Monthly Archives: November 2012

Carbon monoxide poisoning in wood pellet stores

An interesting article on the HSE website has come to our attention.

As many more private companies and public organisations, including schools, are looking to renewables such as wood pellet boilers to reduce their carbon footprint we thought it was wise to publicise the potential hazards associated with wood pellet storage.  It seems that the natural oxidation process can cause a build up of carbon monoxide despite the lack of additives or binders within the pellets, largely due to the oxidation of fatty acids present in the wood, read on below to find out more

(information reproduced from hse.gov.uk/safetybulletins/co-wood-pellets.htm?eban=govdel-safety-bulletins&cr=05-Nov-2012)

Wood pellets are made from dried and milled sawdust and wood shavings that have been compressed into pellets, typically 10-20mm long and 3-12mm in diameter. They do not typically contain any additives or binders.

They are classed as a biofuel, a non-fossil heating fuel. The main countries of manufacture are Canada, North America and the Scandinavian countries within Europe. In 2000, the annual production of wood pellets in Europe and North America was about 1.5 million tons. This was expected to increase to around 16 million tons by 20111. Some wood pellet manufacture is now taking place in the UK.

Since 2002 there have been at least nine fatalities in Europe caused by carbon monoxide poisoning following entry into wood pellet storage areas. Although there have not been any incidents so far in the UK the use of wood pellets is increasing and awareness of this danger is required. Wood pellet boilers are used in homes and businesses as an alternative to oil or gas fired boilers. They are also being installed to replace coal-fired boilers, particularly in schools.

Carbon monoxide can kill quickly without warning. It is a colourless, odourless and tasteless gas that is highly toxic. When carbon monoxide enters the body, it prevents the blood from bringing oxygen to cells, tissues, and organs.

Fatality details:

Fatalities caused by the release of carbon monoxide from wood pellets have previously been reported2 in Europe following personnel entering ships cargo holds (four) or storage silos (two).

Since 2010 there have also been three deaths caused by entry into wood pellet storage facilities in domestic sites3. Two were associated with a work activity and the other was a householder. In each case, the entry had been to resolve a technical problem. Details:

  • In January 2010, a 43-year-old engineer died in Germany after he opened a pellet bunker door. A second worker who was standing right behind him was also affected but still able to call the emergency services. The pellet bunker had a storage capacity of approximately 155 tonnes of pellets, supplying about 700 households.
  • In November 2010 a 38-year-old male householder in Ireland died after entering the 7 tonne wood pellet storage room for his boiler. His wife and another man were treated in hospital after trying to pull him to safety.
  • In February 2011, the 28-year-old pregnant wife of a caretaker, acting on his behalf, died in Switzerland after entering an 82m3 pellet storeroom that supplied 60 households.

Factors affecting the amount of carbon monoxide released from wood pellets

Wood pellets for boilers are normally stored in a large sealed hopper/tank or a storage room that has a screw feeder (auger) connected to the boiler. Alternatively, the hopper/tank can be mounted over the boiler for gravity feeding. Due to the enclosed nature of these hoppers/tanks/rooms, the atmosphere inside can become oxygen depleted and a toxic atmosphere containing carbon monoxide can accumulate. The chemical reactions responsible for carbon monoxide production from wood pellets are assumed to be an auto-oxidation process, especially oxidation of the fatty acids to be found in wood4.

Experimentation has shown3 that small quantities of wood pellets can produce life-threatening quantities of carbon monoxide in a confined space and that there are various factors that will affect the amount of carbon monoxide produced:

  • Age – pellets will produce more carbon monoxide within the first six weeks of being manufactured.
  • Temperature – more carbon monoxide is produced at higher temperatures.
  • Wood type – pellets made from pine contain more unsaturated fatty acids than spruce so produce more carbon monoxide.
  • Other factors – carbon monoxide levels will also increase with the amount of available oxygen present, exposed pellet surface area and amount of mechanical abrasion of the pellets that has taken place.

Note: In addition to the risk of carbon monoxide from wood pellets there is also a possibility of carbon monoxide being present because of a back-flow of flue gases via the fuel supply mechanism from the boiler. Causes for this include inadequate equipment being installed or a poorly designed flue.

