About Pete

Outdoor professional and enthusiast.

Near Miss – April 2022

Potentially dangerous interaction between Petzl RIG & Micro Traxion

It should be noted that this issue may also be possible with other similar equipment from a range of different brands.

It is important to state from the outset that the equipment used in the described incident below was not at fault and was in a good state of repair. Although it was ‘human error’, I don’t believe this type of event has been recorded before and the purpose of this report is to raise awareness of an unlikely, but possible, potentially dangerous interaction between 2 common devices used in the LCMLA Vertical Award scheme.

On the afternoon of the second day of a Vertical Leader training course in April 2022, we were covering the use of Traxion and pulley/jammer systems for hoisting. I had already demonstrated to the two candidates how to use and release the Traxion devices. They both competently demonstrated their ability to do so safely at ground level (but still with a full body weight on it) with both a Pro Traxion and Micro Traxion device. One candidate went up a 5m training pitch to a ledge with a Y hang and installed a Petzl Micro Traxion as part of a haul system. They then proceeded to haul another T/A about 1.5m up the wall. At this point of the exercise, they were to reverse the haul and lower the person on the rope. The candidate used a Petzl RIG (version 2 D021AA00) on the ‘dead’ side of the rope to lift the T/A enough to release the toothed cam on the Micro Traxion. This was successfully achieved but a moment later the T/A on the rope went into freefall, dropping around 1.5m onto the ground. This all occurred under direct supervision of the T/A and at no point had anything been done by the candidate that was not expected or safe.

The exact details of the few minutes after the fall are irrelevant here, but the T/A was thankfully uninjured, although a little bruised. The candidate was asked to leave the equipment exactly as used and make their way down safely.

The 2 devices were being used on Petzl Parallel 10.5mm rope (good condition) and using Petzl OK oval triple action or screw action locking karabiners. All equipment was compatible and being used as per manufacturers instructions and LCMLA scheme best practice.

When the situation was calm again and everyone was known to be okay, I ascended to the look at the setup. I had already formulated a hypothesis about how this had occurred. Seeing the equipment and speaking to the candidate and T/A had confirmed that both the Micro Traxion and Petzl RIG were being used correctly and the RIG handle was in the locked position when the fall occurred. Once I was able to see the exact position of the equipment, I was confident that I had identified the reason for the fall and was able to replicate it in situ (on camera) and again on the ground later.

Probable Cause

The candidate and T/A were similarly matched in terms of bodyweight, but perhaps the T/A was slightly heavier. As the candidate released the teeth of the Micro Traxion from the rope, they were raised up in their harness by the weight of the T/A below. The candidate’s hands were on the Micro Traxion and bracing against the wall. The rope in the RIG was not being held. The RIG had its handle in the locked position. As the participant was lifted, the top of the RIG came into contact with the base of the Micro Traxion. The Micro Traxion moved between the RIG side plates and it pressed the top of the RIG’s cam down, at the point where the ribs are, opening the cam and releasing the lock on the rope. Without a hand on the rope, and with pressure on the cam top, there was no locking or breaking action on the RIG. This resulted in the release and drop of the T/A.

The candidate would not have been expected to have a control hand on the rope at this point. The RIG was in the locked position and is a hands-free device in that mode.

I filmed the interaction in the exact location and have uploaded it to a private link on YouTube:

https://youtube.com/shorts/oEE4bQcBFbc

Comments

  • This interaction was not a fault of the equipment, nor was it something that is isolated to these two items of equipment. I anticipate it would be possible to recreate the issue with a range of cammed belay devices and pulley/jammer setups.
  • The participant was not at fault and operated the devices according to the manufacturers instructions and the training given.
  • The supervising T/A (on the rope) was not at fault and was observing the operation throughout.
  • A heavier casualty on a rope being counterbalanced by a lighter rescuer likely increased the chances of the 2 devices coming together.
  • The position of the Traxion in relation to the RIG was unfortunately in the ‘sweet spot’ to cause this issue. It is something that might take many attempts to recreate, but clearly will, and has, always been possible.
  • This incident would fall under the user-error category, but as it was something that had not been witnessed or reported before, I don’t believe it was reasonably foreseeable by anyone involved. That said, it is now a known issue and should be accounted for in training and safeguarding trainees.

