Designation: E563 − 11
Standard Practice for
Preparation and Use of an Ice-Point Bath as a Reference Temperature 1 This standard is issued under the fixed designation E563; the number immediately following the designation indicates the year of original adoption or, in the case of revis original revision, ion, the year of last revision. revision. A number in paren parenthese thesess indicates the year of last reappr reapproval. oval. A superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Sco Scope pe
3. Terminology
1.1 This practice covers a method of preparing, maintaining, and using a temperature reference bath of a mixture of shaved ice and water, saturated with air at a pressure of 101 325 Pa (1 atm).
3.1 Definitions— Definitions Definitions given in Termino erminology logy E344, E344, unless otherwise defined herein, apply to terms as used in this practice. 3.2 Temper emperature ature relationships relationships given in Guide E1594 Guide E1594,, unless otherwise defined herein, apply to temperature values as used in this practice.
1.2 An industrial industrial practice for relating values referenced referenced to the ice point and to the water triple point on the ITS-90 is included.
3.3 Definitions of Terms Specific to This Standard: 3.3.1 ice-point bath, n— physical physical system containing ice and wate wa terr as asse semb mble led d to re real aliz izee th thee ic icee po poin intt as a re refe fere renc ncee
1.3 Metho Methods ds to prom promote ote uniformity uniformity of bath temper temperature ature by mechanical stirring or agitation are not described in detail. 1.4 1. 4 Metho Methods ds of ap appr prox oxim imat atin ing g th thee ice po poin int, t, as by thermostatical thermo statically-con ly-controlled trolled refrigeration, refrigeration, are not covere covered d by this practic practice. e.
temperature, or to establish a constant temperature near 0 °C. 4. Summ Summary ary of Practice Practice 4.1 The ice-point ice-point bath described by this practice consists consists of an intimate mixture, without voids, of pure shaved ice or ice particles and distilled air-saturated water in a thermally insulating vessel open to the atmosphere.
1.5 This standar standard d doe doess not purport purport to add addre ress ss all of the safetyy co safet conc ncer erns ns,, if an anyy, as asso socia ciate ted d wi with th its us use. e. It is th thee responsibility of the user of this standard to establish appro priate safety and health practices and determine the applicability of regulatory limitations prior to use.
4.2 Th 4.2 Thee ice ba bath th re reali alizat zatio ion n of th thee ic icee po poin intt ph phys ysic icall ally y approx app roximat imates, es, with sma small ll unc uncerta ertaint inty y, a nat natura urall fixe fixed-p d-poin ointt temperature. 4.2.1 An ice-point ice-point bath prepa prepared red by rigorous application application of this practice, using distilled-water ice and air-saturated, chilled distilled water, typically has a temperature of 0.000 6 0.002 °C at a ba baro rome metr tric ic pr pres essu sure re of 10 101, 1,32 325 5 Pa (1 sta stand ndar ard d atm atmoosphere). spher e). See See 8, Precision and Bias.
2. Referenc Referenced ed Documents Documents 2.1 ASTM Standards:2 D1193 Specification for Reagent Water D1193 E344 Terminology Relating to Thermometry and HydromE344 Terminology etry E1594 Guide for Expression of Temperature E1594
4.2.2 4.2 .2 The ice-point ice-point bath is ope open n to the atmospher atmosphere. e. The solubility of air in water, which affects phase change, is directly proportional to the atmospheric pressure. The effect of barometr me tric ic pr pres essu sure re on th thee pu pure re ic icee po poin intt is −7 −74 4 nK nK/Pa /Pa (− (−7. 7.5 5 mK/atm).. Wit mK/atm) With h satura saturated ted air in soluti solution, on, the ef effect fect is increa increased sed to approximately -0.1 µK/Pa (-10 mK/atm). The initial pressure gradien gra dientt with elev elevatio ation n in the atmo atmosph sphere ere is app approx roxima imately tely -11.4 Pa/m. Accordingly, the change in the air-saturated icepoint temperature resulting from an increase in elevation above sea level is approximately 1.1 mK/km for the first 1000 m increase in altitude (0.33 mK per 1000 ft increase in altitude).
