Extinguishers For Metals

Specialist fire extinguishers are required to tackle Class D flammable metal fires. As you might expect when dealing with such volatile and specialist materials, you need the correct agent for the metal being extinguished.

However, flammable metals are more common than you might imagine, as under certain conditions, even powdered aluminium or swarf can catch fire.

All powder-based specialist fire extinguishers designed for fighting metal fires are categorised as a powder extinguisher, so are coloured red with the familiar blue panel above the operating instructions. The most common Class D fire extinguishers are 9kg M28 models, whereas the most common UK lithium-extinguishing model is the 9kg L2.

 

 

How Do Specialist Metal Fire Extinguishers Work?

Specialist fire extinguishers contain a range of fire extinguishing agents designed to tackle certain metal groups. Metals that burn in air also react with other common compounds in potentially dangerous ways. For example, burning magnesium splits water into oxygen and highly explosive hydrogen gas – not what you want in a fire situation!

Specialist fire extinguishers for metal fires work by smothering the fire with a non-reactive agent, which forms a crust and excludes air from contact with the metals.

Specialist Metals and Their Uses

While you may not encounter such metals as pure magnesium potassium or lithium in everyday situations, they are used extensively in industrial processes, engineering, manufacturing and in scientific laboratories. (Volatile metals are no longer used in school science labs, but ask anyone over 40 and they’ll probably have a tale to tell about chemistry experiments with magnesium…!)

Sodium Chloride fire extinguishers are designed for use on Class D fires involving magnesium, sodium, and potassium. They can also be used on fires involving uranium, and waste (swarf) or powdered aluminium. Swarf can be produced by milling or drilling aluminium, so these fires are a more common hazard than you might expect.

When a sodium chloride fire extinguisher is applied to a fire, the heat of the fire makes the sodium chloride cake together and forms an air-excluding crust. And yes, sodium chloride is just plain table salt (NaCl) and it’s the same sort of process as cooking a fish in salt!

Copper powder metal fire extinguishers are designed for use on Class D fires involving lithium. The powdered copper will coat and extinguisher either a static or flowing lithium fire. In addition, the copper powder will stick to any vertical surface, so if the fire is on a wall, you can still extinguish it safely. Most importantly, the low velocity applicator ensures that no burning metal is blown around, causing the fire to spread.

Graphite powder metal fire extinguishers can also be used on lithium fires, although unlike the copper powder, the graphite powder will not stick to a vertical surface. However, graphite powder can be used on metals that burn at very high temperatures, such as zirconium and titanium.

Sodium bicarbonate and sodium carbonate fire extinguishers can both be used on Class D fires. Sodium bicarbonate extinguishers can be used on most metal alkyls, plus liquids that ignite on contact with air. Sodium carbonate fire extinguishers can be used to extinguish fires involving sodium, potassium, or their alloys.

Granulated fire extinguishing powders can be used in place of extinguishers if the fire is on a level surface. Applied with a long scoop or shovel, granulated sodium chloride, copper and graphite can be applied to smother fires involving titanium, magnesium, potassium sodium and aluminium.

Graphite powder can also be applied to burning metal powders, where even the gentle blast from a fire extinguisher could lift up the powder and cause a dust cloud explosion. Graphite powder has the added advantage of drawing heat away from the fire as well as smothering it.

Sand can also be used to extinguish a burning metal fire in the event of an emergency and if no other suitable agent is to hand. However, sand retains moisture, which in the heat of the fire turns rapidly to steam. The resulting steam eruption could then scatter burning metal over a wider area. Sand should always be applied with a long-handled shovel to protect you from flash burns.

Lithium Fires

Lithium fires must be tackled with a specialist lithium extinguisher only, commonly sold as a L2 extinguisher. A sodium chloride extinguisher is not suitable for use on a lithium fire.

Using a Specialist Fire Extinguisher on a Class D Fire

If your work involves a fire risk covered by a D rated extinguisher, you must be provided with specialist training in the proper use of the extinguisher. These specialist fire extinguishers feature a long lance on the end of a hose, so you can safely tackle the fire from a safe distance. The application of the powder is at low pressure to avoid scattering burning materials.

Wet Chemical Extinguishers

Wet chemical fire extinguishers are the new kids on the fire extinguisher scene, developed specifically for use on deep fat cooking fires. The first such extinguisher on the market was the Chubb FryFighter, and its appearance gave rise to a new fire class, Class F and a new British Standard, BS 7937: 2000.

Wet chemical fire extinguishers are red with a yellow panel above the operating instructions.

 

How Wet Chemical Fire Extinguishers Work

Normal fire extinguishers are worse than useless in a deep fat fire, since they cannot cool the oil and cause hot oil to splash up on contact with the extinguisher’s agent. Fat can burn at 340 degrees, and an average fat fryer holds up to 75 litres of oil.

 

Unfortunately, until the invention of the wet chemical extinguisher, many commercial kitchens were supplied with foam or powder units with the occupants falsely thinking these could be used on the fat fryers. The cost can also be high compared to other extinguishers but the risks are much higher in the kitchen and, if bought online at a discounted, the costs are not high these days.

