roof tops and construction sites are very common places for lanyards since there are not always anchor points directly overhead. Energy absorbing lanyards are also light weight, and fairly inexpensive when compared to SRL’s and can be easily inspected. Self-retracting lifelines work similar to car seat belts. They retract and give slack through the housing coil easily under normal conditions, but during a sudden quick jerk, they lock up. Unlike car seat belts, self-retracting lifelines typically have either brakes, an incorporated energy absorbing lanyard or a combination of housing with a locking and braking mechanism that includes an incorporated lanyard. All of these are designed to take force away from the fall. All of these styles (see below) are designed to lock up immediately as the worker experiences a sudden loss of balance and begins to fall. Once they lock up, either the brakes, energy absorbing lanyard, or the combination of brakes and energy absorber are working together to slow the worker down and provide a controlled stop. Even though these styles lock up immediately, keep in mind that there is still a deployment distance just like a lanyard. If the worker has access to anchor points directly overhead, SRL’s in most cases are the equipment of choice. They lock up instantly during a fall event, and the breaks or lanyard component deploy instantly which can reduce fall distances. One key advantage of an SRL is vertical mobility. This feature allows the user to remain connected and traverse multiple work levels without re-connecting. Because SRL’s retract automatically into the housing, there is no concern for the lines tangling in machinery or the lanyard becoming a tripping hazard. Some manufacturers now make SRL’s for anchor points that are not directly overhead (below D-ring ring or at foot level anchors). If you decide to use one of these types of SRL’s, I would highly recommend reviewing the user instructions and manufacturer’s testing documentation. ANSI has not yet fully addressed this type of SRL. There is no standardization of testing and performance so manufacturers are testing their own in-house protocols. This leads to inconsistent testing processes and testing results that will certainly vary between manufactures. I frequently get asked “what’s better, SRL’s or lanyards?” My response includes an explanation of the two applications. One is not necessarily better than the other. Every fall hazard is unique and needs to be addressed as such. Keep in mind that both energy absorbing lanyards and self-retracting lifelines are designed to decelerate the fall forces on the body. I wonder what Isaac Newton would think today if he saw how energy absorbing lanyards and self-retracting lanyards are used to stop a body in motion----- safely?
When unsure of safe work practices and equipment usage, please contact your company’s competent person or feel free to reach out to us at Malta Dynamics for help on correct product selection and usage.
Tim Bambrick Bio
Tim Bambrick holds a degree in Mechanical Engineering from Thaddeus Stevens College and has spent more than a decade in the fall protection and safety industry. He utilizes this wealth of experience as Director of Product Development for fall protection manufacturer Malta Dynamics. Whether developing new and innovative equipment, improving existing products, or validating new ones, he utilizes his unique expertise within the industry to ensure that Malta Dynamics is able to offer the highest quality products on the market. He currently sits as a voting member on the ASSE/ANSI Z359 committee helping to develop new criteria that will eventually become the standard for keeping workers safe. It’s this invaluable experience with the committee that gives him an especially keen eye for detail when qualifying products and developing new ones. His knowledge ranges from not only the science that drives and guides fall protection products, but he is also very aware of the user interface portion of products. He has a direct hand in instruction, training, and the overall use of the very products his group develops. Tim is at the very nerve center of Malta Dynamic’s belief in how they approach all they do - Solutions Bourne. For specific questions concerning technical safety issues or about Malta Dynamics products, Tim can be reached at tbambrick@maltadynamics.com.