Follow up actions

  • This confirms to me the importance of a close-to-ground practice session in a controlled environment when first teaching these skills.
  • I shall now specifically demonstrate this interaction as part of my teaching when using RIGs or similar devices.
  • I shall introduce a requirement when training to either:
    • Maintain a hold of the dead rope during the counterbalance manoeuvre, even on a locked belay device, or,
    • Tie a backup knot a short way down the dead side of the rope to act a blocker in the event of uncontrolled release.
  • I shall highlight the issue when I do Vertical Core Skills assessments if the candidate is unaware.

It should be noted that this issue may also be possible with other similar equipment from a range of different brands.

For Sale – Transit Custom 2016

I’m selling my van and it makes sense to put details all in one place and just send interested people a link to this post. If you have any questions please drop me a message. More details and pics will come as soon as I have time.

Ford Transit Custom 290 LTD E-Tech

2.2 litre diesel. 125ps. Low roof, short wheelbase (L1H1).
100,000 miles just turned. Second owner from new, bought at 49,000 miles.
MOT Oct 2022. Service history and receipts since purchase.

Drives perfectly and hand on heart can say there are no issues with her mechanically that I am aware of. I probably spend about £1k a year on filter and oil changes. The van has been an essential tool for me and so I have treated it as such. I’m moving on her on so that can get something a little newer, and possibly with an electric drive system, to do a full camper conversion on. I’m in no rush to sell, so do ask for more pics or details if you need them.

Limited spec includes loads of great features:

  • Heated windscreen (worth every penny on its own IMO)
  • Heated seats
  • Parking sensors
  • Electric folding mirrors
  • DAB radio + Bluetooth handsfree
  • Auto call emergency services if detects a crash and phone connected
  • 12v plugs and USB sockets
  • 3.5mm jack for iPods etc…
  • Steering wheel audio controls
  • Voice controlled handsfree and radio (can give Siri instructions via steering wheel button)
  • Auto wipers
  • Front fogs
  • Long load bay with hatch under passenger seat (doubles as storage)
  • Floor liner in rear
  • Tyre changing kit and towing eye

My upgrades include:

  • Rear roof lining insulation and boarding with wipe clean shower panels in a cool black and silver flecked pattern (removable).
  • Walls insulated behind OEM wood panels. Panels painted and varnished.
  • Custom coat hanging storage space with heater rail (can be included by negotiation).
  • Rear lighting powered from leisure battery
  • Single bed/seat unit with memory foam mattress. Pulls out to make a sleeping area for 2 people. Mattresses included.
  • Custom units with integrated cooking shelf, storage, leisure battery and 12v & 240v charging panel. Battery and inverter can be included by negotiation.
  • On roof solar panel trickle charger (can be included by negotiation).
  • Roof bars (3x Thule) and body coloured awning (Fiamma F45S) (both can be included by negotiation). The awning has a corroded end cap but I have a replacement new one which will be included in the sale.
  • Matts in front to protect floor and make cleaning easy.
  • Seat covers included. Upholstery underneath is new looking.
  • Road legal but high spec headlamp bulbs
  • LED sidelights front and back so you can leave them on when parked up without draining the battery (I got last van written off while it was parked on a straight road so call me paranoid!)
  • Green vinyl on body is business branding, but I can leave or remove any of it before sale.

I’ve compared several other vans of the same age and similar mileage. With the customisations and mechanical condition, I’m looking for £12,250 or nearest offer for the van itself. The roof bars, awning, heater, battery, solar panel and inverter can be sold with it, but as I intend to use them on the next van I will be looking to charge a bit less than replacement cost for them if you would like to keep it all. Add £750 to negotiated price if you want all of those items with the van. All other contents will obviously be removed for the sale.

The Good

MOT Oct 2022
New power steering pipes and parking sensors Oct 21
Oil change, flush, filters and new disks and pads on front Sept 21
New rear disks and pads Oct 20
Oil and filters done on average once every 10,000 miles
Good quality spare tyre.
2 brand new Michelin M+S tyres fitted to front Feb 2022. Rear tyres about 5000 miles left of tread.

The Bad

Usual scratches from hedges on a van of this age. Worst ones shown in photos. Not as bad in real life thankfully.
35mpg average real world driving is a bit less than Ford website give. Still good for a van doing country lanes.

