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Slouppi • View topic - Karabiinien ja köysien käsittelystä

Slouppi

Rock climbing and Bouldering in Finland
It is currently Sun Mar 29, 2020 13:26

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PostPosted: Fri Mar 04, 2005 20:03 
NOTES FROM THE WORKING GROUP ON BELAY METHODS
UIAA SAFETY COMMISSION


It is not surprising that the meetings of the Working Group on Belay Methods of the UIAA Safety Commission have taken place in and around Padova. Canada has participated in the last three meetings. While there are still many questions to be answered, one can report on a few of the findings (in no particular order).

1. The greatest variable in the magnitude of the force at the top runner is operator behaviour. Values can vary between 20 to 50 percent. Hand pressure and position, reaction time, position of operator and body mass have significant influences.

2. All belay devices seem to work, although the force in the top runner may vary.

3. The force in the top runner is surprisingly small (even if there is only one runner, i.e. very little system friction). It appears that the force in the top runner will rarely reach 10 kN (it did not even come close in the tests). The values fall mostly between 3 and 6 kN. This is independent of fall height (theoretical fall factor). Note again that operator behaviour has a major influence.

4. The 'static' devices such as the Grigri (there may be rope slip through the device of 2 to 5 cm, while it is 50 to 120 cm for a dynamic device) may produce twice the force on the last runner than a dynamic device.

5. The lifting of the operator may reduce the force on the top runner, possibly by as much as 10 % and even more. It is again influenced by operator behaviour. Sometimes no significant reduction could be determined.

6. Lifting of the operator beyond 30 to 40 cm has no influence on the magnitude of the force in the top runner.

7. Lifting of the operator may increase the stance load. These forces are, however, not very significant. Generally from two to three kN except for the 'static' devices, which could produce twice these values. The latter were always attached to the fixed anchor, because of injury concerns.

8. The force on the top runner increases with the mass of the operator.

9. It is highly recommended that a dummy runner is used at the belay.

A final word of caution: while many climbers seem to prefer the body belay in the hope of reducing forces on the last runner, the danger of injury may negate this advantage, particularly in alpine, rock, environment. Several injuries to the operators - and they are very experienced - have occurred because of the uncontrolled lifting. One has to keep in mind that they know when the mass is dropping. Now consider when this force hits without this awareness.


http://www.alpineclubofcanada.ca/servic ... laying.doc


Last edited by Sampsa J. on Fri Mar 04, 2005 21:36, edited 1 time in total.

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 Post subject:
PostPosted: Fri Mar 04, 2005 21:16 
PUOLIKÖYSISTÄ (TIEDOT VUODELTA 1995)

I would very much like to know by how much the forces are reduced in waterfall ice climbing using half ropes.

There are obviously two aspects to it: one is the higher elongation during a fall and the other, as you mention, that one cannot hold on to the rope as well, with two ropes in the hand and one sliding. Another point may be that the rope may be held with a wet mitt, resulting in more sliding. While this may be acceptable on vertical ice, I do not recommend this method of climbing. The runners most often are very far apart, the ropes may be wet or frozen and there could be sharp edges and the ropes are not designed for this use. I would be very scared to do this in some of the mixed climbs done today, where the ropes definitely run around sharp edges. In other words, does the reduction of the forces in the system justify the risk of breaking a rope? What are your views on this?

Carlo's Response (he is the Italian member of UIAA Safety Commission):

"The French have hammered this idea into the heads of our guides and young climbers. First of all, let my say that the greater “elasticity” of a half rope as compared to two half ropes is not the major factor in reducing the load. (Once again, YOU MUST REALISE THAT THE WHOLE TEXT IS DEVOTED TO THIS LOAD PROBLEM, whereas a broader view should be taken. This has not been said explicitly enough, though old Carlo insisted very much on this point). The lower (halved) number of runners passed by each rope has some importance, but altogether this would account to something like 10% reduction, something more if the friction is high. The rest (to something like 30% total reduction) comes from the fact that the HAND does not hold so well when only one rope is sliding. Let us clearly say that this 30% only occurs, IF there are few runners. With many runners and high friction, the differences between the belay methods are strongly reduced. Only the reduction of friction occurring in the alternate placing of the ropes in the runners would be the effective factor in reducing the load.

Concerning your safety considerations, I agree. I am trying to oppose the decision of our guides to go for alternately passing the half ropes in the runners. They are obsessed by the danger that the runners come out. They do not realize that as soon as you have placed a few runners, the friction cancels the advantages of this technique. Only the reduction of friction remains a benefit in a few cases (by alternating ropes), when friction is really bad. And if the runners are in a straight line, the friction is even increased by alternately passing the rope in the runners.

