ABC dry chemical

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An ABC dry chemical fire extinguisher made by Amerex FireExtinguisherABC.jpg
An ABC dry chemical fire extinguisher made by Amerex

Monoammonium phosphate, ABC Dry Chemical, ABC Powder, tri-class, or multi-purpose dry chemical is a dry chemical extinguishing agent used on class A, class B, and class C fires. It uses a specially fluidized and siliconized monoammonium phosphate powder. [1] ABC dry chemical is usually a mix of monoammonium phosphate and ammonium sulfate, the former being the active component. The mix between the two agents is usually 40–60%, 60–40%, or 90–10% depending on local standards worldwide. The USGS uses a similar mixture, called Phos Chek G75F. [2]

Contents

Uses

Common use

Dry chemical powder is used on all classes of fires. Dry chemical powder puts out the fire by coating the burning material with a thin layer of dust, thereby separating the fuel from the oxygen in the air. The powder also works to interrupt the chemical reaction of fire, so these extinguishers are extremely effective at putting out the fire. Pressure is generated by gas cartridges stored inside the cylinder. Its force will last for 45 seconds and can reach 3–4.5 metres (10–15 ft). [3] [1]

Common combustible solids

It insulates Class A fires by melting at approximately 180–200 °C (350–400 °F). Class A fires are caused by the burning of common combustible materials, such as wood, paper, or most plastics. [4]

Burning liquids and gases

The powder breaks the chain reaction of liquid and gas fires by coating the surface to which it is applied. These fires (Class B in the American system; Classes B and C in the European and Australian systems) include the burning of gasoline, oil, propane, and natural gas. [1]

Electrical fires

It is safe and effective for electrical fires since it is a non-conductor of electricity. Fires involving live electrical equipment (Class C in the American system; Class E in the Australian system) need to be put out with equipment that will not conduct its energy back to the user as is the case with water. Electricity can also cause fires of the other classes. [1]

Chimney bombs

Chimney bombs are zip-lock bags or other small bags filled with ABC dry chemical powder. Chimney bombs are used by fire service personnel to help extinguish chimney fires. Creosote, which is the by-product of the incomplete burning of wood (typically due to chronic combustion-air insufficiency), is extinguished by the chain reaction caused by the chimney bombs. Chimney bombs work by first being dropped directly down a chimney, where upon contact with the flue bottom and heat of the fire, they explode, thereby releasing the powder. Then, the natural chimney draft will carry the dry chemical powder up the shaft of the chimney, thus coating the creosote and eventually neutralizing the fire. Use of multiple chimney bombs may be necessary, depending on how severe the fire is. Chimney bombs can also be effective if they are opened and then dropped down the chimney. In order for chimney bombs to be effective, it may be necessary to first unclog the chimney. [5] [6]

Inappropriate uses

ABC dry chemical is inappropriate for chlorine or oxidizer fires. [7] The resulting chemical reaction can cause an explosion or a breakdown of the chemicals releasing toxic gases. Water should be used in that case. [8] [9]

ABC dry chemical is inappropriate for certain metal fires (Class-D) and does not possess a saponification characteristic and should therefore not be used on Class K / Class F fires. [10] ABC dry chemical has been found to be effective in initially ceasing combustion of oils or fats, however re-application of additional dry chemical may be necessary due to the potential for re-flash of oils or fats heated to near or at their flash point. A Class K / Class F extinguisher is more effective in controlling fires involving primarily vegetable oils as it causes a chemical change to the oils or fats making re-flash far less likely. When a Class K / Class F extinguisher is not available an ABC dry chemical extinguisher can be carefully used to control a fire involving cooking oils or fats if the operator is aware of the potential need to re-apply more chemical if the oils or fats reignite. (Class-K). [1]

Due to the corrosive properties of ABC dry chemical, it is not recommended for use around aircraft or sensitive equipment.

Fire class (US)Geometric symbol Pictogram Intended use MnemonicCompatibility
A Class A fire triangle.svg Fire type A.svg Ordinary solid combustiblesA for "Ash"Compatible
B Class B fire square.svg Fire type B.svg Flammable liquids and gasesB for "Barrel"Compatible
C Class C fire circle.svg Class C fire icon.svg Energized electrical equipmentC for "Current"Compatible
D Class D fire icon.svg (none)Combustible metalsD for "Dynamite"Not compatible
K Class K fire hexagon.svg Class K fire icon.svg Oils and fatsK for "Kitchen"Not compatible

Recycling

The powder contains monoammonium phosphate, with the phosphate being a globally valuable material. See the references for links to recycling research projects and companies.

