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May 17, 2024

How Does a Deceleration Device Work?

If you work at elevated heights, then chances are you’ve heard of personal fall arrest systems (PFAS). These are designed to protect workers in areas where it is not possible or practical to construct permanent structures like guardrail systems. PFAS’s can include a combination of components including an anchor, body harness, connectors and a deceleration device. Each of these must meet strict criteria to be deemed compliant with OSHA’s standards and can greatly reduce the risk of injury in the event of a fall.

A deceleration device is one of the most important parts of a fall protection system and is responsible for limiting the forces imposed on an employee during a fall. These devices are also referred to as energy absorbing lanyards and limit the deceleration distance of a fall. They are available in a variety of forms, such as self-retracting lifelines and rope grabs. The most common type of lanyard is a static rope, wire rope or webbing strap that has a connector at each end for connection to a body support and to a deceleration device, shock absorber, or anchorage connector.

During normal movement, the lanyard’s connector can be manually opened to permit the hook to receive an object. The snap hook closes automatically to retain the object. This is a common feature of snap hooks found in a lot of lanyard types, and this allows for the attachment of other safety components to the lanyard.

The term lanyard is used to describe a flexible line of rope, wire rope or webbing strap that hangs freely and with which falls are arrested by the engagement of an internal braking mechanism. Lanyards are connected to or include a deceleration device to reduce the force of a fall and to slow an employee to a stop during the arrest process.

An anchor is a secure point of attachment for lifelines, lanyards or deceleration devices and may be a beam anchor, cross-arm strap, D-bolt, tripod, davit or other suitable device. An anchorage connector is a device to connect an anchor to the anchorage for attachment of other components of a personal fall arrest system.

The free-fall distance is the vertical displacement of an anchorage connector on a body belt or body harness attachment point between the onset of a fall and just before the personal fall arrest system begins to apply arresting forces. This is distinguished from the deceleration device slide distance and lifeline/lanyard elongation of a falling employee, which are measured during the force test. An acceptable free-fall distance is less than or equal to 85% of the average arresting force.