The following typical values are suggested by Vittorio. They are a sort of average of experimental results (the computer model gives a somewhat lower advantage to the third case):

Load on the last runner in case of:

• single rope: 660 daN
• two half-ropes passed together in the runners: 740 daN
• two half-ropes passed alternately in the runners: 450 daN."


http://www.alpineclubofcanada.ca/servic ... niques.rtf


Last edited by Sampsa J. on Fri Mar 04, 2005 21:36, edited 1 time in total.

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 Post subject:
PostPosted: Fri Mar 04, 2005 21:35 
KÄYTÄNNÖN TESTEJÄ JÄÄRUUVEILLA

Re: Rope Question "with some new data"
Author: Chris Harmston
Email: chrish@bdel.com
Date: 1998/03/19
Forums: rec.climbing

On 19 Mar 1998, Tom wrote:
> My interpretation of these results are much worse for two reasons:
> 1) In actual use, the rope would have failed on the very first fall at
> "7.45 kN (1674 lbf)" based on "Sample 1 (end of the rope)" results
> since the rest of the rope ("Sample 2 (middle of the rope)" would
> have been attached to it and I assume to the belayer, etc.
> Admittedly, it would have been a "1.78 fall factor with 178 lbs"
> though.
> I am not impressed at all.

It is certainly possible that this rope could have failed in the field. I doubt it because of the fact that the UIAA setup is far more severe than what you can do with people and belay devices. If this rope were used for aid soloing then I would be very concerned. Aid soloing in my opinion is the most dangerous form of climbing because people usually have a static belay and use large diameter high impact force ropes. This rope was used far in excess of what I would call safe practice. However, I see this level of use on ropes routinely. I too have used my ropes to this extent but, I recognize this risk. Understanding the limitations of the gear is critical here. I would not use a rope with this type of use where the chance of a high fall factor was high. If I had no choice I would ensure that my belayer was aware of this and gave a soft belay by allowing the rope to slip instead of locking it off in the event of a fall. The point of my message is that people need to be very aware of the gear they use, the technique they employ, and the abilities of their partners to also recognize these two issues. I would agree that I am not impressed with the rope because it broke on the first fall. However, this is exactly what I expected to see happen. I also expected to see the section in the middle fail on the first drop but it held two falls and broke on the third. I also expected the impact forces on each of these drops to be in excess of 10 kN and they were really quite close to when the rope was new.

Here is another example of some "uncontrolled" testing I have been involved with.

Last winter Craig Luebben and I conducted some drop tests on ice. Craig published an article in Climbing Mag on some of these results and results of his static tests. I have also written an article on static tests I have conducted in the lab (email me if anyone wants a copy). Anyway, we set up our tests under the bridge in Ouray. This was in pretty bad ice actually and for the most part the gear did not hold. Our setup was with a static belay, a new 10.5 mm BD rope, fall factors in the 1.5 to 1.8 range, and 185 pounds of steel. With this setup the only thing that actually held was a 10 cm screw. Everything else ripped out OR carabiners broke! I attribute this to the bad ice and that the 10 cm screw that held was probably in the only good ice we found.

We decided to conduct a series of tests where we used the same section of rope over again. The first three tests the gear ripped out. On the fourth drop we about keeled over in disbelief. We had a Snarg as the test piece connected to the rope with a draw with BD QS2 biners. A few feet below this was two equalized screws (BD and a Grivel). They were equalized with a single 24" sling and a locked Big Easy was connected to the rope. The biner on the snarg broke, the hanger on the Grivel screw sheared long its long bend, then the big easy locked biner broke! This is three pieces of hardware that broke on one fall.

Now, I am assuming that these were not defective products (a solid assumption based on my knowledge of all the gear and the systems to produce it, and a review of the fracture surfaces of the parts we actually (covered). This means that the forces generated were well in excess of 5000 pounds (multiple times!). Now the tricky part. Conducting a static test on a new rope with the same diameter with the same type of knots caused the rope to break in the 3500 pound range. I don't know why the gear broke and why the rope did not. There was about one hour between drops so the rope had some reasonable time to recover.

Now the good news. When we placed an ATC in the system (i.e. some dynamic aspects) every test we conducted held except for a couple of tests with Spectres.

What does this mean? Dynamic belays are your friend! Climbers have known this for about a century now. Many climbers today do not understand this very well. This is why I am relating these types of info to this news group. I am purposely trying to get this group to discuss this stuff in detail and learn something from it. So Tom, thanks for your response and concern.

