1、Designation: E77 141Standard Test Method forInspection and Verification of Thermometers1This standard is issued under the fixed designation E77; the number immediately following the designation indicates the year of originaladoption or, in the case of revision, the year of last revision.Anumber in p
2、arentheses indicates the year of last reapproval.Asuperscriptepsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S. Department of Defense.1NOTESubsection 5.1 was revised editorially to correct a spelling error.1.
3、 Scope1.1 This test method covers visual and dimensional inspec-tion and test for scale accuracy to be used in the verification ofliquid-in-glass thermometers as specified in Specifications E1and E2251. However, these procedures may be applied to otherliquid-in-glass thermometers.2NOTE 1The use of N
4、IST SP250-232is recommended.1.2 WarningMercury has been designated by EPA andmany state agencies as a hazardous material that can causecentral nervous system, kidney and liver damage. Mercury, orits vapor, may be hazardous to health and corrosive tomaterials. Caution should be taken when handling me
5、rcury andmercury containing products. See the applicable product Ma-terial Safety Data Sheet (MSDS) for details and EPAs website-http:/www.epa.gov/mercury/faq.htm - for additional informa-tion. Users should be aware that selling mercury and/ormercury containing products into your state may be prohib
6、itedby state law.-1.3 This standard does not 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, health, and environmental practices and deter-mine the applicability of regulatory limita
7、tions prior to use.1.4 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization T
8、echnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:3E1 Specification for ASTM Liquid-in-Glass ThermometersE344 Terminology Relating to Thermometry and Hydrom-etryE2251 Specification for Liquid-in-Glass ASTM Thermom-eters with Low-Hazard Precision Liquids3. Terminolog
9、y3.1 Definitions:3.1.1 The definitions given in Terminology E344 apply.Some that are considered essential to this standard are givenbelow.3.1.2 calibration, nof a thermometer or thermometricsystem, the set of operations that establish, under specifiedconditions, the relationship between the values o
10、f a thermo-metric quantity indicated by a thermometer or thermometricsystem and the corresponding values of temperature realizedby standards.3.1.2.1 Discussion(1) The result of a calibration permitseither the assignment of values of temperature to indicatedvalues of thermometric quantity or determin
11、ation of correc-tions with respect to indications. (2) A calibration may alsodetermine other metrological properties such as the effect ofinfluence quantities. (3) The result of a calibration may becommunicated in a document such as a calibration certificate ora calibration report. (4)The term calib
12、ration has also been usedto refer to the result of the operations, to representations of theresult, and to the actual relationship between values of thethermometric quantity and temperature.3.1.3 complete-immersion thermometer, n a liquid-in-glass thermometer, not specified in ASTM documents, de-sig
13、ned to indicate temperature correctly when the entirethermometer is exposed to the temperature being measured.3.1.4 partial-immersion thermometer, n a liquid-in-glassthermometer designed to indicate temperature correctly when1This test method is under the jurisdiction of ASTM Committee E20 onTempera
14、ture Measurement and is the direct responsibility of Subcommittee E20.05on Liquid-in-Glass Thermometers and Hydrometers.Current edition approved May 1, 2014. Published September 2014. Originallyapproved in 1949. Last previous edition approved in 2007 as E77 07. DOI:10.1520/E0077-14E01.2“Liquid-in-Gl
15、ass Thermometer Calibration Service,” NIST Special Publication250-23, 1988, Superintendent of Documents, U.S. Government Printing Office,Washington, DC 20402-9325.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book
16、 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 StatesThis international standard was developed in accordance with internationally recogniz
17、ed principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1the bulb and a specified part of the stem are exposed to thetempera
18、ture being measured.3.1.5 total-immersion thermometer, na liquid-in-glassthermometer designed to indicate temperature correctly whenjust that portion of the thermometer containing the liquid isexposed to the temperature being measured.3.2 Definitions of Terms Specific to This Standard:3.2.1 referenc
