I think you've got it covered Pete, but as I'd already started writing, sorry for any repeats;
There isn't anything different about the way ascenders are used in the workplace compared with either caving or climbing.
Industry Guidelines, Codes of Practice and/or Regulations usually set the minimum standards that should be followed. In the rope access and associated industries, BS7985, BS/ISO22846-1/2 and the current IRATA ICOP all recommend a minimum anchor strength of 15kN.
The recently published BS8610, which is a UK supplement to the EN795 anchor standard, recommends a minimum anchor strength of 21kN where two people could be suspended at the same time, e.g., during a rescue. I think this is a little over the top and so do all the EU standards committees and most of the equipment manufacturers. They are glad of Brexit because of BS8610. We used to have a lot of influence on EU standards committees. The late Paul Seddon got his OBE for his services to the rope access industry, in particular for his work on a number of EN and International standards committees.
One of my close work colleagues sat on the committee that wrote BS8610 and we regularly have debates about the need for the increased anchor strength recommendations. In the industry I work in it wouldn't be possible to achieve substrate strengths much above 15kN. Luckily all my work is in the EU. There was considerable debate when IRATA first recommended a minimum 15kN anchor strength many years ago as most tower block parapet walls wouldn't be strong enough to rig ropes from. EN795 only requires a minimum strength of 12kN and that's one of the reasons we usually always rig ropes in a Y configuration.
EN1891A also requires a minimum breaking strength, at the termination, of 15kN.
Using the 9mm Petzl Push rope as an example, it conforms to EN1891B, has a minimum breaking strength of 20kN, (measured with the rope effectively wrapped around a couple of capstans), but when you terminate it with a Figure 8 knot, the termination strength is only 12kN, and that's the main reason we don't generally use Type B ropes in the workplace.
As for Type L ropes, I'm pretty sure this was the FFS, which is a pretty large organisation with a lot of technical expertise, deciding that some 8mm accessory cords conforming to the EN564 standard were good enough for some technical caving applications, as long as they were strong enough (11kN) at the termination and could take a couple of FF1 falls with an 80kg test mass.
If there is an EN standard manufacturers can test a product against, then they should test it. The Petzl Segment 8mm, which Petzl describe as a Technical Cord, has been tested against the EN564 accessory cord standard because it wouldn't pass the EN1891B standard. With a sewn termination Segment would meet the criteria for a Type L rope with its 13.5kN termination strength, however, tie a Figure 8 in the end and the termination strength would be around 10kN, so it wouldn't meet the criteria for Type L.
The original Petzl Stop was tested against the EN341 Rescue Device standard because there wasn't anything else to test it against that it would pass. The Shunt was tested against the EN567 ascender device standard. They had to jam it up against a knot in the rope in order to stop it slipping when they applied the required static load test. They start to slip at just over 200kg. It was never designed to be an ascender.
Applicable EN standards are always a good starting point when selecting equipment but just because something conforms to a particular EN or other such standard doesn't mean it's appropriate for the task. A double action, twist lock carabiner is a good example. It conforms to the EN362 carabiner standard, just like a triple action carabiner does, but you wouldn't use it, in the workplace anyway, where there was any possibility of 'Rollout' occurring during its intended use. Following the Noel Edmunds incident the tree surgery industry changed their Code of Practice to recommended always using triple action carabiners to help ensure 'Rollout' didn't occur.
Mark
