1、Designation: E126 12E126 13Standard Test Method forInspection, Calibration, and Verification of ASTMHydrometers1This standard is issued under the fixed designation E126; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of l
2、ast revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope1.1 This test method describes the princip
3、les, apparatus, and procedures for the inspection, calibration, and verification ofASTM glass hydrometers. This test method is applicable to ASTM hydrometers and may be used for other general hydrometersof the constant-mass, variable-displacement type.NOTE 1 User must determine the applicability of
4、this method for hydrometers other than ASTM hydrometers. Method studies were completed forASTM hydrometers only and the precision and bias statements were developed usingASTM hydrometers only. References to other types of hydrometersare for user information only.1.2 The values stated in inch-pound u
5、nits are to be regarded as the standard. The values given in parentheses are mathematicalconversions to SI units that are provided for information only and are not considered standard. The metric equivalents ofinch-pound units may be approximate.1.3 This standard does not purport to address all of t
6、he safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D1265 Practice for Sampling
7、Liquefied Petroleum (LP) Gases, Manual MethodD1298 Test Method for Density, Relative Density, or API Gravity of Crude Petroleum and Liquid Petroleum Products byHydrometer MethodD1657 Test Method for Density or Relative Density of Light Hydrocarbons by Pressure HydrometerE1 Specification for ASTM Liq
8、uid-in-Glass ThermometersE77 Test Method for Inspection and Verification of ThermometersE100 Specification for ASTM HydrometersE344 Terminology Relating to Thermometry and HydrometryE2251 Specification for Liquid-in-Glass ASTM Thermometers with Low-Hazard Precision Liquids3. Terminology3.1 Definitio
9、nsThe definitions given in Terminology E344 apply.3.2 Definitions of Terms Specific to This Standard:3.2.1 API gravity, na relative index of density for petroleum products developed by the American Petroleum Institute. APIgravity is defined as:API Gravity,deg5141.5/rel. density 60/60 F!#2131.5 (1)Va
10、lues of API gravity are typically expressed in degrees API, that is, 39.60 API.1 This test method is under the jurisdiction of ASTM Committee E20 on Temperature Measurement and is the direct responsibility of Subcommittee E20.05 onLiquid-in-Glass Thermometers and Hydrometers.Current edition approved
11、 Nov. 15, 2012May 1, 2013. Published December 2012August 2013. Originally approved in 1959. Last previous edition approved in 20052012as E126 05a.E126 12. DOI: 10.1520/E0126-12.10.1520/E0126-13.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at se
12、rviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version
13、. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International,
14、 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.2.2 comparator, nin this test method, a glass or other transparent cylinder to contain a liquid in which hydrometers may beinter-compared Examples of suitable comparators are given in Appendix X1.3.2.3 density, nm
15、ass of a unit volume of material.3.2.3.1 DiscussionUnits of density in hydrometers include kg/l (kilograms per liter), kg/m3 (kilograms per cubic meter), and g/l (grams per liter); eachtypically expressed as mass per volume at a specified temperature, that is, kg/m3 at 15 C. As of this writing, only
16、 the kg/m 3 at15 C scale is offered in ASTM hydrometers (see Specification E100).3.2.4 relative density (formerly specific gravity), nratio of the mass of a given volume of material at a stated temperature tothe mass of an equal volume of gas-free distilled water at the same or different temperature
17、. Both reference temperatures shall beexplicitly stated.3.2.4.1 DiscussionCommon reference temperatures include 60 F/60 F, 20 C/20 C, 20 C/4 C. The historic term, specific gravity, may still befound.3.2.5 specific gravity, nhistoric term, replaced by relative density.3.2.6 thermo-hydrometer, nglass
18、hydrometer having a thermometer combined with a hydrometer in one instrument.3.2.7 verification, nconfirmation, by provision of objective evidence, that the instrument fulfills specified requirements.3.2.7.1 DiscussionIn this test method, if the hydrometer bears an ASTM designation, the requirements
19、 for the maximum scale error and dimensionsfor the hydrometers given in Specification E100 apply.3.2.8 Other descriptions of terms relating to thermometers are included in Test Method E77. Any definitions of measurementuncertainty used in this standard are from Terminology E3444. Significance and Us