Related Research Articles

<span class="mw-page-title-main">Creosote</span> Tar distillation byproduct used as wood preservative

Creosote is a category of carbonaceous chemicals formed by the distillation of various tars and pyrolysis of plant-derived material, such as wood, or fossil fuel. They are typically used as preservatives or antiseptics.

<span class="mw-page-title-main">Sodium bicarbonate</span> Chemical compound

Sodium bicarbonate (IUPAC name: sodium hydrogencarbonate), commonly known as baking soda or bicarbonate of soda, is a chemical compound with the formula NaHCO3. It is a salt composed of a sodium cation (Na+) and a bicarbonate anion (HCO3). Sodium bicarbonate is a white solid that is crystalline but often appears as a fine powder. It has a slightly salty, alkaline taste resembling that of washing soda (sodium carbonate). The natural mineral form is nahcolite, although it is more commonly found as a component of the mineral trona.

Saponification is a process of cleaving esters into carboxylate salts and alcohols by the action of aqueous alkali. Typically aqueous sodium hydroxide solutions are used. It is an important type of alkaline hydrolysis. When the carboxylate is long chain, its salt is called a soap. The saponification of ethyl acetate gives sodium acetate and ethanol:

<span class="mw-page-title-main">Fire triangle</span> Model for understanding the ingredients for fires

The fire triangle or combustion triangle is a simple model for understanding the necessary ingredients for most fires.

<span class="mw-page-title-main">Fire safety</span> Practices to reduce the results of fire

Fire safety is the set of practices intended to reduce destruction caused by fire. Fire safety measures include those that are intended to prevent the ignition of an uncontrolled fire and those that are used to limit the spread and impact of a fire.

<span class="mw-page-title-main">Fire control</span> Practice of reducing the heat output of a fire

Fire control is the practice of reducing the heat output of a fire, reducing the area over which the fire exists, or suppressing or extinguishing the fire by depriving it of fuel, oxygen, or heat. Fire prevention and control is the prevention, detection, and extinguishment of fires, including such secondary activities as research into the causes of fire, education of the public about fire hazards, and the maintenance and improvement of fire-fighting equipment.

<span class="mw-page-title-main">Fire retardant</span> Substance reducing flammability

A fire retardant is a substance that is used to slow down or stop the spread of fire or reduce its intensity. This is commonly accomplished by chemical reactions that reduce the flammability of fuels or delay their combustion. Fire retardants may also cool the fuel through physical action or endothermic chemical reactions. Fire retardants are available as powder, to be mixed with water, as fire-fighting foams and fire-retardant gels. Fire retardants are also available as coatings or sprays to be applied to an object.

Purple-K, also known as PKP, is a dry-chemical fire suppression agent used in some dry chemical fire extinguishers. It is the second most effective dry chemical in fighting class B fires after Monnex, and can be used against some energized electrical equipment fires. It has about 4–5 times more effectiveness against class B fires than carbon dioxide, and more than twice that of sodium bicarbonate. Some fire extinguishers are capable of operation in temperatures down to −54 °C or up to +49 °C. Dry chemical works by directly inhibiting the chemical chain reaction which forms one of the four sides of the fire tetrahedron. To a much smaller degree it also has a smothering effect by excluding oxygen from the fire. "Dry chemical" extinguishers, such as Purple-K, are different from "dry powder" extinguishers that are used to fight Class D flammable metal fires.

<span class="mw-page-title-main">Fire suppression system</span> Systems to extinguish or control fires

Fire suppression systems are used to extinguish, control, or in some cases, entirely prevent fires from spreading or occurring. Fire suppression systems have an incredibly large variety of applications, and as such, there are many different types of suppression systems for different applications being used today. Of these, there are some that are still in use but are no longer legal to manufacture and produce.

Active fire protection (AFP) is an integral part of fire protection. AFP is characterized by items and/or systems, which require a certain amount of motion and response in order to work, contrary to passive fire protection.

