1、Designation: G121 98 (Reapproved 2015)1Standard Practice forPreparation of Contaminated Test Coupons for theEvaluation of Cleaning Agents1This standard is issued under the fixed designation G121; the number immediately following the designation indicates the year oforiginal adoption or, in the case
2、of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1NOTEEditorial changes were made throughout in October 2015.1. Scope1.1 This practice describes the proce
3、dure for the preparationof single- and double-sided contaminated metallic test couponsfor the evaluation of cleaning agents. It is applicable for theevaluation of cleaning agents proposed for the cleaning ofoxygen-enriched systems and components. It also is applicableto other systems where contamina
4、tion is a concern.1.2 Several classes of contaminants most likely to be foundin oxygen-enriched systems and components are identified.However, if the user of this practice has identified contami-nants not included in these classes, such identified contami-nants may be substituted for the preparation
5、 of the testcoupons.1.3 Preparation of nonmetallic substrates is not addressed,although similar methodology may be used. Solvent andcleaning agent compatibility with the nonmetallic substrateshould be verified prior to the preparation of the test coupons.Typical nonmetallic materials utilized in oxy
6、gen systems arecontained in Guide G63.1.4 This practice may involve hazardous materials,operations, and equipment. This practice does not purport toaddress all of the safety concerns associated with its use. It isthe responsibility of whomever uses this practice to consult andestablish appropriate s
7、afety and health practices and deter-mine the applicability of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D1193 Specification for Reagent WaterE1235 Test Method for Gravimetric Determination of Non-volatile Residue (NVR) in Environmentally ControlledAreas for Spac
8、ecraftF303 Practices for Sampling for Particles in AerospaceFluids and ComponentsF312 Test Methods for Microscopical Sizing and CountingParticles from Aerospace Fluids on Membrane FiltersF324 Test Method for Nonvolatile Residue of VolatileCleaning Solvents Using the Solvent Purity Meter (With-drawn
9、1987)3F331 Test Method for Nonvolatile Residue of Solvent Ex-tract from Aerospace Components (Using Flash Evapora-tor)G63 Guide for Evaluating Nonmetallic Materials for Oxy-gen ServiceG94 Guide for Evaluating Metals for Oxygen Service2.2 ANSI:B 46.1 Surface Texture (Surface Roughness, Waviness, andL
10、ay)3. Terminology3.1 Definitions:3.1.1 contaminant, nunwanted molecular and particulatematter that could affect or degrade the performance of thecomponents upon which they reside.3.1.2 contamination, na process of contaminating.3.1.3 surface roughness, Ra,nthe arithmetic average de-viation of the su
11、rface profile from the centerline, normallyreported in micrometres.3.1.4 nonvolatile residue (NVR), nresidual molecular andparticulate matter remaining following the filtration of asolvent containing contaminants and evaporation of the solventat a specified temperature.3.1.5 particle (particulate co
12、ntaminant), na piece of mat-ter in a solid state with observable length, width, and thickness.3.1.5.1 DiscussionThe size of a particle is usually definedby its great dimension and is specified in micrometres.1This practice is under the jurisdiction of ASTM Committee G04 on Compat-ibility and Sensiti
13、vity of Materials in Oxygen Enriched Atmospheres and is thedirect responsibility of Subcommittee G04.02 on Recommended Practices.Current edition approved Sept. 1, 2004. Published October 2015. Originallyapproved in 1993. Last previous edition approved in 2010 as G121 98 (2010)1.DOI: 10.1520/G0121-98
14、R15E01.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3The last approved version of this historical standard
15、 is referenced onwww.astm.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.1.6 molecular contaminant (nonparticulatecontamination), nthe molecular contaminant may be in agaseous, liquid, or solid state.3.1.6.1 DiscussionIt may be
16、 uniformly or nonuniformlydistributed, or be in the form of droplets. Molecular contami-nants account for most of the NVR.3.1.7 blank, nthe contamination level of the fluid whenthe test coupon is omitted.3.1.7.1 DiscussionSometimes referred to as “background”level.3.1.8 control coupon (witness coupo
17、n), na coupon madefrom the same material as the test coupons, but in this testmethod is not coated with the contaminant.4. Summary of Practice4.1 A solution of the contaminant is applied to either oneside or both sides of the precleaned test coupons and driedunder standard conditions. The amount of
18、contaminant on thetest coupons is determined. Nonmetallic material test couponsused as inserts, seats, seals, etc. may also be prepared by thisprocedure and are evaluated in the as-used condition.4.2 Three methods of coupon preparation are used:Method A, NVR sample, single sideMethod B, NVR sample,
