1、Designation: G 121 98 (Reapproved 2004)Standard Practice forPreparation of Contaminated Test Coupons for theEvaluation of Cleaning Agents1This standard is issued under the fixed designation G 121; 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 (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice describes the procedure for the preparationof single- and double-sided contam
3、inated 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 contamination is a concern.1.2 Several classes of contaminants most
4、 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 of the testcoupons.1.3 Preparation of nonmetallic substra
5、tes 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 oxygen systems arecontained in Guide G63.1.4 This practice ma
6、y involve hazardous materials, opera-tions, and equipment. This practice does not purport to addressall of the safety concerns associated with its use. It is theresponsibility of whomever uses this practice to consult andestablish appropriate safety and health practices and deter-mine the applicabil
7、ity of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 1193 Specification for Reagent WaterE 1235 Test Method for Gravimetric Determination of Non-volatile Residue (NVR) in Environmentally ControlledAreas for SpacecraftF 303 Practice for Sampling Aerospace Fluids and
8、 Compo-nentsF 312 Methods for Microscopal Sizing and Counting Par-ticles from Aerospace Fluids on Membrane FiltersF 324 Test Method for Nonvolatile Residue of VolatileCleaning Solvents Using the Solvent Purity MeterF 331 Test Method for Nonvolatile Residue of HalogenatedSolvent Extract from Aerospac
9、e Components (Using Ro-tary Flash Evaporator)G63 Guide for Evaluating Nonmetallic Materials for Oxy-gen ServiceG94 Guide for Evaluating Metals for Oxygen Service2.2 ANSI:B46.1 Surface Texture (Surface Roughness, Waviness, andLay)3. Terminology3.1 Definitions:3.1.1 contaminant, nunwanted molecular an
10、d 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 surface profile from the centerline, normallyreported in micrometres.3.1.4
11、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 contaminant), na piece of mat-ter in a solid state with observable length,
12、width, and thickness.3.1.5.1 DiscussionThe size of a particle is usually definedby its great dimension and is specified in micrometres.3.1.6 molecular contaminant (nonparticulate contamina-tion), nthe molecular contaminant may be in a gaseous,liquid, or solid state.3.1.6.1 DiscussionIt may be unifor
13、mly 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.1This practice is under the jurisdiction of ASTM Committee G4 on Compat-ibility and Sensitivity of Mate
14、rials in Oxygen Enriched Atmospheres and is thedirect responsibility of Subcommittee G04.02 on Recommended Practices.Current edition approved Sept. 10, 1998. Published February 1999. Originallyapproved in 1993. Last previous edition approved in 1998 as G 121 98.2For referenced ASTM standards, visit
15、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.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959
16、, United States.3.1.7.1 DiscussionSometimes referred to as “back-ground” level.3.1.8 control coupon (witness coupon), 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
17、 to either oneside or both sides of the precleaned test coupons and driedunder standard conditions. The amount of 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
18、condition.4.2 Three methods of coupon preparation are provided:Method A, NVR sample, single sideMethod B, NVR sample, 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 o
19、n thesurface. A standard test coupon is described and a list ofcontaminants that have typically been found in oxygen-enriched 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 comp
20、arison within and between testfacilities.5.3 Materials used in other fluid handling systems such asnitrogen, helium, hydrogen, 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 all
21、oys that may be used ifthe specific alloy is unknown are included in Guide G94. Thecoupon configuration is shown in Fig. 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
22、 mg.6.3 Oven-Convection, capable of maintaining 50C 6 5C.6.4 Spray ApplicatorCapable to apply an even coat ofcontaminant; i.e., an artists airbrush, perfume atomizer, or aspray device such as that used with window or tile cleaners hasbeen found to apply an even coating of the contaminant in acontrol
23、led manner.6.5 Other standard equipment such as a vacuum filtrationsystem, solvent resistant filters, gloves, laboratory glassware,syringes, pipettes, desiccator, laboratory tongs, tweezers, andwire.7. Reagents7.1 Contaminant materials-general classes of materials thathave typically been found in ox
24、ygen-enriched systems andcomponents as a result of the manufacturing, assembly, fabri-cation, and construction processes include:silicone oils and greases,fluorinated aerospace fluids and greases,petroleum based oils and greases,ester based oils and greases,phosphate esters,waxes,chlorotrifluoroethy
