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Life Saving Devices

Published: 04th Jul 2013 in OSA Magazine

My personal involvement with confined spaces has included silos containing up to 300 tonnes of product used with cement.This has similar properties to water with regard to fluidity. I’ve worked with smaller silos that could contain up to 120 tonnes of ground, granulated, blast furnace slag (GGBS), a sand like substance. I’ve also worked with various other kinds of industrial equipment, including rotary dryers, scrubbers, ducting, trenches, slurry pits, bearing mills as well as battery charging bays.

All of the above entail a combination of hazards with regard to access, cleaning and maintenance. Hazards that are present range through the difficulty of access and egress should an emergency situation arise, increased temperature, the action of residue materials in contact with the skin and issues with inhalation, air quality and potentially explosive gases.

For example, a bearing mill creates high temperatures. Even after being stood for 24 hours and air swept, it still constitutes a considerable hazard with regard to temperature, atmosphere, the build up of fumes from work carried out within – and egress in the event of an emergency.

I have been fortunate enough to visit what was at the time the second largest warehousing facility in the UK.This had an extensive underground forklift truck battery recharging facility.The air was monitored continuously and extraction fans would cut in to remove the dangerous gases that were formed during the recharging process. A system of maintenance and checks ensured the monitoring system stayed at peak efficiency. As an aside, movement sensing cameras where installed to ensure that correct procedures for the exchanging and charging of batteries was maintained at all times.

Over view

The Confined Spaces Regulations, 1997, state that a confined space is a place including a chamber, vat, trench, pipe, tank, flue, silo, pit, or any other place that forms an enclosure. A closed tank with a restricted access opening is an obvious example of a confined space; such spaces may also include open manholes, sewers, enclosed basements and other places where there is inadequate ventilation.

Accidents in confined spaces are relatively frequent worldwide, and are often fatal. In addition to this it is often the case that several employees or more are killed in an accident involving a confined space. This usually happens when, upon finding someone has collapsed, work colleagues try to carry out an unprepared rescue attempt.

The human instinct to assist colleagues in danger is very strong, often with fatal consequences. Although well intended, no one who has not previously undergone specialist training, and has evaluated the dangers beforehand should attempt to rescue anyone from a confined space.

Main requirements

The main requirements of the regulations are as follows. 

If entry is necessary there must be a safe system of work in place that must include appropriate equipment and isolation of a confined space. Employees must be trained and competent.

Prior to confined space entry emergency procedures must be in place to allow for the rescue of employees should the need arise. This must take into account any risks to the rescuers.

Rescue procedures have to take into account any emergency that may arise, and not only the specific hazards that are present with regard to the confined space.

Resuscitation equipment should be provided if it is identified that resuscitation is likely to be necessary as a consequence of known hazards.

It is good practise to stage an emergency evacuation, monitor and record the activities, then reflect on what went well, what could be improved and make changes accordingly.

The regulations talk about “foreseeable specified risks.” Examples of this are confined spaces that may contain the following:

• The risk of fire or explosion
• The risk of drowning
• Hazardous atmospheres that could include a lack of oxygen, as found in some drains or storage vessels
• Spaces that contain hazardous substances
• A potential risk from increased body temperature due to the conditions present in a confined space
• A confined space such as a silo could contain a free flowing substance. Cement, sand or grain are just three examples and present a significant hazard
• Atmospheric contamination

Atmospheric contamination or dangerous atmospheres can arise when there is a lack of oxygen, or when toxic or flammable gases are present. These could be due to exhaust gases from plant and transport, carbon dioxide that forms in chalk soil, decomposition of sludge in sewers, potential leaks from gas mains, rusting or corrosion of metalwork, or the presence of petrol or petroleum based products, and various kinds of waste from factories and trade premises. Numerous work practises in a confined space can exacerbate the danger. Examples are some painting work, the use of adhesives to fix floor tiles, cleaning fluids and hot works.

Risk assessment

A suitable and sufficient risk assessment must be carried out before any work in a confined space can take place, taking into account the risks arising from all work activities. The person who carries out the risk assessment must have a thorough understanding of confined spaces, any hazards that may be present and control measures that should be implemented. The assessor will be required to have undergone specialist detailed training on the assessment of confined spaces.

Any risk assessment should include consideration of:

• The task at hand
• Access and egress
• The working environment
• Workequipment,materialsandtools
• The suitability of those carrying out the task, training and competence
• The arrangements for emergency rescue

Training

Employees who are expected to enter a confined space need to be made aware of the dangers. They must be fully informed and undergo instruction with regard to potential hazards.They must also be trained in the use of a safe system of work, arrangements that are made for rescue and any equipment that is needed for this to be carried out. They must know how to verify, prior to entry, that the atmosphere in the confined space is safe to breathe.