19、double sideMethod C, NVR and particulate sample5. Significance and Use5.1 This practice will be suitable to direct the preparation oftest coupons with a known amount of contaminant on thesurface. A standard test coupon is described and a list ofcontaminants that have typically been found in oxygen-e
20、nriched systems and components is provided.5.2 These coupons shall be used in the evaluation ofcleaning agents for oxygen-enriched systems and components.This will permit direct comparison within and between testfacilities.5.3 Materials used in other fluid handling systems such asnitrogen, helium, h
21、ydrogen, gasoline, etc. may also be preparedfor evaluation by this practice.6. Apparatus6.1 Test CouponMetal panels of the same material as thecomponent part to be cleaned. Other alloys that may be used ifthe specific alloy is unknown are included in Guide G94. Thecoupon configuration is shown in Fi
22、g. 1.NOTE 1The surface finish of the test coupon should be the same as thepart to be cleaned.6.2 Balance-Range to a minimum of 50 g with an 0.1-mgaccuracy capable of weighing to 60.1 mg.6.3 Oven-Convection, capable of maintaining 50C 6 5C.6.4 Spray ApplicatorCapable of applying an even coat ofcontam
23、inant; that is, an artists airbrush, perfume atomizer, ora spray device such as that used with window or tile cleanershas been found to apply an even coating of the contaminant ina controlled manner.6.5 Other standard equipment such as a vacuum filtrationsystem, solvent resistant filters, gloves, la
24、boratory glassware,syringes, pipettes, desiccator, laboratory tongs, tweezers, andwire.7. Reagents7.1 Contaminant materials-general classes of materials thathave typically been found in oxygen-enriched systems andcomponents as a result of the manufacturing, assembly,fabrication, and construction pro
25、cesses include:silicone oils and greases,fluorinated aerospace fluids and greases,petroleum based oils and greases,ester based oils and greases,phosphate esters,waxes,chlorotrifluoroethylene based oils and greases,inks,cutting oils, anddye penetrants.7.2 Solvent-reagent-grade used to prepare standar
26、d solu-tions of contaminants which may include the following:2-propanol, 2-butanone, hexane, Type II reagent water, orbetter, in accordance with Specification D1193, and perfluori-nated carbon fluids. (WarningSolvents such as 2-propanolhexane and 2-butanone are highly flammable. The readershould ref
27、er to appropriate safe handling procedures.)7.3 Desiccantfor example, silica gel.FIG. 1 Standard Test CouponG121 98 (2015)127.4 Particulate contaminantfine (0- to 80-m), or coarse(0- to 200-m) dusts4available commercially.8. Procedure8.1 Coupon Preparation:8.1.1 The test coupons shall be numbered an
28、d precleanedprior to use; record the number. Determine the surfaceroughness, Ra, of representative coupons of each alloy beingevaluated per ANSI B 46.1 and record. Determine the surfacearea to be contaminated (S) of each of the test coupons andrecord. Attach a handling wire through the hole at the t
29、op ofeach of the test coupons. The precleaning procedure shall beperformed in an ultrasonic cleaner with the coupons immersedin type II reagent water for 10 min. Process a control couponwith the coupons to be contaminated for each cleaning agent tobe evaluated. The coupons shall be dried and stored
30、in adesiccator until needed.8.1.2 Verify that the test coupons have an NVR of 10 mg/sqm (1 mg/sq ft) or less using Test Methods E1235, F324,orF331 and have no particles larger than 300 m when evaluatedusing Test Methods F312. Determine the blank NVR valuesand particle counts on the solvents used to
31、prepare thecontaminating solutions as recommended in Practice F303.These values must be taken into account when preparing thestandard contaminating solutions, especially when very dilutesolutions are desired. Rinse each coupon being prepared forcontamination with the solvent to be used in the contam
32、inantsolution. Allow the coupons to dry overnight or in an oven at40 to 50C for 1 h, cool to room temperature in a desiccator,and weigh. Reweigh the test coupon at intervals, 1 h typically,until a constant weight, 60.1 mg, is achieved. Weigh, recordthe weight (W1) in grams to the nearest 0.1 mg, and
33、 store in adesiccator until needed.NOTE 2It is recommended that coupons be prepared in lots of ten ormore to ensure the necessary sensitivity for the verification.8.1.3 After cleaning, the test coupons should be handledonly with laboratory tongs or tweezers by the handling wire ora hook on the coupo
34、n itself.8.2 Method A, Nonvolatile Residue (NVR) Sample, SingleSide:8.2.1 Prepare a standard solution containing the desiredcontaminant, in a suitable solvent for that contaminant. As analternative, a mixture of as many contaminants as desired maybe prepared in a suitable solvent. The concentration