The Ugly

I’ve not added any dents, but I bought the van with a few already on. They are shown in the pics with an iPhone for scale. Hard to show properly in photos so viewing recommended, but none of them a severe and unless the van is freshly polished they are not very obvious.
The chip in the windscreen appeared a couple of months back. The heater elements work fine and the chip has not spread. It passed an MOT and most Fully Comp insurance policies will do a new screen for a max of £75.

Please feel free to request more photos. Van was washed, swept and mopped immediately prior to having pics taken.

Weather for the Castleton area

So this post is more of a list really. Cavers are always on the lookout for good sources of weather data to allow them to make decisions about where it is safe to head underground. The Rushop Edge – Castleton area contains one of the most complex drainage systems in the Peak District. Water falling near Sparrowpit will eventually emerge at Speedwell. Water falling on Dirtlow Rake above Bradwell will make its way to Peak Cavern. Both the Peak and Speedwell systems can be affected buy one another. Floods trap cavers and occasionally kill, so it is important to have trusted data.

A few years ago a group of cavers started to discuss a project that would see rainfall gauges and river level gauges be installed at useful locations. The data would be displayed online so that cavers could access it easily. This plan is still ongoing but will take some time to implement yet. In the mean time, I started to look at what data sources we did have for this area (beyond the usual weather websites).

Below is a series of links to potentially useful sites. I’ll update these whenever I find a new one.

Castleton weather station at The Hollowford Centre:
Met Office WOW

EA Rainfall API demonstrator. Search for station 3572 close to the Dove Holes / Chapel junction:
https://environment.data.gov.uk/flood-monitoring/assets/demo/index.html

EA River Level data seen via the Riverlevels.uk website for Mytham Bridge. This is near where the Derwent and Noe join and includes the flow from Peakshole.
River Derwent at Mytham Bridge :: the UK River Levels Website

One day wouldn’t it be great to navigate to one webpage and see the rainfall at the top end swallets and the water levels at the bottom where it resurges. This is the dream and the plan. Anyone with the skills (or money!) to help make this happen please get in touch. There is a group of us mainly involved with the TSG club in Castleton.

Tutor XG rope – Nov 2019 Update

As written about in a previous blog post, I have been testing some rope that was kindly given to me by Spanset. The rope is Teufelberger Tutor XG, a 10mm semi-static Type A.
A few months on and with a good bit of use made of it so far, I thought it was time for a quick review on how it is doing.

Since receiving the rope and chopping it down to 40/30/18m sections at the start of September, it has been used a fair bit. From memory and a glance at the dairy:

  • SRT rigging in P8 with clients
  • Used for assisted handline in Giant’s Hole
  • Used by a candidate I was assessing for their LCMLA Module 3 & Tyrolean certificates in Cwmorthin
  • Used as lifelines and SRT rigging on a vertical trip in Knotlow with clients
  • Used for SRT while doing a bit of coaching with a friend in Aberllyn mine
  • LCMLA Tyrolean Module training day in Cwmorthin
  • Fixed rigging over a weekend to allow cavers access into Snelslow Swallet for a conservation project. Must have had around 20 ascents and descents on the 18m & 40m sections.

It has been wet, plastered with slate dust, zinc mud, and proper gritty Derbyshire cave mud. Each use has been followed with a good clean like all my ropes do. I use a low power Karcher K2 domestic washer on daisy-chained ropes and then give them a good rinse whilst they are hanging to remove the last of the abrasive particles that might remain from washing on a concrete surface. Ropes are allowed to dry naturally in the hall or on the washing line if the sun is not directly out. Being a full nylon rope, it does seem to take forever to air dry!

I have just done an inspection on the 3 lengths of rope now they are clean and dry and I can report that they remain in excellent condition. The rope used as fixed rigging for a few days in Snelslow did show some damage (40m). This might have been around one of the anchor points where there was a little area of rough rock below the anchor eye. It probably would not have been an issue for a single trip, but being in the same spot for so long might have contributed to the small rub point making a bigger impact. It is still well within safe wear margins though and not at all a concern to me.

Light abrasion damage following repeated use in one location during November.