The active ingredient in a wet chemical fire extinguisher is potassium acetate, often with added potassium citrate or potassium bicarbonate. When operated, a wet chemical extinguisher creates a fine mist, which cools the flames and prevents splashing.

The potassium salts then have a saponification effect on the oil’s surface, creating a thick, slippery foam layer that smothers the fat and prevents re-ignition. The chemical foam will also cool the fat over a prolonged period of time.

Unlike other extinguishers, the idea is to completely empty the contents into the fat fryer to enable the cooling process to begin.

A point to note is that the contents can be corrosive so the quality extinguishers are made from stainless steel. Beware of the cheap Middle-Eastern imports made from mild steel as the lifespan will not be as good and the linings could be affected.

Saponification: Here’s the Science

Saponification is the same process used to create soap from fats and oils as a result of a reaction with a metallic alkali, or base. The base acts on the oil to convert it into hydrolyzed acid and alcohol. Essentially, a wet chemical fire extinguisher converts the surface of the cooking oil or fat into a non-combustable soap.

An added benefit is that the soap-creation process is endothermic, meaning it absorbs heat energy from the oil, cooling the oil down in the process.

Using a Wet Chemical Fire Extinguisher

Like other specialist fire extinguishers, the wet chemical fire extinguisher has a long lance, allowing the user to stand well back from the fire and to spray the agent gently and evenly over the fire’s surface. As with all specialist extinguishers, full training should be given in the proper and effective use of this extinguisher, a common sight in commercial kitchens and food manufacturing environments.

Just Fats, Please

Wet chemical fire extinguishers only work with animal fats and vegetable oils, so they cannot be used on Class B fires involving flammable liquids such as petrol or diesel.

They have usually been tested to a 13A Class A rating but should not be specified for anything other than a kitchen.

Wet Chemical Fire Extinguishers and Electricity

Wet chemical fire extinguishers are not designed for use on electrical equipment, but in the modern kitchen environment, it is hard to avoid electricity cables. Hence, the lance of a standard wet chemical fire extinguisher is non-conductive, and passes the BSi 35kv conductivity test.

Other Fire Extinguishers in the Commercial Kitchen

Wet chemical fire extinguishers have a very specific function, and are not suitable for other fire types except Class A fires if no other extinguisher is available.

Most Fire Risk Assessments would recommend that wet chemical extinguishers are kept in proximity with other fire safety items such as a CO2 extinguisher for electrical items, and a substantial fire blanket such as a 1.8m x 1.2m size. Fire blankets should be used to smother small pan fires, not to deal with commercial fryer fires.

A small fire blanket is a useful fire safety device for any kitchen, commercial or domestic. Simple to use, yet effective, it should be used to smother a fire and then LEFT ALONE for a considerable length of time to ensure the fire is completely extinguished. If in doubt, smother, get out, stay out and call the Fire Brigade.

Foam Fire Extinguishers

Foam fire extinguishers have come a long way in 30 years. The original foam was thick, gloopy and smelled appalling, due to its high animal protein content. (Not good for vegetarians, then!)

Modern Aqueous Film Forming Foam (AFFF) fire extinguishers are another breed altogether, one of the best all-round units available. Foam extinguishers are red with a cream panel above the operating instructions.

How Aqueous Film Forming Foam (AFFF) Fire Extinguishers Work

When sprayed onto a fire, AFFF foam (pronounced A-triple-F) extinguishes and smothers the flames, then seals in any harmful vapours under the outer film of foam.

 

The foam also penetrates absorbent materials, and cools the fire as the water in the foam evaporates.

Foam is extremely effective on Class A fires, involving paper, wood, etc, so they are a good choice for a general office fire extinguisher are particularly great on man-made furnishings, where the fibres in the fabrics might otherwise liquify in the heat of the fire.

When used on flammable liquid fires (Class B), the foam forms a film that prevents re-ignition of the flammable liquids by sealing the liquids away from oxygen in the air.

Light in Weight but Not Lightweight

AFFF extinguishers are lighter than ordinary water ones because the 6 litre foam has the same 13A fire rating as the heavier 9kg water only equivalent.

Foam Fire Extinguishers and Electricity

The foam spray nozzle that sprays the foam evenly, allowing you to coat the fire area quickly. Since the foam fire nozzle is non-conductive, you can use an AFFF fire extinguisher near (but not directly on) live electrical equipment. The quality models will have been tested to the BS EN3 35,000V dielectric test as defined by BSEN3-7:2004.

Foam Fire Extinguishers Containing PFOS

Perflourooctane Sulphonate (or PFOS) was used for many years in foam extinguishant. However, it has been proved to be toxic and a potential risk to aquatic wildlife, in addition to having a known carcinogenic content. Major manufacturers UK of extinguishers such as Chubb and Thomas Glover have not used PFOS in their foam fire extinguishers since 2001.

3m’s Lightwater was the world’s most popular fire fighting foam but production was stopped long ago.

Chrome Aqueous Film Forming Foam Fire Extinguishers

AFFF fire extinguishers are also available in chrome, for when “red will so clash with the decor, darling!” Chrome finish fire extinguishers of any type are not BS EN3 certificated, as they are not painted red.

