>Confined spaces

Confined spaces

Why do confined spaces come within the scope of protection during work at height ?

The main reason for creating a whole range of fall arrest products and solutions for work in confined spaces is not exactly related to fall protection. Let's explain:

In confined spaces, the reduced oxygen level represents a serious health risk. The inhalation of certain toxic gases, normally present in environment of this type, can even entail a risk of immediate death to those working inside.

To avoid this risk, fall arrest systems are used, specifically designed to immediately evacuate anyone in a high risk situation.

Therefore, confined spaces have their own specific section in the world of safety at height. Primarily because the work involves using an anchor point to hoist up or rescue a person at serious risk.

The anchor devices used for this work are generally transportable, as included in section B of the EN 795 standard. We would mention that transportable devices are used for convenience, while at Elytra we cannot see any reason for not performing the said operation using a fixed anchor device, provided that circumstances permit.

We would therefore like to make it clear that the "transportability" of the anchor devices is, in our opinion, only a requirement in the sense that these devices are more practical to work with. Working in a confined space from a fixed anchor device simply requires a better understanding of the PPE being used.

Evacuation

What are the applicable standards?

At a product level, the devices employed for this type of work simply need to be certified as anchor devices.

Moreover, due to the actual nature of the work, it is more practical to use mobile or transportable devices. They can therefore be taken from one place to another.

Therefore, most anchor devices used in confined spaces are certified to EN 795-B.

However, as already mentioned above, if work circumstances permit, there would be no problem in using a fixed anchor device, certified to EN 795-A. In this case, the difference in relation to a mobile device would be that these anchor devices would be permanently installed at the same place.

It is not only a question of the type of anchor device, the PPE used must permit the rescue of the person at risk.

PPE in confined spaces

The rescue requirement also means that the PPE employed in confined spaces are different and more complex than those used on normal anchor devices.

A device is required to immediately evacuate the person in danger.

A retractable fall arrester with a lever retrieval system is the most suitable device for this purpose. In some circumstances, retractable arresters with a chain drive and hoists mounted with ropes and pulleys, are also used.

Tripod

What is the tripod used for?

Tripods are transportable and are therefore certified to EN 795-B. They are designed for work in confined spaces when access is through a manhole.

Thanks to tripods, work requiring access from a manhole can be performed autonomously, since it does not require the prior installation of fixed anchor point or other protective items.

Retrieval using a fall arrester, lever-based retriever

In this case, work is from the base mounted on one of the tripod legs.

The use of a fall arrester with a retrieval system is the most convenient and safest way of working, given the fact that:

The retriever is fixed to the base, ensuring that it remains in place.
The retrievers include a 4:1 lift hoist, ensuring that no great effort is required for the retrieval.

In addition to the retriever and to the mounting base on the tripod leg, in order to operate this system, it is also necessary to fix a pulley to the tripod anchorage in order to re-send the cable coming from the base of the tripod leg.

Other forms of retrieval from the tripod

Lever-based retrieval is not the only way to work with the tripod.

Other retrieval systems include:

Fall arrest with a chain retrieval system.
A rope and pulley system.

The key difference between these two retrieval methods compared to the first method is that these are mounted on the tripod anchor point instead of on the tripod leg base intended for the lever-based retriever.

Davit arms

How does the Davit Arm work?

Like the tripod, the Davit arm is considered to be transportable, used for multi-site operation and certified to EN 795-B.

The great advantage of the Davit Arm is that is rotates on its own axis, so that, in addition to retrieval, it allows the rescued person to be released on a safe platform.

However, unlike tripods, most Davit arms require the prior installation of sockets in order to subsequently insert the masts. Once the socket has been installed, it is extremely quick and easy to insert the arm.

Some Davit systems do not require these fixture sockets, however they are not as quick to assemble. And, in general, they are expensive systems.

Floor-mounted Davit arm

This is the most popular type of support. It is permanently installed for use in confined spaces requiring constant access.

Wall-mounted Davit arm

Secured to vertical surfaces, these are also intended for frequent work as they are permanently installed.

Davit arm without a socket

As no socket is required, these are more versatile than the arms requiring a socket, given that, as for the tripods, they simply need to be taken to the place of work and mounted, so that they are ready for use.

Brazo Davit
mounted on a bib

Intended for bibs with a minimum thickness of 200mm and maximum of 400mm, the prior installation work is quick and they can be moved from one place to another.

Brazo Davit
with a load winch

Intended for lifting and lowering loads of a maximum weight of 250kg, the load winch fits into one of the Davit arm brackets and also to the tripod.

Brazo Davit
with a load and person winch

After many years, we can now offer an arm that can be used for lifting loads and also for suspension work, which we call rope access.

PPE for work in confined spaces

As already mentioned throughout this section, work in confined spaces requires the use of PPE that permit the urgent lifting of a person at serious risk.

Due to convenience and ease of use, the most popular systems are retractable fall arresters incorporating a retrieval function.

Retrieval is generally by lever. Although a chain retrieval system can also be used, which is also the best form of retrieval with regard to permanent anchorage.

People with a high level of expertise in work at heights, also generally mount rope hoists using pulleys, blocks, etc, to achieve customised systems.

Fall arrest with a lever retrieval system

The most popular and simplest to use

In this video we'll explain the operation of a fall arrester with a lever retrieval system. Suitable for tripods and Davit arms alike.

Fall arrest with a chain retrieval system.

This type of retrieval is better when performed from a fixed anchor point.

It can also be mounted on a tripod. Suspended from a Davit arm, it is almost impossible to do so comfortably.

The great disadvantage of using this system is that the movement generated by the fall generates movements in the fall arrester, so that it is not as convenient to use as the lever-based retriever that is correctly secured to the tripod socket or the Davit arm.

Moreover, retrieval is much slower and time consuming with this chain system.

Evacuation system using a rope hoist

The mounting of a hoist of this type is complex. It requires a great deal of time and people trained to correctly complete the mounting process.

This is generally used by emergency professionals, such as fire fighters. People with profiles and great expertise in the work at height sector.

At Elytra we would advise our customers to use simpler techniques, such as those set out in the two sections above. They are easier to use and ensure that any emergency work is carried out correctly.