1
This practice is under the jurisdiction ofASTM Committee E20 Committee E20 on on Tempe Temperature rature Measurement and is the direct responsibility of Subcommittee E20.07 on Fundamentals in Thermometry. Curren Cur rentt edi editio tion n app approv roved ed May 1, 201 2011. 1. Pub Publis lished hed Jun Junee 201 2011. 1. Orig Origina inally lly approved in 1976. Discontinued February 1996 and reinstated in 1997 as E563 – 97. Last previous ediiton approved in 2008 as E563–08. DOI: 10.1520/E0563-11. 2 For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at
[email protected]. For Annual Book of ASTM Standards volume information, refer to the standard’s Document Summary page on the ASTM website.
4.3 The ice-bath ice-bath temperature temperature can also be measured with an accurately accurate ly cali calibra brated ted the thermo rmomete meterr or com compar pared ed to a wat water er
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tripl plee po poin intt ce cell ll an and d th thee ba bath th tem tempe pera ratu ture re re repo port rted ed as th thee tri measured temperature with an uncertainty that is attributed to the measurement, not to the ice point.
the bath can be enhanced by slowly stirring or agitating the slush of ice and water either manually or by a powered stirring means so that all of the ice and water in the bath come into intimatee contact intimat contact..
5. Sign Significan ificance ce and Use 5.1 Th 5.1 This is pr pract actice ice is ad adeq equa uate te fo forr us usee wi with th ot othe herr AS ASTM TM standards that specify the ice point as a reference. It is also intende inte nded d to be ade adequa quate te for mos mostt oth other er ice ice-po -point int ref refere erence nce purposes.
6.3 Ice mak making ing mach machines ines ope operat ratee belo below w 0 °C. The Theref refore ore,, when excessively large ice particles are used to prepare the ice-point ice-po int bath, the initial temperature temperature of the bath can briefl briefly y be slightly slight ly below the ice point. Also, some of the water may freeze and an d br brid idge ge so some me of th thee pa part rtic icles les.. Us Usee of th thee ba bath th mu must st be
5.2 The ice point is a commo common n practical industrial industrial reference reference point of the point thermo rmometr metry y. The ice poi point nt is rel relativ atively ely sim simple ple to realize real ize and pro provid vides es a rea readil dily y ava availab ilable le nat natura urall fixe fixed-p d-poin ointt reference temperature.
delayed long enough to establish thermal equilibrium, and the particles partic les shall be suf suffficiently small so that the bath approaches approaches the required required sta state te of ice and air-satu air-saturat rated ed wate waterr in inti intimate mate contact.
5.3 Use in Resistance Thermometry : 5.3.1 5.3 .1 The ice poi point nt was a defi definin ning g fixe fixed d point on pra practic ctical al temperature scales prior to 1960. 5.3.2 The ITS-90 ITS-90 defines W(T W(T90) = R(T90)/R(273.16 K), the measured resistance ratio of a S tandard tandard Platinum Resistance T hermometer hermometer (SPRT), in reference to the water triple point, not the ice point (1).3 In many instances, where the water triple point is not available, or when the accuracy obtainable with the water wa ter tr trip iple le po poin intt is no nott re requ quir ired ed,, re refe fere renc ncee to a pr prop oper erly ly establis esta blished hed and main maintain tained ed iceice-poi point nt ref refere erence nce is use used. d. For industrial-quality resistance thermometers, the resistance value is determined for 0 °C, and an uncertainty that is appropriate for the quality of the ice-point realization is assigned.
