1、Designation:D 3946 92(Reapproved 1997)Standard Test Method forEvaluating the Bacteria Resistance of Water-DilutableMetalworking Fluids1This standard is issued under the fixed designation D 3946;the number immediately following the designation indicates the year oforiginal adoption or,in the case of
2、revision,the year of last revision.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 test method covers evaluating relative bioresistanceof aqueous metalworking fluids by challengin
3、g them with abiological inoculum prepared from specific deteriorated met-alworking fluid from the users site.1.2 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 an
4、d health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:E 70 Test Method for pH of Aqueous Solutions with theGlass Electrode2E 686 Method for Evaluation of Antimicrobial Agents inAqueous Metalworking Fluids33.Significance an
5、d Use3.1 This test method is applicable for determining in thelaboratory the ratings of fluids as compounded from fluidmanufacturers and for determining the need for biocide addi-tion prior to utilization of the fluids in working systems.4.Apparatus4.1 Air CompressorA suitable air compressor used to
6、deliver compressed air for standard laboratory functions shouldbe available.For purposes of this test the supply of air shouldbe continuous and sufficient to aerate 1 L of fluid withoutexcessive foaming.4.2 IncubatorIdeally a cabinet used for maintaining tem-peratures at 30 6 1C should be used,but i
7、n the absence ofsuch an instrument it is acceptable to incubate at ambient roomtemperature or at the same temperature at which the test systemis run.4.3 Glassware:4.3.1 French Square Bottles,432 oz(960 mL),with cap.One bottle is needed for each test.This style of bottle is usefulbecause it has a max
8、imum height-to-surface area ratio and willmaximally encourage anaerobic conditions during the perfor-mance of the test.4.3.2 Dilution BottlesContainers are needed for makingappropriate dilutions when performing bacterial plate counts.Inexpensive,easily obtainable and sufficiently accurate areclear,g
9、raduated 6-oz(180-mL)screw-cap prescription ovals.Any other container sterilizable and with a holding capacity ofapproximately 200 mLis sufficient for making serial dilutions.54.3.3 Pipets,for making bacterial plate counts should havea rapid delivery to prevent settling in the pipet.The recom-mended
10、 pipets for this purpose are 2.2-mL bacteriological ordairy pipets.These are available presterilized and disposable.64.3.4 Petri Dishes,100 by 15-mm,are used for makingstandard plate counts.These are available presterilized anddisposable from a variety of sources.74.4 Colony CounterAny one of severa
11、l types may beused,although a colony counter is only a black-lighted surfacewith approximately 23 magnification for counting bacterialcolonies and is not essential for the operation of this test.84.5 Materials:4.5.1 Bacteriological MediumSoybean casein digest agarUSP is used for performing the bacte
12、rial plate counts.94.5.2 Soybean Casein Digest BrothThis medium is usedto prepare the inoculum for challenging the fluids under test.104.5.3 BiostixTM,can be used in Alternative Procedure B in1This test method is under the jurisdiction of ASTM Committee D-2 onPetroleum Products and Lubricantsand is
13、the direct responsibility of SubcommitteeD02.L on Industrial Lubricants.Current edition approved Sept.15,1992.Published November 1992.Originallypublished as D 3946 80.Last previous edition D 3946 80(1986).2Annual Book of ASTM Standards,Vol 15.05.3Annual Book of ASTM Standards,Vol 11.05.4Thirty-two-o
14、unce(960-mL)French square bottles are obtainable from VWRScientific under their Catalog No.16188-140.5Clear,graduated 6-oz screw-cap prescription ovals are available from anypharmaceutical supply house.Standard milk dilution bottles(Corning Catalog No.1372)are acceptable.Science Products Div.,Cornin
15、g Glass Works,Corning,NY14830.6Presterilized and disposable pipets are available from Corning,under theirCatalog No.5173.7Petri dishes,available from a variety of sources,are obtainable from most locallaboratory suppliers.8The American Optical Counter is available from a large number of scientificeq
16、uipment distributors,including Fisher,Scientific Products,and VWR.9Soybean casein digest agar USP is available commercially as tryptic soy agar(DIFCO Corp);as trypticase soy agar(BBL).The procedure for preparation of theagar is listed in detail on the container in which the agar is sold.10Tryptic soy broth(DIFCO Corp);trypticase soy broth(BBL).1AMERICAN SOCIETY FOR TESTING AND MATERIALS100 Barr Harbor Dr.,West Conshohocken,PA 19428Reprinted from the Annual Book of ASTM Standards.Copyright ASTMpl
