1、Designation: E126 05a E126 12Standard 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
2、 last 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 princ
3、iples, 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 o
4、f this method for hydrometers other than ASTM hydrometers. Method studies were completed forASTM hydrometers only and the precision and bias statements were developed using ASTM hydrometers only. References to other types of hydrometersare for user information only.1.2 The values stated in inch-poun
5、d units 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 o
6、f the 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 Sampli
7、ng 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
8、Liquid-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 Defini
9、tionsThe 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
10、)Values 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 appro
11、ved Nov. 1, 2005Nov. 15, 2012. Published December 2005December 2012. Originally approved in 1959. Last previous edition approved in 2005 asE126 05.E126 05a. DOI: 10.1520/E0126-05A.10.1520/E0126-12.2 For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service
12、 at serviceastm.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 v
13、ersion. 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 Internat
14、ional, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.2.2 comparator, nin this test method, a device glass or other transparent cylinder to contain liquid, in which the readingsof the test hydrometer may be evaluated against the values observed on the reference
15、 standard. a liquid in which hydrometers maybe inter-compared Examples of suitable comparators are given in Appendix X1the Appendix3.2.3 density, nmass 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)
16、, 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 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
17、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. 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 hist
18、oric term, specific gravity, may still befound.3.2.5 specific gravity, n obsolete historic term, replaced by relative density.3.2.6 thermo-hydrometer, nglass hydrometer having a thermometer combined with a hydrometer in one instrument.3.2.7 verification, nconfirmation, by examinationprovision of obj
19、ective evidence, that the instrument fulfills specifiedrequirements.3.2.7.1 DiscussionIn this test method, the if the hydrometer bears an ASTM designation, the requirements for the maximum scale error anddimensions for the hydrometers given in Specification E100 apply.3.2.8 Other descriptions of ter
20、ms relating to thermometers are included in Test Method E77. Any definitions of measurementuncertainty used in this standard are from Terminology E3444. Significance and Use4.1 The purpose of this test method is to establish a common method by which manufacturers manufacturers, calibrationlaboratori
21、es, and users of ASTM hydrometers may inspect, verify, or calibrate their hydrometers.4.2 The goal is to provide a standard method that is simple, easily understood, and will produce reliable results.5. Apparatus5.1 Graduated Metal Scales, of the conventional type, for checking linear dimensions. If
22、 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 Micrometers, of the conventional type, for checking diameters.5.3 Polariscope, for viewing strain patterns
23、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 Equipment, for checking the thermometer portion of thermo-hydrometers is described in Test Method E77.5.6 Thermomet
24、er(s), for use in pressure hydrometer cylinder comparator, ASTM 12C (-20/102 C, 0.2 divisions) or divisions),ASTM 12F (-5/215 F, 0.5 divisions), 136C (-20/60C, 0.2 divisions), or ASTM 136F (-5/140F, 0.5 divisions) found in ASTME1 or ASTM S12C (-20/102 C, 0.2 divisions)divisions), or ASTM S12F (-5/21
25、5 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,tested (when possible), and shall have the same or smaller graduation interval.scale graduations equal to or sma
26、ller than those ofthe hydrometer to be calibrated.E126 122NOTE 2The relative density (specific gravity) of liquids used in testing hydrometers may be obtained by hydrostatic weighing instead of by the useof reference standards as described above. Details of the hydrostatic weighing apparatus can be
27、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 precision. The calibration report s
28、hall 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 use, whichever is longer.6.3.1 Visual
29、inspection shall include, but is not limited to, looking for evidence of scratches, etching, scale slippage, depositson the glass, and discoloration. Evidence The presence of any of the effects warrants re-calibration. these defects is an indicationthat the standard may require re-calibration or rep
30、lacement.6.3.2 Experience has shown that the indications of hydrometers may show driftchange with continued use. A procedure shallbe in place to demonstrate continued validity of the calibration results for the standard hydrometer. Such a procedure may include:periodic re-calibration of the standard
31、 hydrometers; measurements 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 are
32、as, or other obviousdamage 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
33、stem. The paper 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
34、 permitted, such 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
35、linear dimensions 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 inter
36、val between graduations 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 bot
37、tom,L = distance 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 al
38、cohol by weight 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 im
39、mersing to take 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 thel
40、iquid. Certain 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 o
41、f sugar, salts, 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, thorough
42、ly rinsed with 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 with3 Dictionary of Applied Physics, MacMillan and Co., London, Vol 3, p. 439.4 “Density of Solids and Liquids,” National Institute of
43、 Standards and Technology, Circular No. 487.5 “Standard Density and Volumetric Tables,” National Institute of Standards and Technology, Circular, No. 19.E126 123alcohol to remove any residual soap film. The stems can usually be kept clean during the testing by wiping with a lint-free clothmoistened
44、with alcohol (preferably 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 perso
45、nnel. Hydrometer 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 throug
46、hout and at the 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 t
47、he same for both 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 thi
48、sequilibrium. To ensure homogeneity and uniformity in the liquid, thorough mixing is required immediately before makingobservations.NOTE 3Thermometers described in 5.55.6, or thermometers with equivalent maximum permissible errors, may be used, if desired.7.3.4 Influence of Surface TensionWhen a hyd
49、rometer is floated 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 Because 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