6.4 Clea Cleanlin nliness ess is ess essenti ential al as sma small ll amo amount untss of dis dissol solved ved salts, and other contaminants can cause the equilibrium temperature to be below that of the ice-point temperature. 7. Pro Procedu cedure re 7.1 In the practical use of the ice-point ice-point bath, two objectives objectives shall be accomplished: ( 1) the bath shall be established and maintained so that its temperature is a good approximation to that of the ice point, and ( 2 ) the object for which the reference temperature is to be obtained shall be in thermal equilibrium with the water-ice equilibrium temperature (water-ice interface temperature). 7.2 Establishing the Ice-Point : 7.2.1 7.2 .1 All equipmen equipmentt tha thatt com comes es in con contact tact with the wat water er and ice of an ice-point bath shall be clean. Thoroughly rinse the equipment with tap water, then rinse with the type of water used for the ice-point bath medium. Use clean plastic gloves to handle the ice and equipment. 7.2.2 Use water of purity purity equivalent equivalent to or better than type type IV reagentt water reagen water,, Specific Specification ation D1193, D1193, fo forr th thee ic icee-po poin intt ba bath th medium. Chill a quantity of the water to near 0 °C in a flask and an d sh shak akee vi vigo goro rous usly ly to aer aerate ate th thee wa water ter.. Fr Free eeze ze an anot othe herr portion of the water to produce ice for the bath. 7.2.3 7.2 .3 Pre Prepar paree fine finely ly div divide ided d ice by sha shavin ving g or cru crushi shing. ng. Shaved ice resembling snow is preferred, but crushed ice is acceptable if the particles are small (not exceeding 2 to 3 mm in diamet diameter). er). 7.2.4 Prepa Prepare re the bath in a clean thermally thermally insulated insulated vessel, preferably a wide-mouthed Dewar vacuum flask fitted with an insulating closure such as a stopper. The vessel should be large enough that its size does not affect the water-ice equilibrium temperature and of such diameter and depth that in thermal equilibrium the test objects will not significantly modify the temperature of the bath over the region to which the ice point is to be applied. For usual applications, a diameter of at least 70 mm and a depth of at least 300 mm may be adequate. 7.2.5 7.2 .5 Alt Altern ernatel ately y add shaved shaved ice and chi chilled lled water to the vessel, using enough water to saturate the ice but not enough to float it. As the vessel fills, compress the ice-water mixture to force for ce out exc excess ess wat water er.. The obj objecti ective ve is to sur surrou round nd eac each h particle of ice with water, filling all voids, but to keep the ice particles as close together as possible. Continue adding ice and water and compressing until the vessel is filled to the required level. Decant or siphon off excess water.
5.4 Use in Thermoelectric Thermometry: 5.4.1 In thermoelectric thermoelectric thermometry thermometry,, the ice point is ordinarily used as the reference temperature (2). 5.4.2 Adequ Adequate ate thermoelectric thermoelectric refer reference ence requires that thermocoup moc ouple le jun junctio ctions ns be wel well-c l-coup oupled led the therma rmally lly to the bath bath,, electrically isolated from each other and from the bath, and adequ ade quate ately ly imm immers ersed ed to avo avoid id per pertur turbin bing g the ref refere erence nce- junction temperatures t emperatures by radiation and longitudinal conduction of heat along the thermoelements ( thermoelements (3 3 and 4) 4). 5.5 Use in Liquid-in-Glass Thermometry: 5.5.1 In liquid-in-glass liquid-in-glass thermometry thermometry,, the ice point is ordinarily used as the reference temperature (6). 5.5.2 5.5 .2 The per period iodic ic rec recalib alibrati ration on of a liq liquid uid-in -in-gl -glass ass the therrmometer at the ice point provides a reliable indication of the effect of gradual relaxation of residual mechanical strains in the glass that have a significant effect on the volume of the bulb (6). 6. Haza Hazards rds 6.1 Excess water accumulating accumulating in any region, particularly particularly around the reference location, can elevate the temperature in that vicinity above the ice point. Errors, usually somewhat somewhat less than 4 °C, can occur from this cause in poorly maintained baths and with poorly positioned test objects (3 and 4) 4). 6.2 Fo 6.2 Forr a sti stirr rred ed ba bath th,, th thee tem tempe pera ratu ture re of th thee ba bath th wi will ll depend on the heat gained by the bath, the amount of water and ice, and the vigor of stirring. The uniformity of temperature of
3 The boldface numbers in parentheses refer to the list of references at the end of this standard.
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ice-point bath to protect it. Use an opaqu opaquee 7.2.6 Cover the ice-point and thermally insulating cover or stopper that is suitable for the application. applica tion. Allow the bath and vessel to equilib equilibrate rate for at least 30 min before using.