Safety equipment should include gas monitors where it is identified that these will be needed, breathing apparatus and access and rescue equipment. A permit to work system must be in place. All employees should have a full understanding of the safe system of work and the permit to work system.

Training should include:

• Ensuring the detectors are fit for the purpose and are correctly configured
• How to determine that the detector is functioning and reading correctly
• Correct use of detectors and how to obtain true readings
• Understanding the results
• The hazards and properties of dangerous substances on site
• The use and need for personal protective equipment – selection, correct fitting and use of respiratory equipment require specialist expertise and training
• What action to take if the portable gas detector alarms
• Emergency procedures

Accidents have been known to happen where a permit to work system has not been strictly adhered to. Supervisors and managers should be aware that a permit to work could be a week link in the chain if the importance of following procedure is not fully understood. It should be remembered that the failure of a permit to work system was contributory to the Piper Alpha oil rig disaster in July 1988.

Refresher training should be implemented and professional advice should be sought on the frequency of this.

Gas detection case study

There have been a number of accidents that could have been avoided had the correct gas detection equipment been in use. I add the following by way of an example – luckily this accident did not end in a fatality. Others have not been so lucky.

A West Midlands based recycling company was prosecuted by the Health and Safety Executive (HSE) after a worker at one of the company’s facilities was knocked out by the nitrogen gas which it used to prevent explosions in a fridge recycling machine.

During a hearing at the Magistrates Court they were told how on June 1, 2009, an employee was working on the recycling machine, which has a chute to feed fridges inside to be broken up, but also contained nitrogen gas to help reduce the risk of a blast from fridges, which have the potential to explode.

The court was told how sometimes the fridges would twist and get stuck, and it was usual for workers to climb in to clear the blockages. On the day of the incident the employee passed out because of the nitrogen inside the chute, and had to be rescued by a colleague before being taken to hospital.

The employee had three days off work before making a full physical recovery. He has since suffered from a lack of sleep, flashbacks and mood swings that are only now subsiding, the court heard.

An HSE inspection found that the presence of nitrogen in the chute had not been assessed before people got inside to clear blockages, and also found that the company had failed to carry out a suitable and sufficient risk assessment that would have identified the risks of climbing into a confined space.

The HSE said the company should also have had a system in place for clearing blockages that did not require entry into the chute.

After pleading guilty to breaching Regulation 3(1) of the Confined Spaces Regulations and Regulation 3(1) of the Management of Health and Safety at Work Regulations 1999, the company was fined £13,000 and ordered to pay £6,107 in costs.

The HSE inspector said the case highlighted the need to ensure companies properly assess processes and all machinery.The inspector also claimed that if the correct gas detection equipment had been in place then the nitrogen would have been recognised as a hazard, and the chute would have been identified as confined space – with the right safety system being installed as a result.

“All too often in cases like this we see multiple fatalities as people try to rescue a colleague from a confined space without taking precautions themselves. It is fortunate that no one was more seriously harmed on this occasion,” the inspector added.

Gas detector use

Gas detectors can provide an early warning of developing problems and are contributory to the safety of employees. They can reduce the possibility of explosion and fire.They can be valuable in helping to alleviate health issues that can arise from flammable, toxic and asphyxiate gases.

Their use is twofold in that they can trigger alarms when gas levels rise above a given point, and can also be used to measure employee’s exposure to dangerous gases.

Gas detectors are used in a wide variety of applications ranging from semiconductor manufacturing, wastewater treatment plants, power plants, chemical plants, and oil and gas production facilities. Countless gas detectors are used every day to warn personnel working in these places about potential hazards like leaking gases, explosive vapours or toxic emissions.

Working in a confined space can create conditions that lead to a build up of potentially dangerous gas, fume or vapour.This can arise from welding, spray painting or by use of volatile and often flammable solvents, adhesives.These may be the more obvious causes of the build up of dangerous life threatening gases.

Perhaps less obvious are the naturally occurring gases or the ingress of gas from another source.These gases can displace any oxygen present and too many people have entered a confined space only to find the atmosphere is not conducive to sustaining life.

If you have any equipment stationed in what could be considered a confined space that gives off or contains potentially hazardous gases, then steps have to be taken to maintain safety and counter possible leaks.

Kinds of detectors

Detectors can be fixed, portable or transportable.

