1、Designation: D5256 14Standard Test Method forRelative Efficacy of Dynamic Solvent Systems forDissolving Water-Formed Deposits1This standard is issued under the fixed designation D5256; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision
2、, 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.1. Scope1.1 This test method covers the determination of the relativeefficacy of dynamic solvent systems for dissolv
3、ing water-formed deposits that have been removed from the underlyingmaterial or deposits attached to the underlying material.1.2 The nature of this test method is such that statements ofprecision and bias as determined by round robin tests couldmislead users of this test method (see Sections 11 and
4、12).Therefore, no precision and bias statements are made.1.3 The values stated in SI units are to be regarded asstandard. The values given in parentheses are mathematicalconversions to inch-pound units that are provided for informa-tion only and are not considered standard.1.4 This standard does not
5、 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 practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards
6、:2D887 Practices for Sampling Water-Formed DepositsD1129 Terminology Relating to WaterD1193 Specification for Reagent WaterD2331 Practices for Preparation and Preliminary Testing ofWater-Formed DepositsD2777 Practice for Determination of Precision and Bias ofApplicable Test Methods of Committee D19
7、on WaterD3263 Test Methods for Corrosivity of Solvent Systems forRemoving Water-Formed Deposits (Withdrawn 2008)3D3483 Test Methods forAccumulated Deposition in a SteamGenerator Tube3. Terminology3.1 Definitions:3.1.1 For definitions of other terms used in this test method,refer to Terminology D1129
8、.3.2 Definitions of Terms Specific to This Standard:3.2.1 dynamic solvent system, nany closed loop system inwhich the solvent is in motion across the deposit surface.3.2.2 single and multiple solvent systems, na single sol-vent system is a one-solution treatment. A multiple solventsystem is a treatm
9、ent using two or more solutions in sequence.3.2.3 solvent system, nspecified chemicals or combinationof chemicals, that may include corrosion inhibitors, formulatedto react with and remove deposits.3.2.4 water-formed deposits, nany accumulation of in-soluble material derived from water or formed by
10、the reactionof water upon the surface in contact with the water.3.2.4.1 DiscussionDeposits formed from or by water in allits phases may be further classified as scale, sludge, corrosionproducts, or biological deposits. The overall composition of adeposit or some part of a deposit may be determined b
11、ychemical or spectrographic analysis; the constituents actuallypresent as chemical substances may be identified by micro-scope or x-ray diffraction studies. Organisms may be identifiedby microscopical or biological methods.4. Summary of Test Method4.1 This test method consists of determining the abi
12、lity of adynamic solvent system to dissolve deposits.4.2 For the unattached deposits, this test method consists ofexposing weighed amounts of deposit to the dynamic solventsystems and determining the weight loss of the exposeddeposit, thereby determining the efficacy of the solvent system.4.3 For th
13、e attached deposits, the amount and time requiredto yield a constant amount of certain loss of interest and the1This test method is under the jurisdiction of ASTM Committee D19 on Waterand is the direct responsibility of Subcommittee D19.03 on Sampling Water andWater-Formed Deposits, Analysis of Wat
14、er for Power Generation and Process Use,On-Line Water Analysis, and Surveillance of Water.Current edition approved March 15, 2014. Published April 2014. Originallyapproved 1992. Last previous edition approved in 2009 as D5256 05 (2009). DOI:10.1520/D5256-14.2For referenced ASTM standards, visit the
15、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 is referenced onwww.astm.org.Copyright ASTM Inte
16、rnational, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1amount of deposit not removed determines the relative efficacyof the dynamic solvent system.5. Significance and Use5.1 This test method is useful because the choice of asolvent system for removing water-fo
17、rmed deposits dependsupon the ability of the dynamic solvent system to dissolve bothunattached and attached deposits.6. Apparatus6.1 Common Equipment:NOTE 1The equipment listed in this section is basic and serves thefunction of this test method. This basic test procedure could be modifiedto meet the
18、 specific needs of a particular investigation. The test apparatus,however, must be identified and reported with the results. For comparativetype tests, as described in the procedure, it is important that all tests be runin an identical manner.6.2 Unattached Deposit Removal (see Fig. 1 and Fig. 2):6.