25、lene based oils and greases,inks,cutting oils, anddye penetrants.7.2 Solvent-reagent grade used to prepare standard solutionsof contaminants which may include the following: 2-propanol,2-butanone, hexane, Type II reagent water, or better, inaccordance with D 1193, and perfluorinated carbon fluids.NO
26、TE 2Warning: Solvents such as 2-propanol hexane and2-butanone are highly flammable. The reader should refer to appropriatesafe handling procedures.7.3 Desiccante.g., silica gel.7.4 Particulate contaminantfine (0- to 80-m), or coarse(0- to 200-m) dusts3available commercially.8. Procedure8.1 Coupon Pr
27、eparation8.1.1 The test coupons shall be numbered and precleanedprior to use; record the number. Determine the surface rough-ness, 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 andre
28、cord. Attach a handling wire through the hole at the top of3Dusts of varying particle sizes are available from the AC Spark Plug Divisionof General Motors, 1300-T N. Dort Hwy., Flint, MI 48556.FIG. 1 Standard Test CouponG 121 98 (2004)2each of the test coupons. The preclean procedure shall beperform
29、ed 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 in adesiccator until needed.8.1.2 Verify that the test coupons have an N
30、VR of 10 mg/sqm (1 mg/sq ft) or less using Test Methods E 1235, F 324,orF 331 and have no particles larger than 300 m when evaluatedusing Test Methods F 312. Determine the blank NVR valuesand particle counts on the solvents used to prepare thecontaminating solutions as recommended in Practice F 303.
31、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 contaminantsolution. Allow the coupons to dry overnight or in an oven at4
32、0 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 store in adesiccator until needed.NOTE 3It is recommended that cou
33、pons 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 coupon itself.8.2 Method A, Nonvolatile Residue (NVR) Sample, SingleSide
34、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 of thesolution, typically between 1 and 100 mg/mL, should beadjusted
35、 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 ofcontamination.8.2.2 Place the test coupon(s), number side down, on
36、 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 square centime-ters of each coupon that was coated.8.2.3 Allow the c
37、ontaminant 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 weighings, 4 h typically, until a constant weight isachieved. Record the
38、 final weight (W2) in grams to the nearest0.1 mg. It may be necessary to make additional applications toachieve the desired contamination level.NOTE 4Warning: Do not place test coupons directly in the oven afterapplication of the solution containing the contaminant. A fire may result ifthe solvent i
39、s flammable; or rapid evaporation of the solvent may causespattering of the contaminant thereby reducing the amount of contaminanton the test coupon. It is recommended that the test coupons be air drieduntil no traces of a liquid phase are visible.8.2.4 Test coupons shall be used immediately after f
40、inalweighing.8.3 Method B, NVR Sample, Double Side8.3.1 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 prepared in a suitable solvent. The concentration of thesolution, ty
41、pically 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 ofcontamination.8.
42、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 ofthe test coupon and the surface area (S) of each coupon thatwas
43、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, untila constant weight is achieved. Record the final weight (W2).NOT
44、E 5Warning: Do not place test coupons directly in the oven afterapplication of the solution containing the contaminant. A fire may result ifthe solvent is flammable; or rapid evaporation of the solvent may causespattering of the contaminant thereby reducing the amount of contaminanton the test coupo
45、n. It is recommended that the test coupons be air drieduntil no traces of a liquid phase are visible.8.3.3 Test coupons shall be used immediately after finalweighing.8.4 Method C, NVR and Particulate Sample8.4.1 Prepare a standard solution containing the desiredNVR contaminant, in a suitable solvent
46、 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 reflect the worstexpected NVR contamination level in the system to
47、 be cleaned.Add 10, 20, or 30 mg of particulate contaminant to each 100mL of solution to provide a light, medium, or heavy particulatelevel, respectively. In some cases, i.e. oils, dye penetrants, orinks, it may not be necessary to use a solvent in the preparationof the coupons to achieve the desire
48、d level of contamination.8.4.2 Place the test coupon(s), number side down, on ahorizontal 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
49、 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).NOTE 6Warning: Do not place test coupons directly in the oven afterapplication of the solution containing the contaminant. A fire may result ifG 121 98 (2004)3the solvent is flammable; or rapid evaporation of the solvent may causespattering of the contamin