Fixed detectors are permanently installed and are designed to provide continuous monitoring of plant and equipment.They are used for giving early warning of leaks from plant containing flammable gases and vapours. They can also be used for monitoring purposes of such concentrations within the plant itself.They are especially useful where there is the possibility of a leak into an enclosed or confined enclosure where flammable gases could accumulate.

The gas detector should be set up so that the alarm triggers at a low enough level to ensure the workforce is protected. Consideration should also be given to false alarms.These can take place with the degrading of the sensor itself over a period of time. Once the concentration of gas in the atmosphere reaches the level the detector is set up to detect an alarm should sound.This sound should be audibly different from the fire alarm, and could be augmented with a visible signal.

When setting a detector up the following should be taken into consideration:

• Industry standards and recommendations
• Whereappropriate,thelowerexplosion limit of the gas or vapour
• Employees working in the area, if any
• The level of toxicity of the gas or vapour that is likely to be present
• The likely size of any potential leak and the time to reach a hazardous situation
• The alarm response time of the detector
• The time it takes to respond to an alarm
• The actions that should be taken following the alarm

It should be understood that instruments used in the detection of flammable gases, and also those for oxygen and toxic gases that are used where flammable substances may be present, should be certified as being safe for use in potentially explosive atmospheres, i.e. ATEX certification in the EU.

Any plant maintenance schedules should include gas detectors, as over a period of time their effectiveness deteriorates. Corrosive, dusty or damp environments are especially harmful. Records should be kept of any maintenance carried out. Trained and competent staff should carry out maintenance work. Suppliers can provide detailed advice. Further information is available in BS EN 60079- 29-2:2007 and the COGDEM gas detection and calibration guide.

Portable detectors usually refer to small devices that are hand held and are used for testing the atmosphere before entry into a confined space.They can also be used for tracing leaks to give warning of the presence of flammable gases and vapour when hot works are being carried out in a hazardous area.

They are designed to be carried by a mobile workforce and can be worn on clothing, harnesses or are hand held. Often these have a useful life of two years and are generally disposable. Depending on the hazard, they can be set up to trigger immediately as gas is detected, or by taking a time weighted average reading.

Employees must be trained before using portable gas detectors and they should not be used unless this has been carried out.The gas detector supplier can usually provide training.

A transportable detector is a piece of equipment that is not intended to be carried by hand but can be easily moved from one location to another. Its prime purpose is to monitor an area while a fixed gas detector is undergoing maintenance or replacement.

Exposure limits

Guidance for exposure limits of toxic substances can be found in the HSE publication EH40/2005 (Second edition 2011) 

Workplace Exposure Limits. Suppliers can also provide advice. Be aware that exposure limits can be subject to change, often to lower values. It is essential to keep up to date. Revised limits would affect workplace risk assessments and any control measures implemented to ensure adequate control of exposure.

Detectors may have to be upgraded to be capable of meeting reduced limits.

Regulations relevant to working in confined spaces are:

• TheConfinedSpacesRegulations,1997
• HealthandSafetyatWorkActetc,1974
• The Management of Health and Safety at Work Regulations, 1999
• The Reporting of Injuries Diseases and Dangerous Occurrence Regulations, 1995
• The Control of Substances Hazardous to Health Regulations, 2002
• Personal Protective Equipment Regulations,1992

Published: 04th Jul 2013 in OSA Magazine

Author


Peter G Brooksbank


Peter first became involved in health and safety in 1979 while working on the then British Steel complex in North Lincolnshire, UK. Studying at North Lindsey Technical College, Peter sat on the health and safety committee as well as the committee to reduce waste, right at the start of the company’s environmental programme.

He also qualified as a National Plant Registration Scheme Train the Trainer. He decided to relocate to the West Country and in order to maintain employment prospects in a non-steel environment, underwent further education at City College Plymouth, gaining both a NEBOSH and Teaching in the Life Long Learning Sector qualification.

Going on from there, Peter became the vocational manager of a regional literacy, numeracy, IT and vocational education training company, with branches throughout the South West of England. He was instrumental in developing a new vocational training centre in Cornwall and making others more efficient.

Peter has since founded Denbrook Consultancies in 2011, who offer health and safety consultancy services and a range of health and safety based training courses.


Peter G Brooksbank

Website:
http://www.denbrookconsultancies.co.uk

Email:
info@denbrookconsultancies.co.uk

Phone:
+44 (0) 1752 30 82 89

info@denbrookconsultancies.co.uk
http://www.denbrookconsultancies.co.uk
+44 (0) 1752 30 82 89

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