19、e point, na temperature at which a thermom-eter is checked for changes in the bulb volume.3.2.2 verification, nthe process of testing a thermometerfor compliance with specifications.3.2.3 verification temperatures, nthe specified tempera-tures at which thermometers are tested for compliance withscal
20、e error limits.3.2.4 Other descriptions of terms relating to thermometersare included in Sections 3 and 17 of Specification E1.4. Significance and Use4.1 The test method described in this standard will ensurethat the thermometers listed in Specifications E1 and E2251will indicate temperatures within
21、 the maximum scale errorslisted, be compatible with the apparatus, and serve the purposefor which they were designed.4.2 Thermometers that do not pass the visual and dimen-sional inspection tests may give erroneously high or lowtemperature readings, or may not fit into existing equipmentused in ASTM
22、 methods. For accurate temperature measure-ments the scale readings of the thermometer should be verifiedas described in this test method.5. Apparatus5.1 Graduated Metal Scales or TemplatesMaximum andminimum specified linear dimensions are measured withgraduated metal scales and templates on which l
23、ines are ruledat suitable distances from reference points corresponding to themaximum and minimum values of the several specified dimen-sions.5.2 Micrometers and Ring GagesSpecified diameters ofASTM thermometers are checked using micrometers, or moreconveniently with ring gages consisting of metal p
24、lates inwhich holes have been formed corresponding to the maximumand minimum values of the several specified dimensions. Thethickness of such gages should approximate the diameters ofthe holes to minimize errors resulting from the axis of thethermometer stem being other than normal to the plane of t
25、hegage. When specified, diameters may also be checked withconventional snap gages having plane parallel working faces.5.3 ComparatorsComparators are required for verifica-tion of scale accuracy of liquid-in-glass thermometers. Suitabletypes are described in Appendix X1.5.4 Primary Standard Thermomet
26、erThe primary standardthermometer in the range from 183 to 630 C (297 to 1166F) is the platinum-resistance thermometer. Temperatures arenot measured directly with this instrument. Its electricalresistance is determined by comparison with a standardresistor, using a potentiometer, a Kelvin-type doubl
27、e bridge, ora Wheatstone bridge, (preferably of the Mueller type) or anACresistance bridge. Temperatures may then be calculated usingsuitable resistance-temperature equations. In order that it shallbe satisfactory for such use, the thermometer should meet therequirement that the ratio of resistances
28、 at the steam and icepoints shall be greater than 1.3925. More complete informationon the construction and use of primary standard thermometersmay be obtained from NIST SP250-22.45.5 Secondary Standard Thermometers Secondary stan-dard thermometers are more suitable for routine work, and maybe of var
29、ious types as described below. They are simpler to usethan a primary standard thermometer with its accessoryequipment, the latter being capable of an order of precision andaccuracy far in excess of that attainable with liquid-in-glassthermometers. The choice of a secondary standard will begoverned b
30、y various factors. The following criteria should, inso far as possible, be satisfied: The standard should be acalibrated thermometer of equal or preferably higher sensitivitythan the thermometer to be verified, and it should be capable ofgiving results of an equal or preferably higher order ofaccura
31、cy and also of an equal or preferably higher order ofreproducibility or precision. Scale corrections should alwaysbe applied in the use of these standards. Secondary standardsmay be of the following types.5.5.1 Direct-Reading Resistance ThermometersDirect-reading resistance thermometers are availabl
32、e commercially,are very convenient to use, and have the advantage over theprimary type that temperature indications are given directly inthe instrument reading. They should be completely recalibratedevery 6 to 12 months, depending upon the temperatures ofusage. Ice points should be taken every 3 mon
33、ths.5.5.2 Liquid-in-Glass ThermometersLiquid-in-glassthermometers, when used as secondary standards, may beclassified into two groups, those intended for testing generalpurpose total or partial-immersion thermometers, and those fortesting special use partial-immersion thermometers.5.5.2.1 Total-Imme
34、rsion ThermometersIn the case of gen-eral purpose total-immersion thermometers, the sensitivity ofthe thermometers to be tested will govern the choice ofstandard. For thermometers graduated in 1, 2, or 5 divisions,a set of well-made thermometers will be adequate whencalibrated and used with applicab
