ASTM E77-14(2021)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation:E77 −14 (Reapproved 2021)
Standard Test Method for
Inspection and Verification of Thermometers
ThisstandardisissuedunderthefixeddesignationE77;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginal
adoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscript
epsilon (´) 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.
1. Scope 2. Referenced Documents
2.1 ASTM Standards:
1.1 This test method covers visual and dimensional inspec-
E1Specification for ASTM Liquid-in-Glass Thermometers
tion and test for scale accuracy to be used in the verification of
E344Terminology Relating to Thermometry and Hydrom-
liquid-in-glass thermometers as specified in Specifications E1
etry
andE2251.However,theseproceduresmaybeappliedtoother
E2251Specification for Liquid-in-Glass ASTM Thermom-
liquid-in-glass thermometers.
eters with Low-Hazard Precision Liquids
NOTE 1—The use of NIST SP250-23 is recommended.
1.2 Warning—Mercuryhasbeendesignatedbymanyregu- 3. Terminology
latoryagenciesasahazardoussubstancethatcancauseserious
3.1 Definitions:
medicalissues.Mercury,oritsvapor,hasbeendemonstratedto
3.1.1 The definitions given in Terminology E344 apply.
be hazardous to health and corrosive to materials. Use caution
Some that are considered essential to this standard are given
when handling mercury and mercury-containing products. See
below.
the applicable product Safety Data Sheet (SDS) for additional
3.1.2 calibration, n—of a thermometer or thermometric
information. The potential exists that selling mercury or
system, the set of operations that establish, under specified
mercury-containing products, or both, is prohibited by local or
conditions, the relationship between the values of a thermo-
national law. Users must determine legality of sales in their
metric quantity indicated by a thermometer or thermometric
location.
system and the corresponding values of temperature realized
by standards.
1.3 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the 3.1.2.1 Discussion—(1) The result of a calibration permits
either the assignment of values of temperature to indicated
responsibility of the user of this standard to establish appro-
priate safety, health, and environmental practices and deter- values of thermometric quantity or determination of correc-
tions with respect to indications. (2) A calibration may also
mine the applicability of regulatory limitations prior to use.
determine other metrological properties such as the effect of
1.4 This international standard was developed in accor-
influence quantities. (3) The result of a calibration may be
dance with internationally recognized principles on standard-
communicatedinadocumentsuchasacalibrationcertificateor
ization established in the Decision on Principles for the
acalibrationreport.(4)Thetermcalibrationhasalsobeenused
Development of International Standards, Guides and Recom-
to refer to the result of the operations, to representations of the
mendations issued by the World Trade Organization Technical
result, and to the actual relationship between values of the
Barriers to Trade (TBT) Committee.
thermometric quantity and temperature.
3.1.3 complete-immersionthermometer,n—aliquid-in-glass
thermometer, not specified in ASTM documents, designed to
This test method is under the jurisdiction of ASTM Committee E20 on
Temperature Measurement and is the direct responsibility of Subcommittee E20.05 indicate temperature correctly when the entire thermometer is
on Liquid-in-Glass Thermometers and Hydrometers.
exposed to the temperature being measured.
Current edition approved May 1, 2021. Published June 2021. Originally
ε1
approved in 1949. Last previous edition approved in 2014 as E77–14 . DOI:
10.1520/E0077-14R21.
2 3
“Liquid-in-Glass Thermometer Calibration Service,” NIST Special Publication For referenced ASTM standards, visit the ASTM website, www.astm.org, or
250-23, 1988. Available from U.S. Government Printing Office, Superintendent of contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Documents, 732 N. Capitol St., NW, Washington, DC 20401-0001, http:// Standards volume information, refer to the standard’s Document Summary page on
www.access.gpo.gov. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E77−14 (2021)
3.1.4 partial-immersion thermometer, n—a liquid-in-glass resistance is determined by comparison with a standard
thermometer designed to indicate temperature correctly when resistor, using a potentiometer, a Kelvin-type double bridge, or
the bulb and a specified part of the stem are exposed to the aWheatstonebridge,(preferablyoftheMuellertype)oranAC
temperature being measured. resistance bridge. Temperatures may then be calculated using
suitable resistance-temperature equations. In order that it shall
3.1.5 total-immersion thermometer, n—a liquid-in-glass
be satisfactory for such use, the thermometer should meet the
thermometer designed to indicate temperature correctly when
requirement that the ratio of resistances at the steam and ice
just that portion of the thermometer containing the liquid is
pointsshallbegreaterthan1.3925.Morecompleteinformation
exposed to the temperature being measured.
on the construction and use of primary standard thermometers
3.2 Definitions of Terms Specific to This Standard: 4
may be obtained from NIST SP250-22.
