Life line
See also: Life line (homonymy)
The life line is a safety device used in Escalade or during work in height, making it possible the user to stick to it in order to make safe itself against the risks of fall.
Definition
One distinguishes three types of life lines:- the horizontal life line
- the vertical life line
- mixed life lines
The horizontal life line
The horizontal life line is a device made up of at least two points of anchoring between which a cable, a cord, a strap or a chain, called flexible support of assurage, are tended. The user sticks directly to this flexible support of assurage. According to the legislations and/or the scopes of application, one regards the life line as horizontal according to his slope with a more or less large tolerance compared to the horizontal perfect one. It is frequent that the flexible support of assurage is constant with regular interval by intermediate additional points of anchoring.The vertical life line
The vertical life line consists of a point of top anchorage at which is fixed a flexible support of assurage. The low end is maintained or left free. It does not take part in the resistance of the system.The user usually sticks to it by means of a device which travels freely along the flexible support of assurage. This device is blocked in the event of fall avoiding thus that the user does not fall.
Mixed life lines
The mixed life line consists of at least a vertical section and a horizontal section.
Scopes of application
Professional
In the work world, the legislations impose more and more the use of means of protection against the fall. The life lines making it possible to the users to circulate over their length while being made safe, they meet one big hit.
Sport
The life lines are in fact better known in the sporting field under the name of Via ferrata.
Efforts to be taken into account
Life line horizontal
Multiplier effect
The fact of posing a flexible support of assurage between two end creates a dangerous geometry for the user not informed.Indeed, if the support of assurage is tended, the decomposition of the forces applied to the flexible support of assurage in the event of fall of the user creates an almost horizontal request of anchorings of end. This request can be higher than that of the fall on the flexible support of assurage.
Un good example which makes it possible to visualize the multiplier effect:
Position two cars provided with hook of towing back to back. Between the hooks of towing, tighten a sufficiently solid cable. Pose your foot on the cable and push. the vehicles will approach one the other and will be inserted slightly. If, by means of your foot, to support you on horizontal with the same force on one of the two vehicles, it will not move or less. It is the multiplier effect. Plus the cable will take arrow, plus you will have to push extremely with your foot so that the vehicles continue to approach.
It is thus understood that it is a question of making sure that the resistance of the points of anchoring of end is sufficient and/or that the flexible support of assurage is not tended too much.
The precise calculation of the requests in a horizontal life line is very complex. It is advisable to take account of the deformations of the system, rubber bands and/or plastics, of the system requirements, of the types of materials used, their elasticities and their resistances according to the temperatures of use, the stress type, the number of simultaneous users and the type of connection used between the users and the support of assurage.
Certain manufacturer of material proposes absorbers of energy which are placed between the ends and the flexible support of assurage. To refer to the note of use.
Vertical life lines
August 1st
Related resources
Internal bonds
External bonds
- Liste of the European standards concerning the material anti-falls
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