19、2.1 Balance, capable of weighing to the nearest 0.1 mg.6.2.2 Heating Bath, thermostatically controlled to 61C.6.2.3 Stirrer, controlled agitation.6.2.4 Temperature Indicator.6.2.5 Reaction Flask, stirred tests are best accomplished inround bottom flasks.6.2.6 Condenser.6.2.7 Glass Filter Crucibles,
20、Gooch 30-mL low form coursefritted disc crucibles.6.2.8 Vacuum Oven, for drying residual deposits.6.2.9 Desiccator.6.3 Attached Deposit Removal (see Fig. 3):6.3.1 Solvent Heater/Solvent Reservoir.6.3.2 Sample Holder.6.3.3 Flow Controller.6.3.4 Sample System (usually with cooler).6.3.5 Pressure Relie
21、f.6.3.6 Pump.6.3.7 Flow Meter.6.3.8 Temperature Controller.7. Reagents7.1 Purity of ReagentsAll solvent materials such as acids,inhibitors, and other additives shall be of the grade normallyemployed in chemical cleaning practices for the removal ofA: Condenser, B: Temperature Measurement, C: Stirrer
22、, D: Heated ReactionFlaskFIG. 1 Low Temperature Test EquipmentA: Stirrer, B: Pressure Control (Gauge, Vent and Relief), C: TemperatureMeasurement, D: Temperature Control, E: Heated AutoclaveFIG. 2 High Temperature Test EquipmentA: High Point Pressure Relief, B: Pressure Gauge, C: Vent, D: Solvent Ad
23、ditionValve, E: Temperature Measurement, F: Flow Measurement, G: Tube SampleHolder, H: Variable Speed Pump, I: Sample Valve With Integral Cooler, J: Regu-lated Heat SourceFIG. 3 Dynamic Test EquipmentD5256 142water-formed deposits. Unless otherwise indicated, it is in-tended that all chemicals shall
24、 conform to the specifications ofthe Committee onAnalytical Reagents of theAmerican Chemi-cal Society,4where such specifications are available.7.2 Purity of WaterUnless otherwise indicated referencesto water shall be understood to mean reagent water conformingto Type IV of Specification D1193.8. Sam
25、pling8.1 Collect and preserve the sample in accordance withPractices D887 (see Note 2).NOTE 2If MethodAof Test Methods D3483 is being used, the depositremoved in that test can be used in this test method.8.2 Collect and preserve the sample(s) obtained during thecleaning of attached deposit sample.9.
26、 Procedure9.1 Prepare a water solution of the solvent systems to betested using a weight percentage basis for the acid or otheractive material including any additives. Add only inhibitorssupplied in liquid form on a volume basis as prescribed by themanufacturer.9.2 Unattached Deposits:9.2.1 Preparat
27、ion of Sample:9.2.1.1 Preliminary ExaminationExamine the sample ascollected, using a microscope if available, for structure, color,odor, oil matter, appearance of mother liquor if any, and othercharacteristics of note (for example, attraction to magnet).Record the results for future reference. Furth
28、er informationabout examination and documentation of the nature of depositscan be found in Practices D2331.(1) Filtration and other steps in the preparation of thesample may frequently be bypassed; for example, a moistsample that contains no separated water or an apparent drysample shall be started
29、in accordance with 9.2.1.3(1), and a drysample shall be started in accordance with 9.2.1.4.9.2.1.2 Filtration of SampleIf the sample includes anappreciable quantity of separated water, remove the solidmaterial by filtration. Save the filtrate, undiluted, pendingdecision as to whether or not its chem
30、ical examination isrequired. Transfer all of the solid sample to the filter, using thefiltrate to rinse the sample container if necessary. Air-drying orpartial air-drying of the filter is frequently helpful towardeffecting a clean separation of the deposit.9.2.1.3 Sample DryingRemove the drained sol
31、id samplefrom the filter, being careful to avoid gross contamination withfilter paper. Spread the entire quantity of sample in a thin layeron a nonreactive, impervious surface.(1) Oven DryingDry the sample using a vacuum oven ata temperature that will not degrade the deposit. A commonchoice is 52C (
32、125F) and 34 kPa (absolute) (20 in. ofmercury). Place the sample in a desiccator and allow it to coolto room temperature. Weigh the sample to the nearest 0.01 g.Repeat until constant weight is obtained.Arecord of the weightloss during drying is often used.(2) Air DryingAir dry the entire quantity of
33、 solid, spreadit in a thin layer on a nonreactive impervious surface. A recordof the loss of weight during air drying is often used.9.2.1.4 Choose a representative portion of the dried samplefor testing.9.2.2 Pour a measured volume of the test solvent (see 9.1)into the chosen test apparatus (see Sec
34、tion 6).9.2.2.1 The weighed deposit can be added to the solventprior to heating the solvent; however, a controlled and reportedtemperature must be maintained so that the results betweentests can be readily compared.9.2.3 Heat the solvent to the test temperature while stirringat the specified RPM (se