The key to supple ropes is cleaning. Clean your kit well and keep as many particles out of the textiles as you can. Dusty stiff ropes are invariably a byproduct of poor washing. I am pleased to say that the suppleness of this rope remains very good. Unlike it’s doppelganger, the Mammut Pro, which goes like steel wire eventually, this seems to be retaining it’s off-the-reel flexibility. Obviously it has a lot more use ahead of it before I declare the stiff rope problems a thing of the past.

In use it is easy to rig with, takes a knot well and feels solid in the hand. It interacts with the Petzl RIGs I use very effectively when abseiling or lowering and I have no complaints about it when ascending using an SRT kit. It might even be a bit better to SRT on than the Petzl Parallel rope I also have. The Parallel is my favourite rope, but being super supple, it takes a while to get it to run through your chest ascender on it’s own. With the Tutor XG being just slightly stiffer owing to the increased sheath percentage, the rope seems to push through the ascender’s cam quite soon after take off.

So, thus far the rope remains supple, intact and solid.

I have noticed that Caving Supplies has begun selling the Tutor XG rope, so those local to Derbyshire can get hold of some at a pretty reasonable price. I’m also happy to lend out the 3 lengths of it that I have in anyone wants to have a go before they buy some.

I’ll probably hold off on another review now until it has had a really good spell of use. Maybe check back in 6 months.

Tutor XG rope test – Thanks to Spanset

I have spent some time at Spanset in Middlewich over the last couple of months, doing my IRATA L1 and a few other bits. Some of you will perhaps know that Spanset have been particularly friendly to cavers, donating large amounts of new rope to expedition groups and competition winners on places like UKCaving forum. On my last visit to Middlewich last week, I was offered some rope to play with and provide feedback on. Although this is not a new type of rope, it is something that is only recently been taken on by Spanset and as far as I’m aware, there are no cavers out there using this stuff just yet. I’ve been kindly given 100m of this rope to test and report back on. If anyone wants to borrow a bit for a day or 2, just ask.

The first thing that some of you will notice is that this looks exactly the same as the Mammut Pro Static that has been available for some time. You might be tempted to click away now as that rope was truly terrible once it had stiffened up, but this is not the same stuff. From my understanding, Teufelberger took over the production of Mammut ropes some time back and now produce similar looking, but different spec ropes. Only time will tell if this doppelganger remains supple.

So, the details are as follows.

Teufelberger Tutor XG 10.0mm
Semi-static EN1891 Type A

Polyamide construction divided into 41% sheath and 59% core.
Stretch in normal use <5%
Shrinkage <6%
61g per meter

Apparently this is designed with teaching in mind (hence Tutor) and as a general rope access rope. Off the reel it feels supple and as you’d expect a new rope. The instructions provided did not give specific advice on whether it needed a pre-soak before its first use, so I did so anyway. Soaking for 24 hours, with 2 changes of water, before air drying and cutting. The 100m drum was reduced to a 44m, 33m and 19m rope, showing some shrinkage straight off the reel (as expected). In use, the ropes are marked up as a 40m, 30m and 18m. This is my most frequently used range and should permit me to get lots of use out of this stuff.

The rope was prepared and logged onto my system on the 1st of September. I’ll be keeping a track of how much use it has and reporting back when I have something interesting to say. I’ll probably start with an initial use post as soon as I can and follow it up with something longer term.

Mineral ID

It is sometimes really hard to relate the minerals I see underground to the professional sample pictures on places like Wiki and Google. All I wanted was to be sure that what I saw was a certain thing. Well, I’ve started a Flickr album showing actual minerals in actual mines in the hope that I can make it easier for everyone else to identify what you’re looking at. There are loads of omissions still, but it is a start!

Sphalerite (Gerionydd) (2)
LCMLA Mineral ID album.
A collection of various minerals that you are likely to encounter in LCMLA caves and mines around the UK. It is hoped that these real sample pictures will aid you in identifying what you are looking at underground. All specimens were collected for education purposes from waste hillocks or loosely on the floor and no mineral chipping occurred!

New Petzl Stop

Rumers have been circulating for a while now about a redesigned Petzl Stop being in development and test. The first pictures have now emerged following an expo in China. Thanks to Qi Woo for posting these on the Rope Test Lab Facebook Group. I have made a few limited observations based on these few images.

