Posted on: 01/18/18

Unconscious and Hanging: Part 4 Constant Rate Descenders

So far in this series of blog posts we’ve considered the use of a number of rescue systems to rescue an unconscious casualty hanging in free space. Specifically, for the purposes of clarity and focus, we’ve narrowed our consideration to techniques which might be employed by workers on communications towers who are not professional rope rescue technicians in any way, shape or form. This means that any system employed needs to be simple to operate with minimal training, be fairly easy to transport and preferably able to serve a number of different rescue functions.

Today we’ll consider the use of Constant Rate Descenders for pick-off rescues. Constant Rate Descenders are commonly used in a wide range of industries and situations, from alpine gondolas to wind turbines and offer a number of different functions. Their original intended use was as a descent device which required minimal input from the user. For this reason they are often used simply as a device for self-evacuation, automatically lowering the user down at a constant speed (commonly between 0.7 and 0.9 metres per second). Their design has however evolved to allow them to serve a wider range of functions, including lifting and controlled lowering. For the following rescue the Constant Rate Descender is used by the rescuer as a descender and also a lifting device. Here Ian Rawlinson, Senior Instructor at Reax, carries out a pick-off rescue of a suspended exercise casualty. In this case the rescue is filmed from the point of view of the casualty.

In this video Ian uses a Skylotec Milan 2.0 Hub. The Milan has become such a popular device that many people now call all such devices Milans, when really they mean a Constant Rate Descender! Kind of like Hoover’s dominance of the vacuum cleaner market…! Don’t get confused though, Milan is a brand name! Good bit of kit though that we train with quite a lot. Devices like the Milan are also available with a Rescue Device Driver attachment (a high torque battery powered drill) or with handles rather than a wheel. All of these need training to use, but are designed to be straightforward to operate.

This is just one example of how such equipment can be used. They can also be incorporated into reach pole based systems, used to lower a casualty separately (known as a passive rescue, with the rescue device fastened directly on to an anchor point, rather than onto the rescuer) and for many other things. We haven’t got space to list all the uses of these in rope rescue, work at height or confined spaces. There’s lots! We use them regularly on training courses. Maybe another article about the many uses of Constant Rate Descenders is required…!

What’s the process (briefly)

-Rescuer descends to the casualty using Constant Rate Descender

-Rescuer clips on to the casualty with a sling or adjustable lanyard, connected to the rescue device.

-A few turns of the wheel lifts the casualty up, unweighting their original attachment (in this case a work positioning lanyard).

-The casualty can then be detached and lowered with the rescuer to the ground

Advantages

-Very simple to operate

-Offers a fail-safe in that if the rescuer loses control of the tail rope or wheel they will simply descend slowly and be able to quickly regain control.

-Do not require the user to add or remove individual bits of kit when changing between lifting and lowering

-Some (including those pictured) can take large rescue loads eg. 260kg

-Require training and familiarity with only one piece of equipment; other pick-off techniques usually require the use of a separate descender and lifting/cutting mechanism

-No cutting of ropes (big sigh of relief!)

-Very flexible as they can be used for a wide range of different rescues

Disadvantages

-More expensive than some other systems (difficult to compete with shears/ cutters on price!)

-Slightly more bulky than some other systems

-Some designs require care to be taken that nothing gets trapped in the wheel/ mechanism.

-Can’t think of many other disadvantages for the environment we’re looking at….

How easy is it to remember?

This one does pretty well on this count. As there’s only one piece of kit to be trained in using, which itself is simple to operate, we’ve got a good score here:

8/10

There are lots of different techniques to be considered, and as we move through this series we’ll be looking at possible approaches from a range of perspectives. What systems are you using to rescue an unconscious casualty hanging on a fall arrest lanyard in free space?

These articles are designed only to provide an overview of certain approaches to rescue. They should not be used as a substitute for proper training, in person, by professionals. Very conveniently, that is exactly what we do! Reax provide training in work at height, confined space, rope rescue and many other disciplines. Please contact us at www.reaxltd.com for more information or call us on 01253 767775.