However, from the quality manufacturers such as Chubb Fire, Thomas Glover and Amerex, they still feature all the required safety instructions, and CE mark and use the same components as their red versions.

Dry Powder Extinguishers

Dry powder fire extinguishers are excellent all-round fire extinguishers, often recommended for use on vehicles and in the home. All powder fire extinguishers are red with a blue panel, are either ABC or BC rated and are safe to be used on fires involving electrical equipment. (Remember to look for the electrical safety pictogram.)

Dry powder extinguishers are not suitable for use in enclosed spaces such as offices, hotels, schools, etc, as the fire-fighting agent creates a cloud that can obscure vision. The contents may also create breathing problems.

How Dry Powder Fire Extinguishers Work

Dry powder fire extinguishers contain an extinguishing agent, which is propelled out of the extinguisher body by a compressed, non-flammable gas. The agent forms a ‘blanket’ over the fire, smothering it and preventing re-ignition. All used powder residue must be cleaned away and properly disposed of once the fire is extinguished.

Sodium bicarbonate is an effective fire extinguishing agent as it decomposes at 158 degrees F, releasing CO2 which starves the fire of oxygen.

There Are Three Main Types Of Dry Powder Extinguishers

  1. ABC rated or multi-purpose powder, which contain ammonium phosphate
  2. BC rated extinguishers, containing potassium bicarbonate or sodium bicarbonate (otherwise known as bicarbonate of soda or baking soda!) Some BC rated powder fire extinguishers contain Monnex. The pressurising gas is usually nitrogen
  3. A and D rated graphite powder fire extinguishers are usually used only in Class D fires

Both types of non-graphite dry powder extinguisher are potentially corrosive to soft metal such as aluminium, and can also be abrasive when sprayed.

Dry Powder Extinguishers and Water

Unfortunately, the additional benefit of ABC rated dry powder fire extinguishers being able to tackle flammable gas fires also has a major drawback. Ammonium phosphate can react with any water present to form phosphoric acid, which is corrosive and can seep into even the slightest cracks in equipment.

For this reason, dry chemical ABC rated fire extinguishers should not be used on sensitive electrical equipment such as computers, switch installations, scientific instruments or aircraft, if other fire extinguishing options are available.

Left in place, powder will draw moisture from the air and a common example of corrosion will be the chrome on tools being replaced with rust.

In the event of an emergency when only a dry powder fire extinguisher is available, however, always remember that electrical equipment can be replaced, a human life cannot. If in doubt, get out, stay out and call the fire brigade immediately.

Monnex Dry Powder Fire Extinguishers

Invented by ICI, Monnex powder is the most effective dry powder you can get. A 9kg Monnex fire extinguisher is ideal for situations where flames must be extinguished as quickly as possible.

You’ll find Monnex dry powder fire extinguishers at airports, fuel depots, on oils rigs, in flammable liquid stores, at motor racing tracks and at other high-octane fuelled locations. Proper training is recommended for effective use of this type of powder fire extinguisher.

Water Additive Extinguishers

Chemical additives can radically increase the effectiveness of a water fire extinguisher by up to 300%, as well as reducing the size of extinguisher required. Water additive fire extinguishers, often referred to by Chubb Fire’s brand name of Hydrospray, are smaller and lighter than standard water fire extinguishers.

A 3 litre Hydrospray Elite extinguisher matches the 13A rating of an ordinary 9 litre water extinguisher and, if you have ever picked up a 9 litre extinguisher, you’ll understand the benefit. A 6 litre water additive will normally have a 21A rating. As premises need a minimum of 13A, these have become extremely popular.

Water additive extinguishers are still solid red in colour, and bear the usual rating and safety marks.

 

How Water Additive Fire Extinguishers Work

The additives work by removing water’s natural surface tension, making the water ‘wetter’ or ‘stickier’, so it adheres to and soaks into the burning materials more effectively. Can you remember school chemistry experiments with water tension and then adding detergent to break the tension down?

The additive extinguishers also has a special spray nozzle attached that atomizes water and spreads it in a more effective arc than a conventional nozzle. In addition, the nozzle enables safe use in the vicinty of (but not directly on) electrical equipment. They will have passed the BSi 35,000V dielectric test to BSEN3-7:2004, just in case.

What’s Special About a Hydrospray Fire Extinguisher?

Since ‘Hydrospray’ fire extinguishers operate at a higher pressure than standard water fire extinguishers (15bars), they are available in smaller, high grade steel cylinders of 3 litre and 6 litre capacity.

This makes them much easier to handle and lighter to lift, and with a modern external coating of epoxy polyester, they are also scuff and dirt resistant. Inside, the cylinder is lined with polyethylene to prevent the inside of the fire extinguisher corroding.

The 3 litre version weighs just 5.5kgs, yet easily equals its 9 litre water-only equivalent’s 13A rating. The 6 litre weighs 10kg and earns a 21A fire rating, thanks to its increased efficiency. A standard 9 litre version tops the scales at 15kg.

