Purple-K

Last updated

Purple-K, also known as PKP, is a dry-chemical fire suppression agent used in some dry chemical fire extinguishers. [1] It is the second most effective dry chemical in fighting class B (flammable liquid) fires after Monnex (potassium allophanate), and can be used against some energized electrical equipment fires (USA class C fires). [2] 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 (heat + oxygen + fuel + chemical chain reaction = fire). 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. [3]

Contents

Purple-K was developed by the United States Naval Research Laboratory in 1959, as an improvement over sodium bicarbonate for extinguishing oil and gasoline fires. It was named due to the characteristic lavender tint imparted to flames, owing to the potassium (chemical symbol "K") content. [4]

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 bicarbonate (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%). [2]

Purple-K is normally non-toxic, but ingestion of a large amount can cause alkalosis.

Uses

Purple-K is commonly used in oil refineries, airport ramps, service stations, military facilities, naval warships, power plants, and other places where large volumes of flammable liquids are handled. It is often paired with foam in twin agent systems, 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 forms a residue 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.[ citation needed ]

Purple-K should never be mixed with phosphate-based fire suppression agents (ABC dry chemical), as the resulting chemical reaction will destroy its efficiency.[ clarification needed ]

Related Research Articles

<span class="mw-page-title-main">Sodium</span> Chemical element, symbol Na and atomic number 11

Sodium is a chemical element with the symbol Na and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 of the periodic table. Its only stable isotope is 23Na. The free metal does not occur in nature, and must be prepared from compounds. Sodium is the sixth most abundant element in the Earth's crust and exists in numerous minerals such as feldspars, sodalite, and halite (NaCl). Many salts of sodium are highly water-soluble: sodium ions have been leached by the action of water from the Earth's minerals over eons, and thus sodium and chlorine are the most common dissolved elements by weight in the oceans.

<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. It is a component of the mineral natron and is found dissolved in many mineral springs.

<span class="mw-page-title-main">Potassium chloride</span> Ionic compound (KCl)

Potassium chloride is a metal halide salt composed of potassium and chlorine. It is odorless and has a white or colorless vitreous crystal appearance. The solid dissolves readily in water, and its solutions have a salt-like taste. Potassium chloride can be obtained from ancient dried lake deposits. KCl is used as a fertilizer, in medicine, in scientific applications, domestic water softeners, and in food processing, where it may be known as E number additive E508.

A substance is pyrophoric if it ignites spontaneously in air at or below 54 °C (129 °F) or within 5 minutes after coming into contact with air. Examples are organolithium compounds and triethylborane. Pyrophoric materials are often water-reactive as well and will ignite when they contact water or humid air. They can be handled safely in atmospheres of argon or nitrogen. Class D fire extinguishers are designated for use in fires involving pyrophoric materials. A related concept is hypergolicity, in which two compounds spontaneously ignite when mixed.

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

Potassium bicarbonate (IUPAC name: potassium hydrogencarbonate, also known as potassium acid carbonate) is the inorganic compound with the chemical formula KHCO3. It is a white solid.

<span class="mw-page-title-main">Potassium carbonate</span> Chemical compound

Potassium carbonate is the inorganic compound with the formula K2CO3. It is a white salt, which is soluble in water. It is deliquescent, often appearing as a damp or wet solid. Potassium carbonate is mainly used in the production of soap and glass.

<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 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">Potassium citrate</span> Chemical compound

Potassium citrate (also known as tripotassium citrate) is a potassium salt of citric acid with the molecular formula K3C6H5O7. It is a white, hygroscopic crystalline powder. It is odorless with a saline taste. It contains 38.28% potassium by mass. In the monohydrate form, it is highly hygroscopic and deliquescent.

<span class="mw-page-title-main">Potassium nitrite</span> Chemical compound

Potassium nitrite (distinct from potassium nitrate) is the inorganic compound with the chemical formula KNO2. It is an ionic salt of potassium ions K+ and nitrite ions NO2, which forms a white or slightly yellow, hygroscopic crystalline powder that is soluble in water.

<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.

<span class="mw-page-title-main">Firefighting foam</span> Foam used for fire suppression

Firefighting foam is a foam used for fire suppression. Its role is to cool the fire and to coat the fuel, preventing its contact with oxygen, thus achieving suppression of the combustion. Firefighting foam was invented by the Russian engineer and chemist Aleksandr Loran in 1902.

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. This is used to determine the type of extinguishing agent that can be used for that fire class.

A twin-agent fire extinguishing system (TAFES), also commonly referred to as a twin-agent unit (TAU), incorporates the benefits of dry chemical and foam fire extinguishing agents. It is most commonly used for AR-FF operations and in industrial areas with high class B hazards.

<span class="mw-page-title-main">ABC dry chemical</span>

Monoammonium phosphate, ABC Dry Chemical, ABE 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. 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.

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, and/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">Condensed aerosol fire suppression</span> Particle-based form of fire extinction

Condensed aerosol fire suppression is a particle-based form of fire extinction. It is similar to dry chemical fire extinction).

<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. Glenn Corbett (ed.), Fire Engineering's Handbook for Firefighter I and II Penn Well 2009, ISBN   1593701357 page 98
  2. 1 2 Fire extinguishing powders. A. E. Finnerty US. Army Research Laboratory, L. J. Vande Kieft. Halon Options. Technlcal Working Conference 6-8 May 1997.
  3. Dry Chemical Agents- Purple-K in Chemguard
  4. "Purple K Powder", "Naval Aviation News", September 1959, page 19,