eter will yield values of temperature that vary over a range of about 4 mK with a sample standard deviation of about 1 mK (5). 8.2 The variability variability represents represents the repro reproducib ducibility ility of the ice point under the conditions of this practice, and the standard deviation may be interpreted as a measure of the imprecision of realizing an ice point.
7.3 Using the Ice-Point Bath: 7.3.1 Form a well in the ice-point ice-point bath that has the diameter diameter and intended immersion depth of the test object. 7.3.2 7.3 .2 Coo Cooll the test object object in water less than 3 °C before before immer imm ersi sing ng it in th thee ba bath th.. Th This is re redu duce cess th thee tim timee to re reach ach
8.3 The mean of values determined determined under the conditions conditions of 8.1 will be biased from 0 °C by an amount negligible compared 8.1 will to the variability variability (5).
equilibrium at the ice point. Pre-cooling the sensor helps to preserve the bath at the ice point for a prolonged time and helps ensure that the water-ice interface will be in contact with the thermometer thermo meter because negligible negligible melting will occur to increa increase se the water film thickness. 7.3.3 7.3 .3 Ins Insert ert the test object object with the sen sensor sor portion portion of the object, such as the sensing element of an SPRT, to a depth of at least ten object diameters below the surface. For thermoelectric thermo-elements of high thermal conductivity, as much as 200 mm immersion may be necessary. For total immersion liquidliqu id-inin-gla glass ss the thermo rmomete meters, rs, imm immers ersee to the 0 °C (32 °F) mark. mar k. For par partial tial imm immers ersion ion liqu liquidid-inin-gla glass ss ther thermom mometer eters, s, immerse imme rse to the imm immers ersion ion lin linee or stat stated ed imm immers ersion ion dep depth. th. Keep the sensor portion of the object several centimeters above the bottom of the flask to avoid the zone at the bottom where
8.4 An ice-point bath prepared prepared by rigor rigorous ous application application of this practice may be assigned a temperature of 0 °C with an expanded total uncertainty (k = 2) of about 2 mK (5). 8.5 Sources of Error and Uncertainty: 8.5.1 8.5 .1 The temperatur temperaturee of a poo poorly rly made or poo poorly rly maintained ice-point bath can differ from 0 °C by as much as several kelvins. kelvin s. Impurities in the water usuall usually y lower the tempera temperature. ture. Excessive water in the bath can cause an increase in temperature as denser warm water settles to the bottom. Large chunks of very cold ice added to a bath can produce local temperature depression. 8.5.2 Type IV grade reagent water prepared with dif differen ferentt apparatus appar atus can prod produce uce ice-po ice-point int baths with slight slightly ly dif different ferent
denser melt water tends to accumulate. 7.3.4 Close the top of the vessel around around the test object object with an opaque insulating stopper or other thermal barri barrier er to reduc reducee heat transfer through the surface of the bath.
temperatures that are detectable with very precise thermometry. Temperature differences of 0.4 mK have been observed in ice-point baths made from water purified in different stills ( (5 5) . 8.5. 8. 5.3 3 The te temp mper erat atur uree of an ic icee-po poin intt ba bath th ma made de wi with th typicall potable city tap water may be low by 10 to 20 mK ( typica mK (3 3,5). 8.5. 8. 5.4 4 The te temp mper erat atur uree of th thee ice ice-p -poi oint nt ba bath th is sl slig ight htly ly dependent on pressure. The temperature is lowered by about 6.3 µK for each centimeter of depth below the liquid surface 6.3 due to hydrostatic pressure. There is a corresponding effect for change cha ngess in atmo atmosph spheric eric pre pressu ssure. re. In mos mostt case cases, s, pre pressu ssure re effects can be ignored ( (4 4). 8.5.5 In an ice-point bath, the actual temperature temperature of a point in an immersed test object that conducts heat into the bath depends on time, position in the bath, and the amount of heat
NOTE 1—When liquid-in-glas liquid-in-glasss therm thermomete ometers rs are tested in an ice point bath, the bath may be left uncovered. The loss of precision between a covered and uncovered bath may be below the resolution of liquid-in-glass thermometers. The user must test for this condition.
