Rope testing

Under EN 892, diameter is measured with the rope loaded with 10 kg for single ropes, 6 kg for half ropes and 5 kg for twin ropes. Checking a rope's diameter precisely at home is therefore quite tricky.

Weight is the rope's weight per metre of length: single ropes without any additional treatment weigh 52 to 88 grams, half ropes about 50 grams and twin ropes roughly 42 grams per metre. The core must make up at least 50% of the rope's total weight.

EN 892 requires single ropes to hold at least five falls with an 80 kg weight. Half ropes are tested with a 55 kg weight; for twin ropes, two ropes are always loaded together with an 80 kg weight and the minimum number of falls is 12. The number of falls held is a direct measure of the rope's safety (strength) margin — in practice, no new rope in good condition and handled correctly can break under shock loading.

Impact force is the force generated during the first fall under defined conditions and absorbed by the rope. In testing it rises with every further fall — the higher the number of standard falls, the longer the rope's lifespan for the user. In practice, belay devices and systems allow a certain amount of rope slip: with dynamic belaying, part of the fall energy is dissipated, which reduces the impact force. That's why it's important to master and use proper dynamic belaying.

Static elongation is tested by loading the rope with an 80 kg weight and must not exceed 10% for single and twin ropes and 12% for half ropes. Dynamic elongation during the first standard fall may be at most 40% and reflects the rope's properties better than the static working elongation value.

Sheath slippage relative to the core is determined in a special device through which a test sample 2 230 mm long is pulled — the slippage must not exceed 20 mm. If the core shifts relative to the sheath, lumps and so-called ‘socks’ can form. TENDON ropes have their ends ultrasonically sealed into a single inseparable unit, so as long as the sheath slippage requirements are met, this won't happen.

Knotability is measured by tying an overhand knot in the rope, loading it with 10 kg for single ropes and measuring the inner diameter of the knot. The calculated knotability coefficient may be at most 1.1 times the rope's diameter.

Diameter is measured with the rope loaded with a 10 kg weight; ropes may have a minimum diameter of 8.5 mm and a maximum of 16 mm. Static elongation is tested with a 150 kg weight (after pre-tensioning with 50 kg) and must not exceed 5%. Type A ropes must have a minimum static strength without terminations of 22 kN, type B ropes at least 18 kN — the strength is always stated on the rope's hang tag.

Static ropes must be made from a material with a melting point above 195 °C, so polyethylene and polypropylene can't be used. Ropes made from these materials for canyoning don't fall under the standard, even though they meet it in terms of static strength and other parameters.

Sheath slippage matters mainly when rappelling on static ropes: for type A ropes it must not exceed roughly 40 mm over a length of 2 m (applies to ropes up to 12 mm in diameter), for type B ropes 15 mm. Dynamic performance is tested with fall factor 1 falls on a rope roughly 2 m long with figure-eight knots at the ends — the rope must hold five falls; type A ropes are tested with a 100 kg weight, type B ropes with an 80 kg weight. The knotability coefficient may be at most 1.2 times the rope's diameter.

Under EN 564, cords should have diameters of 4, 5, 6, 7 and 8 mm. Diameters of 2 mm (avalanche cord), 3 mm (hammer cord) and 9 mm (strength cord) don't comply with the standard.