fire extinguisher

(redirected from Wet Chemical)
Also found in: Dictionary, Thesaurus, Acronyms.

fire extinguisher:

see fire fightingfire fighting,
the use of strategy, personnel, and apparatus to extinguish, to confine, or to escape from fire. Fire-Fighting Strategy

Fire fighting strategy involves the following basic procedures: arriving at the scene of the fire as rapidly as possible;
..... Click the link for more information.
The Columbia Electronic Encyclopedia™ Copyright © 2013, Columbia University Press. Licensed from Columbia University Press. All rights reserved.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Fire Extinguisher


a device for stopping fires by means of fire-extinguishing substances. It is carried to the location where it is to be used and is operated manually.

A fire extinguisher consists of a cylindrical vessel with a volume of 1–100 cubic decimeters, a release valve, and a nozzle for forming a stream of the fire-extinguishing substance, which is usually forced out of the vessel by excess pressure within the vessel. The pressure can be maintained continuously (in fire extinguishers of the pressurized type), or it can be generated when the extinguisher is operated. Pressurized fire extinguishers are filled either with the fire-extinguishing substance alone or with a propellant (such as air or nitrogen) as well. In the second type the pressure may be generated by a propellant contained in a flask or as a result of chemical reaction of substances that are components of the fire-extinguishing material.

Among the substances used as fire-extinguishing materials are carbonic acid (carbon dioxide), chemical foams and mechanically produced aerated foams, halogenated hydrocarbons (ethyl bromide or Freon), powders, and water. The carbon dioxide in a fire extinguisher is in the liquid state; it leaves the extinguisher through a diffusing nozzle as a jet that consists of a gaseous phase and a solid phase (snow). Chemical foams are formed in a fire extinguisher as the result of a reaction between an alkaline solution (based on NaHCO3) and an acid solution (based on H2SO4) that takes place when the solutions are mixed before entering the nozzle. The foam ratio—that is, the ratio of the volume of foam to the volume of solution—is 4–6. Mechanically produced aerated foams are obtained by passing a 5–6-percent aqueous solution of a surface-active agent through the nozzle. The solution is broken down into small droplets in the atomizer of the nozzle. The stream of droplets is mixed with the air that is ejected into the nozzle, thus forming a foam with a foam ration of 6–8. In nozzles of the mesh type, foam is produced from bubbles that are generated on the mesh by blowing; the foam ratio in this case is 50–70. The jet of foam is 3–6 m long. Upon passing through the nozzle, the halogenated hydrocarbons form a stream of the aerosol type consisting of finely dispersed drops; powders produce a cloud-forming stream.

The uses of fire extinguishers depend on such properties as extinguishing capacity, the corrosive activity, toxicity, and electric conductivity of the fire-extinguishing substance, capacity, and ability to withstand vibrational loads.

The design of a fire extinguisher depends on the type of the fire-extinguishing substance and the means used to expel the substance. The steel gas cylinders of carbon dioxide fire extinguishers are built for operating pressures of 15 meganewtons per sq m (MN/m2), or 150 kilograms-force per sq cm (kgf/cm2). In all other fire extinguishers the pressure does not exceed 2 MN/m2. The vessels of small fire extinguishers that use powders can be made of plastic.

Fire extinguishers are checked throughout their period of use (beginning with the time of charging) for strength of the vessel and operability. Inspection intervals and procedures are determined in the specifications.


The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.

fire extinguisher

[′fīr ik‚stiŋ·gwish·ər]
Any of various portable devices used to extinguish a fire by the ejection of a fire-inhibiting substance, such as water, carbon dioxide, gas, or chemical foam.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

fire extinguisher

A portable device, for immediate and temporary use in putting out a fire: class A: used on fires involving ordinary combustible materials (such as wood, cloth, paper, rubber, and many plastics), which require the cooling effects of water or certain dry chemical coatings to retard combustion; class B: used on fires involving liquids, gases, greases, etc., extinguished most readily by excluding air or inhibiting the release of combustible vapors; class C: used on fires in live electrical equipment; class D: used on fires involving certain combustible metals, such as magnesium, sodium, etc., requiring a heat-absorbing extinguishing medium not reactive with the burning metals.
McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.
References in periodicals archive ?
The wet chemical agents are proprietary mixtures of potassium carbonate, potassium acetate, potassium citrate, or a combination, in water with other additives to form an alkaline fire suppressant, which enhances saponification.
The discharged wet chemical forms froth on or over hot oil and grease, to blanket flammable liquids, suppress the release of flammable vapours, displace air from the fuel surface, and cool hot surfaces.
Herein, we report an alternative approach to the fabrication of crosslinked polymer thin films that can act as wet chemical etch resists in creating microstructures on silicon wafers.
The Council is a peer group that holds events specially tailored to the unique real estate and operational needs of medical and wet chemical laboratories, and is chaired by Marisa Manley, president of Commercial Tenant Real Estate Representation (CTRR).
Due to the inherent difficulties in digestion and analysis of product materials using wet chemical methods, x-ray fluorescence is receiving attention as an analytical technique for RoHS compliance analysis.
Recording a hard copy of a digital image is done by exposing a film with emulsion coating to light (mainly laser light) and then developing the film by wet chemical processing or by dry thermal processing.
The geochemical analysis of the rock samples was carried to know the major elemental composition, using the wet chemical analysis (Shappiro & Brannock, 1962).
Methods that have been used for preparing nano HA include chemical precipitation [4,5,6,7], in some cases followed by spray drying [8,9,10] or hydrothermal treatment [5,11], sol-gel approach [12,13,14], microemulsion techniques [15,16,17,18], precipitation from complex solutions followed by microwave heating [19,20], wet chemical methods incorporating a freeze drying step [21], mechanochemical synthesis [22,23], and electrodeposition [24].
In various applications, analyses previously done with techniques such as Fourier transform infrared (FTIR), near infrared (NIR), and wet chemical processes are being replaced with NMR.
The proofers use a direct, dry process without intermediate transfer steps or wet chemical processing, so dots stay crisp and accurate.
FIA technology is used to automate many standard methods in wet chemical analysis.
Chemical analytical data: Wet chemical analysis gave: [Na.sub.2]O 7.50, [K.sub.2]O 1.62, MgO 20.10, CaO 2.86, MnO 0.29, FeO 0.79, [Al.sub.2][O.sub.3] 1.47, [Fe.sub.2][O.sub.3] 5.76, [SiO.sub.2] 56.76, [TiO.sub.2] 0.51, [H.sub.2]O 0.84, F 2.80, sum 101.30, less O = F 1.18, Total 100.12 wt.%.