RAD LINE: small diameter hyperstatic cord
The cord sold with the RAD SYSTEM was carefully chosen to be suitable for the intended uses, while remaining compact and lightweight. Its specific qualities limit its application: it is not as versatile as a normal mountaineering rope.
- Carefully read the Instructions for Use used in this technical advice before consulting the advice itself. You must have already read and understood the information in the Instructions for Use to be able to understand this supplementary information.
- Mastering these techniques requires specific training. Work with a professional to confirm your ability to perform these techniques safely and independently before attempting them unsupervised.
- We provide examples of techniques related to your activity. There may be others that we do not describe here.
1. A fall on a hyperstatic cord is dangerous
The rope is an essential component; its energy absorption capacity helps reduce the maximum impact force experienced in a fall. Dynamic ropes have greater energy absorption capacity than static ropes.
Comparison test of energy absorption by the rope: fall factor FF 0.4.
0.8 m fall on 2 m of rope with figure-eight knot in each end, knots tightened with 80 kg. 80 kg dummy.
Note: the test scenario does not correspond to a realistic belay situation; the goal is only to characterize the ropes' behavior without measurement bias.
A hyperstatic cord has minimal elasticity; it can not absorb the energy of a fall.
- High impact force (peak height of the blue curve)
- Sudden deceleration (slope of first peak of the blue curve)
The RAD LINE hyperstatic cord must not be used to arrest a fall... unless another element of the system is able to absorb the energy of the fall.
Examples of energy absorption factors in addition to the rope:
- Belayer displacement
- rope friction, for example cutting through the lip of a crevasse
- energy absorbers integrated into the system
2. Compatibility with ascenders
The RAD LINE cord sold with the RAD SYSTEM is 6 mm in diameter and theoretically incompatible with the MICRO TRAXION and the TIBLOC.
To offer a kit with this cord and these ascenders, Petzl conducted a series of tests to be sure of their compatibility.
Compatibility test between RAD LINE and MICRO TRAXION:
Strength of cord sheath greater than 5 kN
Compatibility test between RAD LINE and TIBLOC with ATTACHE carabiner:
Strength of cord sheath greater than 4 kN
Compatibility test between RAD LINE and other ascenders:
Wide range of results: cord sheath breakage observed at between 2.9 and 5 kN depending on the ascender.
In certain cases, the cord's thinness is incompatible with the geometry of the locking system: the cord comes out of the ascender.
Alway follow the recommendations of the Instructions for Use furnished with your ascenders.
Test of the RAD LINE's tear resistance with different ascenders
Compatibility test between MICRO TRAXION and other Dyneema cords of less than 8 mm in diameter:
Wide range of results: cord sheath breakage observed at between 1.7 and 5.5 kN.
Cords behave less predictably than ropes, certain small diameter cords are stronger than others of larger diameter. There can be a significant difference between test results on two models of cord with the same diameter.
Tear resistance test of small diameter cords with the MICRO TRAXION.
Only the MICRO TRAXION and the TIBLOC (with ATTACHE carabiner) were confirmed suitable for use with the RAD LINE cord. Do not use any other ascender with the RAD LINE, or any other rope less than 8 mm in diameter with the MICRO TRAXION or TIBLOC.