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Right Fire Extinguisher for Paper and Wood Fires

Fire safety is crucial, especially in environments where paper and wood materials are present. Having the proper fire extinguisher on hand can help minimize damage and save lives in the event of a fire emergency. But with different classes and colours of extinguishers available, it can be confusing to know which one is right for your needs. This comprehensive guide examines the different types of fire extinguishers and provides recommendations on the best choices for extinguishing fires fueled by paper, wood, and similar combustible materials.

The Fire Tetrahedron: Understanding the Components of Fire

To understand fire extinguishers, it helps to first look at the fire tetrahedron. This is a model that illustrates the four elements needed for fire to occur and continue burning:

  • Heat
  • Fuel
  • Oxygen
  • Chemical chain reaction

Remove any one of these four components and a fire will cease to burn. Fire extinguishers work by disrupting one or more parts of this tetrahedron.

For Class A fires involving ordinary combustibles like paper, wood, cloth and many plastics, the key is to cool the fuel source while displacing oxygen. Extinguishers that use water, foam, wet chemical, or dry chemical accomplish this in different ways.

Fire Extinguisher Types, Ratings and Uses

Fire extinguishers are classified by the type of fire they are designed to fight. The NFPA 10 standard identifies the following classifications:

Class A Extinguishers

Class A extinguishers are for ordinary combustible materials such as paper, wood, cardboard, and most plastics.

Recommended for paper and wood fires.

Examples: Water, foam, wet chemical, and dry chemical extinguishers

Class B Extinguishers

Class B extinguishers are for flammable or combustible liquids such as grease, gasoline, oil, and oil-based paints.

Not recommended for paper and wood fires.

Examples: Foam, CO2, and dry chemical extinguishers

Class C Extinguishers

Class C extinguishers are for fires involving energized electrical equipment.

Not recommended for paper and wood fires.

Examples: CO2 and dry chemical extinguishers

Class D Extinguishers

Class D extinguishers are for combustible metals such as magnesium, titanium, and sodium.

Not recommended for paper and wood fires.

Examples: Dry powder extinguishers

Class K Extinguishers

Class K extinguishers are for fires involving cooking oils and greases such as animal fats and vegetable fats.

Not recommended for paper and wood fires.

Examples: Wet chemical and potassium acetate extinguishers

Matching Extinguisher Types to Fuel Sources

Choosing the right type of extinguisher for the fuels present is extremely important. Using the wrong extinguisher on certain fires can actually make the fire worse. Here are some basic guidelines:

  • For paper and wood fires, use Class A water, foam, wet chemical or dry chemical extinguishers. These agents cool the fire while coating the fuel source, suppressing vapors, and displacing oxygen.
  • Avoid using Class B and C extinguishers containing carbon dioxide, dry chemical powder, or halon on deep-seated Class A fires involving paper or wood. The pressurized stream of these extinguishers may scatter burning materials.
  • Class B extinguishers for flammable liquids are ineffective at cooling Class A solid combustibles like wood. The use of water on a grease or oil-based fire could cause splattering or spreading.
  • Class C extinguishers displace oxygen but don’t cool the fuel source. They should only be used once electricity is disconnected.
  • Class D extinguishers are ineffective on paper and wood fires.
  • Class K extinguishers contain agents that could react dangerously with certain metals and hot ashes.

So in summary, verified Class A extinguishers using water, foam, wet chemical or dry chemical are the best choices when dealing with burning paper, wood, cloth, or similar materials. They all work to cool the fuel while displacing oxygen for quick suppression.

Water Extinguishers

Water extinguishers, often called pump-type or stored-pressure models, are perhaps the most common type found in homes and offices. They contain water and compressed air and will put out Class A fires involving common combustibles.

Advantages:

  • Effective at quickly cooling fires involving paper, wood, fabric and plastics
  • Water is an easily accessible extinguishing agent
  • Low cost to recharge

Disadvantages:

  • The water stream may scatter lightweight materials like paper or shred wood surfaces
  • Water conducts electricity; cannot be safely used on energized fires
  • Water can cause spattering of burning liquids
  • Susceptible to freezing temperatures
  • Heavy weight of stored-pressure models

Water extinguishers are marked red in colour and designated with a “W” for the agent inside. They will have a numerical rating indicating the extinguishing capacity, such as 1-A:10-B:C. The higher the number, the larger the fire it can effectively extinguish.

Foam Extinguishers

Foam extinguishers contain foaming agents plus water. The foam coats the fuel source, separating it from oxygen while also providing a cooling effect. The foam blanket suppresses vapors and steam production.

Advantages:

  • Effective on Class A fires involving paper, wood, cloth, rubber and plastics
  • Foam provides cooling and clings to vertical surfaces
  • Vapour-sealing foam prevents re-ignition
  • Typically non-conductive agent

Disadvantages:

  • Foam decomposes and requires replacement over time
  • Less effective on fires involving highly polar solvents
  • Clean-up can be messy

Foam extinguishers are red with a cream panel. They will be marked with “AFFF” for the agent inside. Ratings will indicate the size of fire they can handle, such as 2A:10B:C.

Wet Chemical Extinguishers

Wet chemical extinguishers are designed for commercial kitchens and contain potassium acetate, citrate, or carbonate-based agents. They work by creating a chemical reaction that saponifies the burning oils, rendering them non-combustible. The resulting soapy foam cools the fire and clings to surfaces.

Advantages:

  • Highly effective for extinguishing fires involving vegetable oils or animal fat
  • Coats and clings to surfaces
  • Quickly cools the burning oil and adjacent surfaces
  • Applicator sticks allow for precision under fryer baskets

Disadvantages:

  • Primarily designed for commercial kitchen fires
  • Agents may be corrosive to metals
  • Requires experienced technique to use properly

Wet chemical extinguishers have an oatmeal-coloured shell. They will be marked as “Wet Chemical” and rated for the size of fire they can handle, such as 2-A:1-B:C.