3.2.1 referencepoint,n—atemperatureatwhichathermom-
5.5 Secondary Standard Thermometers—Secondary stan-
eter is checked for changes in the bulb volume.
dardthermometersaremoresuitableforroutinework,andmay
3.2.2 verification, n—the process of testing a thermometer
beofvarioustypesasdescribedbelow.Theyaresimplertouse
for compliance with specifications.
than a primary standard thermometer with its accessory
3.2.3 verification temperatures, n—the specified tempera-
equipment,thelatterbeingcapableofanorderofprecisionand
tures at which thermometers are tested for compliance with
accuracy far in excess of that attainable with liquid-in-glass
scale error limits.
thermometers. The choice of a secondary standard will be
governed by various factors. The following criteria should, in
3.2.4 Other descriptions of terms relating to thermometers
so far as possible, be satisfied: The standard should be a
are included in Sections 3 and 17 of Specification E1.
calibratedthermometerofequalorpreferablyhighersensitivity
4. Significance and Use
thanthethermometertobeverified,anditshouldbecapableof
giving results of an equal or preferably higher order of
4.1 The test method described in this standard will ensure
accuracy and also of an equal or preferably higher order of
that the thermometers listed in Specifications E1 and E2251
reproducibility or precision. Scale corrections should always
will indicate temperatures within the maximum scale errors
be applied in the use of these standards. Secondary standards
listed, be compatible with the apparatus, and serve the purpose
may be of the following types.
for which they were designed.
5.5.1 Direct-reading Resistance Thermometers—Direct-
4.2 Thermometers that do not pass the visual and dimen-
reading resistance thermometers are available commercially,
sional inspection tests may give erroneously high or low
are very convenient to use, and have the advantage over the
temperature readings, or may not fit into existing equipment
primary type that temperature indications are given directly in
used in ASTM methods. For accurate temperature measure-
theinstrumentreading.Theyshouldbecompletelyrecalibrated
ments the scale readings of the thermometer should be verified
every 6 to 12 months, depending upon the temperatures of
as described in this test method.
usage. Ice points should be taken every three months.
5.5.2 Liquid-in-glass Thermometers—Liquid-in-glass
5. Apparatus
thermometers, when used as secondary standards, may be
5.1 Graduated Metal Scales or Templates—Maximum and
classified into two groups, those intended for testing general
minimum specified linear dimensions are measured with
purposetotalorpartial-immersionthermometers,andthosefor
graduated metal scales and templates on which lines are ruled
testing special use partial-immersion thermometers.
atsuitabledistancesfromreferencepointscorrespondingtothe
5.5.2.1 Total-immersion Thermometers—In the case of gen-
maximumandminimumvaluesoftheseveralspecifieddimen-
eral purpose total-immersion thermometers, the sensitivity of
sions.
the thermometers to be tested will govern the choice of
5.2 Micrometers and Ring Guages—Specified diameters of
standard. For thermometers graduated in 1, 2, or 5° divisions,
ASTM thermometers are checked using micrometers, or more
a set of well-made thermometers will be adequate when
conveniently with ring gauges consisting of metal plates in
calibrated and used with applicable corrections. For fraction-
which holes have been formed corresponding to the maximum
ally graduated thermometers a calibrated set of the following
and minimum values of the several specified dimensions. The
thermometers is recommended. Specifications for theseASTM
thickness of such gauges should approximate the diameters of
Precision Thermometers appear in Specification E1.
the holes to minimize errors resulting from the axis of the
ASTM
thermometer stem being other than normal to the plane of the
Ther- Length,
Range Celsius Divisions
mometer mm
gauge. When specified, diameters may also be checked with
Number
conventional snap gauges having plane parallel working faces.
