Purple-K

From Wikipedia, the free encyclopedia

Purple-K is a dry chemical fire suppression agent used in some dry powder fire extinguishers. It is the most effective dry chemical in fighting class B (flammable liquid) fires, and can be used against some class C (energized electrical equipment) fires. It is about 4-5 times more effective against class B fires than carbon dioxide, and more than twice than 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 + CCR = Fire). To a much smaller degree it also has a smothering effect - excluding oxygen from the fire.

1 Characteristics
2 Uses
3 Other uses of Purple-K
4 External links

[edit] Characteristics

Purple-K powder has an acrid taste and odour, is free-flowing, floating on most liquids, non-abrasive, does not wet with water & is compatible with most Foam Concentrates. It has violet color, to distinguish it from other dry agents. Its principial component is potassium bicarbonate (78-82 weight %), with addition of sodium bicarbonate (12-15%), mica (1-3%), Fuller's earth (1-3%), amorphous silica (0.2-1%), 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 corrosive.

[edit] Uses

Purple-K is commonly used in oil refineries, airport ramps, service stations, military facilities, and other places where flammable liquids are handled. It is often paired with foam in Twin Agent systems, usually found fitted to ARFF (Aviation Rescue & Fire Fighting) 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 a difficult task, as it creates quite a mess when discharged. If the spent agent is still dry it can be removed by suction, however 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 type dry chemicals), as the resulting chemical reaction will destroy its efficiency.