Fall comparison with rigid/human mass - Petzl USA
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Fall comparison with rigid/human mass

The tests presented above were designed to help us evaluate falls involving real people. For comparison, we redid the same series of falls based on the standard model: rigid mass with a GRIGRI 2 fixed to the anchor.

Warnings

  • Read the technical notice before viewing the following techniques.
  • It is important to fully understand the information provided in the technical notice before using this complementary information
  • Mastering these techniques requires training.
  • Consult a professional before attempting to perform these techniques on your own.

 

Test with rigid mass

Factor 0.3

Factor 0.7

 
Force on the anchor
Force on the climber
 

These tests revealed very significant differences between the two protocols: the force on the climber increases by up to 70% with a rigid mass.

These differences are explained by the many factors, other than the rope, that contribute to fall energy dissipation: the absorption of the two bodies, belayer displacement, rope slippage in the device...

Conclusion

These tests help us evaluate falls involving real people.

Such measurements necessarily carry a high degree of uncertainty, but help provide important information:

  • The forces at work in a real fall differ greatly from the results of standard testing.
  • In practice, factors other than the rope contribute to dissipating the energy of a fall.
  • To understand a fall, one must take into account all of these factors and not focus only on the rope.
  • It is difficult to control all of the factors that dissipate fall energy. However, it is easy to influence the potential for belayer displacement. Belayer displacement helps dissipate a significant part of the energy and thus limits the forces at work. On the ground, it is essential to allow displacement to occur for a dynamic belay. At the belay station, it is wise to use a long tether, when the situation allows it, to allow displacement to occur.

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