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<span class="mw-page-title-main">Fire-retardant fabric</span> Flame retardant fabric

Fire-retardant fabrics are textiles that are more resistant to fire than others through chemical treatment of flame-retardant or manufactured fireproof fibers.

<span class="mw-page-title-main">Combustibility and flammability</span> Ability to easily ignite in air at ambient temperatures

A combustible material is a material that can burn in air under certain conditions. A material is flammable if it ignites easily at ambient temperatures. In other words, a combustible material ignites with some effort and a flammable material catches fire immediately on exposure to flame.

Commonly referred to as "Fast Flow" or "High Performance" extinguishers. Available in 6 kg (13 lb), 9 kg (20 lb), and 14 kg (30 lb). capacities and contain ABC Dry Chemical, Purple-K, or sodium bicarbonate. They are currently manufactured by Ansul in cartridge-operated form, along with Amerex, Badger and Buckeye stored pressure design.

<span class="mw-page-title-main">Fire extinguisher</span> Active fire protection device

A fire extinguisher is a handheld active fire protection device usually filled with a dry or wet chemical used to extinguish or control small fires, often in emergencies. It is not intended for use on an out-of-control fire, such as one which has reached the ceiling, endangers the user, or otherwise requires the equipment, personnel, resources or expertise of a fire brigade. Typically, a fire extinguisher consists of a hand-held cylindrical pressure vessel containing an agent that can be discharged to extinguish a fire. Fire extinguishers manufactured with non-cylindrical pressure vessels also exist but are less common.

<span class="mw-page-title-main">Automatic fire suppression</span> Fire suppression systems that operate without human control

Automatic fire suppression systems control and extinguish fires without human intervention. Examples of automatic systems include fire sprinkler system, gaseous fire suppression, and condensed aerosol fire suppression. When fires are extinguished in the early stages loss of life is minimal since 93% of all fire-related deaths occur once the fire has progressed beyond the early stages.

<span class="mw-page-title-main">Ammonium dihydrogen phosphate</span> Chemical compound

Ammonium dihydrogen phosphate (ADP), also known as monoammonium phosphate (MAP) is a chemical compound with the chemical formula (NH4)(H2PO4). ADP is a major ingredient of agricultural fertilizers and dry chemical fire extinguishers. It also has significant uses in optics and electronics.

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<span class="mw-page-title-main">Class B fire</span> Class of fire

In fire classes, a Class B fire is a fire in flammable liquids or flammable gases, petroleum greases, tars, oils, oil-based paints, solvents, lacquers, or alcohols. For example, propane, natural gas, gasoline and kerosene fires are types of Class B fires. The use of lighter fluid on a charcoal grill, for example, creates a Class B fire. Some plastics are also Class B fire materials.

References

  1. 1 2 3 4 5 The Assessment of Fire Suppression Capability for the Ammonium Dihydrogen Phosphate Dry Powder of Commercial Fire Extinguishers. Chung-Hwei Su, Chan-Cheng Chen, Horng-Jang Liaw, Shiuan-ChengWang. Procedia Engineering Volume 84, 2014, Pages 485-490
  2. "Ecological Effects of Fire Retardant Chemicals and Fire Suppressant Foams". Archived from the original on 2007-08-18. Retrieved 2011-02-16.
  3. "Classes Of Fires And Extinguishers". Safety Notes. 2019. Retrieved 2019-08-08.
  4. "Classes of Fire – A, B, C, D, and K – Falck Productions".
  5. "Fire Engineering". Archived from the original on 2018-11-03. Retrieved 2013-02-27.
  6. "Chimney Bombs" . Retrieved 2015-10-19.[ permanent dead link ]
  7. "Selection of Fire Extinguishers for Fires Involving Oxidizers (Swimming Pool Chemicals)". Archived from the original on 2009-03-07. Retrieved 2008-09-13.
  8. "Chlorine facts". Archived from the original on 2008-04-30. Retrieved 2008-09-13.
  9. "Sprinkler protection for swimming pool chemicals". NFPA Journal. 2004. Retrieved 2008-09-13.
  10. Cholin, Roger (1975). "NFPA - ABC Dry Chemical". Triangle Fire Safety. Archived from the original on June 6, 2019. Retrieved June 5, 2019.