Action required:

The HSE is advising all those who use, install, maintain or distribute wood pellet boilers and/or manufacture/store/distribute wood pellets to consider the following:

  • Wood pellet hoppers/tanks/storage rooms and boilers should always be installed and commissioned by a competent person, normally approved by the manufacturer/supplier. This is particularly important if the installation involves the replacement of a coal-fired boiler, where existing boiler room and storerooms are often utilised.
  • Do not enter the pellet storage area or place your head into a wood pellet hopper as they can contain toxic gases. No personnel should enter the hopper/tank unless fully trained and competent in confined space entry procedures. Controls should be put in place to ensure safe entry as per the HSE’s Code of Practice for Working in Confined Spaces5. This should include adequately ventilating the storage area and checking carbon monoxide and oxygen levels with an appropriate device prior to entry. It is recommended that the store room is ventilated at all times, either mechanically or by being designed to have a through draft.
  • Ensure that the boiler and pellet feed mechanism etc. is cleaned and serviced by a competent person as specified by the manufacturers’ instructions.
  • If any problems are encountered with the unit, such as the system not heating correctly or flue gas is flowing into the boiler room, turn the unit off and contact the supplier and/or manufacturer and request assistance.
  • Duty holders who store wood pellets, particularly in bulk should have a suitable risk assessment and safe system of work in place.
  • Manufacturers, suppliers and distributors of wood pellets should provide adequate health and safety information to the user in their materials safety data sheet.
  • Warning signs should be placed on the pellet storage area access door, ideally on both sides so it can be seen when the door is open. The warning sign should include the following information:
    • DANGER – RISK OF CARBON MONOXIDE POISONING – There is a danger to life from odourless carbon monoxide and lack of oxygen. Check atmosphere before entry with an appropriate device. No entry for unauthorised persons. Keep children away from the storeroom.
    • No smoking, fires or naked flames.
    • The room should be adequately ventilated before entering. Keep the door open whilst inside.
    • There is a danger of injury from movable parts.
    • Filling procedures should be carried out accordance to the instructions of the heating installation company and the pellet suppliers.
Posted by Roger Hart

Limiting the cost of No Win No Fee compensation claims

If there’s one thing guaranteed to raise the ire of both businesses and safety consultants its the mention of no win no fee.  The advent of the legislation has seen payouts to solicitors specialising in the field rise to over 150% of claims – so, what can you do to protect yourself?

Claimants are encouraged to sue businesses by a wide range of organisations advertising on TV and in all types of other media including within hospitals but the steps which you take following an accident or incident which may lead to a claim can be instrumental in defending yourself from liability. (more…)

Posted by Roger Hart

HSE Fee For Intervention (FFI): where will the money go?

HSE’s Fee For Intervention (FFI) scheme has been active since the 1st October and many businesses have already been affected.  The scheme allows HSE to charge businesses for their time at the rate, currently, of £124 per hour when a ‘material breach’ of health and safety is discovered.

However, the proportion of the fee that will actually go back to HSE may be lower than it had initially hoped.

HSE programme director, Gordon MacDonald, has revealed that HSE will now keep less than half of the projected £37 million which will be raised during FFI’s first year with the remainder going straight to the Treasury for other projects. (more…)

Posted by Roger Hart

Accident injury rates and ill health in the UK, HSE figures published

Published on October 30th HSE’s figures show a reduction in deaths in UK workplaces withe to total falling from 175 last year to 173. However, workplace ill health continues to be a concern and this strengthens the likelihood of it being a key issue for FFI as we thought in our recent FFI white paper.

In the year to March 2012 fewer people were killed or injured at work in the UK (173 Vs 175) compared to 2010/11 and numbers remain below the five-year average (more…)

Posted by Roger Hart

Anti entrapment measures in MEWPS (Mobile Elevating Work Platforms)

Many of our clients use MEWPS for access and recent months have seen the major contractors taking steps to safe guard the use of MEWPS in terms of trapping incidents.

These solutions, though well intended, are often prescriptive and can lead to solutions being put into place which are relied upon to protect users when they are not perhaps the best choice so much so that HSE has now issued the following statement; (more…)

Posted by Roger Hart
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