62C −38 to +2 °C 0.1 °C 380
5.3 Comparators—Comparators are required for verifica-
63C −8 to +32 °C 0.1 °C 380
tionofscaleaccuracyofliquid-in-glassthermometers.Suitable
64C 25 to 55 °C 0.1 °C 380
types are described in Appendix X1.
5.4 Primary Standard Thermometer—The primary standard
“Platinum Resistance Thermometer Calibrations,” NIST Special Publication
thermometer in the range from−183 to 630 °C (−297 to
NIST Special Publication 250-22.Available from U.S. Government Printing Office,
1166°F)istheplatinum-resistancethermometer.Temperatures
Superintendent of Documents, 732 N. Capitol St., NW, Washington, DC 20401-
are not measured directly with this instrument. Its electrical 0001, http://www.access.gpo.gov.
E77−14 (2021)
process below the freezing point of the liquid, care should be
ASTM
Ther- Length,
exercised to warm the stem sufficiently during the melting
Range Celsius Divisions
mometer mm
process so that no solidification occurs in the stem; otherwise
Number
65C 50 to 80 °C 0.1 °C 380
thebulbmayburstorthecapillarymaysplitinternallybecause
66C 75 to 105 °C 0.1 °C 380
of the expansion forces generated in the bulb.
67C 95 to 155 °C 0.2 °C 380
68C 145 to 205 °C 0.2 °C 380 6.1.1.1 If a mercury separation is observed in the stem,
69C 195 to 305 °C 0.5 °C 380
several different ways are suggested for joining the columns,
70C 295 to 405 °C 0.5 °C 380
dependingontheconstructionofthethermometerandthetype
ASTM
of separation. If a small portion of the liquid has separated at
Ther- Length,
Range Fahrenheit Divisions
mometer mm
the top of the column and the thermometer is provided with an
Number
expansion chamber, the liquid usually can be joined by
62F −36 to +35 °F 0.2 °F 380 carefully and slowly heating the bulb until the separated
63F 18 to 89 °F 0.2 °F 380
portion is driven into the expansion chamber. Never heat the
64F 77 to 131 °F 0.2 °F 380
bulb in an open flame.When the column itself follows into the
65F 122 to 176 °F 0.2 °F 380
66F 167 to 221 °F 0.2 °F 380 chamber, the separated portion usually will join onto the main
67F 203 to 311 °F 0.5 °F 380
column. A slight tapping of the thermometer against the palm
68F 293 to 401 °F 0.5 °F 380
of the hand will facilitate this joining. This method should not
69F 383 to 581 °F 1.0 °F 380
70F 563 to 761 °F 1.0 °F 380
be employed for high-temperature thermometers (above
The foregoing set is calibrated for total immersion.With the 260°C or 500 °F), because the heating of the bulb, which is
exception of the first two, each thermometer is provided with
necessary to drive the liquid into the expansion chamber, may
anauxiliaryscaleincluding0°C(32°F),thusprovidingmeans
overheat the glass and either break the bulb, because of the
for checking at a fixed point, which should be done each time
pressureofthegas,ordestroytheaccuracyofthethermometer
the thermometer is used. The change in ice-point reading
by expanding the bulb. Thermometers that have a contraction
should then be applied to all readings. It is only necessary to
chamber below the lowest graduation are likely to develop
have a liquid-in-glass thermometer completely calibrated one
separations either in the chamber or above it. It is frequently
time. Recalibration is performed as described in 6.3.8.
possibletojoinsuchseparationsbycoolingthethermometerso
5.5.2.2 Partial-immersion Thermometers— General pur-
that the separated portion as well as the main column both
pose partial-immersion thermometers, as commonly listed in
stand in the chamber. Tapping the tube against the hand or the
manufacturers’ catalogs according to their own specifications,
bulb on a soft spongy material, such as a rubber stopper,
are normally bought and sold without specification of the
usually will bring the liquid together. For more stubborn
temperatures of the emergent column for the various tempera-
separations it may be necessary to cool the bulb in dry ice to a
tureindicationsofthethermometers.Insuchcases,verification
point low enough to bring all of the liquid into the bulb itself.
is usually carried out for the emergent column temperatures
Bysoftlytappingonasoftspongymaterialoragainstthehand
prevailing with the verification equipment being employed.
it usually is possible to bring the liquid together in the bulb.