Dry Chemical Extinguishers

Dry chemical extinguishers contain powdered agents such as sodium bicarbonate, potassium bicarbonate, ammonium phosphate, or potassium chloride. They extinguish the fire by coating the fuel, interfering with the chemical chain reaction, and displacing oxygen. The powder also absorbs heat from the fire.

Advantages:

  • Effective on Class A, B and C fires
  • Leaves no residue which can damage electronics
  • Non-conductive agent won’t spread flammable liquids
  • Can be swept up for quick clean-up after use

Disadvantages:

  • Powder discharge may obscure visibility of the fire
  • Some chemical salts may be corrosive to metals
  • Frequent maintenance required to avoid packing of the powder

Dry chemical units will be red with a blue panel indicating the powder type inside. Common ratings are 2A:10B:C or 3A:40B:C.

Using Extinguishers Safely and Effectively

All extinguishers should be installed, maintained, and used according to the manufacturer’s instructions and local regulations. Proper selection, training, placement, and maintenance are critical. Additionally:

  • Know the locations of extinguishers in your building and how to use them.
  • Immediately evacuate the area if the fire grows or you can’t safely reach the extinguisher.
  • Position yourself upwind and stand back 6-10 feet when operating.
  • Squeeze the handle to discharge in short bursts, sweeping side to side at the base.
  • Ensure the fire is completely out and watch for re-ignition once extinguished.
  • Replace or recharge extinguisher immediately after use per the manufacturer’s guidelines.

Choosing the Right Extinguisher Size

Extinguisher size indicates the duration of discharge time, not strength. Larger extinguishers simply provide a longer-lasting discharge. Match the unit size to the potential size of the fire:

  • Small extinguishers (typically 2.5 lbs or less) are suitable for small trash can or waste paper basket fires. Look for a minimum rating of 2A:10B:C.
  • Mid-sized units (around 5 lbs) can handle small woodworking benchtop fires. Aim for 4A:60B:C ratings or higher.
  • Larger units (10 lbs or more) are appropriate where Class A combustible loads are greater, such as offices, meeting rooms, workshops, and storage areas. Look for extinguisher ratings of 6A:80B:C or greater.
  • Commercial/industrial models (20+ lbs) may be needed in manufacturing facilities, warehouses, milling operations and areas with high fuel load densities. Ratings of 10A:120B:C and up are available.

Finally, make sure the extinguisher matches the types of materials present. An extinguisher made for Class B flammable liquid fires won’t be effective on burning paper or wood. Verify the manufacturer’s recommended uses before purchasing and installing units.

Maintaining Extinguishers for Reliability

Regular inspection, testing and maintenance ensures extinguishers function properly when needed. Follow the manufacturer’s guidelines on upkeep. In general:

  • Check pressure gauges monthly. Ensure the needle is in the green zone.
  • Visually inspect extinguishers for damage, corrosion or expiration.
  • Weigh cartridge models annually to verify full charge.
  • Perform hydrostatic testing on water & foam extinguishers every 5 years.
  • Break down dry chemical units annually to check for hardening or caking.
  • Recharge extinguishers immediately after any use.
  • Keep detailed records of all maintenance work performed.

Installing Extinguishers for Fast Accessibility

Proper placement of fire extinguishers allows for quick access in an emergency:

  • Locate extinguishers near room exits, escape routes, and close to potential fire hazards.
  • Position units so the top handle is no more than 5 feet above the floor.
  • Ensure signage and markings are clear and unobstructed.
  • Avoid placing units in extremely high or low temperatures.
  • Mount in open, easily seen locations free of blocking or clutter.
  • Place larger wheeled models in central locations that can be transported to a fire quickly.

By selecting the right fire extinguisher, maintaining them properly, and installing them in accessible locations, you can help protect paper, wood, and other Class A combustibles in your environment. Matching the extinguisher to the fuels present and using them safely and effectively is key. Taking these proactive fire protection steps today can prevent devastating losses tomorrow.

Frequently Asked Questions

What is the difference between dry chemical and dry powder extinguishers?

Dry chemical extinguishers contain powder-based agents such as sodium bicarbonate, potassium bicarbonate, or monoammonium phosphate. Dry powder extinguishers contain sodium chloride-based powders and are intended for Class D combustible metal fires only. The agents used are specific to the type of extinguisher.

How can I tell what type of extinguisher I have?

The shell colour and markings will indicate the extinguisher type and contents. Class A models are red with either no color panel (water) or a cream panel (foam). Class B models are red with a red panel. Class C units are red with a blue panel, and Class D are red with a yellow panel. The label will also state the specific extinguishing agent inside.

What should I do if an extinguisher is damaged or needs recharging?

You should immediately remove any damaged, discharged, or over-pressurized extinguisher from service. Replace it with a verified working unit of the same type and size. Recharging should only be done by companies specializing in fire extinguisher repair and recharging using OEM parts from the manufacturer.

Can I just inspect my own fire extinguishers?

Monthly quick checks should be done by the owner to check basic things like pressure gauges and obvious damage. But professional third-party inspections are required annually for commercial buildings. Trained personnel perform thorough examinations, maintenance, and necessary repairs or recharging. This ensures extinguishers are working properly and helps prevent liability issues.

Where should extinguishers be located in large open warehouses?

In large open structures like warehouses, extinguishers need to be located so they can be reached quickly from any point. The recommended maximum travel distance is 75 feet. Ideally extinguishers should be mounted on posts or columns evenly spaced throughout the building so there is always one within 75 feet, or less, of any location.

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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