From this pre-sale version, we can see the device remains an assisted braking descender but is now marked as certified to EN 15151-2 (2012), which is the “Breaking Device” standard and indicates this can be used as an assisted belay device, which the previous version was not certified to. This would be a major draw for instructed caving where there is a shift away from ‘historical’ use of the current Stop and towards devices with full certification for each job we ask them to do while at work. It’ll be interesting to see this new Stop go head to head with the RIG2 device which is being picked up by more and more cave leaders.
The new Stop is compatible with 8.5mm to 11mm ropes, which just about covers the full range of diameters cavers are likely to need, although not quite down to the 8mm stuff which is becoming more popular with sport cavers. Interestingly, the new Croll S is compatible with 8-11mm rope.
The assisted braking / control handle has changed from a push-in to a pull-down style operation, much like the Petzl RIG or Kong Indy Evo, something that will be welcomed by some, but disliked by others. I am happy about this, as I’m someone who has started to develop hand pain from the current squeeze operated handle after longer trips or many lowered clients.
The device no longer seems to have user replaceable bobbins, as evidenced by the lack of hex head nuts and bolts on the frame. It does seem that both bobbins are made from the same metal, making me think this is a full stainless steel bobbin device, which should give much longer lifespan over the alloy bobbin version. We should also see an end to grey ropes in the kit store now there is no alloy to wear and coat the rope.
We’ll need to wait and see what that little hole is for in the handle. Remote braking release perhaps or just a pre-production moulding feature?

I have not seen a release date for the UK market yet and I look forward to getting my hands on the user instructions when they are issued. What will be very interesting to see is specifically how Petzl supports the use of this device for lifelining (and rescue hauling) as it might be used in instructed caving. Could this be the Stop we’ve always wanted, or will the professional caving market continue to migrate to the excellent RIG2 device, with its multi-function EN standard compliance?

In addition to the Stop pictures, we can see a completely redesigned Freino krab, with its braking spur repositioned to the opposite end of the karabiner when compared to the previous version. Eagle eyed readers will spot that this krab is attached to a red device in the photo below. We are also looking at a new version of the Petzl Simple. This does still have hex head bolts so may retain its user-replicable bobbins. They bobbins even seem to be symmetrical, making them reversible too.
I’m sure we’ll see more in the coming weeks.

I’ll get my hands on one of these new Stops as soon as they become available. Until then, if you need to talk about lifelining or abseil devices appropriate to your underground operation, feel free to get in touch. For technical advice to the outdoor industry or LCMLA courses, see www.undergroundspecialist.co.uk

Holmebank Chert Mine

Holmebank Chert Mine
Fan Entrance lock installation 9th January 2018

Today I was up at Holmebank Chert Mine near Bakewell on behalf of the Derbyshire Caving Association and the Peak Instructed Caving Affiliation. One of the access points to the mine required a new locking mechanism which allowed explorers to access the locking bolt from inside and out.

Using some high strength steel components bought by the DCA, I fabricated up a simple rotating hatch, allowing a person to reach through and access the sliding bolt on the inside of the gate. The hatch is locked with a combination padlock and cavers can obtain the code from the usual source. Currently it is set to the same combination as the other lock on the top entrance.

Many thanks to Ewan Cameron from Evolution Outdoors for the company and assistance installing the hatch today and of course to Joe at the architects firm for his continued support of access to the mine for outdoor centres and instructor training.

Testing the strength of heavy duty caving belts

A Method of Testing the Strength of Heavy Duty Caving Belts

The aim of this was to establish a method to test the strength of heavy duty caving belts that did not rely on having access to a load cell. I hoped to produce a simple system that needed very little equipment and that would deliver a test load to a belt that exceeded the minimum strength requirement for its use.

Why? Well I felt that I needed to have some kind of empirical justification to use an item of non-PPE equipment in the role of a height security device. I didn’t feel that “because we have always used them in this way” was a sufficient argument for their use. As far as I’m aware there has never been a failure of a caving belt that led to an accident, but that is not really a reason for never questioning their use in this role. These are my personal thoughts and it does not constitute ‘advice’ or the position of the BCA Training schemes.

A quick note on use of belts – The user should never be in a position where they can become suspended on a belt alone. Additionally, they must never be subjected to falls or dynamic loads. They are for restraining movement to keep someone away from a fall hazard or preventing a slip becoming a fall on easy angled ground. They are no substitute for a harness where suspension is possible.

