Editing Sodium (section)

==Safety and precautions==
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| PPhrases = {{P-phrases|223|231+232|280|305+351+338|370+378|422}}<ref>{{cite web|url=https://www.sigmaaldrich.com/catalog/product/aldrich/262714|title=Sodium 262714|website=Sigma-Aldrich|access-date=1 October 2018|archive-date=15 January 2016|archive-url=https://web.archive.org/web/20160115025601/http://www.sigmaaldrich.com/catalog/product/aldrich/262714|url-status=live}}</ref>
| NFPA-H = 3
| NFPA-F = 1
| NFPA-R = 2
| NFPA-S = w
| NFPA_ref =<ref>[http://www.ehs.neu.edu/laboratory_safety/general_information/nfpa_hazard_rating/documents/NFPAratingSZ.htm Hazard Rating Information for NFPA Fire Diamonds] {{webarchive|url=https://web.archive.org/web/20150217135922/http://www.ehs.neu.edu/laboratory_safety/general_information/nfpa_hazard_rating/documents/NFPAratingSZ.htm |date=17 February 2015 }}. Ehs.neu.edu. Retrieved on 11 November 2015.</ref>
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Sodium forms flammable hydrogen and caustic [[sodium hydroxide]] on contact with water;<ref>{{cite book |author1-link=Robert Angelici | author= Angelici, R. J.|title= Synthesis and Technique in Inorganic Chemistry |publisher = University Science Books |place = Mill Valley, CA | date = 1999 | isbn = 978-0-935702-48-4}}</ref> ingestion and contact with moisture on skin, eyes or [[mucous membrane]]s can cause severe burns.<ref name=":0" /><ref name="prudent">{{cite book |title=Prudent Practices in the Laboratory: Handling and Disposal of Chemicals |year=1995 |url=https://archive.org/details/prudentpractices00coun_887 |url-access=limited |author1=((U.S. National Research Council Committee on Prudent Practices for Handling, Storage, and Disposal of Chemicals in Laboratories)) |publisher=National Academies |page=[https://archive.org/details/prudentpractices00coun_887/page/n403 390]|isbn=978-0-309-05229-0}}</ref> Sodium spontaneously explodes in the presence of water due to the formation of hydrogen (highly explosive) and sodium hydroxide (which dissolves in the water, liberating more surface). However, sodium exposed to air and ignited or reaching autoignition (reported to occur when a molten pool of sodium reaches about {{cvt|290|C|disp=comma}})<ref>{{cite journal |url=http://terpconnect.umd.edu/~pbs/2013-An-et-al-FSJ.pdf |url-status=dead |archive-url=https://web.archive.org/web/20170808160323/http://terpconnect.umd.edu/~pbs/2013-An-et-al-FSJ.pdf |archive-date=8 August 2017 |title=Suppression of sodium fires with liquid nitrogen |journal=Fire Safety Journal |last1=An |first1=Deukkwang |last2=Sunderland |first2=Peter B. |last3=Lathrop |first3=Daniel P. |date=2013 |volume=58 |pages=204–207|doi=10.1016/j.firesaf.2013.02.001 |bibcode=2013FirSJ..58..204A }}</ref> displays a relatively mild fire.

In the case of massive (non-molten) pieces of sodium, the reaction with oxygen eventually becomes slow due to formation of a protective layer.<ref>{{Cite report |title=Behaviour in the Atmosphere of the Aerosol from a Sodium Fire |first1=W. S.|last1=Clough |first2=J. A.|last2=Garland |publisher=U.S. Department of Energy Office of Scientific and Technical Information |date=1 July 1970 |osti = 4039364}}</ref> [[Fire extinguisher]]s based on water accelerate sodium fires. Those based on carbon dioxide and [[bromochlorodifluoromethane]] should not be used on sodium fire.<ref name="prudent" /> Metal fires are [[Fire extinguisher|Class D]], but not all Class D extinguishers are effective when used to extinguish sodium fires. An effective extinguishing agent for sodium fires is Met-L-X.<ref name="prudent" /> Other effective agents include Lith-X, which has [[graphite]] powder and an [[organophosphate]] [[flame retardant]], and dry sand.<ref>{{cite book|title=Industrial fire prevention and protection|last= Ladwig|first=Thomas H.|publisher=Van Nostrand Reinhold, 1991|isbn=978-0-442-23678-6|page=178|year= 1991}}</ref>

Sodium fires are prevented in nuclear reactors by isolating sodium from oxygen with surrounding pipes containing inert gas.<ref name="fission">{{cite book|title=Sustainable and Safe Nuclear Fission Energy: Technology and Safety of Fast and Thermal Nuclear Reactors|author=Günter Kessler|publisher=Springer Science & Business Media, 2012|isbn=978-3-642-11990-3|page=446|edition=illustrated|date=8 May 2012}}</ref> Pool-type sodium fires are prevented using diverse design measures called catch pan systems. They collect leaking sodium into a leak-recovery tank where it is isolated from oxygen.<ref name="fission" />

Liquid sodium fires are more dangerous to handle than solid sodium fires, particularly if there is insufficient experience with the safe handling of molten sodium. In a technical report for the [[United States Fire Administration]],<ref name=":0">{{cite tech report|first=Routley J.|last=Gordon|title=Sodium explosion critically burns firefighters, Newton, Massachusetts|number=75|institution=[[United States Fire Administration]]|date=1993-10-25 }}</ref> R. J. Gordon writes (emphasis in original)

{{blockquote|Molten sodium is <u>extremely</u> dangerous because it is much more reactive than a solid mass. In the liquid form, every sodium atom is free and mobile to instantaneously combine with any available oxygen atom or other oxidizer, and any gaseous by-product will be created as a rapidly expanding gas bubble within the molten mass. Even a minute amount of water can create this type of reaction. Any amount of water introduced into a pool of molten sodium is likely to cause a violent explosion inside the liquid mass, releasing the hydrogen as a rapidly expanding gas and causing the molten sodium to erupt from the container.


When molten sodium is involved in a fire, the combustion occurs at the surface of the liquid. An inert gas, such as nitrogen or argon, can be used to form an inert layer over the pool of burning liquid sodium, but the gas must be applied very gently and contained over the surface. Except for soda ash, most of the powdered agents that are used to extinguish small fires in solid pieces or shallow pools will sink to the bottom of a molten mass of burning sodium – the sodium will float to the top and continue to burn. If the burning sodium is in a container, it may be feasible to extinguish the fire by placing a lid on the container to exclude oxygen.}}