ASTM E2551-20

Standard Test Methods for Humidity Calibration (or Conformation) of Humidity Generators for Use with Thermogravimetric Analyzers

SIGNIFICANCE AND USE
5.1 These test methods calibrate or demonstrate conformity of the humidity level in a purge gas generated by a humidity generator at a fixed temperature. Such calibration or demonstration of conformity may be required by quality initiatives.  
5.2 Conformance demonstrates that the humidified purge gas is within some established limits.  
5.3 Calibration provides an offset and or slope value that may be used for establishing the relative humidity scale of the apparatus.
SCOPE
1.1 These test methods describe the humidity calibration (or conformance) of humidity generators for use with thermogravimetric analyzers and other thermal analysis apparatus. The humidity range covered is 5 % relative humidity (% RH) to 95 % RH and the temperature range is 0 °C to 80 °C.  
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.4 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.

General Information

• Status: Published
• Publication Date: 14-Mar-2020
• ICS: 71.040.40 - Chemical analysis
• Technical Committee: E37 - Thermal Measurements
• Drafting Committee: E37.10 - Fundamental, Statistical and Mechanical Properties

Relations

• Referred By: ASTM D8506-23 - Standard Guide for Microbial Contamination and Biodeterioration in Turbine Oils and Turbine Oil Systems
• Effective Date: 15-Mar-2020

Standards Content (Sample)

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: E2551 − 20
Standard Test Methods for
Humidity Calibration (or Conformation) of Humidity
1
Generators for Use with Thermogravimetric Analyzers
This standard is issued under the fixed designation E2551; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope* E1582 Test Method for Temperature Calibration of Thermo-
gravimetric Analyzers
1.1 These test methods describe the humidity calibration (or
conformance) of humidity generators for use with thermogra-
3. Terminology
vimetric analyzers and other thermal analysis apparatus. The
3.1 Specifictechnicaltermsusedinthisstandardaredefined
humidity range covered is 5 % relative humidity (% RH) to
in Terminologies E473 and E1142. These terms include first-
95 % RH and the temperature range is 0 °C to 80 °C.
deviation-from-baseline, isohume, relative humidity, thermal
1.2 The values stated in SI units are to be regarded as
curve, and thermogravimetric analysis.
standard. No other units of measurement are included in this
standard.
4. Summary of Test Method
1.3 This standard does not purport to address all of the
4.1 Humidity generators are devices aimed at producing a
safety concerns, if any, associated with its use. It is the
specific level of humidity in the purge gas used by thermogra-
responsibility of the user of this standard to establish appro-
vimetric analyzers or other thermal analysis apparatus. The
priate safety, health, and environmental practices and deter-
requested humidity levels may be held constant (isohume) or
mine the applicability of regulatory limitations prior to use.
increased or decreased in a continuous or stepped fashion.
1.4 This international standard was developed in accor-
4.2 The humidified purge gas is submitted to a thermogra-
dance with internationally recognized principles on standard-
vimetric analyzer in which the weight of a hygroscopic
ization established in the Decision on Principles for the
material is observed. The relative humidity (or activity) of the
Development of International Standards, Guides and Recom-
moisture in the purge gas is stepped or scanned through a
mendations issued by the World Trade Organization Technical
humidity range. At a fixed humidity of the purge gas, the test
Barriers to Trade (TBT) Committee.
specimen deliquesces and gains weight. In Test MethodA, the
2. Referenced Documents
humidity of the onset of this weight gain is taken as the
2
humidity calibration point. In Test Methods B and C, the rate
2.1 ASTM Standards:
of weight change is zero at the humidity calibration point.
D1193 Specification for Reagent Water
E177 Practice for Use of the Terms Precision and Bias in
5. Significance and Use
ASTM Test Methods
E473 Terminology Relating to Thermal Analysis and Rhe- 5.1 These test methods calibrate or demonstrate conformity
ology of the humidity level in a purge gas generated by a humidity
E691 Practice for Conducting an Interlaboratory Study to generator at a fixed temperature. Such calibration or demon-
Determine the Precision of a Test Method stration of conformity may be required by quality initiatives.
E1142 Terminology Relating to Thermophysical Properties
5.2 Conformance demonstrates that the humidified purge
gas is within some established limits.
5.3 Calibration provides an offset and or slope value that
1 may be used for establishing the relative humidity scale of the
These test methods are under the jurisdiction of ASTM Committee E37 on
ThermalMeasurementsandarethedirectresponsibilityofSubcommitteeE37.10on
apparatus.
Fundamental, Statistical and Mechanical Properties.
Current edition approved March 15, 2020. Published April 2020. Originally
6. Interferences
approved in 2007. Last previous edition approved in 2018 as E2551 – 18. DOI:
10.1520/E2551-20.
6.1 Temperature regulation of any solution-head space en-
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
vironment to within 60.1 °C is essential for realizing gener-
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
ated relative humidity values stable to within 61% RH
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. (expected).
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
E2551 − 20
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: E2551 − 18 E2551 − 20
Standard Test Methods for
Humidity Calibration (or Conformation) of Humidity
1
Generators for Use with Thermogravimetric Analyzers
This standard is issued under the fixed designation E2551; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope Scope*
1.1 These test methods describe the humidity calibration (or conformance) of humidity generators for use with thermogravi-
metric analyzers and other thermal analysis apparatus. The humidity range covered is 5 % relative humidity (% RH) to 95 % RH
and the temperature range is 0 °C to 80 °C.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.4 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.
2. Referenced Documents
2
2.1 ASTM Standards:
D1193 Specification for Reagent Water
E177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods
E473 Terminology Relating to Thermal Analysis and Rheology
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
E1142 Terminology Relating to Thermophysical Properties
1
These test methods are under the jurisdiction of ASTM Committee E37 on Thermal Measurements and are the direct responsibility of Subcommittee E37.10 on
Fundamental, Statistical and Mechanical Properties.
Current edition approved Oct. 1, 2018March 15, 2020. Published October 2018April 2020. Originally approved in 2007. Last previous edition approved in 20132018 as
E2551 – 13.18. DOI: 10.1520/E2551-18.10.1520/E2551-20.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
E2551 − 20
E1582 Test Method for Temperature Calibration of Thermogravimetric Analyzers
3. Terminology
3.1 Specific technical terms used in this standard are defined in Terminologies E473 and E1142. These terms include
first-deviation-from-baseline, isohume, relative humidity, thermal curve, and thermogravimetric analysis.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 water activity, n—the ratio of actual partial pressure of water to the saturated water vapor pressure at the same temperature,
expressed as a decimal fraction.
3.2.1.1 Discussion—
Water activity is also known as relative pressure in some applications areas.
4. Summary of Test Method
4.1 Humidity generators are devices aimed at producing a specific level of humidity in the purge gas used by thermogravimetric
analyzers or other thermal analysis apparatus. The requested humidity levels may be held constant (isohume) or increased or
decreased in a continuous or stepped fashion.
4.2 The humidified purge gas is submitted to a thermogravimetric analyzer in which the weight of a hygroscopic material is
observed. The relative humidity (or activity) of the moisture in the purge gas is stepped or scanned through a humidity range. At
a fixed humidity of the purge gas, the test specimen deliquesces and gains weight. In Test Method A, the humidity of the onset
of this weight gain is taken as the humidity calibration point. In Test Methods B and C, the rate of weight change is zero at the
humidity calibration point.
5. Significance and Use
5.1 These test methods calibrate or demonstrate conformity of the humidity level in a purge gas generated by a humidity
generator at a fixed temperature. Such calibration or
...