Water and Electricity

Water conducts electricity, so non-additive water should never be used near exposed live electricity cables. High quality water additive nozzles have passed the 35kv conductivity test, so can be used with minimal risk near (but never directly on) electrical equipment.

For the best protection in an office or retail environment, water additive extinguishers are usually provided alongside a CO2 fire extinguisher to make the best combination.

Water Additive on non-Class A Fires

These modern marvels should only be used on Class A fires, although unlike the simple water extinguishers, they have a safety nozzle. Both types of water fire extinguisher, however, are actually more dangerous if used on other classes of fires.

The jet of water will, for example, simply spread a Class B fire of flammable liquids over a larger area, whilst the same action will scatter the burning metals of a Class D fires, causing more fires to erupt. Equally, never use any extinguisher other than wet chemical on a Class F fire, as this is extremely dangerous.

What’s In a Name?

Once Chubb Fire has devised and effectively marketed their Hydrospray and Hydrospray Elite, other manufacturers came out with similar models so you may find a TurboSpray, AquaPlus, WaterPlus, Ecojet and other wacky names.

Water Extinguishers

Water remains one of the most effective fire-extinguishing agents we have, from the humble fire bucket to today’s more sophisticated water fire extinguishers.

Water extinguishers should only be used where they work best, on Class A fires, sometimes called ordinary combustible fires. Paper, wood, fabrics, furniture, indeed most things you’ll have stored in your home or office, will provide the fuel for a Class A fire.

A water fire extinguisher is solid red in colour, unless your premises have invested in designer stainless steel extinguishers for a better look. (These are just as effective as their bright red counterparts, but are not BS EN3 certificated, simply because they are not painted red.) Water untis have a hose and nozzle attached, so you can direct a jet of water at the base of the fire.

How Water Fire Extinguishers Work

Water works in two ways, by both extinguishing the flames and soaking the materials in the fire, cooling them down and preventing them from burning any further. (As any Boy Scout will tell you, wet wood won’t burn!)

Most water fire extinguishers are 13A rated (with 21A being better), as they have a limited fire fighting capacity. They also are heavy to handle, as the standard size contains 9 litres of water and weighs 15kgs.

Why Use Water Extinguishers?

Water extinguishers are simple to use, and their contents are neither harmful to people or damaging to the environment. If one is set off accidentally, all you get is a large puddle of water, so you will often see these in schools (usually secured by anti-tamper seals or covers to keep away prying fingers…).

Water and Electricity

Water conducts electricity, so water fire extinguishers should never be used in a situation where there are exposed live electricity cables, or a danger of wiring becoming exposed during a fire. They are best paired with another that is suitable for use on electrical equipment fires, such as a CO2.

Water Extinguishers and Other Classes of Fires

Water is only suitable for Class A fires, as they can do more harm than good on other classes of fires. For example, in a Class B fire involving flammable liquids, the water will simply spread the burning liquid over a larger area rather than extinguish it. On a Class D fire, the spray action will simply blow the burning metal into a wider area, and probably cause it to spark more in the process.

Water additives

The efficiency and effectiveness of a humble water fire extinguisher can be radically improved with additives. See our page on water additive fire extinguishers for more details.

CO2 Fire Extinguishers

CO2 fire extinguishers (carbon dioxide) are the only fire extinguisher recommended for fires involving electrical equipment. CO2 is safe to use on and around electrical equipment, as the gas itself is non-conductive, and once used, there is no sticky foam or messy powder left behind. They are also effective on Class B fires (flammable liquids).

Carbon dioxide fire extinguishers are painted bright red with a black panel above the operating instructions. They have a distinctive horn-shaped nozzle at the side on the smaller models with 5kgs and above having a hose and horn.

Extinguishers of 9kgs or higher are available but tend to come mounted onto a wheeled trolley as they will be far too heavy to be carried safely. It is possible to find 45kg twin cylinder wheeled units for offshore or airport use.

How Carbon Dioxide Fire Extinguishers Work

CO2 extinguishers stores carbon dioxide gas under great pressure (55 bar or 825psi), where the gas becomes a liquid. When you operate the fire extinguisher levers, the pressure is released, the CO2 pressure is reduced by the diffuser (horn) and expands back into a gas, rapidly cooling the surrounding air.

This process is so fast, it can cause ice to form on the horn, so never hold a CO2 fire extinguisher by the horn to avoid freezing your skin. To be most effective, a carbon dioxide fire extinguisher should be used no closer than 3 feet and no further than 8 feet from the fire itself.

For the UK, they are commonly made in two sizes, 2kg and 5kg. The compressed gas required an extremely thick cylinder so many buyers prefer super-strong aluminium rather than heavier steel models, so that their staff can lift and use the CO2 extinguishers more easily. Steel is normally used for marine extinguishers although many of the cheap imports are made from steel.

The 2kg models tend to have a swivel horn, which must not be held during operation to avoid freezing your hands. The 5kg models usually feature a hose with the horn attached with the horn normally having a handle.

CO2 Fire Extinguishers and Electricity

CO2 fire extinguishers are safe to use on fires in, on or around electrical equipment and live cables. CO2 gas is dry, inert in air, and leaves behind no residue that will affect electrical equipment’s future operation. So, you will often find a CO2 fire extinguisher next to precious electrical equipment, from switchgear to mobile discos.