35、of thesolution, typically between 1 and 100 mg/mL, should beadjusted to reflect the worst expected contamination level inthe system to be cleaned. In some cases, i.e. oils, dyepenetrants, or inks, it may not be necessary to use a solvent inthe preparation of the coupons to achieve the desired level
36、ofcontamination.8.2.2 Place the test coupon(s), number side down, on ahorizontal surface and carefully apply the solution containingthe contaminant to the upper surface of the coupon using apipette, syringe, brush, or spray applicator. Record the numberof the test coupon and the surface area (S) in
37、square centime-ters of each coupon that was coated.8.2.3 Allow the contaminant to dry overnight or in an ovenat 40 to 50C for 1 h, cool to room temperature in a desiccator,remove from the desiccator, and weigh. Reweigh the testcoupon at intervals while storing the coupons in a desiccatorbetween weig
38、hings, 4 h typically, until a constant weight isachieved. Record the final weight (W2) in grams to the nearest0.1 mg. It may be necessary to make additional applications toachieve the desired contamination level. (WarningDo notplace test coupons directly in the oven after application of thesolution
39、containing the contaminant. A fire may result if thesolvent is flammable; or rapid evaporation of the solvent maycause spattering of the contaminant, thereby reducing theamount of contaminant on the test coupon. It is recommendedthat the test coupons be air dried until no traces of a liquidphase are
40、 visible.)8.2.4 Test coupons shall be used immediately after finalweighing.8.3 Method B, NVR Sample, Double Side:8.3.1 Prepare a standard solution containing the desiredcontaminant, in a suitable solvent for that contaminant. As analternative, a mixture of as many contaminants as desired maybe prepa
41、red in a suitable solvent . The concentration of thesolution, typically between 1 and 100 mg/mL, should beadjusted to reflect the worst expected contamination level inthe system to be cleaned. In some cases, e.g. oils, dyepenetrants, or inks, it may not be necessary to use a solvent inthe preparatio
42、n of the coupons to achieve the desired level ofcontamination.8.3.2 Carefully dip the test coupon into the contaminantsolution until it is completely immersed. Slowly withdraw thetest coupon from the contaminant solution. Other methods ofapplication include brushing or spraying. Record the number of
43、the test coupon and the surface area (S) of each coupon thatwas coated. Hang the test coupon by the handling wire andallow the contaminant to dry overnight or in an oven at 40 to50C for 1 h. Cool to room temperature in a desiccator, andweigh. Reweigh the test coupon at intervals, 4 h typically, unti
44、la constant weight is achieved. Record the final weight (W2).(WarningDo not place test coupons directly in the ovenafter application of the solution containing the contaminant. Afire may result if the solvent is flammable; or rapid evaporationof the solvent may cause spattering of the contaminant, t
45、herebyreducing the amount of contaminant on the test coupon. It isrecommended that the test coupons be air dried until no tracesof a liquid phase are visible.)8.3.3 Test coupons shall be used immediately after the finalweighing.8.4 Method C, NVR and Particulate Sample:8.4.1 Prepare a standard soluti
46、on containing the desiredNVR contaminant, in a suitable solvent for that contaminant.As an alternative, a mixture of as many NVR contaminants asdesired may be prepared in a suitable solvent. The NVRcontaminant concentration of the solution, typically between 1and 100 mg/mL, should be adjusted to ref
47、lect the worstexpected NVR contamination level in the system to be cleaned.Add 10, 20, or 30 mg of particulate contaminant to each 1004Dusts of varying particle sizes are available from the AC Spark Plug Divisionof General Motors, 1300-T N. Dort Hwy., Flint, MI 48556.G121 98 (2015)13mL of solution t
48、o provide a light, medium, or heavy particulatelevel, respectively. In some cases, that is, oils, dye penetrants,or inks, it may not be necessary to use a solvent in thepreparation of the coupons to achieve the desired level ofcontamination.8.4.2 Place the test coupon(s), number side down, on ahoriz
49、ontal surface and carefully apply the solution containingthe contaminant, which is agitated or stirred to keep theparticulate suspended, to the top upper surface of the couponusing a pipette, syringe, brush, or spray applicator. Hang thetest coupon by the handling wire and allow the contaminant todry overnight or in an oven at 40 to 50C for 1 h. Cool to roomtemperature in a desiccator, and weigh. Reweigh the testcoupon at intervals, 4 h typically, until a constant weight isachieved. Record the final weight (W2). (WarningDo notplace test coupons
