Mono ammonium phosphate, ABC Dry Chemical, ABC Powder, 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 fluidizes and simonized mono ammonium phosphate powder. ABC dry chemical is usually a mix of mono ammonium phosphate and ammonium sulfate, the former being the active component. The mix between the two agents is usually depending on local standards worldwide. The uses a similar mixture, called Dry Chemical Fire Extinguisher (DCP)
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 metres Dry Chemical Fire Extinguisher (DCP)
Common combustible solids

It insulates Class A fires by melting at approximately Class A fires are caused by the burning of common combustible materials, such as wood, paper, or most plastics Dry Chemical Fire Extinguisher (DCP)
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.
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.
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 Dry Chemical Fire Extinguisher (DCP)
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.

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.

Due to the corrosive properties of ABC dry chemical, it is not recommended for use around aircraft or sensitive equipment.
Where Can Dry Powder Fire Extinguishers Be Used?

Dry Powder Extinguisher A dry powder fire extinguisher can be used in a large variety of situations, these are as follows:

Use of a standard dry powder fire extinguisher:

Class A fires; fires that involve flammable solids like textiles, paper, and wood
Class B fires; fires that involve flammable liquids, for example, paint, diesel, and petrol
Class C fires; fires that involve flammable gases, for instance, butane or methane
Electrical fires where the electrical equipment is up to a maximum of 1000v

Use of a specialist dry powder fire extinguisher:

L2 powder extinguishers (and only this type) can be used for fires that involve lithium
M28 powder extinguishers (and only this type) can be used for fires involving all remaining flammable metals

Where Can Dry Powder Fire Extinguishers Not Be Used?

A dry powder fire extinguisher is not to be used in any of the following situations:

Class F fires; cooking fires, such as chip pan fires
Fires that are in enclosed spaces
Fires that involve electrical equipment which is over 
Fires that involve flammable metals (with the exception of specialist dry powder fire extinguishers)

How Do You Identify a Dry Powder Fire Extinguisher?

A dry powder fire extinguisher can be identified by using the following:

There will be a BLUE-coloured label which will read – POWDER
It should have an ID sign nearby which will read – POWDER EXTINGUISHER

What Are Dry Powder Fire Extinguishers Also Known As?

A dry powder fire extinguisher can also be known by one of the following names:

Dry chemical fire extinguisher
ABC fire extinguisher
Multi-purpose fire extinguisher

How Do Dry Powder Fire Extinguishers Work?

A dry powder fire extinguisher forms a barrier that separates the oxygen source and the fire. Hence the fire is smothered.

Since this type of fire extinguisher does not actually cool the fire, a small chance of re-ignition exists.What Are the Pros and Cons?

There are several pros to using this type of fire extinguisher, as follows:

It will work on most fire types
It can suppress a fire within a rapid timeframe
Specialist dry powder fire extinguishers are the only extinguisher type that is to be used on flammable metals


The cons that exist with this fire extinguisher type are as follows:Dry Chemical Fire Extinguisher (DCP)

A residue can be left since the powder spreads over a large area
There is a small risk of the fire re-igniting
Vision can be obscured
Inhalation can occur in enclosed areas

Who Needs Dry Powder Fire Extinguishers?

For outdoor environments where various fire type risks are present, such as fuel, vehicle, and chemical, a dry powder fire extinguisher is a very good choice. Such environments include the following:

Large workshops
Big commercial boiler rooms
Garage forecourts
Fuel tankers
Flammable liquid storage facilities

How Do You Use a Dry Powder Fire Extinguisher?

Safety Note: You should NEVER use a dry powder fire extinguisher in any type of enclosed area

To safely use a dry powder fire extinguisher, use the following steps:

Remove the safety pin and position yourself at a safe distance
Point towards the base of the fire and then use rapid backward and forward movements with the jet
In the case of an electrical fire, check if it is safe to switch the power off and do so if possible, then direct the jet of powder so that it is aimed right at the fire itself

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