ASTM D4579-2000(2006) Standard Practice for Handling an Acid Degreaser or Still《脱脂酸或不起泡酸管理的标准实施规程》.pdf

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1、Designation: D 4579 00 (Reapproved 2006)Standard Practice forHandling an Acid Degreaser or Still1This standard is issued under the fixed designation D 4579; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision.

2、 A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) 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)

3、 is equipped with 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 practice

4、s and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D2110 Test Method for pH of Water Extractions of Halo-genated Organic Solvents and Their AdmixturesD 2942 Test Method for Total Acid Acceptance of Haloge-nated Organic Solvents (Nonre

5、flux Methods)D 3698 Practice for Solvent Vapor Degreasing OperationsD 4276 Practice for Confined Area Entry2.2 Federal Regulations:29 CFR 1910.146, Permit-Required Confined Spaces33. Terminology3.1 Definition:3.1.1 acid degreaser, nan acid degreaser is the result ofthe decomposition of the degreasin

6、g solvent to acid products.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 st

7、ills.44.3 This practice is 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 unusuall

8、y dark brown to black-colored solvent inthe degreaser sumps.5.1.4 Dark spots and pitting of aluminum parts after de-greasing.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 fo

9、rmed blush rusting of stainless steel de-greaser components, especially welded seams.5.1.8 Low pH of solvent as determined by Test MethodD2110by water extraction or a low acid acceptance of thesolvent as determined by Test Method D 2942, or both.5.1.9 Severe pitting and corrosion inside water separa

10、tor.6. Possible Causes of an Acid Degreaser6.1 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

11、, the accumulations of solubleand insoluble 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 ElementsDete

12、rioration of eithergas or electrical heating elements can cause arcing or hot spotsresulting in an acid condition of the solvent. The deteriorationmay be due to damage, corrosion or accumulation of contami-nants on the heating surface.6.3.2 Exposed Heating SurfacesExposure of gas andelectric heating

13、 surfaces to the air can cause solvent decom-position. Heating elements exposure is caused by a low solventlevel that is not detected by low liquid level controls.1This practice is under the jurisdiction of ASTM Committee D26 on Haloge-nated Organic Solvents and Fire Extinguishing Agents and is the

14、direct responsi-bility of Subcommittee D26.02 on Vapor Degreasing.Current edition approved Jan. 1, 2006. Published February 2006. Originallyapproved in 1986. Last previous edition approved in 2000 as D 4579 00.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Custo

15、mer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from the Superintendent of Documents, U. S. Government PrintingOffice, Washington, DC 20402.4See also Practice D 3698.1Copyright ASTM Intern

16、ational, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.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

17、chlorinatedand sulfonated oils used in deep drawing processes begin tobreak down at 150F (65C), liberating acidic components.When in contact with boiling solvents such as trichloroethyl-ene, and perchloroethylene that have boiling points above150F, an acid condition can develop.6.6 Addition of Acid

18、to a DegreaserThe addition ofcertain soils on parts being cleaned, such as solder fluxes,pickling compounds, phosphoric acid for deoxidizer baths, ororganic acids such as stearic acid to a degreaser can lead to thedevelopment of an acid condition.6.7 Mixing of SolventsDifferent solvents, such as 1,1

19、,1-trichloroethane with trichloroethylene, shall not be mixed in adegreaser. Dilution of the solvent stabilizers can lead to thedevelopment of an acid condition.NOTE 1Some paints, tapping compounds, or cooling fluids maycontain an incompatible solvent(s).6.8 Use of Inadequately Stabilized SolventsMa

20、ke-up sol-vent for the degreaser from auxiliary equipment, such ascarbon adsorbers, should be portioned with virgin solvent tomaintain proper stabilization levels or accumulated and resta-bilized in accordance with the manufacturers instructions. Ifreclaimed solvent is used, care shall be taken to e

21、nsure that itis fully stabilized for use in a vapor degreaser.6.9 Improper Degreaser/Still DesignDegreaser/still de-sign shall be compatible with the solvent used, includingmaterials of construction, such as tank walls, piping, heatingelements, pumps, etc.7. Immediate Action for Handling an Acid Deg

