Ensuring Personnel Safety In A Confined Space

“There are no second chances with a confined space entry. It has to be right first time.“

Identifying a confined space…

The HSE Confined Space Regulations 1997 define a confined space as:

“A space of an enclosed nature where there is a risk of death or serious injury from hazardous substances or dangerous conditions”

Some confined spaces are easy to identify others may not be as clear and are (more often than not) disregarded as a confined space – examples of this include open topped / combustion chambers. It is also important to know that a confined space is not necessarily restricted to industrial applications; a confined space can range from cellars to enclosed sewers and drains and to canals.

If a space has a large enough space for someone to enter and work in but;

• Has limited restriction of entry / exit

• Volume of less than 100 m3

• No means of ventilation

• Below two metres in length, width and height

Then it can then be defined as a confined space, and cautionary action must be taken to ensure the safety of the worker.

The first step is to carry out a risk assessment test in accordance with The Management of Health and Safety at Work Regulations 1999 guidelines. Once this has been carried out the worker must ask themselves, can this work be carried out from an outside point? The worker must check if there is an alternative method, the dangers of confined space working are not to be taken lightly. If there isn’t another option, the next question to ask is can it be altered so that entry isn’t necessary? If all options have been exhausted and the confined space must be entered then the necessary action and equipment should be put into place for personnel protection.

Facing hazards of a confined space….

Before entering into a confined space it must be ensured that there are no toxic gases present. Limited volume easily allows a build up of gases – this can be extremely harmful – inadequate air leads to an oxygen deficiency and a replacement of harmful gases such as H2S or CH4 (depending on the application).

When in a confined space, fires and explosions become a lot more volatile and have a larger impact, the results of which can be disastrous for the personnel.

Some of the afore mentioned risks are already present in a confined space before a worker enters; however, there are other hazards that arise as a result of work being carried out in a confined space.

Free flowing liquids and gases can be disturbed as a result of using heavy duty machinery or even carrying out basic tests. A less apparent risk as a result of work in a confined space is the build up of temperature, if there is a confined space that is gradually becoming overheated then the worker is at risk of raising their body temperature to unnatural levels.

Know your gases!

Common gases found in a confined space may seem non-toxic at a low level, but this low level over a gradual period of time and in a confined space can add up and impose a serious threat.

Nitrogen oxide

In lower levels nitrogen oxide causes irritation of the throat and mucus cells, eventually leading to a burning sensation in the throat. If the worker is removed after a short period of time, the symptoms will cease, however if prolonged it can lead to long term irritation and headaches.

Lack of oxygen

If oxygen depletes to concentrations of 10% or less the worker will experience nausea and vomiting, leading to a loss of consciousness, at levels <6% the user will struggle with respiration and heart action will cease.

Oxygen surplus

Too much oxygen increases the likelihood of a fire or an explosion, it may not be as common as oxygen depletion but the risks are as serious.

Carbon monoxide

Carbon monoxide is a ‘toxic asphyxiant’ it has properties which reduce the flow of oxygen through the blood. In a similar effect to oxygen, an increase in CO starts with a mild frontal headache increasing to dizziness, unconsciousness and death.

Hydrogen Sulphide

Hydrogen sulphide produces a smell that is one of it give away signs, it is a colourless gas with a rotten egg odour. The national exposure limit set by NIOSH states that H2S should not reach levels higher than 100ppm, at this level there will be marked conjunctivitis, at levels higher and ranging to above 1000 there is immediate unconsciousness followed by death.

(NB: Exposure to smell deadens senses; you could be walking into the gas rather than walking away from the gas)

How to approach a confined space…

Before deciding the right equipment you need to carry out a confined space check list; have you done the following?

1. An assignment of responsibilities

2. Written hazard assessment

3. Safe work Procedures (identifying procedures for each hazard)

4. A signed permit (where required)

5. Employee Training

6. An escape route

Note – it is also essential to keep records of every action for future audits and liability purposes

How can a1-cbiss help you to ensure safety?

Long gone are the days when a canary in a cage would provide protection for people working in confined spaces.

Technology has vastly improved and we can now provide the technology to keep you as safe as possible in a confined space and thus alert you if there are any impending dangers.

a1-cbiss have over 20 years experience in the gas detection industry and are on hand to offer you high quality and reliable advice where gas detection is concerned. As well as this we have an extensive catalogue of gas detection products which are available to hire and purchase.

If you’re looking for a rugged, durable area monitoring solution, then the BM25 from industrial scientific will cater for your needs. The BM25 provides the security and reliability of a fixed gas detector, but it is a portable detector with over 1000 different sensor combinations. The flexibility of the BM25 allows this detector to be used in a variety of different confined space applications with ease. The main benefit that the BM25 boasts in confined space protection is its additional parasitic sampling pump – it allows the monitor to be used both for remote sampling applications in confined spaces providing clear alarm signalling to the area outside of the confined space. The BM25 is often used by maintenance teams working within confined spaces. A number of BM25's will be daisy-chained around the perimiter of the working hazardous area to alert the maintenance teams of any potential gas hazards.

If the solution is to provide the personnel with personal monitoring then a1-cbiss can also provide suitable equipment for this too. One of the more popular choices for confined space monitoring is the ISC Ventis MX4, the Ventis is compact and lightweight yet rugged, it’s simple to use and has up to 4 different sensor options to detect a variety of gases. The Ventis comes with an optional brightly coloured, high visibility orange casing, meaning if it’s dropped or misplaced, it’s easier to detect in the darkness of a confined space.

With a vast amount of ATEX approved products in our catalogue and an array of gas detection specialists - a1-cbiss are on hand to help you.

Find the best method of gas detection for you >

sales@a1-cbiss.com 0151 666 8300

In confined space detection there is as much of an emphasis on the calibration of the equipment as the type. The only way then to know that the sensor in the detector is actually present working is to test it with gas. a1-cbiss are aware of this and offer a variety of calibration options.

Read our recalibration & bump test overview >

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