5.5.2.3 Special Use Partial-immersion Thermometers—
The bulb should be allowed to warm up slowly. The liquid
Special use partial-immersion thermometers, such as those
should emerge into the bore with no separation.
covered in Specification E1, have specified emergent mercury
6.1.1.2 In organic-liquid-filled thermometers distillation
columns or stem temperatures. These thermometers can be
may occur, with subsequent condensation of the colorless
used as standards to calibrate other thermometers similar in all
parent liquid in the upper part of the thermometer. Such
details of construction above the immersion point, but may
thermometersshouldalwaysbeinspectedfortheseseparations,
differ below the immersion point to the extent of including an
which can be repaired by the procedures described above. If
auxiliary ice point scale.
the thermometer has an expansion chamber that is observed to
5.6 Engraving Date on ASTM Thermometers—If a ther-
befilledwithliquid,thecolumncanbereunitedbyverycareful
mometer’s specification was changed, the year that it was
heating of the chamber to drive the liquid into the bore where
changed is engraved on the back of the thermometer after the
it can be rejoined to the main body as described above.
ASTM designation. For example, “12C-98.”
6.1.1.3 Organic liquids as used in thermometers, in contrast
6. Procedure to mercury, wet the glass. Sufficient time should always be
allowed for drainage to occur, particularly when using or
6.1 Visual Inspection:
verifying such thermometers below 0 °C (32 °F). It is fre-
6.1.1 Gas Bubbles and Separations—Gas bubbles are read-
quently a good practice to immerse only the bulb of the
ily detected and are more likely to occur in shipment than
thermometer. This keeps the viscosity of the liquid in the
during service. No method has been discovered that will
capillary low and aids in hastening drainage.
entirely prevent such displacement of the gas. If bubbles are
6.1.2 Globules of Liquid—Globules of liquid in the stem,
observedinthebulb,theycangenerallyberemovedbycooling
which result from mechanical separation, can normally be
the bulb with dry ice or other convenient coolant until all the
liquid is drawn into the bulb. Gentle tapping of the thermom- rejoined by heating the bulb until the liquid column merges
with the globules. If such globules appear to unite and then
eter while held upright will cause the bubbles to rise to the
surface. It is very important that, if the bulb is cooled in this reappear on cooling the bulb, they are indicative of oxidation
E77−14 (2021)
of the mercury or the presence of obstructions in the bore, and are of appreciable width. The best practice is to consider the
should result in rejection of the thermometer. position of the lines as defined by their middle parts.
6.1.3 ForeignMatter—Foreignmatterintheborecansome-
6.3.2 Depth of Immersion for Total-immersion
times be detected with the unaided eye, but it is generally
Thermometers—Although by definition total-immersion ther-
convenient to use a magnifying glass of low power for this
mometers should have the bulb and stem containing the
examination. A magnifier of 10× is recommended for visual
mercury immersed both in use and in verification, it is
examination.The most common types of foreign matter which
frequently inconvenient to do so. If any portion of the stem
shouldbecauseforrejectionareglasschips,particlesofdirtor
containing mercury is exposed, the emergent mercury column
lint,oxideofmercury(eitherred,yellow,orblack),productsof
correction should be determined. No correction need be ap-
glassweatheringcommonlycalledwhitedeposit,andstonesor
plied if it is found to be less than one fifth of the verification
iron spots traceable to faulty glass fabrication.
error; otherwise, the proper correction should be applied. In
6.1.3.1 Whereaspecificgasisspecifiedtobeusedasfilling
some instances total-immersion thermometers may be used
above the liquid, any other gas present may be treated as
under conditions of complete immersion. With thermometers
foreign matter. The most common example is the use of air
such as the kinematic-viscosity thermometer 30F, a significant
instead of nitrogen in mercury-in-glass thermometers, which
error will be introduced unless the thermometer is verified
may have been introduced by accident or in violation of the under the same conditions as those in use. This is due to the
specifications. The presence of air can readily be detected by
effect of increased gas pressure above the column producing a
visual inspection under slight magnification (2× to 5×). The distortion of the bulb.
mercurywilloxidizeandwillshowasdull,moist,orwillshow
6.3.3 Depth of Immersion for Partial-immersion
a red oxide.
