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Choosing the Right Fire Extinguisher for Common Materials

Fires involving combustible materials like paper, textiles and wood are extremely common, accounting for a large percentage of fire incidents each year. Having the proper fire extinguisher on hand can mean the difference between controlling a small fire or allowing it to rage out of control. But with different extinguisher types available, how do you choose the right one for paper, textile and wood fires?

Why Paper, Textiles and Wood are Fire Hazards

Paper, fabrics and wood are considered Class A combustibles. This means they burn primarily by forming glowing embers or moderate heat release. The key things that make these materials fire hazards are:

  • High surface area – Materials like paper and fabrics have a very high surface area compared to their mass. This allows oxygen to easily reach the material’s surface and sustain combustion.
  • Low thermal conductivity – Paper, fabrics and wood are poor conductors of heat. This causes them to ignite and burn easily.
  • Light and porous – Lightweight materials like paper burn rapidly. Their porous nature also promotes thorough combustion.
  • Readily available fuels – Paper products and wood materials are everywhere – homes, offices, factories etc. Their widespread presence increases fire risks.

So the high surface area, low conductivity, light weight and ubiquity of these combustibles make them some of the most common fuels involved in fire incidents. Choosing the right extinguisher for paper, textile and wood fires is crucial.

Water Extinguishers

Water extinguishers are one of the most common types found in workplaces and homes. They contain water under pressure and may also have additives like anti-freeze. Water extinguishers work by cooling the fuel surface. This stops the chemical reactions sustaining the fire. The advantages of water extinguishers are:

  • Effective – Water is highly effective at extinguishing fires involving Class A combustibles like paper, textiles and wood.
  • Cools fuel – Water cools the fuel surface rapidly so fire cannot re-ignite.
  • Widely available – Simple water extinguishers are inexpensive and widely available.

However, water extinguishers also have some drawbacks:

  • Damage – Water can cause collateral damage by soaking papers, furniture etc.
  • Avoid on electrics – Water conducts electricity so avoid using on live electrical fires.
  • Heavy – Larger water extinguishers weigh over 30 pounds when full.

So water extinguishers are a good first choice for paper, textiles and wood fires as long as electrical hazards are not present.

Dry Chemical Extinguishers

Dry chemical extinguishers contain a powdered extinguishing agent and compressed gas propellant. They smother the fire by forming a coating over the fuel. Common dry chemical agents include sodium bicarbonate, potassium bicarbonate and urea-based formulations. The advantages of dry chemical extinguishers are:

  • Multi-purpose – Effective on Class A fires as well as Class B flammable liquid fires.
  • Non-conductive – Dry agents won’t conduct electricity so these extinguishers are safe on live electrical fires.
  • Lightweight – An average dry chemical extinguisher weighs just 5 to 15 pounds.
  • No cleanup – They leave behind minimal residue compared to water extinguishers.

The drawbacks of dry chemical extinguishers include:

  • Obscures vision – The fine dust discharged can obscure visibility of the fire.
  • Breathing hazard – The chemicals may be irritants if inhaled.
  • Less cooling effect – Unlike water, dry agents provide less of a cooling effect on fuels.

So dry chemical extinguishers are a good second choice after water types for paper, textile and wood fires. Their versatility and non-conductive agents make them ideal back-ups.

Carbon Dioxide Extinguishers

Carbon dioxide (CO2) extinguishers work by displacing oxygen or reducing it to a level that cannot sustain combustion. The carbon dioxide is stored as a compressed liquid in the extinguisher. CO2 extinguishers have these advantages:

  • Leaves no residue – They discharge a clean agent that leaves behind no messy cleanup.
  • Safe for electronics – CO2 is non-conductive and does not damage sensitive electronics or documents.
  • Cold discharge – The ultra cold temperature of the CO2 can cool fuels below ignition temperature.

However, CO2 extinguishers also have some limitations:

  • Short discharge range – The heavy gas tends to sink so it has a short range of just 3 to 8 feet. Needs to be applied close to the base of the fire.
  • Obscures vision – The discharged gas forms a white cloud that can obscure visibility.
  • Asphyxiation risk – High concentrations of CO2 gas pose an asphyxiation hazard.

So CO2 extinguishers are a backup option for paper, textiles and wood fires where clean up and damage are a concern. Provide adequate ventilation when using them.

Class K Extinguishers

Class K extinguishers contain a potassium-based extinguishing agent effective on fires involving cooking oils and fats. Although designed for commercial kitchens, Class K extinguishers can also be effective backups for Class A fires. The pros of Class K extinguishers are:

  • Multi-purpose – Agents are effective on Class A combustibles as well as Class F cooking oil fires.
  • Coats fuels – Forms a soapy film that coats and cools fuels.
  • Low pH – Potassium salts have a low pH compared to alkaline sodium bicarbonate-based dry chemicals. Less damaging to skin.

