ASTM E344-00
(Terminology)Terminology Relating to Thermometry and Hydrometry
Terminology Relating to Thermometry and Hydrometry
SCOPE
1.1 This terminology is a compilation of definitions of terms used by ASTM Committee E20 on Temperature Measurement.
1.2 Terms with definitions generally applicable to the fields of thermometry and hydrometry are listed in 3.1.
1.3 Terms with definitions applicable only to the indicated standards in which they appear are listed in 3.2.
1.4 Information about the International Temperature Scale of 1990 is given in Appendix X1 .
General Information
Relations
Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
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Designation: E 344 – 00
Terminology Relating to
Thermometry and Hydrometry
This standard is issued under the fixed designation E 344; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope Thermal-EMF Indicators
E 825 Specification for Phase Change-Type Disposable Fe-
1.1 This terminology is a compilation of definitions of terms
ver Thermometer for Intermittent Determination of Human
used by ASTM Committee E20 on Temperature Measurement.
Temperature
1.2 Terms with definitions generally applicable to the fields
E 839 Test Methods for Sheathed Thermocouples and
of thermometry and hydrometry are listed in 3.1.
Sheathed Thermocouple Material
1.3 Terms with definitions applicable only to the indicated
E 879 Specification for Thermistor Sensors for Clinical
standards in which they appear are listed in 3.2.
Laboratory Temperature Measurements
1.4 Information about the International Temperature Scale
E 1061 Specification for Direct-Reading Liquid Crystal
of 1990 is given in Appendix X1.
Forehead Thermometers
2. Referenced Documents
E 1104 Specification for Clinical Thermometer Probe Cov-
ers and Sheaths
2.1 ASTM Standards:
E 1112 Specification for Electronic Thermometer for Inter-
E 1 Specification for ASTM Thermometers
mittent Determination of Patient Temperature
E 77 Test Method for Inspection and Verification of Ther-
E 1129/E 1129M Specification for Thermocouple Connec-
mometers
tors
E 100 Specification for ASTM Hydrometers
E 1137 Specification for Industrial Platinum Resistance
E 126 Test Method for Inspection and Verification of Hy-
Thermometers
drometers
E 1159 Specification for Thermocouple Materials,
E 220 Test Method for Calibration of Thermocouples by
Platinum-Rhodium Alloys, and Platinum
Comparison Techniques
E 1256 Test Methods for Radiation Thermometers (Single
E 230 Specification and Temperature-Electromotive Force
Waveband Type)
(EMF) Tables for Standardized Thermocouples
E 1299 Specification for Reusable Phase-Change-Type Fe-
E 452 Test Method for Calibration of Refractory Metal
ver Thermometer for Intermittent Determination of Human
Thermocouples Using a Radiation Thermometer
Temperature
E 574 Specification for Duplex, Base Metal Thermocouple
E 1350 Guide for Testing Sheathed Thermocouples Prior to,
Wire with Glass Fiber or Silica Fiber Insulation
During, and After Installation
E 585/E 585M Specification for a Radiation Thermometer
E 1502 Guide for Use of Freezing-Point Cells for Reference
E 601 Test Method for Comparing EMF Stability of Single-
Temperatures
Element Base-Metal Thermocouple Materials in Air
E 1594 Guide for Expression of Temperature
E 608 Specification for Metal-Sheathed Base-Metal Ther-
E 1750 Guide for Use of Water Triple Point Cells
mocouples
E 1965 Specification for Infrared Thermometers for Inter-
E 644 Test Methods for Testing Industrial Resistance Ther-
mittent Determination of Patient Temperature
mometers
E 667 Specification for Maximum Self-Registering
3. Terminology
Mercury-in-Glass Clinical Thermometers
3.1 Definitions:
E 696 Specification for Tungsten-Rhenium Alloy Thermo-
couple Wire
accuracy, n—of a temperature measurement, closeness of
E 710 Test Method for Comparing EMF Stabilities of Base-
agreement between the result of a temperature measurement
Metal Thermoelements in Air Using Dual, Simultaneous,
and a true value of the temperature.
DISCUSSION—Accuracy is a qualitative concept.
This terminology is under the jurisdiction of ASTM Committee E20 on
Temperature Measurement and is the direct responsibility of Subcommittee E20.91 base metal thermocouple, n—thermocouple whose thermo-
on Editorial and Terminology.
elements are composed primarily of base metals and their
Current edition approved July 10, 2000. Published September 2000. Originally
alloys. (See also noble metal thermocouple; refractory
published as E 344–68. Last previous edition E 344–99.
metal thermocouple.)
