HSE: Industrial rope access - investigation into items of personal ...

6.1 INTRODUCTION
6 ROPE ADJUSTMENT DEVICES
There is an increasing range of devices on the market, some originating in sport, some designed
specifically for industry. As in prEN 12841, rope adjustment devices are divided into three
categories:
• Type A - Back-up devices
• Type B - Ascenders
• Type C - Descenders
A key feature of equipment for rope access is versatility. Almost all rope adjustment devices
will have secondary uses, especially during rigging for rescues etc. This reduces the amount of
hardware an operative has to carry and increases their operational abilities and safety margin.
Some newer devices are not as versatile as those currently in use and this must detract from
their suitability for rope access. Their specialist nature may, however, make them more suitable
for certain specific purposes.
The line diagrams in the following sections are intended to show the principles of operation of
the devices, they are not intended to illustrate the entire device. The diagrams are partial
sections and have been reproduced at approximately 35% full size.
6.2 TYPE A – BACK-UP DEVICES
6.2.1 Introduction
The adoption of two-rope systems, one for progression (the working rope), and one for security
(the back-up or safety rope) requires that a third device be installed on the safety rope. It must
slide when required, and lock on to the rope when required. This is the origin and the function
of the back-up device. The adopted definition of back-up devices differs slightly from that in the
standard prEN 12841, where they are called "Type A Rope adjustment devices". For the
purposes of this report the definition adopted is:
“A rope adjustment device, for a safety line, which accompanies the user
during changes of position, allows adjustment of the safety line, and which
locks automatically to the safety line under static or dynamic loading and
which can be intentionally released while under load.”
The performance and limitations of the back-up device were one of the HSE’s main concerns
when commissioning this project. Over the years, the Petzl Shunt has become almost
universally accepted as the industry standard and was stated as meriting particular attention.
At present, the back-up system incorporating the Petzl Shunt is effectively standardised by the
IRATA Guidelines 8 . The Shunt is connected to the harness with a cow’s tail made from
dynamic rope tied to the user’s required length. The Shunt remains where it is placed on the
secondary (safety) rope and must be repositioned whenever the user moves upwards or
downwards. When ascending, this is done by pushing it up the rope ahead of the user. When
descending, users fit the Shunt with a short cord to enable it to be towed downwards.
8 INDUSTRIAL ROPE ACCESS TRADE ASSOCIATION
General requirements for the certification of personnel engaged in industrial rope access
methods: Edition 2, 1998
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