35、le corrections. For fraction-ally graduated thermometers a calibrated set of the followingthermometers is recommended. Specifications for theseASTMPrecision Thermometers appear in Specification E1.ASTMTher-mometerNumber RangeCelsiusDivisionsLength,mm62C 38 to +2C 0.1C 38063C 8 to +32C 0.1C 38064C 25
36、 to 55C 0.1C 38065C 50 to 80C 0.1C 38066C 75 to 105C 0.1C 38067C 95 to 155C 0.2C 3804“Platinum Resistance Thermometer Calibrations,” NIST Special Publication250-22, Superintendent of Documents, U.S. Government Printing Office,Washington, DC 20402-9325.E771412ASTMTher-mometerNumber RangeCelsiusDivisi
37、onsLength,mm68C 145 to 205C 0.2C 38069C 195 to 305C 0.5C 38070C 295 to 405C 0.5C 380ASTMTher-mometerNumber RangeFahrenheitDivisionsLength,mm62F 36 to +35F 0.2F 38063F 18 to 89F 0.2F 38064F 77 to 131F 0.2F 38065F 122 to 176F 0.2F 38066F 167 to 221F 0.2F 38067F 203 to 311F 0.5F 38068F 293 to 401F 0.5F
38、 38069F 383 to 581F 1.0F 38070F 563 to 761F 1.0F 380The foregoing set is calibrated for total immersion. With theexception of the first two, each thermometer is provided withan auxiliary scale including 0 C (32 F), thus providing meansfor checking at a fixed point, which should be done each timethe
39、thermometer is used. The change in ice-point readingshould then be applied to all readings. It is only necessary tohave a liquid-in-glass thermometer completely calibrated onetime. Recalibration is performed as described in 6.3.8.5.5.2.2 Partial-Immersion Thermometers General pur-pose partial-immers
40、ion thermometers, as commonly listed inmanufacturers catalogs according to their own specifications,are normally bought and sold without specification of thetemperatures of the emergent column for the various tempera-ture indications of the thermometers. In such cases, verificationis usually carried
41、 out for the emergent column temperaturesprevailing with the verification equipment being employed.5.5.2.3 Special Use Partial-Immersion ThermometersSpecial use partial-immersion thermometers, such as thosecovered in Specification E1, have specified emergent mercurycolumns or stem temperatures. Thes
42、e thermometers can beused as standards to calibrate other thermometers similar in alldetails of construction above the immersion point, but maydiffer below the immersion point to the extent of including anauxiliary ice point scale.5.6 Engraving Date on ASTM ThermometersIf a ther-mometers specificati
43、on was changed, the year that it waschanged is engraved on the back of the thermometer after theASTM designation. For example, “12C-98.”6. Procedure6.1 Visual Inspection:6.1.1 Gas Bubbles and SeparationsGas bubbles are read-ily detected and are more likely to occur in shipment thanduring service. No
44、 method has been discovered that willentirely prevent such displacement of the gas. If bubbles areobserved in the bulb, they can generally be removed by coolingthe bulb with dry ice or other convenient coolant until all theliquid is drawn into the bulb. Gentle tapping of the thermom-eter while held
45、upright will cause the bubbles to rise to thesurface. It is very important that, if the bulb is cooled in thisprocess below the freezing point of the liquid, care should beexercised to warm the stem sufficiently during the meltingprocess so that no solidification occurs in the stem; otherwisethe bul
46、b may burst or the capillary may split internally becauseof the expansion forces generated in the bulb.6.1.1.1 If a mercury separation is observed in the stem,several different ways are suggested for joining the columns,depending on the construction of the thermometer and the typeof separation. If a
47、 small portion of the liquid has separated atthe top of the column and the thermometer is provided with anexpansion chamber, the liquid usually can be joined bycarefully and slowly heating the bulb until the separatedportion is driven into the expansion chamber. Never heat thebulb in an open flame.
48、When the column itself follows into thechamber, the separated portion usually will join onto the maincolumn. A slight tapping of the thermometer against the palmof the hand will facilitate this joining. This method should notbe employed for high-temperature thermometers (above 260C or 500 F), becaus
49、e the heating of the bulb, which isnecessary to drive the liquid into the expansion chamber, mayoverheat the glass and either break the bulb, because of thepressure of the gas, or destroy the accuracy of the thermometerby expanding the bulb. Thermometers that have a contractionchamber below the lowest graduation are likely to developseparations either in the chamber or above it. It is frequentlypossible to join such separations by cooling the thermometer sothat the separated portion as well as the main colu
