What Percentage is Dry Chemical Powder?

Views: 3     Author: Site Editor     Publish Time: 2023-09-05      Origin: Site

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Dry chemical powder is widely used as an extinguishing agent to put out a wide range of fires. As the fire-suppressing agent in dry fire extinguishers, it coats burning materials with an insulating layer that keeps oxygen in the air from reaching the fuel. The powder also impedes the chemical reactions of fire.

There are several types of dry chemical powders used in dry fire extinguishers. The chemical composition and physical properties of the powder determine its efficiency for extinguishing fires and the specific classes of fires it is rated to put out.

Each type of dry chemical powder is based on a specific active compound mainly responsible for its fire-extinguishing properties. The powder contains a mixture of this base component and other chemical additives. This article explores the percentages of active extinguishing agents in the different types of dry chemical powder.

dry chemicla powder

1. Monoammonium Phosphate-Based Powder

Monoammonium phosphate-based powder is one of the most widely used dry chemical powders in multi-purpose fire extinguishers. The powder usually contains a mixture of monoammonium phosphate (MAP) and ammonium sulfate plus an anti-caking agent, moisture-proofing agent, flow-enhancing agent, and silicone oil.

MAP-based dry chemical powder comes in a range of percentages, including 30%, 40%, 60%, 70%, and 90%. The percentages are based on local production standards for the manufacture of dry chemical powder specified for combating various classes of fires. Dry chemical powder percentages indicate that the chemical formulation of the powder contains that percentage of the MAP (the primary fire-suppressing ingredient).

Ammonium sulfate is used in the formulation due to its flame-retardant properties. The chemical increases the combustion temperature of fuel material and also increases the production of residue. Overall, this amalgam of chemical ingredients makes MAP-based dry chemical powder highly effective against different types of fires, including:

●Class A – paper, textiles, and wood

●Class B – flammable liquids like gasoline and alcohol

●Class C – electrical wiring and electronic devices

2. Sodium Chloride-Based Powder

Dry chemical powder based on sodium chloride is used to tackle Class D fires, which can be particularly challenging. Class D fires affect combustible metals such as potassium, lithium, and sodium. The metals usually absorb water vapor and oxygen to produce combustible compounds such as hydrogen and alkaline gases.

Class D dry chemical powder contains 80% sodium chloride as the primary extinguishing agent. It also contains a flow-enhancing agent. This type of dry powder works by covering the metal in a crust, which forms when heat from the fire cakes the agent.

This keeps oxygen away from the metal, thus preventing any chemical reactions. The crust also dissipates heat from the metal, preventing further damage. The sodium chloride-based formulation does not react with metals, ensuring effective and safe use.

3. Potassium Bicarbonate-Based Powder

The dry chemical powder based on potassium bicarbonate as its primary active component is known as Purple-K (PKP).  This violet-colored dry powder is one of the most effective extinguishing agents against class B fires and may also be used on some class C fires (energized electrical components).

The most commonly used PKP formulation contains 80% potassium bicarbonate and about 12-15% sodium bicarbonate. The rest of the dry powder includes Fuller’s earth, mica, and amorphous silica. PKP dry powder combats class B fires by impeding the chemical chain reactions in combustions. To a lesser extent, it also keeps oxygen away from the fire, thus helping smother it.

4. Sodium Bicarbonate-Based Dry Powder

Sodium bicarbonate, or baking soda, is used as an alternative to monoammonium phosphate in BC dry fire extinguishers. The dry chemical powder contains the salt mixed with other compounds to improve flow and expelling properties. Purple-K powder contains around 15 percent baking soda.

Sodium bicarbonate is mainly used to extinguish class B and C fires. It achieves this by releasing water and carbon dioxide, both of which are flame-retardants. Overall, baking soda is a dependable, potent, and cheap fire-suppressing agent.


Dry chemical powder helps extinguish multiple types of fires quickly and effectively. It is also cheap and user-friendly. There are different types of dry chemical powder, which come in specific percentages. The percentage indicates the amount of the base extinguishing agent relative to the rest of the formulation.

It's important to purchase dry chemical powder from reputable manufacturers for use in dry fire extinguishers. Macro is your trusted supplier of high quality dry chemical powder and fire extinguishers. With years of manufacturing experience, our products and services cater to the needs of numerous clients worldwide. Browse our product page to learn more about Macro offerings!