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]
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]
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]
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]
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 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]
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 | Mnemonic | Compatibility | |
---|---|---|---|---|---|---|
A | Ordinary solid combustibles | A for "Ash" | Compatible | |||
B | Flammable liquids and gases | B for "Barrel" | Compatible | |||
C | Energized electrical equipment | C for "Current" | Compatible | |||
D | (none) | Combustible metals | D for "Dynamite" | Not compatible | ||
K | Oils and fats | K for "Kitchen" | Not compatible |
The powder contains monoammonium phosphate, with the phosphate being a globally valuable material. See the references for links to recycling research projects and companies.
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.
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:
The fire triangle or combustion triangle is a simple model for understanding the necessary ingredients for most fires.
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.
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.
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.
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.
A fire class is a system of categorizing fire with regard to the type of material and fuel for combustion. Class letters are often assigned to the different types of fire, but these differ between territories; there are separate standards for the United States, Europe, and Australia. The fire class is used to determine the types of extinguishing agents that can be used for that category.
Fire-retardant fabrics are textiles that are more resistant to fire than others through chemical treatment of flame-retardant or manufactured fireproof fibers.
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.
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.
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.
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.
Home safety is the awareness of risks and potential dangers in and around a home that may cause bodily harm, injury, or even death to those living there.
Condensed aerosol fire suppression is a particle-based method of fire extinction. It is similar to but not identical to dry chemical fire extinction methods, using an innovative pyrogenic, condensed aerosol fire suppressant. It is a highly effective fire suppression method for class A, B, C, E and F. Some aerosol-generating compounds produce a corrosive by-product that may damage electronic equipment, although later generations lower the effect.
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.