Air duct systems are particularly vulnerable to an enhanced risk of fire both because they are a good place for inflammable deposits like dust or grease to collect, particularly in commercial catering kitchens but also in the extract systems in laundries and because they could be a channel for fire to spread.

In 2006 in the UK strengthened legislation came into force by which anyone with responsibility for a building described as “non-domestic” has a duty to actively ensure fire safety and take responsibility for the building’s users, whether they are staff or visitors .

In the new order the main duties are to carry out regular fire risk assessments

, take steps to eliminate the risks and pay particular attention to fire safety where flammable materials are involved as well as having an emergency plan in place.

A very useful guide to fire risk assessment has been produced by the Association of British Insurers for the most vulnerable group, the catering industry, where fire is a particular problem in extractor hoods and air duct systems.

The main risk it identifies is the build-up of oily and fatty deposits, with the main culprits being deep fat frying, chargrilling using solid fuel and oriental cooking, which creates a thick, syrupy deposit that cannot be scraped from surfaces easily.

It continues, that some deposits, particularly a mixture of chicken fat and vegetable oil, ignite particularly easily.

The first step in a fire safety and emergency plan in a kitchen is to detail precisely what situations could spark a fire, such as flames, sparks or hot gases from cooking can igniting deposits inside extract ducts, superheated oils leading to spontaneous ignition, fan-motor failure or overheating caused by hardened grease, thermostats not working correctly, individual equipment not switched off, and the fact that metal extract ducts are good conductors of heat and can ignite nearby building materials or litter.

It warns that the person responsible should ensure that any  cleaning contract the organisation has should not be confined to only covering hoods and easily accessible visible areas like those areas inside the ducting which are only within arm’s reach.

Plainly also all areas of the air duct system should be accessible for cleaning regularly and filters should be regularly checked and changed.

The document suggests that in assessing risk questions should be asked about whether someone competent to handle a fire emergency is always on the site, whether the staff are adequately informed and trained in how to handle different materials including cleaning solutions and whether they understand both the cleaning systems and how to isolate an area in the event of a fire as well as the correct method for dealing with it, for example where deep fat is involved.

The assessment should also evaluate whether the frequency of regular maintenance and cleaning is adequate for the type of cooking and frequency of cooking. A great deal of this can be done with the help of a reputable commercial cleaning company, since they will have ensured that their own staff are properly trained and informed and should also know all that is required in the legislation.

Above all, however, the message is that prevention is better than cure using regular ductwork cleaning to minimise the risk of fire.

Copyright (c) 2011 Alison Withers