Purple-K
Encyclopedia
Purple-K is a dry-chemical fire suppression agent used in some dry powder fire extinguisher
s. It is the most effective dry chemical in fighting class B
(flammable liquid) fire
s, and can be used against some energized electrical equipment fires (USA class C 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 Powder works by directly inhibiting the chemical chain reaction which forms one of the four sides of the fire tetrahedron (Heat + Oxygen + Fuel + Chemical Chain Reaction = Fire). To a much smaller degree it also has a smothering effect —by excluding oxygen from the fire.
(78–82% by weight), with addition of sodium bicarbonate
(12–15%), mica
(1–3%), Fuller's earth
(1–3%), amorphous silica (0.2–%), and is made hydrophobic by methyl hydrogen polysiloxane (0.2–1%).
Purple-K is non-toxic. Ingestion of large amount can cause alkalosis
. In high temperatures it decomposes to carbon dioxide
and potassium oxide
. It is highly-corrosive.
, usually found fitted to airport fire appliances
.
Purple-K is used in many forms, from small handheld fire extinguishers to large mobile and stationary units, including fixed-nozzle piping systems.
Cleanup of spent agent can be difficult, as it creates a mess when discharged. If the spent agent is dry it can be removed by suction, but when combined with water, hydrocarbons and other liquids, it forms a thick crusty scum that can be challenging to remove.
Purple-K should never be mixed with phosphate
-based fire suppression agents (ABC Dry Chemical
), as the resulting chemical reaction will destroy its efficiency.
Fire extinguisher
A fire extinguisher or extinguisher, flame entinguisher is an active fire protection device used to extinguish or control small fires, often in emergency situations...
s. It is the most effective dry chemical in fighting class B
Fire classes
In firefighting, fires are identified according to one or more fire classes. Each class designates the fuel involved in the fire, and thus the most appropriate extinguishing agent. The classifications allow selection of extinguishing agents along lines of effectiveness at putting the type of fire...
(flammable liquid) fire
Fire
Fire is the rapid oxidation of a material in the chemical process of combustion, releasing heat, light, and various reaction products. Slower oxidative processes like rusting or digestion are not included by this definition....
s, and can be used against some energized electrical equipment fires (USA class C fires). It has about 4–5 times more effectiveness against class B fires than carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
, and more than twice that of sodium bicarbonate
Sodium bicarbonate
Sodium bicarbonate or sodium hydrogen carbonate is the chemical compound with the formula Na 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 . The natural mineral form is...
. Some fire extinguishers are capable of operation in temperatures down to −54 °C or up to +49 °C. Dry Chemical Powder works by directly inhibiting the chemical chain reaction which forms one of the four sides of the fire tetrahedron (Heat + Oxygen + Fuel + Chemical Chain Reaction = Fire). To a much smaller degree it also has a smothering effect —by excluding oxygen from the fire.
Characteristics
Purple-K powder has an acrid taste and odor, is free-flowing, floating on most liquids, non-abrasive, does not wet with water and is compatible with most Foam Concentrates. It has violet color, to distinguish it from other dry agents. Its principal component is potassium bicarbonatePotassium bicarbonate
Potassium bicarbonate , is a colorless, odorless, slightly basic, salty substance...
(78–82% by weight), with addition of sodium bicarbonate
Sodium bicarbonate
Sodium bicarbonate or sodium hydrogen carbonate is the chemical compound with the formula Na 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 . The natural mineral form is...
(12–15%), mica
Mica
The mica group of sheet silicate minerals includes several closely related materials having highly perfect basal cleavage. All are monoclinic, with a tendency towards pseudohexagonal crystals, and are similar in chemical composition...
(1–3%), Fuller's earth
Fuller's earth
Fuller's earth is any non-plastic clay or claylike earthy material used to decolorize, filter, and purify animal, mineral, and vegetable oils and greases.-Occurrence and composition:...
(1–3%), amorphous silica (0.2–%), and is made hydrophobic by methyl hydrogen polysiloxane (0.2–1%).
Purple-K is non-toxic. Ingestion of large amount can cause alkalosis
Alkalosis
Alkalosis refers to a condition reducing hydrogen ion concentration of arterial blood plasma . Generally, alkalosis is said to occur when pH of the blood exceeds 7.45. The opposite condition is acidosis .-Causes:...
. In high temperatures it decomposes to carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
and potassium oxide
Potassium oxide
Potassium oxide is an ionic compound of potassium and oxygen. This pale yellow solid, the simplest oxide of potassium, is a rarely encountered, highly reactive compound...
. It is highly-corrosive.
Uses
Purple-K is commonly used in oil refineries, airport ramps, service stations, military facilities, naval warships, power plants, and other places where flammable liquids are handled. It is often paired with foam in twin agent systemsTwin agent fire extinguishing system
A twin-agent fire extinguishing system incorporates the benefits of dry chemical and foam . Most commonly used for AR-FF operations and in industrial areas with high class B hazards....
, usually found fitted to airport fire appliances
Airport Crash Tender
An airport crash tender is a specialised fire engine designed for use at aerodromes and airports in aircraft accidents.Airport Crash Tenders are extremely powerful machines...
.
Purple-K is used in many forms, from small handheld fire extinguishers to large mobile and stationary units, including fixed-nozzle piping systems.
Cleanup of spent agent can be difficult, as it creates a mess when discharged. If the spent agent is dry it can be removed by suction, but when combined with water, hydrocarbons and other liquids, it forms a thick crusty scum that can be challenging to remove.
Purple-K should never be mixed with phosphate
Phosphate
A phosphate, an inorganic chemical, is a salt of phosphoric acid. In organic chemistry, a phosphate, or organophosphate, is an ester of phosphoric acid. Organic phosphates are important in biochemistry and biogeochemistry or ecology. Inorganic phosphates are mined to obtain phosphorus for use in...
-based fire suppression agents (ABC Dry Chemical
ABC Dry Chemical
ABC or multi-purpose dry chemical is a dry chemical extinguishing agent. It uses a specially fluidized and siliconized monoammonium phosphate powder. ABC dry chemical is usually a mix of monoammonium phosphate and ammonium sulfate, the former being the active one. The mix between the two agents is...
), as the resulting chemical reaction will destroy its efficiency.
External links
- U.S. Naval Research Laboratory Purple-K-Powder
- MSDS Sheets for Purple-K Powder