Thermometers—Thermometersofthistypeshallbeverifiedby
6.1.4 Glass Faults—Glass faults may be of various types.
one of the methods described in 6.3.7.2, 6.3.7.3, and 6.3.7.4
Any stones or striae that distort the bore or its appearance
using the appropriate comparators. If the thermometer is of the
should be cause for rejection. Strains in the glass as observed
general-purposetype,itshouldbeverifiedbyimmersiontothe
with a polarized light strain gauge near enlargements in the
specified depth and the readings compared with those of the
stem or bore, or at the top of the thermometer, are detrimental.
secondary standard.
If so, severe fire cracks may later occur. Strains near the bulb
6.3.4 Verification at Ice Point:
are indicative of incomplete glass stabilization and are particu-
6.3.4.1 Select clear pieces of ice or ice made from distilled
larly objectionable in thermometers for use above 150 °C (302
or pure water. Discard any cloudy or unsound portions. Rinse
°F).
the ice with distilled water and shave or crush into small
pieces, avoiding direct contact with the hands or any chemi-
6.2 Dimensional Inspection:
cally unclean objects. Fill the Dewar vessel with the crushed
6.2.1 Determine compliance with lineal dimensional speci-
ice and add sufficient distilled, preferably precooled, water to
fications by comparison of the thermometer with the appropri-
form a slush, but not enough to float the ice. As the ice melts
ate scale or template described in 5.1. In the case of diameter
itwillbenecessarytodrainoffsomeofthewaterandaddmore
measurements, the bulb or other portions of the thermometer
beingtestedshouldnotenterthesmalleroftheholesinthering crushed ice. Insert the thermometer, packing the ice gently
about the stem, to a depth approximately one scale division
gauge (see 5.2), or fail to enter the larger of the holes. In the
case of ASTM thermometers, the diameter limits apply over below the 0 °C (32 °F) gradation.
theentirelengthofthesectionofthethermometerbeingtested. 6.3.4.2 Afteratleast3minhaveelapsed,tapthestemgently
6.2.2 Inspect the thermometers for uniformity of graduation and observe the reading. Successive readings taken at least 1
spacing. Normally, the effect of taper in the capillary or minapartshouldagreewithinonetenthofadivision.Itmaybe
nonlinearity in the expansion characteristics of organic liquids necessary to repack the ice around the thermometer because of
is manifested by a gradual change in the spacing of the melting.
graduations. Discontinuities in the spacing are evidence of
6.3.5 Verification at Steam Point:
faulty graduating. Inspection for uniformity of spacing can
6.3.5.1 If the range of the thermometer is such that the ice
generally be accomplished by eye, but for greater accuracy a
pointisnotincluded,thesteampointat100°C(212°F)canbe
pair of dividers may be used to advantage.Adjust the dividers
used. For a description of the equipment and techniques best
to extend over 10 or 20 graduations, and successive intervals
suited to the purpose, reference may be made to NIST
can be intercompared rapidly. Where marked changes in
SP250-23.
spacing are noted, it is well to include in the verification
6.3.6 Verification of Total-immersion and General Use
several temperatures in that region.
Partial-immersion Thermometers at Temperatures Other Than
6.3 Verification of Scale Accuracy: Fixed Points:
6.3.1 Reading Thermometers to Avoid Parallax—The error 6.3.6.1 Determine the ice point of the primary or secondary
due to parallax may be eliminated by taking care that the standardandthethermometertobetestedasdescribedin6.3.4.
reflectionofthescalecanbeseeninthemercurythread,andby If the secondary standard is of the liquid-in-glass type, it
adjusting the line of sight so that the graduation of the scale shouldbeheldatroomtemperatureforatleast72hbeforethis
nearest the meniscus exactly hides its own image; the line of determination unless the ice point was originally determined
sight will then be normal to the stem at that point. In reading immediately after heating to a specified temperature. The
thermometers, account must be taken of the fact that the lines thermometer to be tested should be treated in similar manner.