20、e4.1 The purpose of this test method is to establish a common method by which manufacturers, calibration laboratories, and usersof hydrometers may inspect, verify, or calibrate hydrometers.them.4.2 The goal is to provide a standard method that is simple, easily understood, and will produce reliable
21、results.5. Apparatus5.1 Graduated Metal Scales, of the conventional type, for checking linear dimensions. If more convenient, metal templates maybe used on which lines are ruled at suitable distances from reference points corresponding to the maximum and minimum valuesof the specified dimensions.5.2
22、 Micrometers, of the conventional type, for checking diameters.5.3 Polariscope, for viewing strain patterns in the glass developed during the manufacturing of the hydrometer.5.4 Comparators, for the calibration and verification of hydrometers. Suitable types are described in the Appendix.5.5 Equipme
23、nt, for checking the thermometer portion of thermo-hydrometers isas described in Test Method E77.5.6 Thermometer(s), for use in pressure hydrometer cylinder comparator, ASTM 12C (-20/102 C, 0.2 divisions), ASTM 12F(-5/215 F, 0.5 divisions), 136C (-20/60C, 0.2 divisions), orASTM 136F (-5/140F, 0.5 di
24、visions) found inASTM E1 orASTMS12C (-20/102 C, 0.2 divisions), or ASTM S12F (-5/215 F, 0.5 divisions) found in Specification E2251.6. Reference Standards6.1 Standard HydrometersStandard hydrometers shall have similar dimensions and shape to the instruments to be tested(when possible), and shall hav
25、e scale graduations equal to or smaller than those of the hydrometer to be calibrated.NOTE 2The relative density (specific gravity) of liquids used in testing hydrometers may be obtained by hydrostatic weighing instead of by the useE126 132of reference standards as described above. Details of the hy
26、drostatic weighing apparatus can be found in the Dictionary of Applied Physics3 or Densityof Solids and Liquids.46.2 Standards shall be calibrated by either a national metrology body (such as the National Institute of Standards andTechnology) or other laboratory competent to test instruments of such
27、 precision. The calibration report shall provide traceabilityto a national metrology body and shall contain a statement of measurement uncertainty. It is desirable that the corrections be statedto one-tenth of a scale division.6.3 Standards shall be visually inspected every six months or prior to us
28、e, whichever is longer.6.3.1 Visual inspection shall include, but is not limited to, looking for evidence of scratches, etching, scale slippage, depositson the glass, and discoloration. The presence of any of these defects is an indication that the standard may require re-calibrationor replacement.6
29、.3.2 Experience has shown that the indications of hydrometers may show change with continued use. A procedure shall be inplace to demonstrate continued validity of the calibration results for the standard hydrometer. Such a procedure may include:periodic re-calibration of the standard hydrometers; m
30、easurements of hydrometers retained by the testing laboratory for use ascheck standards; or checks of one standard hydrometer against another.7. Procedure7.1 Visual Inspection:7.1.1 Inspect the hydrometer carefully to be certain there are no cracks, fissures, deep scratches, rough areas, or other ob
31、viousdamage to the glass. Reject the hydrometer if any of these defects are present.7.1.2 Inspect the hydrometer carefully for loose pieces of ballast or other foreign material within the instrument. If present,reject the instrument.7.1.3 Inspect the paper scale within the hydrometer stem. The paper
32、 scale shall be straight and without twist.7.1.4 Inspect for the presence of a scale slippage indicator. Typically, this is a thin strand of red glass, fused to the inside topof the stem, and terminating at the first major graduation of the hydrometer scale; however, other schemes are permitted, suc
33、h asetching a line on the glass corresponding to a reference line printed on the scale. If a permitted scale slippage indicator is damaged,incorrectly positioned, or not present, reject the instrument. See Specification E100 for more details.7.2 Dimensional Inspection:7.2.1 Check the linear dimensio
34、ns and diameters for compliance with Specification E100 requirements by comparing thehydrometer with the appropriate device described in 5.1 and 5.2.7.2.2 Inspect the hydrometers for correctness of graduation spacing. API and Baum hydrometers are graduated with equalspacing. The interval between gra