Annual Book of ASTM Standards, Vol 14.03.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
E 344
DISCUSSION—Base metals used in thermoelements include nickel,
complete immersion thermometer, n—a liquid-in-glass ther-
iron, chromium, copper, aluminum. Letter-designated types E, J, K, T,
mometer designed to indicate temperatures correctly when
and N are considered base metal thermocouples.
the entire thermometer is exposed to the temperature being
measured. (Compare total immersion thermometer and
bias, n—the scatter between the mean values of subsets of
partial immersion thermometer.)
data, from each other or from the accepted value.
connection head, n—a housing enclosing a terminal block for
blackbody, n—the perfect or ideal source of thermal radiant
an electrical temperature-sensing device and usually pro-
power having a spectral distribution described by the Planck
vided with threaded openings for attachment to a protecting
equation.
tube and for attachment of conduit.
DISCUSSION—The term blackbody is often used to describe a furnace
defining fixed point, n—thermometric fixed point of an
or other source of radiant power which approximates the ideal.
idealized system, to which a numerical value has been
bulb, n—of a liquid-in-glass thermometer, reservoir for the
assigned, used in defining a temperature scale.
thermometric liquid.
degree Celsius, °C, n—derived unit of temperature in the
calibration, n— of a thermometer or thermometric system, the
International System of Units (SI). (See kelvin).
set of operations that establish, under specified conditions,
DISCUSSION—At any temperature, an interval of one degree Celsius is
the relationship between the values of a thermometric
the same as an interval of one kelvin, by definition. For information
quantity indicated by a thermometer or thermometric system
about the relation between units and values of temperature expressed in
and the corresponding values of temperature realized by
different units, see Guide E 1594.
standards.
degree centigrade, n—obsolete term. Use degree Celsius.
DISCUSSION—(1) The result of a calibration permits either the
degree Fahrenheit, °F, n—non-SI unit of temperature com-
assignment of values of temperature to indicated values of thermomet-
monly used in the United States of America.
ric quantity or determination of corrections with respect to indications.
(2) A calibration may also determine other metrological properties such DISCUSSION—At any temperature, an interval of one degree Fahren-
as the effect of influence quantities. (3) The result of a calibration may heit is the same as an interval of 5/9 kelvin (or 5/9 degree Celsius). For
be communicated in a document such as a calibration certificate or a information about the relation between units and values of temperature
calibration report. (4) The term calibration has also been used to refer expressed in different units, see Guide E 1594.
to the result of the operations, to representations of the result, and to the
electromotive force (emf), n—the electrical potential differ-
actual relationship between values of the thermometric quantity and
ence which produces or tends to produce an electric current.
temperature.
error, n—of a temperature measurement, result of a tempera-
calibration point, n—a specific value, established by a refer-
ture measurement minus a true value of temperature.
ence, at which the indication or output of a measuring device
extension wires, n—those having temperature-emf character-
is determined.
istics that when connected to a thermocouple effectively
Celsius, adj—pertaining to or denoting something related to
transfer the reference junction to the other end of the wires
the expression of temperature in degrees Celsius.
(compare compensating wires).
Fahrenheit, adj—pertaining to or denoting something related
DISCUSSION—For example, “A Celsius thermometer has a scale
marked in degrees Celsius.”
to the expression of temperature in degrees Fahrenheit.
center wavelength, n—a wavelength, usually near the middle DISCUSSION—For example, “A Fahrenheit thermometer has a scale
marked in degrees Fahrenheit.”
of the band of radiant power over which a radiation
thermometer responds, that is used to characterize its per-
fixed point, n— in thermometry, reproducible temperature of
formance.
equilibrium of a system of two or more phases under
DISCUSSION—The value of the center wavelength is usually specified specified conditions.
by the manufacturer of the instrument.
freezing point, n—fixed point of a single component system in
which liquid and solid phases are in equilibrium at a
clinical thermometer, n—thermometer of any type designed
specified pressure, usually 101 325 Pa, and the system is
to measure human body temperature.
losing heat slowly. (Compare melting point.)
DISCUSSION—Some clinical thermometers may be designed to mea-
ice point, n—thermometric fixed point of ice and water
sure the body temperature of animals.
saturated with air at a pressure of 101 325 Pa.
International Practical Temperature Scale (IPTS-48),
coaxial thermocouple—a thermocouple consisting of a ther-
n—the temperature scale adopted by the 11th General
moelement in wire form within a thermoelement in tube
Conference on Weights and Measures in 1960 and replaced
form with the wire being electrically insulated from the tube
in 1968 by the International Practical Temperature Scale of
except at the measuring junction.
