ASTM E77-2007 288 Standard Test Method for Inspection and Verification of Thermometers《温度计的检验和鉴定用标准试验方法》.pdf

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1、Designation: E 77 07Standard Test Method forInspection and Verification of Thermometers1This standard is issued under the fixed designation E 77; the number immediately following the designation indicates the year of originaladoption or, in the case of revision, the year of last revision.Anumber in

2、parentheses indicates the year of last reapproval.Asuperscriptepsilon (e) 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 covers visual and dimensional inspec-tion, test

3、for permanency of pigment, test for bulb stability, andtest for scale accuracy to be used in the verification ofliquid-in-glass thermometers as specified in Specification E1.However, these procedures may be applied to other liquid-in-glass thermometers.2NOTE 1The use of NIST SP250-232is recommended.

4、1.2 Warning- Mercury 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 mercury andmercury containin

5、g 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 prohibitedby state law.1.3 This

6、standard does not purport to address all of thesafety problems, 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

7、.1 ASTM Standards:3E1 Specification for ASTM Liquid-in-Glass ThermometersE 344 Terminology Relating to Thermometry and Hydrom-etry3. Terminology3.1 Definitions:3.1.1 The definitions given in Terminology E 344 apply.Some that are considered essential to this standard are givenbelow.3.1.2 complete-imm

8、ersion thermometer, na liquid-in-glass thermometer, not specified in ASTM documents, de-signed to indicate temperature correctly when the entirethermometer is exposed to the temperature being measured.3.1.3 partial-immersion thermometer, na liquid-in-glassthermometer designed to indicate temperature

9、 correctly whenthe bulb and a specified part of the stem are exposed to thetemperature being measured.3.1.4 total-immersion thermometer, na liquid-in-glassthermometer designed to indicate temperature correctly whenjust that portion of the thermometer containing the liquid isexposed to the temperatur

10、e being measured.3.2 Definitions of Terms Specific to This Standard:3.2.1 calibration, nthe determination of the indications ofa thermometer with respect to temperatures established by astandard resulting in scale corrections to be applied whenmaximum accuracy is required.3.2.2 reference point, na t

11、emperature at which a ther-mometer is checked for changes in the bulb volume.3.2.3 verification, nthe process of testing a thermometerfor compliance with specifications.3.2.4 verification temperatures, nthe specified tempera-tures at which thermometers are tested for compliance withscale error limit

12、s.3.2.5 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 Specification E1will indicatetemperatures within the maximum scale errors

13、 listed, becompatible with the apparatus, and serve the purpose for whichthey were designed.Fig. 11This test method is under the jurisdiction of ASTM Committee E20 onTemperature Measurement and is the direct responsibility of Subcommittee E20.05on Liquid-in-Glass Thermometers and Hydrometers.Current

14、 edition approved Dec. 1, 2007. Published January 2008. Originallyapproved in 1949. Last previous edition approved in 2003 as E 77 98(2003).2“Liquid-in-Glass Thermometer Calibration Service,” NIST Special Publication250-23, 1988, Superintendent of Documents, U.S. Government Printing Office,Washingto

15、n, DC 20402-9325.3For referenced ASTM standards, visit the 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.1Copyright ASTM International, 100 Barr Harb

16、or Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.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 methods. If the pigment in the scale etchings

17、washes out or fades, the thermometer will be difficult to read.Improper annealing of the bulb, as determined by the bulbstability test, will result in thermometer readings rapidlychanging with time and use. For accurate temperature mea-surements the scale readings of the thermometer should beverifie

18、d as described in this test method.5. Apparatus5.1 Graduated Metal Scales or TemplatesMaximum andminimum specified linear dimensions are measured withgraduated metal sales and templates on which lines are ruled atsuitable distances from reference points corresponding to themaximum and minimum values

19、 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 plates inwhich holes have been formed corresponding to the maximumand minimum values of the several speci

20、fied 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 thegage. When specified, diameters may also be checked withconventional snap gages having plane parallel

21、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 OvenThe test for permanency of pigment may beconducted with any suitable oven, such as the type shown inFig. 1.5.5 Metal Block Bat

22、hsThe bulb stability test may beconducted with a variety of devices. Metal block baths and thesalt and tin comparator baths, described in Appendix X1, areexamples of the type of equipment that has been found to besuitable for this purpose.5.6 Primary Standard ThermometerThe primary standardthermomet

