1、Designation: D7933 15Standard Test Method forEngine Coolant Stagnation in Flux-Brazed Aluminum HeatExchangers1This standard is issued under the fixed designation D7933; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of la
2、st revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers a laboratory screening proce-dure for evaluating engine coolant compatibility and corrosionprote
3、ction after aging two weeks at 90C in an aluminum heatexchanger brazed using flux.1.2 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.3 This standard does not purport to address all of thesafety concerns, if any, associated wi
4、th its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D1176 Practice for Sampling and Preparing Aqueous Solu-tions of En
5、gine Coolants or Antirusts for Testing PurposesD1193 Specification for Reagent WaterD4340 Test Method for Corrosion of Cast Aluminum Alloysin Engine Coolants Under Heat-Rejecting ConditionsE230/E230M Specification and Temperature-ElectromotiveForce (emf) Tables for Standardized Thermocouples3. Summa
6、ry of Test Method3.1 An aluminum heat exchanger that was brazed using fluxvia any application method or as part of the material claddingis filled with engine coolant, plugged, and placed in an oven fortwo weeks (336 h) at 90C. Engine coolant compatibility isassessed based on changes in coolant physi
7、cal and composi-tional properties, and engine coolant aluminum corrosionprotection is based on performance in the Test Method D4340test.4. Significance and Use4.1 Automobile and truck radiators and heater cores are nowpredominantly made with aluminum alloys using variousmanufacturing processes inclu
8、ding brazing with a flux (SeeAppendix X1 for additional information). The presence ofresidual internal brazing flux in heat exchangers along with thehigh ratio of internal aluminum surface area to coolant volumemay affect certain physical and chemical properties and corro-sion protection of the cool
9、ant. This test method provides ascreening test to assess engine coolant physical and chemicalproperties and corrosion protection after aging it in a heatexchanger brazed with flux at elevated temperature understagnant conditions. This method cannot stand alone as evi-dence of satisfactory coolant pe
10、rformance in flux-brazed alu-minum heat exchangers. The actual service of an enginecoolant formulation can be determined only by more compre-hensive bench, dynamometer, and field tests.5. Apparatus5.1 Aluminum Heat Exchanger Brazed with FluxThe heatexchanger may be a radiator, heater core, or other,
11、 liquidcooled heat exchanger.NOTE 1The aluminum brazed heat exchangers used in this testmethod may be commercially produced or experimentally prepared by theheat exchanger supplier. The aluminum grade, alloying, flux loadingduring brazing, and residual flux remaining in the heat exchanger afterbrazi
12、ng may vary from part to part. The heat exchanger type,manufacturer, size, and other design parameters are decided by mutualagreement of the parties involved.5.2 Coolant Hoses, Clamps, Hose Adapters, and Caps orPlugsRubber engine coolant hoses (approximately 15 cmlength) of appropriate diameter shal
13、l be fitted onto heatexchanger inlet/outlets to allow for coolant expansion. EPDMis one type hose material suitable for the test. Metal clamps,hose adapters, and threaded caps or plugs (stainless steel, orsteel) shall be used to seal the heat exchanger during the1This test method is under the jurisd
14、iction of ASTM Committee D15 on EngineCoolants and Related Fluids and is the direct responsibility of SubcommitteeD15.21 on Extended Life Coolants.Current edition approved May 1, 2015. Published May 2015. DOI: 10.1520/D7933-152For referenced ASTM standards, visit the ASTM website, www.astm.org, orco
15、ntact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1stagnation test. All
16、materials used in the preparation andplumbing of the test specimen shall not be galvanic to thealuminum heat exchanger.5.3 Temperature-Measuring Instrument (Thermocouple)An ASTM partial immersion temperature-measuring instru-ment having a range from -20 to 150C and conforming to therequirements for
17、thermocouple as summarized in SpecificationE230/E230M.6. Reagents and Materials6.1 Reagent Grade WaterSpecification D1193 Grade areavailable.7. Test Solution7.1 Engine Coolant Test FluidThe engine coolant testfluid shall be a 50 vol % engine coolant prepared usingSpecification D1193 Type IV reagent
18、water and prepared perPractice D1176 directions.7.2 The engine coolant test fluid shall be tested before andafter the stagnation period for physical and chemical propertiesalong with performance testing in the Test Method D4340. Thespecific physical and chemical property tests (appearance,water and