In most office, workplace, factory or warehouse situations, the best combination is to have a water additive or foam unit alongside your CO2 extinguisher, for maximum fire fighting ability.

Carbon Dioxide Fire Extinguishers and Other Fire Classes

CO2 fire extinguishers should not be used on Class D fires, involving flammable metals. The CO2 gas reacts with many volatile metals, and as with other non-D rated extinguishers, can also blow burning metal over a wide area, making the situation worse. And it is not affective on Class A fires such as paper, wood or cloth.

Carbon Dioxide Fire Extinguisher Pressure Gauges

CO2 fire extinguishers do not have pressure gauges, as the gas is condensed in the cylinder. The only way to assess if a CO2 fire extinguisher is empty is to weigh it. The gross weight (G W) is stamped into the meatl of the cylinder shoulder with other information. To assess how full your CO2 fire extinguisher is, weigh it (without the swivel horn) and compare this to the stamped gross weight.

However, rather than take the risk of a part-used fire extinguisher, or have the expense of a call-out visit and factory refilling or service exchange, it is often more cost effective to replace a used CO2 fire extinguisher with a new one. Expert firms or your local Civic Amenity Centre (the local dump) will be happy to recycle your old CO2 fire extinguisher.

Chrome CO2 Fire Extinguishers

CO2 fire extinguishers are also available in a smart “chrome” finish – highly polished aluminium, in fact. The combination of jet-black printing and shiny metal gives a CO2 chrome fire extinguisher a true designer look, without compromising your fire safety in any way.

Chrome fire extinguishers are not BS EN3 certificated, as they are not painted red, but will still have the required usage instructions, coloured panel, quality marks, etc.

Fire Extinguisher Myths Answered

We asked Anthony Buck BSc (hon) CMIOSH MIFPO, who is a Qualified Extinguisher Service Technician and one of the most knowledgeable fire extinguisher experts we know to write us a post about a few fire extinguisher myths.

This ‘FAQ’ document sets out to dispel incorrect information often given to uses about fire extinguishers by suppliers/maintainers/health & safety staff

1. Fire extinguishers must be replaced after 10 years

Answer – No

There is no statutory maximum service life for a fire extinguisher. Some bodies recommend a 20 year limit, but in practice an extinguisher can continue in service indefinitely whilst:

  • Parts remain available
  • The extinguisher has no damage, defect or corrosion rendering it unsafe for use
  • It is not an Obsolescent type (see below)
  • It is serviced, including extended services and for CO2 statutory overhaul, as required

2. If a fire extinguisher hasn’t been serviced for a few years it must be replaced

Answer – No

It just means that a service is all the more urgent. As long parts are available and it passes it’s basic, extended service or overhaul (as required) and is not Obsolescent it can continue to be used

3. Old colour coded extinguishers are obsolete and must be replaced.

Answer – No

Many pre BS EN3 extinguishers still have suitable spares & parts available and can continue in service as long as in serviceable condition.

4. Fire extinguishers must be replaced at their 5 yearly Extended Service interval as it’s not cost effective to carry this out

Answer – No

What they mean is it’s too time consuming for them to carry out this test & they’d rather just replace it. The actual cost of carrying out an extended service is less than replacement, particularly for water and foam types – the actual ‘cost’ price in parts & refills to Extended Service a water extinguisher is less than £5.

5. Stainless steel/polished finish extinguishers are illegal

Answer – No

Although they cannot be kite marked to BS EN3 due to their colour, they remain perfectly legal as long as new models are CE marked; and are preferred where aesthetics are important. A competent fire risk assessment can justify their use, normally where signage & staff awareness is in place.

6. CO2 extinguishers must have a 5 year extended service

Answer – No

For a short time around 2000 the servicing standard BS 5306-3 did require this, but after feedback from manufacturers this was removed in the 2003 revision as not required or of value

7. CO2 extinguishers must be replaced after 10 years

Answer – No

It may be more profitable and less time consuming for the engineer to do this, but what is required at 10 years is an Overhaul, which includes a hydraulic pressure test of the cylinder (to meet requirements of Pressure systems legislation) and new valve. An overhaul is better for the environment, recycling an existing cylinder and cheaper than a new extinguisher, which only has 10 years before overhaul anyway – there is no longer a lifespan advantage.

8. Every ‘kitchen’ requires a fire blanket and powder extinguisher

Answer – No

Extinguisher provision is risk based and most ‘kitchens’ in premises are just tea points with kettle, microwave, dishwasher, etc. A fire blanket is not needed if there is no small Class F risk, i.e. no cooker with hobs that a chip pan or frying pan could be used on. A powder extinguisher is not very effective on enclosed electrical equipment such as microwaves and causes severe secondary damage and CO2 is more appropriate. Full working kitchens will require Wet Chemical extinguishers if fryers are in use.