22、reaser/Still7.1 Turn off heat source to the degreaser. Do not turn off thecondenser water or the ventilation fan.7.2 Send all unnecessary personnel away from the affectedarea. Personnel sent in to clean the unit shall be properlytrained and equipped for such exposure.7.3 Introduce enough water into

23、the unit to cover all solventto a depth of 2 to 4 in. Add a water solution of soda ash(sodium carbonate) at a concentration of about14 to12 lb/galof water. This will help neutralize the acid decompositionproducts and will facilitate cleaning the machine. Do not usecaustic soda (sodium hydroxide) or

24、caustic potash (potassiumhydroxide) or other strong alkali, because an explosive productmay result.8. Recommended Procedure for Cleaning an AcidDegreaser8.1 Make sure enough soda ash solution is present in thedegreaser to prevent solid residue from being exposed to airwhen the solvent is pumped out

25、of the machine. (The watersolution floats on top of the solvent.) Pump the acid solventinto steel drums containing about one pound of soda ash. Careshould be taken to remove all solvent from water separators,pumps etc. Do not insert the bungs in the drums untilneutralization reaction is complete. (C

26、arbon dioxide is formedby the neutralization reaction. If sealed, pressure from theevolution of carbon dioxide could rupture the drums.)8.2 After the solvent has been removed from the degreaser,inspect the surface of the water solution in the degreaser. If aboiling action is observed, break up any l

27、umps that may existon the bottom of the degreaser using a metal rod or similardevice. Boiling action is most likely to occur in the boilingchamber of the degreaser where chips and oils concentrate butmay also occur in the spray sump or other reservoirs. After allaction ceases, pump the water solutio

28、n out of the degreaser intodrums.8.3 Shut off the water to the condenser.8.4 Remove the clean-out doors and heating elements.8.5 Thoroughly air out the degreaser. Do not enter withoutensuring that no solvent or solvent fumes are present. Makeabsolutely certain that proper tank entry procedures are f

29、ol-lowed. For proper tank entry procedures, see Practice D 4276and Federal Standard 29 CFR 1910.146.8.6 Transfer all solids from the unit into metal drumscontaining soda ash water solution. Remove the drums to anisolated area and treat as a hazardous waste. Handle the drumswith care.8.7 Scrape or wi

30、re brush all internal areas on which solidresidues remain, being careful to remove all residue.8.8 Wash down all interior surfaces of the degreaser with thesoda ash solution to neutralize residual acid products. Beparticularly diligent in neutralizing corners, condensatetroughs, and conveyor systems

31、.8.9 Remove and dismantle all pipes, fittings, pumps, andvalves. Do not neglect the water separator, spray system,storage tank, and the still. Clean and inspect carefully to ensurethat all solid residues have been removed and that all surfaceshave been neutralized. An undetected deposit of unneutral

32、izedresidues as small as a match head can cause the degreaser tobecome acidic again.8.10 Rinse thoroughly with clean water.8.11 Dry all interior surfaces of the degreaser body, con-veyor, and components.8.12 Reassemble the degreaser.8.13 Replace damaged or corroded components and con-trols.8.14 Read

33、just spray piping and nozzles.8.15 Reposition all clean-out doors using new gaskets witha proper sealing compound.8.16 Recharge the degreaser with suitably stabilized vapordegreasing grade solvent and follow normal start up proce-dures.8.17 Monitor the condition of the degreasing solvent usingacid a

34、cceptance tests or other procedures as recommended bythe solvent supplier, or both. This should be done at least dailyuntil the system has reached a stable operating condition.8.18 Do not reuse the solvent removed from the degreaser.8.19 The solvent and soda ash water solutions shall behandled, tran

35、sported, and disposed of in accordance withfederal, state, and local regulations.9. Keywords9.1 acid degreaser; chlorinated solvents; degreaser; vapordegreasersD 4579 00 (2006)2ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item ment

36、ionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee

37、and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting

38、 of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO B

39、ox C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).D 4579 00 (2006)3