23、er 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 standard resis-tor, using a potentiometer, a Kelvin-type double bridge, or aWheatstone brid

24、ge, (preferably of the Mueller type) or an ACFIG. 1 Oven for Permanency of Pigment TestE77072resistance 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

25、ratio of resistances 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 SP250-22.45.7 Secondary Standard ThermometersSecondary stan-dard thermometers are more suitable for routine wor

26、k, and maybe of various types as described below. They are simpler to usethan a primary standard thermometer with its accessory equip-ment, 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 stand

27、ard will begoverned by 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

28、higher order ofaccuracy 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.5.7.1 Direct-Reading Resistance ThermometersDirect-reading resistance ther

29、mometers are available 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

30、 be taken every 3 months.5.7.2 Liquid-in-Glass ThermometersLiquid-in-glass ther-mometers, when used as secondary standards, may be classi-fied into two groups, those intended for testing general purposetotal or partial-immersion thermometers, and those for testingspecial use partial-immersion thermo

31、meters.5.7.2.1 Total-Immersion 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 whencalibrat

32、ed and used with applicable 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

33、 8 to +32C 0.1C 38064C 25 to 55C 0.1C 38065C 50 to 80C 0.1C 38066C 75 to 105C 0.1C 38067C 95 to 155C 0.2C 38068C 145 to 205C 0.2C 38069C 195 to 305C 0.5C 380ASTMTher-mometerNumber RangeCelsiusDivisionsLength,mm70C 295 to 405C 0.5C 380ASTMTher-mometerNumber RangeFahrenheitDivisionsLength,mm62F 36 to

34、+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 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 ther

35、mometer is provided withan auxiliary scale including 0 C (32 F), thus providing meansfor checking at a fixed point, which should be done each timethe 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

36、completely calibrated onetime. Recalibration is performed as described in 6.5.8.5.7.2.2 Partial-Immersion ThermometersGeneral purposepartial-immersion thermometers, as commonly listed in manu-facturers catalogs according to their own specifications, arenormally bought and sold without specification

37、of the tempera-tures of the emergent column for the various temperatureindications of the thermometers. In such cases, verification isusually carried out for the emergent column temperaturesprevailing with the verification equipment being employed.5.7.2.3 Special Use Partial-Immersion ThermometersSp

38、ecial use partial-immersion thermometers, such as thosecovered in Specification E1, have specified emergent mercurycolumns or stem temperatures. These thermometers can beused as standards to calibrate other thermometers similar in alldetails of construction above the immersion point, but maydiffer b

39、elow the immersion point to the extent of including anauxiliary ice point scale.5.8 Engraving Date on ASTM ThermometersIf a ther-mometers specification 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

40、 Visual Inspection:6.1.1 Gas Bubbles and SeparationsGas bubbles arereadily detected and are more likely to occur in shipment thanduring service. No method has been discovered that willentirely prevent such displacement of the gas. If bubbles areobserved in the bulb, they can generally be removed by

41、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 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 liq

42、uid, care should beexercised to warm the stem sufficiently during the meltingprocess so that no solidification occurs in the stem; otherwise4“Platinum Resistance Thermometer Calibrations,” NIST Special Publication250-22, Superintendent of Documents, U.S. Government Printing Office, Washing-ton, DC 2

43、0402-9325.E77073the bulb 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

44、typeof separation. If a 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 the

45、bulb in an open flame. 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

46、 260C or 500 F), because 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 contractio

47、nchamber 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 column bothstand in the chamber. Tapping the tube against the hand or

48、 thebulb on a soft spongy material, such as a rubber stopper,usually will bring the liquid together. For more stubbornseparations it may be necessary to cool the bulb in dry ice to apoint low enough to bring all of the liquid into the bulb itself.By softly tapping on a soft spongy material or agains

49、t the handit usually is possible to bring the liquid together in the bulb.The bulb should be allowed to warm up slowly. The liquidshould emerge into the bore with no separation.6.1.1.2 In organic-liquid-filled thermometers distillationmay occur, with subsequent condensation of the colorlessparent liquid in the upper part of the thermometer. Suchthermometers should always be inspected for these separations,which can be repaired by the procedures described above. Ifthe thermometer has an expansion chamber that is