35、e Note 3).NOTE 3A stir rate of 60 to 90 RPM is commonly used.9.2.4 Take a portion of the deposit (see 9.2.1), weigh to thenearest 0.01 g and record an original deposit weight. Thedeposit weight should meet a solvent volume/deposit weightratio for this specified application (see Note 4).NOTE 4A solve
36、nt volume/deposit weight ratio of 100 mL solvent/1 gdeposit is commonly used.9.2.5 After the solvent has stabilized at the test temperature,draw a sample for analysis, then add the deposit to the solvent.This is considered as “time zero.”9.2.6 If required, samples can be drawn at periodic timeinterv
37、als. Maintain strict control of all sample weights (tonearest 0.01 g).9.2.7 At the termination of the test, cool and filter thesolvent.9.2.7.1 Weigh a clean, dry filter crucible to the nearest0.01 g. Record the weight as original crucible weight.9.2.7.2 Filter the solvent-deposit mixture through the
38、weighed filter crucible. Vacuum filtration increases the filtra-tion rate.9.2.7.3 Rinse the filter crucible and residual deposit withwater.9.2.7.4 Dry the crucible and residual deposit in the vacuumoven. Choose a temperature and vacuum that will not degradethe residual deposit. A common choice is 52
39、C (125F) and 34kPa (absolute) (20 in. of mercury).9.2.7.5 Place the dried crucible and residue in the desiccatorand allow them to cool to room temperature.9.2.7.6 Weigh the crucible plus residue to the nearest 0.01 g.9.2.7.7 Repeat 9.2.7.4 to 9.2.7.6 until a constant weight isobtained. Record this w
40、eight as the final crucible weight.9.3 Attached Deposit (Comparative Tests):9.3.1 Establish accumulated deposition in accordance withTest Methods D3483 on a portion of the sample adjacent to andrepresentative of the section to be tested below. Furtherinformation about examination and documentation o
41、f thenature of deposits can be found in Practices D2331.9.3.2 The ratio of the weight of attached deposit on the testspecimen to test apparatus volume must be recorded andshould be appropriate for the application (see Note 5).4Reagent Chemicals, American Chemical Society Specifications , AmericanChe
42、mical Society, Washington, DC. For Suggestions on the testing of reagents notlisted by the American Chemical Society, see Annual Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Roc
43、kville,MD.D5256 143NOTE 5Due to the constraints imposed by the solvent circulationsystem, the solvent volume/deposit weight ratio on attached deposits isoften larger than desired. This excess capacity can be partially compen-sated by reducing the concentration of the active components of thesolvent.
44、 However, in all cases the actual cleaning operation should bedesigned and controlled according to the accepted practice for theparticular solvent system being applied and not according to the valuesgenerated by this test method.9.3.3 Use a measured volume of test solvent to fill the testapparatus.9
45、.3.4 Establish solvent flow in the test apparatus. Thesolvent flow should bypass the test specimen until the properflow rate, system pressure, and solvent temperature is reached.9.3.4.1 Establish and record the solvent flow rate based onthe cross section area of the test specimen.9.3.5 Heat the solv
46、ent to the appropriate test temperature.After the solvent temperature and flow rate have stabilized,draw a sample for analysis.9.3.6 Establish flow through the test specimen. This isconsidered as “time zero.”9.3.7 Monitor and record flow rate, pressure and tempera-ture during the test interval.9.3.8
47、 Draw samples at periodic time intervals and analyzefor ions of choices.9.3.9 If necessary, use intermediate visual examinations todetermine cleaning efficacy.9.3.10 At the completion of the test period, determined by9.3.8 and 9.3.9, determine the remaining deposit accumulationaccording to Test Meth
48、ods D3483 (see Note 6). This value aswell as the time required to achieve the level of cleanliness isused as the relative measure of cleaning efficacy for attacheddeposit.NOTE 6Since the remaining deposit may be acid insoluble, thepreferred method is Method A of Test Methods D3483.10. Calculation10.
49、1 Unattached Deposits:10.1.1 Determine the amount of deposit that was dissolvedby subtracting the amount not dissolved (see 9.2.7) from theoriginal deposit weight (see 9.2.4).10.1.2 Express the efficacy of the solvent system as thepercent deposit dissolved, by dividing the amount dissolved(see 10.1.1) by the original amount (see 9.2.4) and convertingthe resultant decimal to a percentage.10.1.3 Use the following formula to calculate solvent effi-cacy:SE 5OS 2 FS!OS3100 (1)where:SE = solvent efficacy,OS = original deposit weight, g, andFS = final deposit resi