19、glycol content, pH, coolant composition andcontamination, glycol degradation and oxidation products,corrosion and brazing flux components) as well as test condi-tions (temperature, pressure, duration, and test fluid dilution) inthe Test Method D4340 are decided by mutual agreement ofparties using th
20、e test.8. Test Conditions8.1 Engine Coolant Test FluidThe amount of enginecoolant required for the test is dependent on the size of the heatexchanger and shall be 80 % of the volume of the heatexchanger.8.2 Test TemperatureThe test shall be conducted at 90C.The temperature shall be maintained at 62C
21、 throughout thetest.8.3 Test DurationThe test shall be run continuously fortwo weeks (336 h).9. Procedure9.1 Aluminum Heat Exchanger Brazed with FluxThealuminum heat exchanger shall be used in the test as received.There shall be no internal washing, rinsing, flushing of the heatexchanger before the
22、test (Note 2). New heat exchangers shallbe used for each test. Attach engine coolant hoses to inlet andoutlet tubes of heat exchanger with metal clamps. Install hoseadapter and clamp on the other end of the hose.NOTE 2Some manufacturers internally wash the heat exchangers toreduce the amount of inte
23、rnal manufacturing flux residues. If the heatexchanger is internally washed, it shall be recorded and reported that itwas washed and there shall be no additional washing, rinsing, flushing ofthe heat exchanger prior to running the test.9.2 ChargingDetermine the volume capacity of the heatexchanger.
24、Fill the heat exchanger to 80 % capacity with theengine coolant test solution. Place cap or plug on the ends ofthe coolant hoses and tighten firmly to seal the heat exchangerduring aging in the oven. An example of an assembled heatexchanger with hoses, clamps, and caps is shown in the digitalimage i
25、n Fig. 1. The Test Method D4340 test requires aminimum of 500 mL of 50/50 engine coolant. If the heatexchanger is less than 500 mL, use additional heat exchangersto produce sufficient quantity of engine coolant to perform theTest Method D4340 test.9.3 AgingPlace heat exchanger in a suitable convecti
26、onoven for two weeks (336 h) at 90C (Note 3). The oven testchamber shall be brought to test temperature prior to placingthe heat exchanger in the oven. Maintain oven temperaturewithin 62C during the test. (WarningThe heat exchangerand hoses may build up pressure during the test. Place heatexchanger
27、in a tray to contain any coolant in the event of aleak. Avoid handling during the test. If handling is required,use protective safety glasses and gloves during handling theheat exchanger.)NOTE 3Maintaining the correct temperature within the specifiedlimits of 62C during the entire test run is an imp
28、ortant factor for assuringboth repeatability and reproducibility of the test results. Care should betaken to maintain a constant airflow across the heat exchangers externalheat transfer surfaces (fin, tube). No direct radiant heating is permitted.9.4 Test TerminationRemove the heat exchanger from th
29、eoven and cool to room temperature. Pick up the heat exchangerfrom the lay down position to a vertical orientation and gentlyrotate 180 degrees clockwise then counter-clockwise 180degrees, repeat 4 times to mix coolant and pour engine coolanttest solution into suitable containers. See Fig. 2.9.5 Pos
30、t Stagnation TestingThe engine coolant test fluidshall be tested before and after the stagnation period forphysical and chemical properties along with performancetesting in the Test Method D4340. The specific physical andchemical property tests (appearance, water and glycol content,FIG. 1 Aluminum H
31、eat Exchanger with Hoses, Clamps, and CapsD7933 152pH, coolant composition and contamination, glycol degrada-tion and oxidation products, corrosion and brazing flux com-ponents) as well as test conditions (temperature, pressure,duration, and test fluid dilution) in the Test Method D4340 aredecided b
32、y mutual agreement of parties using the test. Test theengine coolant sample after Test Method D4340 test forphysical and chemical properties (appearance, water and glycolcontent, pH, coolant composition and contamination, glycoldegradation and oxidation products, corrosion and brazing fluxcomponents
33、) as decided by users of the test. Compare testresults and analyses to determine if there has been any changeduring fluid stagnation or if stagnation has any effect on fluidperformance in Test Method D4340. If a loss of corrosioninhibitors or other adverse effect to the coolant is apparent, theheat