What strength does a belt need to be?

Well, this one is a potential can of worms…. Let’s be clear, the manufacturers do not condone the use of their heavy duty belts for taking any load at all beyond hanging your battery or lunch box from it. There is a historical use in cave and mine exploration that involves using the belt for the purpose of slip prevention and security on steep ground when combined with a rope belay or cowstails. If you were intending to use it for this purpose, especially as a leader of others, you’d need to be 100% sure that the belt was strong enough for that role. The manufacturers do not state this type of use is approved or list any strength rating on the product or the literature accompanying it. You must conduct your own test and risk assessment if you are to use them in this way.

If you want an item that has a certified standard for this type of use, you could choose to use a climbing harness, caving harness or potentially an EN358 work positioning/restraint belt.

For anticipating loads that could be applied to a belt in use, I have used a mass that is comparable to the maximum user weight ratings on some of the common PPE equipment at the time of writing: 120kg (Mass)
The caver has a short dynamic rope lanyard of 50cm length, fixed from their belt to an anchor. As discussed above, the user should never be subjected to a fall or suspension, but I am using the forces that it is possible to generate in ‘foreseeable misuse’ as a starting point for considering how strong a belt needs to be.
If they climb above the anchor, until the lanyard is tight, then ignoring all stretch or slack in a system, a possible FF2 fall of 1 metre can occur.
This FF2 fall will likely result in injury and, as a rule, cavers avoid putting themselves in a position where this kind of drop can be taken. By not climbing above the attachment point of there lanyard, the resulting fall cannot exceed FF1, or 50cm in this case.
When using dynamic rope cowstails, the UIAA standard permits stretch up to 40% of original length. For a 50cm cowstail, this is 20cm, or 0.2m (Impact Distance).

For a Fall Factor 2 (1m drop on to 0.5m cowstails)

velocity = √ (distance x acceleration due to gravity x 2)

v = √ (1 x 9.81 x 2)
v = 4.43 m/s

Kinetic energy = 0.5(mass x velocity²) 

Ke =  0.5 (120 x 4.43²)   
Ke = 1177.5 Joules

Impact force = Kinetic energy / Impact distance

IF = 1177.5 / 0.2
IF = 5887.5 N

Impact Force = 5.89 kN

This is clearly a very serious amount of force and is only a hair under the threshold that the work at height industry uses as a maximum safe force the human body should be subjected to. An impact of around 6kN on the body will cause injury in a lot of cases and should certainly never be taken on a heavy duty caving belt. It is beyond anything we should ever do when wearing belts and is included only to demonstrate the risk of improper use. A FF1 drop is still something to be avoided, but is more realistic of a potential real world scenario.

For a Fall Factor 1 (0.5m drop on to 0.5m cowstails)

velocity = √ (distance x acceleration due to gravity x 2)

v = √ (0.5 x 9.81 x 2)
v =  3.13 m/s

Kinetic energy = 0.5(mass x velocity²) 

Ke =  0.5 (120 x 3.13²)   
Ke =  587.8 Joules

Impact force = Kinetic energy / Impact distance

IF = 587.8 / 0.2
IF = 2939 N

Impact Force = 2.94 kN

So a 0.5m drop on to a 0.5m dynamic lanyard may produce a force of around 3kN for a 120kg caver. This does not take into account any stretch or bounce. This figure seems pretty reasonable, but we should seek more evidence to reinforce this for our follow up testing.

When considering the use of caving belts, can we can compare it to something done in another industry? Well yes, work restraint systems often make use of padded restraint belts instead of harnesses. One of the critical requirements for this system is that a user may not be permitted to go into suspension on this system. That seems very close to how we should be using heavy duty caving belts. When consulting BS8437 – Code of practice for the selection use and maintenance of personal fall protections systems and equipment for use in the workplace, we can identify that restraint belts need to conform to EN 358. Accessing this standard is expensive and no doubt the items conforming to this standard will have a very high safety factor. What we can get from BS8437 is the recommended strength of anchor points for use in a work restraint system. This is 3 x the mass of the user. A correctly installed and utilised work restraint system is only required to have an anchor of 3 x users mass. For our 120kg caver, this would be 360kg, or 3.6kN in force.

