Lanyard Fall Arrest System Slows And Eventually Stops

Lanyard Fall Arrest Systems: How They Slow and Eventually Stop a Fall

Falls from height are a significant hazard in numerous industries, leading to serious injuries or fatalities. Fall arrest systems are crucial safety equipment designed to mitigate these risks. Among these systems, lanyards play a vital role in arresting a fall, slowing the descent, and ultimately preventing a catastrophic impact. Understanding how these systems function is critical for both users and safety professionals. This article delves into the mechanics behind lanyard fall arrest systems, explaining how they effectively slow and eventually stop a fall.

The Physics of a Fall Arrest

Before diving into the specifics of lanyards, let's establish the basic physics involved in a fall. When a worker falls, gravity accelerates their body downwards. This acceleration generates kinetic energy, which is directly proportional to the worker's mass and the square of their velocity. The higher the fall, the greater the velocity and consequently, the greater the kinetic energy at the point of impact. A fall arrest system's primary function is to dissipate this kinetic energy before it can cause injury.

Kinetic Energy and its Dissipation

The force of impact during a fall is directly related to the kinetic energy. If this energy isn't effectively managed, it's transferred to the worker's body, potentially resulting in severe injuries such as fractures, internal bleeding, or even fatalities. Fall arrest systems, including lanyards, are designed to gradually dissipate this energy over time, significantly reducing the impact force.

The Role of the Lanyard in Fall Arrest

Lanyards are typically flexible components made of high-strength materials, such as webbing or rope. They connect the worker's harness to an anchorage point, creating a lifeline that limits the distance of a fall. However, their primary function isn't just to limit the fall distance; it's to manage the energy of the fall.

Energy Absorption Mechanisms

Several mechanisms contribute to the energy absorption capabilities of a lanyard:

• Stretching: Many lanyards incorporate elastic components or are designed to stretch under load. This stretching action extends the time over which the kinetic energy is dissipated, reducing the peak force experienced by the worker. The more the lanyard stretches, the lower the deceleration experienced. This is a crucial aspect of minimizing injury.

• Shock Absorption: Specialized shock-absorbing components within the lanyard, often located near the connection points, play a vital role in reducing impact forces. These components are engineered to deform or compress upon impact, further dissipating the kinetic energy. They often rely on controlled deformation or internal mechanisms to achieve this.

• Friction: The friction between the lanyard and its anchorage point, as well as internal friction within the lanyard itself, contributes to the overall energy dissipation process. While not as significant as stretching and shock absorption, friction still plays a small part in slowing the descent.

Types of Lanyards and Their Energy Absorption Characteristics

Different lanyard types offer varying levels of energy absorption:

• Shock-Absorbing Lanyards: These lanyards contain a specifically designed energy absorber, often a sewn-in component or a separate device incorporated into the lanyard's design. This component is responsible for the majority of energy dissipation during a fall.

• Self-Retracting Lanyards (SRLs): SRLs are more complex systems that use a spring-loaded mechanism to automatically retract the lanyard when not in use. While they offer convenient handling, their energy absorption mechanism often relies more on the controlled braking action of the internal mechanism rather than significant stretching.

• Standard Lanyards (Non-Shock Absorbing): These lanyards are typically made of less-stretchy materials and rely primarily on the elasticity of the material itself to dissipate some energy. However, they offer significantly less energy absorption compared to shock-absorbing lanyards. It's crucial to understand that standard lanyards without an integrated shock absorber are generally NOT suitable for typical fall arrest applications.

The Deceleration Process: A Step-by-Step Analysis

Let's break down the deceleration process during a fall arrest using a shock-absorbing lanyard:

1. Initial Fall: The worker begins to fall, accelerating under the influence of gravity.

2. Lanyard Engagement: The lanyard tightens as the worker's fall continues.

3. Energy Absorption Begins: The shock-absorbing component within the lanyard starts to stretch or deform. This stretching action transforms the kinetic energy of the fall into potential energy within the lanyard.

4. Peak Force: At a certain point, the lanyard reaches its maximum elongation or deformation. This is where the peak force on the worker is experienced. However, thanks to the energy absorption mechanisms, this peak force is significantly lower than the force that would have been experienced without the lanyard.

5. Deceleration Phase: After the peak force, the lanyard begins to decelerate the worker. The stretching and deformation of the shock absorber slows the descent gradually, extending the duration of the deceleration phase.

6. Complete Stop: The lanyard eventually stops the worker's fall, bringing their velocity to zero.

Factors Affecting Lanyard Performance

Several factors influence the effectiveness of a lanyard fall arrest system:

• Lanyard Length: Longer lanyards can lead to greater fall distances and increased deceleration forces. Shorter lanyards minimize the fall distance and reduce the overall energy that needs to be absorbed.

• Worker's Weight: A heavier worker possesses more kinetic energy during a fall, requiring the lanyard to absorb a greater amount of energy.

• Fall Factor: The fall factor is the ratio of the fall distance to the length of the lanyard. A higher fall factor indicates a greater risk of excessive deceleration forces. It's crucial to keep the fall factor as low as possible.

• Lanyard Material and Construction: The strength, elasticity, and overall quality of the lanyard material directly impact its energy absorption capabilities.

• Regular Inspection and Maintenance: Regular inspection and maintenance are crucial to ensure the lanyard's continued effectiveness. Damage, wear, and tear can significantly compromise its performance and increase the risk of failure.

Importance of Proper Training and Selection

The proper selection and use of lanyard fall arrest systems are paramount. Workers must receive thorough training on the correct application, inspection, and maintenance of their equipment. The selection of the appropriate lanyard for the specific work environment and potential fall distances is also critical. Using the wrong type of lanyard can lead to serious injury or death.

Conclusion: A Vital Safety Component

Lanyard fall arrest systems are indispensable safety devices that play a crucial role in preventing serious injuries and fatalities from falls. By understanding the mechanics behind their energy absorption mechanisms and the factors affecting their performance, we can better appreciate their vital contribution to workplace safety. Proper selection, training, and regular maintenance are essential to ensure these systems function effectively and protect workers from the devastating consequences of falls from height. Continuous advancements in lanyard technology continue to improve their safety and effectiveness, highlighting the ongoing commitment to workplace safety and fall protection.