In households, rope characteristics are usually given superficial attention. When assessing technical and operational qualities, 2-3 criteria are applied, among which length and thickness. In the best case, material of manufacture is taken into account. The situation is different in the areas of professional use of this item of equipment, where it is of key importance. Climbers, climbers and speleologists are well aware of the difference between dynamic and static ropes, which allows them to carry out their tasks efficiently and safely.
Basic classification and rope arrangement
Specialists conditionally divide climbing ropes into three categories, highlighting not only dynamic and static, but also special models, which will be discussed separately. By design, all products for professional use consist of two elements - the core and its protection. The first, in turn, includes the braid and internal fibers, and the second performs the function of external insulation and can consist of a variety of materials depending on the specific purpose. Also, the external knit retains the shape of the core, giving it the appearance of a cylinder.
From the point of view of reliability, in principle the number of threads in the braid of the rod. More commonly used configurations are 32, 40 and 48 fibers. To understand the degree of strength, it can be noted that, for example, the Kolomna dynamic rope 10 mm thick for 48 twisted threads is allowed to be used in EMERCOM divisions of Russia. Moreover, the core does not bind to the braid, which logically determines the shear effect. This design feature is sometimes useful, but recently technologies of “bonding” of insulating material and the core have been increasingly used to increase the safety of the product.
Assigning dynamic rope models
Insurance is the main function of this type of rope. Their distribution has allowed in many areas of sports tourism to abandon the etching technique in order to reduce the load on the upper point due to stretching. The dynamic property itself involves a reduction in the energy of the jerk as a result of the natural extension of the structure. It can be said that this is the same etching effect, but does not require any effort on the part of the user. In the event of a breakdown, the dynamic rope reduces the load on both the broken and the upper point to a safe rate. This does not exclude the risk of injury, but the depth of the fall is leveled to the extent that corresponds to effective etching, at least. To this it is worth adding that the simultaneous use of structural dynamic tension and insurance, produced by friction through a protective element (for example, a ledge of a rock or a carbine), is not allowed.
Varieties of dynamic rope models
According to the structure and purpose of use, the following types of insurance equipment can be distinguished:
- Single. A rope with a standard design, which is used for simple safety operations. Single models have a thickness of 8.7 mm and above, and are also marked with the number 1 in the circle.
- Double. Rope with a minimum thickness of 7.5 mm. Its feature is the pair application with another attribute of the same. In preparation, they are alternately embedded in different safety nodes at intervals. For marking, use the 1/2 symbol.
- Double. A kind of dynamic rope for mountaineering, the initial diameter of which is also 7.5 mm. Unlike the previous version, products of this type involve the insertion of both ropes at the same point without breaking. A dual model is marked with an intersecting ring icon.
It is important to note that neither double nor double rope is used in a single configuration.
Characteristics of dynamic rope models
One of the main operating parameters is the strength of the first jerk. This is the ultimate effort arising at the moment with a dynamic factor. For a typical rope with such a structure, this value should not exceed a draft of 1200 kg, i.e. 12 kN. The limitation is due to the fact that the force contradicts the dynamic properties in the form of elongation.
The following characteristic is expressed in the number of jerks. The standard dynamic test of the rescue rope for this parameter is carried out as follows:
- The rope is firmly fixed at one end.
- A load of up to 80 kg is suspended to the other edge.
- The object of weighting is dropped so that the rope each time hits the carbine.
The test is repeated at intervals of 5 minutes. The number of jerks performed without damaging the structure of the rope will be the normative value.
Another important parameter is elongation. This is the percentage that the rope will stretch. On average, this ratio is 35-40%. Also, for railings, the value of static elongation will be important - the limit to which the rope does not stretch under the load.
Water protection rope
In wet fibers, technical and operational qualities change - any professional climber knows this. Even if their strength is enough to work in “wet” conditions, the dirty aquatic environment brings abrasives that will make themselves felt when the threads dry. For a dynamic rope with a stretching and tapering structure, the presence of small sand particles is particularly destructive. For this reason, the presence of water-repellent impregnation is of great importance.