For our 120kg fictitious caver, we can mathematically predict a theoretical force of just under 3kN for a FF1 drop. We can also see that and anchor of 360kg (3.6kN) would be required if using similar techniques in work restraint. The figures are not exactly a match, but are comparable. Taking the worse case figure is probably the safest option going forward, so our belts must be capable of taking a force greater than 3.6kN for a scenario that does not involve wildly inappropriate use.

Safety Factor?

Apply to this any safety factor you wish. The 3kN figure from the maths is indicative of the maximum possible force generated in a FF1 drop on 50cm cowstails, the real world figure will be far lower due to stretch and slippage of the belt on the body and the sagging of the rope the caver is connected to. The BS8437 figure is a 3 x safety factor over the user’s mass anyway. You could argue that belts tested to 3.6kN would be sufficient as an indicator of appropriate strength if you never operated with cavers heavier than 120kg.

Belt Strength

Accepting all this, we are left with the figure of 3.6kN as our chosen minimum requirement for the strength of the heavy duty caving belt for any user we might encounter regularly (3 x 120kg based on BS8437).

So as long as we can apply a test force of 3.6kN or more to the belt, we can be assured that the item can hold the greatest possible force we can apply to it in proper use. The only remaining factor of concern is that would applying this force in test render the belt unsafe to use again, in essence, are these tests destructive? Only 1 way find out…..

Testing

Using 1 very large Corsican Pine and a good sized Birch tree, we set up a pull testing rig with a simple 3:1 theoretical configuration. I used a Rock Exotica load cell to get live feedback on the testing here but if you copy the method, you would not need to use one.

For the estimation of test force we regarded each person capable of pulling 50kg (see Gethin Thomas’ work on tyroleans). Through a theoretical 3:1 MA system that would be 150kg per person. With 5 undertaking the pull reaching 750kg and 6 equalling 900kg or approximately 7.5kn and 9kN respectively.

Kit used (minus load cell): Petzl rescue pulley, Petzl Basic jammer, Petzl Partner pulley, Lyon wire sling for tree, assorted karabiners, 20m rope.

Due to the force expected to be placed on the rope, I did not anticipate that I would be able to untie the end knot (fig 8 loop). This was accurate and the knot had to be cut from the rope end. Bare this in mind with your own rope!

We also used a Petzl Rollclip to redirect the angle of pull to make it easier to stand on the tarmac of the road alongside the trees.

Initially we had 5 people pulling the first test on a Lyon roller-buckle belt (brand new).
This produced a force of 5.9kN with no damage or slippage. This is lower than expected but there was a lot of tightening in the knot and stretch in the rope coupled with a general timidness of the pulling team.

The remaining tests used 6 people to pull. This one was conducted on my 10 year old Caving Supplies square buckle belt (already retired). This belt has nicks, fluff and rust and comfortably took a force of 7.74kN showing no damage or slippage. Next came my current AV belt, with it’s central maillon removed and directly attached to the pull line. This belt held 7.7kN without failure or slippage. Finally, the pulling team seemed at their most confident that nothing was going to break and send shards of metal and wood at them so they really gave the last belt some pain. This Warmbac square buckle belt was subjected to 8.64kN with no damage or slippage noted at the time.

It is not surprising that the force exerted by the pulling team was less than the theoretical 3:1 system implied. In practice with the loss of friction due to bearings and turns in the rope a 2.5:1 is a more real world figure and so our 5 x 50kg pulling average adults could be expected to make 625kg/6.25kN using this system.

On this test we pulled the belts to a far higher force than would be needed in a periodical strength test to simply demonstrate that this lower level of testing would not damage the belts. Using 4 people to pull on a 3:1 MA (2.5:1 actual) system in a reasonable way with un-gloved hands, would produce a force exceeding 3.6kN. This would not require a load cell to demonstrate if the method was followed correctly. Using 3 strong people on the same 3:1 (2.5 actual) system would probably be reasonable too.

50kg x 4 people = 200kg x 2.5 mechanical advantage = 500kg or 5kN
50kg x 3 people = 150kg x 2.5 mechanical advantage = 375kg or 3.75kN

Conclusions

Using a system like the one shown here, with 4 people pulling at average strengths, you can apply a force greater than 3.6kN to your test belt.