34、exchanger(s) should be sectioned to look for build-up orplugging or any accumulation of residual solids or gels. Ifmaterial is present, it should be analyzed.9.6 Heat Exchanger Reference TestSince commerciallymanufactured heat exchangers may contain varying amounts ofmanufacturing residues, a refere
35、nce test shall be run on aseparate heat exchanger from the same manufacturer and lotwith Specification D1193 Type IV water to determine thetypical amount of manufacturing residue that may be presentfrom the heat exchanger. For the reference test, the heatexchanger shall be filled with Specification
36、D1193 Type IVwater and stored for 24 h at room temperature (22C 6 2C ).The post water solution shall then be tested for heat exchangermanufacturing residue as decided by the users of the test. (SeeAppendix X1 for additional information on the reference testand use of the test.)10. Report10.1 Report
37、the following information:10.1.1 Report the specifics on the heat exchanger used in thetest (make, model, lot number, type of heat exchanger, flux andflux application method and volume of fluid tested.10.1.2 Report the amount of flux residue components in thewater solution after the control test, if
38、 agreed upon by the users(see Appendix X1).10.1.3 Report coolant physical and chemical propertiesbefore and after stagnation and Test Method D4340 testing.The report summarizing the test results should include all thetest information agreed to by the users.10.1.4 Report the Test Method D4340 test re
39、sult.10.1.5 Report if the heat exchanger was sectioned and if anymaterial deposits were observed.10.1.6 Report analysis of any material deposits.11. Precision and Bias11.1 PrecisionThis test method is intended as a screeningtool. Test results obtained on engine coolants after heatexchanger stagnatio
40、n testing may inherently be lacking inprecision and bias due to potential variability in quality andconsistency of the heat exchanger used in the test. Repeatabil-ity and reproducibility limits currently do not exist.11.2 BiasSince there is no accepted reference heat ex-changer or engine coolant for
41、 determining the bias for theprocedure in this method, bias has not been determined.12. Keywords12.1 corrosion; engine coolants; heater core; heat ex-changer; radiatorFIG. 2 One Rotation CycleD7933 153APPENDIX(Nonmandatory Information)X1. A BRIEF DISCUSSION OF CONTROLLED ATMOSPHERIC BRAZING OF ALUMI
42、NUM HEAT EXCHANGERSX1.1 SignificanceX1.1.1 Automobile and truck radiators and heater cores arenow predominantly made with aluminum alloys via brazingwith a flux. An example is the controlled atmosphere brazing(CAB) process, in which a fluxing agent (such as potassiumfluoro-aluminate) is applied to t
43、he surfaces to be joined. Thefluxing agent melts, dissolves, and displaces the aluminumoxide layer that naturally formed on the aluminum surface andfrees up and allows the metal filler to flow and form brazedjoints. The presence of residual internal brazing flux in heatexchangers along with the high
44、 ratio of internal aluminumsurface area to coolant volume may affect certain physical andchemical properties and corrosion protection of the coolant.X1.2 Heat Exchanger Reference TestingX1.2.1 Since commercially manufactured CAB heat ex-changers may contain an amount of post-braze flux, it isimporta
45、nt to run a heat exchanger reference test to determinethe amount that may be solubilized by water.X1.2.2 The reference heat exchanger shall be from the samemanufactuer and same lot. The reference heat exchanger shallbe filled with Specification D1193 Type IV water and stored for24 h at room temperat
46、ure (22C 6 2C). The post watersolution shall then be analyzed for residue components, asdecided by users of the test.X1.2.3 In cases where potassium fluoro-aluminate brazingflux is used as the brazing flux, the presence of potassium in thepost water heat exchanger reference test may be used as amark
47、er to reflect the amount of brazing residue solubilized bywater. In addition, to ensure a minimum test severity to assessthe coolant stability and performance, the post water solutionfrom a reference heat exchanger test shall contain a minimumof 125 g/mL potassium.X1.2.4 In cases where another type
48、of brazing flux ( such ascesium, zinc, or silicon) is used, the parties shall establish areference marker and a required amount of the marker to obtaina certain test severity.ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentio
49、nedin 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 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