E77−14 (2021)
6.3.6.2 Insert the thermometer to be tested and the standard turer in order to perform these computations. This method has
in the thermometer holder, and adjust the temperature of the theadvantagethatthestandardmaybeselectedtohavegreater
comparator to a value approximately 5 °C (10 °F) below the
sensitivity than the thermometer being tested, thus increasing
verification temperature. It may be advantageous to use two
the accuracy of measurement.
secondary standard liquid-in-glass thermometers, since obser-
6.3.7.3 A second method, which is the one best suited to
vational errors of the standard may then be readily detected.
large-quantity testing, involves comparison of the thermom-
Applysufficientheattoraisethetemperatureataslowuniform
eters with standards similar in all details of construction above
rate. At the verification point the rate should not exceed one
theimmersionpoint,butmaydifferbelowtheimmersionpoint
scale division in 3 to 10 min. Fulfillment of this requirement
to the extent of including an auxiliary ice-point scale. Such
will ensure that any exposed portion of the stem will have
thermometers, when completely calibrated, as by the National
attained thermal equilibrium before readings are taken.
Institute of Standards and Technology, may then be employed
6.3.6.3 When the proper rate of temperature rise has been
indefinitely for verification purposes if periodic ice-point
established, read the thermometers in the following order at
checks are made. The particular field of application of this
equaltimeintervals:standard,thermometerorthermometersto
secondmethodisevidencedbythefactthatmanyoftheASTM
be tested, standard, thermometers to be tested in reverse order,
thermometers include the ice point in the specified range, but
standard. The average of the first and third readings of the
the following fractionally graduated thermometers are not
standard should agree with the second. A comparison of
provided with an ice-point scale:
differences in successive readings will also indicate if the rate
Paraffin Wax Melting Point: 14C, 14F
of rise has been uniform.
High Softening Point: 16C, 16F
6.3.6.4 Calculate the average readings for all thermometers.
SayboltViscosity:17C,17F,18C,18F,19C,19F,20C,20F,
Apply the appropriate corrections to the reading of the stan-
21C, 21F, 22C, 22F, 77F to 81F, 108F, 109F
dard. Calculate the corrections to be applied to the thermom-
eters under test. Engler Viscosity: 23C, 24C, 25C
Stability Test of Soluble Nitrocellulose: 26C
6.3.6.5 For verification purposes, one series of readings is
usuallysufficient.Ifthethermometerisbeingcalibrated,check Turpentine Distillation: 27C
determinations should be made. The results of each of at least Aniline Point: 34C, 34F, 35C, 35F
three series should agree with the mean of the series within
Solvents Distillation: 38C, 39C, 40C, 41C, 42C, 102C,
plus or minus one tenth of a division.
103C, 104C, 105C, 106C, 107C
6.3.6.6 Unlessotherwisespecified,testsshouldbemadenot
Stormer Viscosity: 49C
less than 40 nor more than 100 divisions apart throughout the
Gas Calorimeter Inlet: 50F
range of the thermometer.
Gas Calorimeter Outlet: 51F
6.3.6.7 Comparisons may be made at constant temperature
Congealing Point: 54F
in preference to the use of slowly rising temperatures. Such a
Petrolatum Melting Point: 61C, 61F
procedure is satisfactory if the bath temperature does not vary
Antifreeze Freezing Point: 76F
more than the precision of reading and if the thermometer is
Solidification Point: 91C to 96C, 100C, 101C
jarred, as by tapping, before taking a reading in order to
Tar Acids Distillation: 111C
overcome any sticking of the mercury to the glass. Such
Brookfield 122C, 123C, 124C, 125C
tapping is particularly important with thermometers having a
The ice point was omitted from the above listed thermom-
capillary diameter of the order of 0.1 mm or less and may be
eters as a matter of necessity. In order to supply an ice point,
employedtoadvantageintherisingtemperaturemethodoftest
w
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