9. Fire extinguisher service personnel are experts

Answer – No

The fire trade is sales driven and there are no requirements to hold any qualification in extinguisher maintenance or, as important, to attend refreshers. For every competent engineer there are several who are unqualified or cut corners, or will use any excuse to sell new equipment. Care must be taken when choosing a provider and should you require to know your extinguisher requirements a competent fire risk assessor is a more unbiased source of advice.

10. Is my extinguisher engineer servicing my equipment properly?

Answer – Maybe yes, maybe no

Corners are sometimes cut to save time/money or through ignorance. Some staff just ‘shine & sign’, a term for wiping the extinguisher down so it looks like it’s been attended to and filling in the label. Things to look for:

If any of these activities were not done and the original extinguisher remains, then they are not correctly serviced. Likewise not performing an extended service at the correct interval is also negligent.

Label terminology: A correctly completed service label should include:

  • Date (year and month)
  • Type of service- Initial, Basic, Extended, Recharge or Overhaul. NOT obsolete terms such as Serviced (S), Inspected (I), Discharge Test (DT) which suggest a lack of refresher training.
  • Weight in kg
  • Next extended service or Overhaul date
  • iv. Other checks. Many other factors can be checked by suitably trained auditors such as the author of this guide

11. What genuine reasons for condemning an extinguisher exist

Answer – Even correctly serviced equipment will deteriorate to an unsafe condition and reach end of life. The only reasons are:

  • i. corrosion, wear or damage to threads of any pressure retaining part
  • ii. corrosion of welds
  • iii. extensive general corrosion or severe pitting;
  • iv. significant dents or gouges in the body
  • v. fire damage to the body or body fittings
  • vi. any split in a plastics lining, or any significant bubbling or lifting from the metal of a plastics lining
  • vii. corrosion of the metal body under a plastics lining
  • viii. corrosion of the metal body under a zinc or tin/lead lining
  • ix. overpainting or application of any other coating, film or colouring to any plastics component that could be subject to pressure
  • x. UV degradation of plastics components
  • xi. illegible marking or operating instructions
  • xii. instructions not in English

12. What genuine reasons for replacing an extinguisher due to Obsolescence exist?

Answer – Eventually an extinguisher will become obsolete for a variety of reasons, usually relating to availability of parts, ineffectiveness or safety concerns. Types included are;

  • i. chemical foam extinguishers
  • ii. soda acid extinguishers
  • iii. extinguishers with a riveted body shell
  • iv. extinguishers with a plastics body shell
  • v. extinguishers that require inversion to operate
  • vi. non-refillable extinguishers that have reached their expiry date
  • vii. extinguishers for which parts are no longer available and servicing cannot be completed
  • viii. halon extinguishers (prohibited by statute)
  • ix. extinguishers manufactured after 2002 which do not carry a CE mark This excludes refurbished extinguishers (see Note).NOTE Refurbished extinguishers cannot carry the CE mark and cannot be condemned for not carrying it.
  • i. All new extinguishers require Commissioning by a competent person. This has been introduced due to the growth in internet sales. Often extinguishers are supplied to users in their original factory cartons and are not fully assembled. This has led to extinguishers in use that were defective or dangerous due to incorrect or non assembly by unqualified users and difficulties I ongoing maintenance due to vital information about the extinguisher’s age, mass, etc not being recorded
  • ii. A tolerance of +/- 1 month is given for annual Basic Servicing, so that a few weeks delay in a service visit is no longer a non conformity
  • iii. Due to it being impossible to determine if a plastic headcap has suffered internal cracking from impact or degradation from UV light or chemicals unless it fails during discharge (a safety risk), extinguishers with such headcaps must have them replaced at ever 5 year Extended Service. Some service companies for their convenience will suggest total replacement, but in reality for the many models where the parts are still available it is cheaper for the user to simply replace the headcap
  • iv. Additional safety reasons to condemn an extinguisher – see ix to xii in Paragraph 12 above
  • v. Additional extinguishers that cannot be serviced due to Obsolescence/Nonconformity – see ix in Paragraph 13 above
  • vi. A more detailed description of the requirements to become a Competent Person

KFC – Keep Frying correctly

Frying tonight – the ‘f’ class fire classification

Over 10 years ago a new classification of fire was introduced for fires involving cooking oils, however there is still some ignorance around the need to have specialised equipment to safely tackle fires in this category and many establishments remain unprotected against this dangerous fire risk

Classifications

For fire fighting purposes fires have been classified, first under BD 4547 and now EN2, according to the main type of fuel involved.

Class A – fires involving flammable solids

Class B – fires involving flammable liquids and liquefiable solids

Class C – fires involving flammable gases

Class D – fires involving flammable metals

Class F – fires involving cooking oils and fats

There used to be a Class E for electrical fires, but this was discontinued as electricity doesn’t burn – an electrical fire can involve any of the above classes, with the presence of electricity being an additional hazard rather than a fuel. Fires where electricity are present are still categorised separately on extinguisher labels so that a non-conductive agent that is safe for use where a live electrical supply is involved can be identified.