7.3.5 7.3. 5 Al Allo low w th thee ba bath th an and d tes testt ob obje ject ct to co come me to th ther erma mall equilibrium. 7.4 Maintaining the Bath: 7.4.1 As ice particles in the bath melt, excess water begins begins to accu accumul mulate. ate. This melt wat water er has a temp temperat erature ure slig slightly htly warmer than 0 °C. Since the density of water is at a maximum at 4 °C, the slightly warm melt water will collect at the bottom of the bath and, hence, around the test object. Under these conditions, the bath will no longer be at 0 °C and cannot serve as an ice-point bath. For this reason surplus water should be removed, as it accumulates, from the bottom of the bath by decanting or siphoning. The presence of excess water can be detected if water overspill occurs when the ice is depressed. Add ice particles, and chilled water, as necessary so that the ice slush slu sh co colu lumn mn al alwa ways ys ex exten tends ds to at le leas astt 30 mm be belo low w th thee lowest point of the test object. 7.4. 7. 4.2 2 In or orde derr to su sust stain ain th thee ice po poin intt ov over er pr prol olon onge ged d periods, the ice-point bath may be immersed in another bath that is kept near 0 °C. 8. Pre Precisi cision on and Bias
conducted into the bath. A water-ice interface in the bath acts as a heat sink. As ice melts, the interface moves away from the test object, and a temperature difference, which can be as much as several kelvins, is established between the test object and the heatt sin hea sink. k. At stea steady dy stat statee con condit dition ions, s, an err error or tha thatt dep depend endss primarily on the thermophysical properties of the object, its dimensions and its depth of immersion in the ice-point bath results . 8.5.6 In resistance thermometery thermometery the applied applied electric current results in Joule heating, which raises the temperature of the sensor above that of the water-ice interface. The temperature increase depends on the electric power being dissipated and the thermal resistance between the sensor and the water-ice interface.
8.1 If a succession of ice-point ice-point baths is prepared by following all of the pro proced cedure uress des describ cribed ed in thi thiss pra practic ctice, e, rou routin tinee determination of the temperature of each of the baths with a stable, well-calibrated standard platinum resistance thermom-
9. Keywords Keywords 9.1 fixedfixed-point point temperature temperature references; references; ice bath; ice point point;; ITS-90; water triple point
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REFERENCES
(1) Preston-Thomas, H., “The International Temperature Scale of 1990
Review of Scientific Instruments, 32, 1961, pp. 313–316. (5) Mangum, B. W., “Reproducibility of the Temperature of the Ice Point in Routine Measurements,” NIST Technical Note 1411, U.S. Government Printing Office, Washington, DC, June 1995. (6) “A Pro Proced cedure ure for the Ef Effec fectiv tivee Rec Recalib alibrati ration on of Liq Liquid uid-in -in-Gl -Glass ass Thermo The rmomet meters ers,” ,” NIS NIST T Spe Specia ciall Pub Publica licatio tion n 819 819,, US Gov Govern ernmen mentt Printing Office, 1991.
(ITS-90),” Metrologia, Vol 27, 1990, pp. 3–10 and 107 (errata). (2) Manual on the Use of Thermocouples in Temperature Measurement , MNL 12, ASTM, West Conshohocken. (3) Caldwell, F. R., “Temperatures of Thermocouple Reference Junctions in an Ice Bath,” Journal of Research, NBS Engineering and Instrumentation, 69C, 1965. (4) Bauerle, Bauerle, J. E., “Anal “Analysis ysis of Imme Immersed rsed Thermocouple Thermocouple Juncti Junctions, ons,””
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