The parameter is measured after applying a load of 10 kg to single ropes, 6 kg to half ropes and 5 kg to twin ropes. This means that it might be very difficult to accurately test the diameter of your rope in domestic conditions.
The parameter is expressed as the weight of the rope per 1 m of its length. The weight of single ropes free of any finishes ranges from 55 to 88 grams per a meter, half ropes weigh approx. 50 gram and twin ropes approx. 42 grams. The rope core must account for at least 50% of its total weight.
Number of standard falls
In the language of the laymen: it gives the number of falls the tested rope has to withstand. The EN 892 standard requires at least 5 falls for single ropes given a load of 80 kg. Half ropes are tested with a 55 kg load applied. With twin ropes, the two ropes are loaded with 80-kg weights at all times and the minimum number of falls withstood is 12. The number of falls withstood in the course of the testing is a direct measure of the safety (strength) margin of the rope. New ropes cannot practically get ruptured at shock loading provided that the rope is in satisfactory condition and well handled (protected against sharp edges). The safety of the rope will gradually decrease as a function of the material aging and wear, i.e. as a result of the factors detrimental to its strength. Also, humidity, which often attacks the polyamide fibres, of which the rope is produced, decreases its strength.
Maximum impact force
In the course of the testing, the impact force is derived from the testing load at standard falls with the elongating rope gradually absorbing the impact energy before impeding the fall. The lower the impact force, the more comfortable the absorbed fall is for the climber. During the testing, each fall increases the impact force in the rope and the final number of withstood standard loadings is dependent on the rate at which it increases. The higher the number of standard falls withstoods, the higher is the rope life.
Practical usage of the ropes on the rocks or training walls is different than in the laboratory conditions. During standard rope tests, the rope ends are tightly fixed, yet in field operation, the belaying tools and systems allow for certain rope slippage, which allows for dynamic withstanding of the falls. As a result of the dynamic belaying, a proportion of the fall energy is dissipated and the impact force diminished. For this reason, it is essential to control and use appropriate dynamic belaying tools.
The so-call fall factor is also key to the magnitude of the fall force. The fall factor is a one-dimensional quantity giving the ratio between the length of the fall and that of the rope withstanding the fall. Practically, it is of no importance for the magnitude of the impact force how long the fall is, but rather the magnitude of the fall factor. Falls of 5 meters with a fall factor of 1.5 will give rise to a considerably higher impact force than a fall of 6 meters with a fall factor of 0.5 m.
The test seeks to quantify the displacement of the sheat with regard to the core when loading the rope surface. A special machine is used for the test and the EN 892 standard specifies that the displacement cannot be higher that 40 mm at the rope length elongation of 1930 mm, i.e. approx. 2%. If, in real practice, the core gets displaced with regard to the sheat, swelling or so-called "stockings" may occur. If the ends of the ropes have been poorly welded, the core at the rope end may slip out of the sheat or the sheat may slip outside the core. The ends of our ropes are ultrasonically welded into a single indivisible unit and if the displacement requirements are complied with, the above condition will not occur.
The useful static elongation is tested by applying a load of 80 kg onto the rope and may not exceed 8 % for single ropes (one-strand ropes) and twin ropes (two strands tested at the same time) and 10% for half ropes (single strand).
ELONGATION AT INITIAL FALL
This parameter gives information on the elongation of the rope in the course of the initial standard fall. The maximum permissible dynamic elongation is 40% and it reflects the properties of the rope more efficiently that the static value of working elongation. All LANEX ropes with elongation ranging between 30 and 35% comply with the requirement of this (still optional) EN standard by a wide margin.
Excellent flexibility is one of the most important requirements imposed on climbing ropes. How is this parameter quantified? A simple knot is fastened on the tested rope and a 10 kg load is subsequently applied. Then, the inner diameter of the knot is measured and the knotability coefficient is derived from the rope diameter. The maximum permissible value amounts to 1.1-multiple of the rope diameter
Poor flexibility essentially impedes both the fastening of knots and the rope's passage through the karabiners of the belaying system and, when withstanding falls, even poor dissipation of the shock force into the entire rope length. The effects of the weather and insufficient care of the rope are also detrimental to the rope flexibility.
Rope testing at drop tower
At LANEX, there is a fully equipped testing room where the individual parameters are tested, including the fall tests. Therefore, when newly developed ropes are shipped to European testing rooms for certification, they have already been fully conditioned and furnished with values representing the known technical parameters. LANEX uses a Radvanice-based accredited testing room for its products.