35、duations of density and relative density (specific gravity) hydrometers is smaller near the bottomof the scale. The proper spacing shall be obtained from the following formula:l 5L 3d2/d 3d 2d1!/d22d1! (2)where:l = distance from the top line to any line, d, between the top and the bottom,L = distanc
36、e between the top and the bottom graduations of the scale,d2 = density value, or relative density (specific gravity), of the bottom line, andd1 = density value, or relative density (specific gravity), of the top line.7.2.3 Check the scale of hydrometers graduated to read percent of alcohol by weight
37、 or by volume by comparison with thevalues for master scales given in the Standard Density and Volumetric Tables.57.3 General Considerations:7.3.1 In order that readings shall be uniform and reproducible, the hydrometer must be clean, dry, and at the temperature of theliquid before immersing to take
38、 a reading. It is particularly important that the stem be clean so that the liquid will rise uniformlyaround the stem and merge into an imperceptible film on the stem.7.3.2 CleanlinessThe readiness with which proper cleanliness can be obtained depends somewhat on the character of theliquid. Certain
39、liquids, such as mineral oils and strong alcoholic mixtures, adhere to the stem very readily. In such cases, wipingwith a lint-free cloth moistened with acetone or alcohol and drying immediately before each reading is usually sufficient. On theother hand, with weak aqueous solutions of sugar, salts,
40、 acids, and alcohol, scrupulous cleaning of the stem is required. For suchliquids, two methods for preparing instruments for testing are in common use. In one method, hydrometers are dipped in a mixtureof one part concentrated sulfuric acid and two parts fuming sulfuric acid, thoroughly rinsed with
41、water, and dried by wiping witha clean cloth. In the other method, hydrometers are washed with soap and water, dried, and wiped with a cloth moistened withalcohol to remove any residual soap film. The stems can usually be kept clean during the testing by wiping with a lint-free cloth3 Dictionary of
42、Applied Physics, MacMillan and Co., London, Vol 3, p. 439.4 “Density of Solids and Liquids,” National Institute of Standards and Technology, Circular No. 487.5 “Standard Density and Volumetric Tables,” National Institute of Standards and Technology, Circular, No. 19.E126 133moistened with alcohol (p
43、referably absolute) and drying before each reading. (Warning EXTREME CAUTIONThe cleaningprocess using concentrated sulfuric acid and fuming sulfuric acid is extremely hazardous. This process should only be carried outin a laboratory setting with appropriate equipment and trained personnel. Hydromete
44、r must be dry before being inserted in theacids. The steam created by a wet hydrometer may splash acids on the operator.)7.3.3 Influence of TemperatureFor a hydrometer to indicate the density or strength of a specified liquid correctly, it is essentialthat the liquid be uniform throughout and at the
45、 temperature specified on the instrument. However, in comparing two hydrometershaving the same standard temperature and made of the same type of glass, the temperature of the liquid need not be consideredsince the correction required due to variation from the standard temperature is the same for bot
46、h instruments. But the temperaturesof the liquid, the hydrometers, and the surrounding atmosphere should be nearly equal during the comparison; otherwise, thetemperature of the liquid will be changing, causing differences in density. The operator shall allow enough time to achieve thisequilibrium. T
47、o ensure homogeneity and uniformity in the liquid, thorough mixing is required immediately before makingobservations.NOTE 3Thermometers described in 5.6, or thermometers with equivalent maximum permissible errors, may be used, if desired.7.3.4 Influence of Surface TensionWhen a hydrometer is floated
48、 in a liquid, a small quantity of the liquid rises about the stemto form a meniscus. This liquid adhering to the stem above the general level of the liquid in which the instrument is floating hasthe same effect as adding to the mass of the hydrometer, thus increasing the depth of immersion.7.3.4.1 B
49、ecause a hydrometer will indicate differently in two liquids having the same density but different surface tensions, andsince surface tension is a specific property of liquids, it is necessary to specify the liquid for which a hydrometer is intended.Although hydrometers of equivalent dimensions may be compared, without error, in a liquid differing in surface tension from thespecified liquid, the results of comparisons of dissimilar instruments in such a liquid shall be corrected for the effect of the surfacetension.7.3.4.2 In many
