Even in our previous publication on "hardware" for high-altitude work, I already had to mention the kilonewton. Last time I did not dwell on properly explaining what it was, so today I intend to correct this omission.
All equipment for high-altitude work, whether it be carabiners, launching / lifting devices, anchor loops or a rope, have one or even several numerical values marked "kN" corresponding to kilonewtons. Now, however, it is not entirely clear at once what this kilonewton is?
Kilonewton (kN or kN) is a multiple of (10 3N) a value from Newton (N or N), defined as a force that changes in 1 second the speed of a body weighing 1 kg by 1 m / s in the direction of the force. Sounds scientific, but it doesn't make it much clearer, right? So let's take a few steps back and I'll try to explain it in a simpler way.
When we move into a vertical environment where movement is possible in all three directions, we have to take into account the forces, the impact of which on the plane was less relevant to us. Speaking of powers, I think you already know that:
Force = mass acceleration
Mass is measured in kilograms, and acceleration in meters / second., Respectively, the unit of measure of force, which is a newton, will be equal to:
1 N = 1 kg 1 m / s 2
But this example in itself says little, so let's find something more vital. On Earth, the acceleration of gravity is a constant value and is 9.81 m / s², and for the acceleration of household and engineering calculations, this value is usually rounded up to 10 m / s². You most likely know the exact weight of your body, but for illustrative purposes, let's agree that the body weight of a climber with all his clothes and carried high-altitude equipment will, on average, be about 100 kg. Let's plug these values into the formula above.
100 kg 10 m / s 2= 1000 N
As you can see, the force exerted by our body when falling from a height of only 1 meter is much more impressive, and 1000 N (10 3H) just equal 1 kilonewton (kN or kN) ... If we take out the acceleration of gravity from our example, then we can also say that under static conditions 1 kilonewton = 1000 kilograms. Based on this consideration, high-altitude equipment is checked in laboratory conditions on dynamometers, gradually increasing the load. Having established critical indicators, an item of equipment receives a safe rating, and a corresponding value in kN, which is then applied to it by the manufacturer.
For carabiners, three measurements are even taken: longitudinal load, cross loaded load, and longitudinal load with an open clutch. Please note that when correctly positioned, the carabiners are capable of withstanding about 20 kN, and if not correctly positioned, this value decreases to only one third of the original value. For a general presentation, you can compare the indicators of breaking loads with other types of high-altitude equipment: zhumar \ krol - 4 kN, friends - 6-11 kN, tabs - 9 kN, "horned eights" - 20 kN, guys, anchor loops (dyneema) - up to 22 kN, blocks - 20-32 kN, static rope 10 mm. - 24-31 kN, etc. For a dynamic rope, the kN indicator is not at all associated with breaking loads, but reflects the force transmitted to a person when stretching the rope itself, and the lower the kN indicator, the smoother the damping of the jerk will be, and, accordingly, the softer it will be perceived.
Источники и связанное содержимое
Ньютон — wikipedia.org
Fall Factors and kN Ratings: What They Actually Mean — vdiffclimbing.com