> 2)Since, "2 sections of rope were cut off (15 feet from each end)
> due to core shots", these results are even worse! . . . because
> I interpret the cutting off of these sections to mean they had been
> thrown away sometime before the testing while it was being used
> by Merill Bitter. The 2 sections apparently were even more abused
> and would have failed well before "7.45 kN (1674 lbf)" had they
> been included in the testing.
> How's my logic ?
> Tom

Your logic is fine as I can tell. Yes, the two sections Merill cut off were not tested. These were thrown out (I actually saw one of them and it was severely abused and had a large core shot). It is certainly possible that they would have failed at even lower forces. We couldn't test them because they were too short.

Overall, I am impressed with how well Merill's rope performed. However, I do think that it was used beyond what was reasonably safe for the majority of climbers.


http://www.fishproducts.com/tech/rope.html


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 Post subject:
PostPosted: Fri Mar 04, 2005 22:08 
KYPÄRISTÄ:

Kannattaa lueskella seuraavat:
http://www.thebmc.co.uk/safety/tech/art ... elmet1.pdf
http://www.thebmc.co.uk/safety/tech/art ... lmets2.pdf

Etenkin ylhäältä tulevien iskujen suhteen (lue kivet) on suuria eroja. Kannattaa varmaan miettiä kaksi kertaa, onko oma vehje soveltuva nykyiseen käyttöön. Listasin alle ne mallit, joita lienee eniten suomalaisten käytössä.

Testitilanne ylhäältä tulevalle objektille:
BD:n Half Dome 12.0kN
Grivelin The Cap 9.8kN
Campin StarTech 9.3kN
Petzlin Meteor 9.2kN
Campin Rock Star 7.1kN
Petzlin Erin Roc 4.4kN.

Erot ovat huomattavan suuria, sillä käytännössä 8kN vastaa 800 kiloa. Siinä katkeaa tukevampikin niska... Yleisesti ottaen noissa testeissä pärjäsivät parhaiten brittivalmistaja HB:n kypärät.


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 Post subject:
PostPosted: Fri Mar 04, 2005 22:39 
Yhteenvetoa:

Vaarallisia asioita:
1) Terävät kulmat pudotessa (mitä uudempi köysi, sen paremmin asiat)
2) Köyden kiinnittäminen karabiinilla valjaisiin
3) Huonosti toimiva karabiinin portti (aukiporttisen kesto ylittyy helposti pudotessa)
4) Akkuhappo (ei näy silmällä)

Haitallisia asioita, mutta ei suoranaisesti vaarallisia:
1) Märkä köysi (superdry ei auta asiaa)
2) Merkitsemismuste (myös Bealin myymä)
3) Köyden ikä
4) UV-säteily

Suhteellisen harmittomia asioita:
1) Jäätynyt köysi
2) Bensan ja dieselin kaatuminen köyden päälle
3) Köyden päälle astuminen (jääräudoilla tai ilman)
4) Metallikamojen pudottelu
. . (pudottelusta ei synny mikrohalkeamia, mutta silmällä näkyvät viat ovat toki ongelma)

Muuta kivaa tietoa:
1) Liidiputoamisessa tyypillinen iskuvoima ylimpään varmistukseen on alle 7kN, todella harvoin yli 10kN
2) Vertailun vuoksi voidaan todeta että monet kevyet karabiinit kestävät portti auki vain 7kN.
. . kestävyys portti auki on siis yksi karabiinin tärkeimmistä ominaisuuksista.
3) Puoliköysien käyttö pienentää iskuvoimaa noin 30-40%.
. . tästä noin 10% on seurausta köyden paremmasta joustosta
. . ja loput siitä, että varmistaja ei pysty pitelemään köyttä yhtä tehokkaasti kuin sinkkua
. . siis suomeksi sanottuna köysi luistaa väkisin varmistajan käsissä
. . ja jos luistaminen eliminoidaan (köysikitka, reversino), iskuvoima ei juurikaan pienene
4) Suurin vaikutus iskuvoimiin on varmistajan käyttäytymisellä (20-50%).
. . dynaaminen varmistaminen kannattaa opetella hyvin.

5) GriGriä voi suositella vain yläköysikiipeilyyn tai pulttireitille.
. . kaikkialla muualla se aiheuttaa vaarallisia iskuvoimia.
6) Jääruuvien kesto riippuu täysin jään laadusta.
. . 10cm ruuvi kestää hyvässä jäässä kakkosen testiputoamiset staattisella varmistuksella
7) Kypärissä on eroja.
. . putoavan kiven iskuvoima voi olla jopa kolminkertainen (4kN vs 12kN)


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