The basic rule in determining this parameter is: if it is really about the risks of getting wet, then semi-impregnated products should not be considered at all. Further, the choice is made according to its purpose - for ordinary conditions, all-weather or with abundant water contact. It should focus on specific exogenous factors.
Static rope purpose
This variety combines increased strength and a low coefficient of static elongation of the order of 5%. Such qualities are useful in organizing mountain rails, in rescue operations and industrial mountaineering, as well as in various extreme sports such as arborism and canyoning. And if the structure of a dynamic rope is developed taking into account the safety function, then static models are not recommended for use in cases with a high risk of falling (jerk factor not higher than 1). Almost all configurations of the lower protection are prohibited, and the upper one is used depending on the circumstances.
Static rope characteristics
In assessing the possibilities of using static rope models, one should proceed from the following parameters:
- Relative lengthening of the structure. The tensile coefficient under load is about 150 kg. The maximum value should not exceed 5%, and on average it is 3%.
- Braid shift. This characteristic is important when organizing descents. For a dynamic safety rope, this is not the primary criterion for selection, but for a static one it is very significant, since with a large shift, loss of connection with the core can stop the same descent process, in particular. The maximum allowable displacement of the braid is 2 cm per 2 m of the core.
- Shrinkage. The rope made at the plant has the property of shrinkage, that is, it is shortened and generally decreases in size by about 10-15%. Large foreign manufacturers of safety equipment already at the stage of rope manufacture apply the heat setting procedure, after which the fiber structure does not change size. However, most domestic products shrink only during operation, so it will not be out of place to make a reserve of the same 15% when purchasing.
It should also be noted that there are two types of rope, involving minimal elongation under load. These are models of groups A and B. In principle, they differ in terms of strength - in the former it is 22 kN, and in the latter - 18 kN.
The difference between dynamic and static rope
Operational differences between the two types of ropes under consideration are based on fiber design features. The dynamic structure is softer, load-sensitive and energy-absorbing. Due to the high coefficient of stretching with a damper effect, such equipment is actively used in insurance (lower) of the first participant on the route. But what is the difference between a dynamic rope and a static one, if we compare the universal application for support? In this case, the difference is caused by hard weaving with tight tightening of the threads in static models. It is these qualities that allow the use of such products in rescue operations and with the organization of climbing rails. Conversely, a dynamic tensile structure is not allowed to the device of crossings, traverses and the same fences.
What is the difference between static-dynamic modifications?
Although at first glance the technical and operational properties of static and dynamic rope models are mutually exclusive, manufacturers are able to combine them. How it's done? It uses the same cable form factor, but consisting of three components: in addition to the core and the braid, another central level of the core is used from Kevlar or polyester threads. The operational differences between dynamic and static ropes in this case are leveled, which is expressed in the special principle of operation of the combined product. During the ascent and descent, the load is transferred to the elastic core, which provides a static behavior of the equipment with efforts up to 700 kg. Beyond this load, the main rod breaks, absorbing part of the energy in the process of falling. This ensures a safety dynamic effect.
Special rope features
The third kind of climbing ropes, the distinguishing features of which include structural design and operational properties. As for the structure, its feature is the presence of an inner layer of a metal mesh and an aramid braid on the outside. Compared to a temperature and moisture sensitive dynamic rope, special modifications are characterized by increased resistance to external influences. If we talk about the static-power qualities, then the elongation coefficient is minimal. Technical security and durability are the main functional qualities of such models.
Conclusion
Choosing a rope for critical events is an important and difficult matter. Consideration should be given not only to the type of product design, but also to specific parameters of shape and size. The optimal option in extreme conditions will be a dynamic rope of 10 mm - this is the standard that is used by both professionals and amateurs. If we talk about static models, it is important to focus on the knitting coefficient. For example, the diameter may be smaller (8-9 mm), which will make it easier to control knitting. After all, do not forget - static models have a more rigid structure and a low degree of flexibility.