Cooking oils and fats were traditionally part of Class B, along with substances like petrol and spirits. However a major difference in how they burn means that normal agents for Class B fires are ineffective. Most flammable liquids, such as petrol or heptane (which is used for fire test rating of Class B extinguishers), burn around 50 degrees Centigrade. However, cooking oil fires commonly start when the oil is heated to past it’s auto-ignition temperature, usually between 285 & 385 degrees Centigrade, but sometimes up to 499 degrees Centigrade. The oil burns at this temperature, but it’s auto-ignition temperature is reduced (by this burning) by about 30 degrees Centigrade. Thus, the fire will be self sustaining unless it’s temperature is significantly reduced. This high temperature makes the fires very dangerous and presents problems when trying to use normal extinguishing methods on these fires. A tble at the end of this article summarises the problems with traditional agents.

Case studies

The following case studies illustrate the problem when using traditional agents.

  1. South Mimms Service Area – A fast food restaurant’s fryer caught fire and was immediately tackled with CO2 extinguishers. These had no effect and the fire spread to the ductwork. The entire service area burnt down as a result.
  2. Heathrow Terminal One – A fast food restaurant’s fryer caught fire and was immediately tackled with CO2 extinguishers. These had no effect and the fire spread to the ductwork. The terminal was severely damaged. Millions of pounds were lost through damage and disruption.
  3. Royals Shopping Centre – A fryer caught fire in one of the units and was immediately tckled with two fire blankets. One was too small, the other burnt through. Despite the rapid attendance of the fire service and the use of a fixed BC Powder extinguishing system the fire was only just contained with great difficulty.

Following lobbying by the fire industry, Class F, a new fire classification, was introduced for all fires involving cooking oils.

A new symbol for use on extinguishers, depicting a burning frying pan with the letter F in the top right corner, was also introduced.

The only type of extinguisher to be Class F rated is the Wet Chemical extinguisher. This contains an alkaline liquid solution of up to 20% potassium salts (potassium acetate, potassium citrate, potassium carbonate) and it is the unique effect of these salts on the fats in cooking oils that is the key to their effectiveness.

Wet Chemical saponifies the oil, i.e. by hydrolysis rapidly converts the burning substance to a non-combustible soap. This process is endothermic, meaning it absorbs thermal energy from its surroundings, decreasing the temperature and eliminating the fire. The soapy scum formed also secures vapours and generates steam, assisting the extinction further.

Even a raging fryer with 75 litres of oil can be extinguished in under 2 seconds, however the entire extinguisher must be discharged onto the oil to ensure a complete crusting of the surface and maximise cooling.

Potassium salts had been used in the US for many years in the form of ‘loaded stream’ extinguishers for greater effectiveness on Class A fires and it was the US who developed the first Wet Chemical extinguishers for cooking oil fires in the 1990’s

Chubb Fire first introduced US made Badger Wet Chemical extinguishers to the UK in the late 1990’s, followed by the UK base of the US firm Amerex and currently there are several manufactures of these extinguishers around the world.

In the UK Wet Chemical extinguishers are made to BS 7937: 2000 and are identifiable by a Canary Yellow panel to the front of the extinguisher and the class F symbol. They bear a Fire Rating based on the maximum size, in litres of oil, the extinguisher can extinguished when used by a skilled operator. A typical 6 or 9 litre extinguisher would be rated 13A:75F (the water base makes it suitable for Class A fires as well)

Because they discharge as a fine mist they pass the 35kv conductivity test for extinguishers and can be used in the presence of energised electrical equipment, although care needs to be taken with pools of agent on the floor.

The cost of the agent makes them slightly dearer than traditional extinguishers and to make them available to smaller establishments are produced in a range of sizes with ratings from 25F to 75F. The German manufacturer Total has a compact 2 litre model with an impressive 40F rating.

Comparison of agents

Extinguishing media Effectiveness on Class F fires
Light duty fire blanket BSEN1869 Only tested and effective on small cooking oil fires up to 3 litres and containers of no more than 345mm diameter.Difficult to apply as requires getting close to the fire. Can eventually burn through or sink into the burning oil
Water/water additive Water mixes with the fat, boils and the steam ejects burning fat
Aspirated Foam Branchpipe Used to be used in kitchens, not commonly available now. Requires skilled application and high delivery rates as the extreme heat destroys the foam blanket
Foam Spray The extreme heat breaks up the extinguishing film preventing it sealing off the fire
CO2 The gas is readily dispersed by the air currents produced by the raging fire and the lack of cooling action means the oil remains at auto ignition temperature
ABC Dry powder (Acidic Ammonium Phosphate) In virtually all current powder extinguishers. Being acidic cannot saponify the oil and although the flames may be temporarily knocked down the oil reignites as the extinguisher runs out
BC Dry powder (alkaline sodium bicarbonate) Used to be used in most powder extinguishers and does have some effect, but requires several larger extinguishers and there is a re-ignition risk
Halon 1211 BCF Illegal except for exempted special users.

 

This is a guest post from Anthony Buck of http://sm-ms.co.uk

Anthony’s knowledge of UK fire extinguishers and the Regulations is unsurpassed

Do I need …..Fire Extinguishers?

 

So many people seem to be asking me ” Do I need Fire extinguishers?” So I hope this post helps highlight that really we should all be safe and secure.

