1、Designation:D457900(Reapproved 2012)Standard Practice forHandling an Acid Degreaser or Still1This standard is issued under the fixed designation D4579;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number
2、 in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This practice covers the procedures required for recog-nizing and handling an acid vapor degreaser or still.1.2 If the degreaser(s)is equipped wi
3、th a still,follow theprocedure in this practice for all of the equipment.1.3 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the
4、 applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D2110 Test Method for pH of Water Extractions of Haloge-nated Organic Solvents and Their AdmixturesD2942 Test Method for Total Acid Acceptance of Haloge-nated Organic Solvents(Nonreflux Methods)D3698 Pra
5、ctice for Solvent Vapor Degreasing OperationsD4276 Practice for Confined Area Entry2.2 Federal Regulations:29 CFR 1910.146,Permit-Required Confined Spaces33.Terminology3.1 Definitions:3.1.1 acid degreaser,nan acid degreaser is the result ofthe decomposition of the degreasing solvent to acid products
6、.4.Significance and Use4.1 This practice describes the symptoms and causes of anacid degreaser as well as methods for correcting the problem.4.2 This practice is intended as a reference for use bypersons responsible for the operation or maintenance of vapordegreasers or stills.44.3 This practice is
7、not intended to cover every possiblesituation.5.Symptoms of an Acid Degreaser/Still5.1 An acid condition in a vapor degreaser may be recog-nized by one or more of the following symptoms:5.1.1 A strong acid odor.5.1.2 A dense white smoke in the vapor zone.5.1.3 An unusually dark brown to black-colore
8、d solvent inthe degreaser sumps.5.1.4 Dark spots and pitting of aluminum parts afterdegreasing.5.1.5 Rusting of mild steel parts immediately after removalfrom the degreaser.5.1.6 New formation of green deposits on copper condens-ing coils or chiller coils.5.1.7 Newly formed blush rusting of stainles
9、s steeldegreaser components,especially welded seams.5.1.8 Low pH of solvent as determined by Test MethodD2110 by water extraction or a low acid acceptance of thesolvent as determined by Test Method D2942,or both.5.1.9 Severe pitting and corrosion inside water separator.6.Possible Causes of an Acid D
10、egreaser6.1 It is rare for a solvent vapor degreaser to go acid whenproperly operated and maintained.An acid degreaser can resultfrom any one or a combination of the following causes:6.2 Lack of Proper MaintenanceIf a degreaser is notcleaned out on a regular basis,the accumulations of solubleand ins
11、oluble contaminants,especially reactive white metalchips(for example,aluminum),can cause both thermal andchemical breakdown of the solvent resulting in the generationof hydrochloric acid.6.3 Deterioration of Heating Surfaces:6.3.1 Damaged Heating ElementsDeterioration of eithergas or electrical heat
12、ing elements can cause arcing or hot spotsresulting in an acid condition of the solvent.The deterioration1This practice is under the jurisdiction of ASTM Committee D26 on Haloge-nated Organic Solvents and Fire Extinguishing Agents and is the direct responsi-bility of Subcommittee D26.02 on Vapor Deg
13、reasing.Current edition approved March 1,2012.Published June 2012.Originallyapproved in 1986.Last previous edition approved in 2006 as D4579 00(2006).DOI:10.1520/D4579-00R12.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annu
14、al Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3Available from U.S.Government Printing Office Superintendent of Documents,732 N.Capitol St.,NW,Mail Stop:SDE,Washington,DC 20401,http:/www.access.gpo.gov.4See also Practice D3698.Copyright AS
15、TM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 may be due to damage,corrosion or accumulation of contami-nants on the heating surface.6.3.2 Exposed Heating SurfacesExposure of gas and elec-tric heating surfaces to the air can cause solvent decomposi
16、-tion.Heating elements exposure is caused by a low solventlevel that is not detected by low liquid level controls.6.4 Excessive Amounts of WaterHydrolysis of certainsolvents and impurities can be a factor in the formation of anacid condition.Free water can also remove stabilizer.6.5 Chlorinated and Sulfonated OilsSome chlorinated andsulfonated oils used in deep drawing processes begin to breakdown at 150F(65C),liberating acidic components.When incontact with boiling solvents such as trichloroeth