1968.
compensating extension wires, n—those extension wires
International Practical Temperature Scale of 1968 (IPTS-
fabricated from materials basically different in composition
68), n—the temperature scale adopted by the 13th General
from the thermocouple.
Conference on Weights and Measures in 1968.
DISCUSSION—They have similar thermoelectric properties and within
DISCUSSION—The IPTS-68 was superseded in 1990 by the Interna-
a stated temperature range effectively transfer the reference junction to
tional Temperature Scale of 1990.
the other end of the wires.
E 344
International Temperature Scale of 1990 (ITS-90), n—the sensing device and protect it from the deleterious effects of
temperature scale prepared in accordance with instructions the environment.
of the 18th General Conference on Weights and Measures,
DISCUSSION—It may provide for attachment to a connection head but
and adopted on January 1, 1990.
is not primarily designed for pressure-tight attachment to a vessel. (See
kelvin, K, n—base unit of temperature in the International
also thermowell.)
System of Units (SI).
radiation thermometer, n—a radiometer calibrated to indicate
liquid-in-glass thermometer, n—a temperature-measuring in-
the temperature of a blackbody.
strument whose indications are based on the temperature
radiometer, n—a device for measuring radiant power that has
coefficient of expansion of a liquid relative to that of its
an output proportional to the intensity of the input power.
containing glass bulb.
range, n—the region between the limits within which a
lower range value, n—the lowest quantity that an instrument
quantity is measured, and is expressed by stating the lower
is adjusted to measure.
and upper range-values.
maximum permissible errors, n—of a thermometer or ther-
reference junction, n—that junction of a thermocouple which
mometric system, extreme values permitted by regulation or
is at a known temperature.
specification of the difference between the indication of a
reference temperature, n—a fixed, reproducible temperature,
thermometer or thermometeric system and the true value of
to which a value is assigned, that can be used for the
temperature.
calibration of thermometers or other purposes.
DISCUSSION—The term tolerance is sometimes used in ASTM stan-
refractory metal thermocouple, n—(1) one whose thermo-
dards to represent this concept.
elements have melting points above 1935 °C (3515 °F).
maximum self-registering clinical thermometer, n—clinical
(2) thermocouple whose thermoelements are composed
thermometer designed to retain the indication of its maxi-
primarily of refractory metals and their alloys. (See also
mum measured temperature until reset.
base metal thermocouple; noble metal thermocouple.)
measuring junction, n—that junction of a thermocouple
which is subjected to the temperature to be measured.
DISCUSSION—Refractory metals used in thermoelements include
melting point, n—fixed point of a single component system in
tungsten, rhenium, and molybdenum.
which liquid and solid phases are in equilibrium at a
repeatability, n—of results of temperature measurements,
specified pressure, usually 101 325 Pa, and the system is
closeness of agreement between the results of successive
gaining heat slowly. (Compare freezing point.)
measurements of the same temperature carried out under the
noble metal thermocouple, n—thermocouple whose thermo-
same conditions of measurement.
elements are composed primarily of noble metals and their
alloys. (See also base metal thermocouple; refractory
DISCUSSION—(1) Repeatability conditions include the same measure-
metal thermocouple.) ment procedure; the same observer; the same thermometer or thermom-
eteric system, used under the same conditions; the same location; and
DISCUSSION—Noble metals used in thermoelements include platinum,
repetition over a short interval of time. (2) Repeatability may be
rhodium, gold, palladium, iridium. Letter designated types B, R, and S
expressed quantitatively in terms of the dispersion characteristics of the
are considered noble metal thermocouples.
results such as the mean value and standard deviation.
partial immersion thermometer, n—a liquid-in-glass ther-
reproducibility, n—of results of temperature measurements,
mometer designed to indicate temperatures correctly when
closeness of agreement between the results of measurements
the bulb and a specified part of the stem are exposed to the
of the same temperature carried out under changed condi-
temperatures being measured. (Compare complete immer-
tions of measurement.
sion thermometer and total immersion thermometer.)
DISCUSSION—(1) A valid statement of reproducibility requires speci-
Peltier coefficient, n—the reversible heat which is absorbed or
fication of the conditions changed. (2) The changed conditions may
evolved at a thermocouple junction when unit current passes
include principle of measurement, method of measurement, observer,
in unit time.
thermometer or thermometric system, reference standard(s), location,
platinum 27 (Pt-27), n—the platinum standard to which the
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