Once the test is complete you should thoroughly examine the belt like any other item of textile PPE to see if any damage or slippage has occurred. Any that do show signs of damage should be retired. Any slippage may be down to the buckle, but if the belt comes off or strap slides through the buckle under load, it should be deemed as having failed. If a belt has taken the test load and shows no damage or deformity then you can be comfortably sure that the belt will be fit for its intended use whilst still in that condition.

Final inspection of belts:
Lyon roller buckle                                5.9kN            No damage
Caving Supplies square buckle           7.74kN          No damage
AV maillon closed harness buckle       7.7kN            No damage
Warmbac square buckle                      8.64kN          No damage, slight curvature to webbing now when hung vertically which indicates over stretching or broken fibres down one side.

Again, this level of force was beyond what you would test to, but demonstrates that the 4 person 3:1 pull will not damage a belt that is not already fit for the bin.

A Note on Load Testing PPE

We don’t load test PPE. PPE is supplied with declarations of conformities and CE/EN markings. So long as you purchase via a reputable retailer or from the maker, this is the evidence that the product meets the minimum criteria set out in its approval standard.
Caving belts are not PPE and have no categorisation under the PPE Regulations. It therefore falls to the user to ensure they are fit for purpose, and that may involve a test of strength as outlined in this blog post. Ultimately, you must conduct your own risk assessment and define a way to show they are fit for use, copying a blog post won’t cut it with HSE!

Inspections

Lastly – all of this testing and use is predicated on you treating your belts as an item of PPE. They should be purchased new, inspected prior to use and have a recorded inspection every 6 months like any other PPE item. They should be in the same good condition as any textile item of PPE and retired from service if damaged, worn, contaminated or subjected to any load exceeding their safe limit. It is recommended that anyone in charge of inspecting PPE be trained and certified to do so.

As a side note, I maintain that the Caving Supplies belts are the tanks of the heavy duty caving belt world and, if kept very clean, will ultimately outperform every other type or brand available. I think this test shows that well as the CS belt had at least 5 more years of abuse over the other belts. I will dispose of the Warmbac belt just in case but don’t tend to use these anyway, but that’s another blog post!

Worn Connectors – Pull Testing 11-6-2017

Over the last few months I’ve been collecting a few bits of retired equipment from stores checks and ‘isolation’ bins with a view to looking at loss of strength due to wear. Nothing here constitutes a scientific test and this is purely for my own satisfaction, but I’m writing it up anyway. I used my home made breaking rig with the Hilti HAT-28 anchor tester to provide the pull force. Each item was pulled up to the maximum possible load of the Hilti, 20kN, and the results were recorded.

Petzl Omni SL

Rated to 20kN main axis. Worn inside arc in 2 places after use with large steel pulley for 12 months. Failed PPE inspection due to wear depth being felt by fingernail and visually obvious.

Pulled to 20kN – No breakage, gate / lock working correctly.

I suspect that the wear on this item had not yet reached a sufficient depth to form a significant weak point. The connector was certainly retired at an appropriate time, i.e. with visible wear but before strength loss occurred.

Petzl M33 OK Oval SL

Rated to 24kN main axis. Wear visible at both ends of the connector. Large radius wear from twin cheeks of a steel pulley and small / deep radius wear from a long term connection to a steel 7mm Maillon Rapide.

Pulled to 20kN – No breakage, deformed beyond elastic recovery. Gate no longer closes and shape is visibly distorted. This item deformed at 15% below its rated strength. This shows that wear had already reduced the strength of this connector and it should really have been retired before reaching this level of wear.

Petzl Vertigo Twist Lock

Rated to 25kN on main axis. Worn on inner surface due to repeated contact with steel cable zip wires whist in use as a cowstail. Retired during routine PPE inspection.

Pulled to 20kN – No breakage, deformed heavily under test but recovered almost completely after. Connector permanently deformed and the gate locking mechanism does not function correctly. This item deformed 20% below its rated strength. This shows that wear had already reduced the strength of this connector and it should really have been retired before reaching this level of wear.

Do not take this test as advice to use kit beyond it’s manufacturer stated working life. Get a qualified person to advise you if unsure or go and do a PPE/FPE inspector course. If you have any retired gear you want to send to me to test in this manner then please get in touch.