The change in legislation from prescriptive requirements from the state to risk based provision by responsible persons has undoubtedly given more freedom to businesses and also ensured that technical progress is accounted for.

Unfortunately the change has removed a useful safety blanket for responsible persons and particularly budget holders – whereas under previous legislation there was a clear detailed description of the requirements of law and what was needed to meet it (in the Form of the Fire Precautions Act; Blue, Red & Yellow guides; and resulting fire certificates) the current legislation (The Regulatory Reform [Fire Safety} Order and it’s Scottish and Northern Irish counterparts) simply sets out the broad general duties, leaving it to the interpretation of the Responsible Person & their Competent Person as to what provision exactly meets these general duties in their premises.

As a result, conflicting views can be held and those budget holders trying to seek approval for necessary works on the basis of explicit legal requirements have to deal with the fact the detail is not explicit in law – merely implicit in the findings of a fire risk assessment.

So, with respect to portable fire fighting equipment where do we stand in law?

Statute:

Fire-fighting and fire detection
13. —(1) Where necessary (whether due to the features of the premises, the activity carried on there, any hazard present or any other relevant circumstances) in order to safeguard the safety of relevant persons, the responsible person must ensure that—(a) the premises are, to the extent that it is appropriate, equipped with appropriate fire-fighting equipment and with fire detectors and alarms; and

(b) any non-automatic fire-fighting equipment so provided is easily accessible, simple to use and indicated by signs.

(2) For the purposes of paragraph (1) what is appropriate is to be determined having regard to the dimensions and use of the premises, the equipment contained on the premises, the physical and chemical properties of the substances likely to be present and the maximum number of persons who may be present at any one time.

(3) The responsible person must, where necessary—

(a)    take measures for fire-fighting in the premises, adapted to the nature of the activities carried on there and the size of the undertaking and of the premises concerned;

(b) nominate competent persons to implement those measures and ensure that the number of such persons, their training and the equipment available to them are adequate, taking into account the size of, and the specific hazards involved in, the premises concerned; and

(c) arrange any necessary contacts with external emergency services,      particularly as regards fire-fighting, rescue work, first-aid and emergency medical care.

It is clear that in all premises a fire risk assessment must be carried out to determine the number, type, and location of fire fighting appliances.

If no risk is present then no fire equipment is required – however, should a risk be present, appropriate equipment must be provided.

The law does not let a lack of training or procedure over rule the need for equipment – if the risk requires it, it shall be provided and persons nominated to ensure suitable training is provided (which can vary from a summary in fire safety training as part of induction to full practical fire team exercises – the risk determines how far the training need go).

There is sufficient case law and guidance in the Government Risk Assessment Guides (increasingly used as a benchmark by courts) to support this interpretation.

Determining the requirements – multi occupied premises

So having realised that some provision is required, it now remains to decide what and by whom.

The underlying factor is risk.

Tenanted Areas

Without a doubt the biggest risk area within premises is in the tenant’s demise.

Considerable amounts of readily combustible materials and ignition sources, plus the largest number of persons are present in these areas.

More often than not the primary risk is class A (flammable solids) along with an associated risk from energised electrical equipment, although some areas may have Class B (flammable liquid/liquefiable solids) risks or even the notorious Class F (cooking oils) risks.

The bulk of fire fighting provision therefore falls to tenants, who must make provision suitable to the risks – usually following the scales in BS5306-8, although in smaller premises the use of small multipurpose ABC Powder extinguishers is considered sufficient in the entry level Government Guide.

Common areas

These areas present the biggest debate and also the biggest examples of unnecessary provision.

Remember – risk is the key.

Most common areas consist of stairwells and landings. A number of these are usually plain concrete fire stairs or sparsely decorated, perhaps with carpet/floor tiles and similar. They are like this because they are protected routes for means of escape and must be fire resisting, free from combustibles & obstruction & have limited surface spread of flame

Do these require extinguishers? No – there is no risk – once the building is well alight and fire doors loose integrity the floor coverings will become involved, but we are well past the first aid attack stage.

What if contractors are working in these areas? Unless they are introducing a risk then there is still no need for extinguishers. If they are, then they should be working under Permit To Work and have been required to supply their own equipment appropriate to the risks they are introducing.

But I have a reception area with furnishing, a commissionaire’s desk & CCTV monitor, etc? This is indeed a risk in which case this area should have a suitable fire point – but the other areas still do not.

What about other common areas? Well these are often areas such as loading bays, switch rooms, boiler rooms, lift motor rooms, building manager’s offices, etc. All have risks present, both ignition risks and fuel sources, so these would require appropriate extinguishers.

What about the Housing Associations who removed extinguishers? Again, look at risk – the common areas in flat blocks (not HMO’s) are often protected routes and contain no risk, so it could be justified. The flats themselves are responsible for their own provision, which being single dwellings contain Relevant Persons, but otherwise are not covered by the Fire Safety Order so it is up to the householder what (if anything) is provided for fire fighting in their area.

This is a guest post from Anthony Buck of http://sm-ms.co.uk

Anthony’s knowledge of UK fire extinguishers and the Regulations is unsurpassed