Safety Harnesses and The Correct Use of Shock Absorbing Lanyards
The Correct Use of Shock Absorbing Lanyards
Falls from height are one of the leading causes of death and serious injury in the work place, with a high personal cost to families and the subsequent financial cost to businesses. It is incumbent upon employers to mitigate this by either designing out the fall hazard or by providing adequate restraint or fall arrest systems.
A personal fall prevention or arrest system comprises of three components:
· An anchorage point
· Body harness
· Intermediate attachment - connecting (tethering) device between harness and anchor point
Two types of lanyard are available for working at height these are Non Shock Absorbing, and Shock Absorbing lanyards, the latter includes an energy absorbing element to reduce the fall arrest forces.
Fixed Length Restraint Lanyards - Non Shock Absorbing
In a fall restraint system, a lanyard connection is used between the anchor point and the body harness preventing the user from reaching the fall area. This type of lanyard is used exclusively as a tethering lead. An example would be using a restraint lanyard in a MEWP. If a non-shock absorbing type of lanyard is used the utmost care must be taken that it is not possible for the user to gain access to the fall area. A non-shock absorbing lanyard must never be used to arrest a fall, as the arrest forces will be too high without an energy absorber to lower those forces.
Shock Absorbing Lanyards
Alternatively a personal fall arrest system protects the user should they fall, by arresting the fall. In this system the connecting lanyard bears the greater forces during a fall. The strength of an anchor point can easily be identified with training, and the harness has its arrest forces distributed throughout the body and over many webbing components. A shock absorbing lanyard has only one strength member to withstand the fall forces and can easily be compromised by physical damage and incorrect storage. And yet it is not unusual for harnesses to be replaced more frequently by employers than the connecting lanyard.
Lanyards must be inspected frequently (see lanyard inspection later in this article)
There are two basic categories of shock absorbing lanyard, fixed length energy absorbing lanyard, and adjustable length energy absorbing lanyard.
Fixed length - shock absorbing lanyards
This type of lanyard is usually a webbing or rope lanyard which includes a shock absorbing element made from a specially woven inner webbing that smoothly tears, decelerating forces over a given length reducing the fall arrest forces to a level which is safe and avoids injury.
Fixed length shock absorbing lanyards are available in a variety of materials and choice is dependent upon the working environment and application. These materials are mostly: webbing (Nylon, and Polyester which has better chemical resistance than nylon), rope - which has better wear characteristics than webbing, and steel wire which has good abrasion and heat resistance properties but is dangerous around high voltage electrical hazards, and is not as user friendly.
At leading edge we have a preference for rope shock absorbing lanyards, as we believe they have better wear and strength characteristics and are less vulnerable to damage if the fall is over a sharp edge.
If a webbing lanyard sustains a cut on its edge the strength of the lanyard is greatly reduced, often to the point of failure in the event of a fall.
Fall distance - its is not unusual for workers to greatly underestimate the clearance required when using fixed length shock absorbing lanyards. The shock absorbing element extends as it is deployed and decelerates. As a Guide when using 2M length lanyards the fall distance required (to provide adequate clearance to the fallen operative) is 5.2M when attached above head height, 5.75M when connected at shoulder height and 6.75M when attached at foot level. It is often difficult to judge the exact fall distance (even if its known) to be sure there is sufficient clearance should the operative fall.
Dos and Donts - when using fixed length shock absorbing lanyards
· Lanyard length must not exceed 2M including energy absorber and connectors, shorter lanyards should be used if possible
· If the user needs to turn round under an anchor point a lanyard incorporating a swivel should be used to prevent the lanyard twisting.
· Never tie a knot in a lanyard to make it shorter, it reduces the lanyard strength up to 50%
· Lanyards should not be connected together to increase the lanyard length, as this will lead to increased fall distances higher and excessive fall arrest forces on the user, anchor points and lanyard.
Pros: Low cost, lightweight, easily portable.
Cons: fixed length- providing limited reach, often needing frequent repositioning, easily damaged-becoming unsafe. Operators require sufficient working height providing the necessary clearance to prevent hitting the lower surface in the event of a fall. Can be damaged if subject to cutting or high temperature burning
Adjustable Length - Shock Absorbing Lanyards
This type of lanyard allows an operative to work in restraint and work positioning, while providing back up fall arrest - should the user inadvertently misuse the equipment and put them within reach of the fall area.
The adjustable lanyard is available in lengths from 1M upwards (with fall arrest back up) providing plenty of scope for movement within the work area.
The adjustable lanyard is a rope based system it has a sliding cam fixed permanently on the rope in the correct direction of use, eliminating operator error. The cams profile is designed to automatically bite against the rope immediately the operator releases the trigger setting the position on the rope. This allows the operative to set the length of his lanyard to limit his travel and provide restraint up to the maximum of his work area. It can be easily be adjusted as work and space demands.
In the event of a fall the aluminium cam acts as an energy absorber, arresting the fall within a matter of inches (tested to EN353) and arrest forces under 6kN (typically 3kN). The short fall distance results in a limited fall where the casualty is often conscious and without significant injury, allowing a speedy rescue, which is now recognised as critical to the wellbeing of the casualty.
Pros & Cons
Pros: Low cost, lightweight, easily portable, fall distance clearance is greatly reduced (a few inches), works in restraint and fall arrest, easy adjustment for length allows maximum flexibility, comfortable very little pressure on workers back- unlike Inertia Reels-and can be used in both horizontal and vertical positions.
Cons: requires competent training before use, can be damaged if subject to cutting or high temperature burning. If using with fixed anchorage point in restraint, can be subject to pendulum effect the same as self retracting lifelines (inertia reels).
Selection considerations
Attention needs to be given to the HSE hierarchy of protective measures given in the Work at Height Regulations 2005. The highest in the provision is work equipment which prevents a fall, e.g. designing out the fall possibility or personal work restraint systems. A lower provision is work equipment which minimises the consequences of a fall, e.g. personal fall protection systems.
The type of work being carried out and the environment in which the work is being done has a great bearing on the selection of the connecting lanyard. The presence of oil, grease, acids, dirt, electrical hazards, even moisture need to be taken into account as do abrasion or exposure to UV .
Inspection
Fall protection and restraint lanyards deteriorate with age and use, regardless of brand or type. The strength of the lanyard can easily be compromised be physical damage such as cuts, abrasion, wear and excessive exposure to dirt, dust, oil, grease, acid, moisture, UV and improper storage.
Leading Edge recommend that operatives and employers attend a training course that covers equipment inspection as part of their working at height training, enabling operatives and employers to inspect webbing, rope and wire lanyards including the metal hard-wear for the following:
· Cuts
· Abrasions
· Broken stitching
· Swelling
· Unusual patterns
· Fraying
· Burns
· Chemical damage
· Weld Spatter
· Discolouration
· Deformed and damaged hardware including distortions, cracks, corrosion and pitted surfaces.
Workers are being killed and seriously injured by equipment which initially passed the required safety standards.
Correct lanyard selection and use is a key component in both fall prevention and fall arrest and it is important to bear in mind that in these systems the connecting lanyard bears the greater forces during a fall. Leading Edge strongly recommends that both management and operatives receive training to assist them in making the correct choices when selecting and using lanyards.
Current Legislation & Applicable Standards
EN 363 - fall arrest systems
EN 354 - lanyards
8432:2005 - code of practice for selection, use and maintenance of personal fall protection systems and equipment for use in the work place
Leading Edge Safety height safety courses and equipment are specifically designed for anyone whose job requires them to work at height and involves using the necessary safety equipment required to do this.