But Class K extinguishers also have some downsides:

  • Obscures vision – Discharge creates a fine mist that can reduce visibility.
  • Slippery residue – Leaves behind slippery potassium salts on surfaces.

So Class K extinguishers provide an alternative backup option to sodium-based dry chemical extinguishers for fighting paper, textile and wood fires.

Fire Extinguisher Size and Ratings

Fire extinguishers for Class A combustibles like paper, textiles and wood are rated based on the equivalent size fire they can extinguish. The higher the numerical rating, the larger the fire fighting capacity. Common sizes for Class A extinguisher ratings:

  • 1-A – For trash and wastebasket-sized fires
  • 2-A – For small fires confined to a small area
  • 3-A – For typical office or workspace fires
  • 4-A and up – For large storage, warehouse or facility fires

Make sure extinguishers around the home or office have at least a 2-A or 3-A rating for the typical Class A fire hazards expected. Higher temperature or fast burning fires may require models with larger extinguishing capacities.

Installing extinguishers on each floor or wing of a building is vital for fire safety. Experts also recommend keeping an extinguisher near locations with increased risk like kitchens, workshops, server rooms, chemical storage etc.

Using Fire Extinguishers on Class A Fires

When responding to a paper, textile or wood fire with an extinguisher, follow the PASS technique:

Pull the pin – This unlocks the operating lever to allow discharge.

Aim low – Aim the extinguisher nozzle at the base of the fire.

Squeeze the lever – To discharge the extinguishing agent.

Sweep from side to side – Move the nozzle side to side to coat the area of the fire.

Always evacuate if the fire starts growing out of control. When in doubt, get out.

Keep the extinguisher aimed at the fire even after the flames appear to be extinguished to prevent re-ignition. Class A combustibles like wood and fabrics can re-kindle easily if not cooled sufficiently.

Also be aware of flashover danger when dealing with room and confined space fires involving these fuels. Once extinguished, avoid entering the space without proper protective equipment in case of lingering hot spots.

Maintaining and Recharging Extinguishers

Fire extinguishers need regular maintenance to stay fully pressurized and functional. Here are some tips for upkeep:

  • Check pressure gauges monthly to ensure the needle is in the green zone.
  • Have professional maintenance done annually as required by NFPA 10 standards.
  • After any use, ensure extinguishers are fully recharged by a certified technician.
  • Follow manufacturer guidelines for replacement of hoses, fittings, valves etc.
  • Check extinguisher shells for any signs of corrosion or damage.
  • Ensure locations remain clearly marked and accessible.

Regular maintenance and recharging after use ensures extinguishers work reliably when needed. It’s cheap fire insurance compared to the devastation caused by uncontrolled fires involving Class A fuels.

Frequently Asked Questions

What are the different classes of fires?

Fires are classified based on the type of fuel involved:

  • Class A – Ordinary combustibles like paper, wood, textiles etc.
  • Class B – Flammable liquids and gases.
  • Class C – Energized electrical equipment.
  • Class D – Combustible metals.
  • Class K – Cooking oils and fats.

Why are water mist extinguishers not recommended for these fires?

Water mist extinguishers atomize water into fine droplets. But paper and textiles soak up water quickly, reducing effectiveness. Wood can also warp and split if saturated with water. So water mists have less penetration and cooling ability on these fuels.

Can I just smother a small fire with a blanket or towel?

For very small fires just starting, an emergency response like smothering with a blanket can work. But fires can grow rapidly out of control. Having the right extinguisher on hand allows a fast, controlled response.

Are there fire extinguisher alternatives for Class A fires?

Some alternatives like passive fire suppression systems or sprinklers may help control small fires. But they are less portable or practical than extinguishers in most settings. Nothing beats having the right ABC extinguisher nearby when a fire starts.

Can dry chemical extinguishers be used on cooking oil fires too?

Although Class K extinguishers are specially formulated for cooking oils/fats, dry chemical types can also be used if no other options are available. Start by turning off the heat source, then aim at the base of the flames. The key is using a sweeping motion to cover the entire pan surface.

Laura Kassovic

Laura Kassovic, a former engineer at Intel SOC, now dedicates her efforts to mentoring startups in the realms of Wearables and AI. As a co-founder of New Tech Brake, she spearheads a wireless sensing solution enterprise catering to diverse applications including product development, research, location tracking, and people monitoring, as well as asset and cargo supervision. The platform empowers developers to craft an array of innovations such as fitness trackers, temperature-monitored cargo systems, medical trial tools, smart running garments, or even straightforward transmission of unprocessed accelerometer data to cloud-based repositories.

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