ASTM D4178-23

Standard Practice for Calibrating Moisture Analyzers

SIGNIFICANCE AND USE
3.1 This practice is intended to provide a method to calibrate moisture analyzers used on-stream or in the laboratory.
SCOPE
1.1 This practice covers a calibration technique based on the preparation of standards of known water content. This technique is applicable to the production of standards between 20 cm3/m3 and 2000 cm3/m3 water.  
1.2 The values stated in SI units are to be regarded as standard.  
1.2.1 Exception—The values given in parentheses are for information only.  
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.  
1.3.1 The user is advised to obtain LPG safety training for the safe operation of this test method procedure and related activities.  
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: 30-Sep-2023
• ICS: 71.040.10 - Chemical laboratories. Laboratory equipment
• Technical Committee: D02 - Petroleum Products, Liquid Fuels, and Lubricants
• Drafting Committee: D02.D0 - Hydrocarbons for Chemical and Special Uses

Relations

• Replaces: ASTM D4178-82(2017) - Standard Practice for Calibrating Moisture Analyzers
• Effective Date: 01-Oct-2023
• Referred By: ASTM D5234-92(2017) - Standard Guide for Analysis of Ethylene Product
• Effective Date: 01-Oct-2023
• Referred By: ASTM D8446-22 - Standard Test Method for Water Vapor Content in Compressed Air Using Electronic Moisture Analyzers
• Effective Date: 01-Oct-2023
• Referred By: ASTM E1747-95(2019) - Standard Guide for Purity of Carbon Dioxide Used in Supercritical Fluid Applications
• Effective Date: 01-Oct-2023
• Referred By: ASTM D5274-00(2019) - Standard Guide for Analysis of 1,3–Butadiene Product
• Effective Date: 01-Oct-2023
• Referred By: ASTM D5273-18 - Standard Guide for Analysis of Propylene Concentrates
• Effective Date: 01-Oct-2023
• Referred By: ASTM D5454-11(2020) - Standard Test Method for Water Vapor Content of Gaseous Fuels Using Electronic Moisture Analyzers
• Effective Date: 01-Oct-2023

Overview

ASTM D4178-23: Standard Practice for Calibrating Moisture Analyzers outlines an established method for the calibration of moisture analyzers used either in laboratory or on-stream environments. Issued by ASTM International, this standard describes a procedure involving the preparation of calibration standards with known water content, ensuring reliable and accurate measurement of moisture across a specified range.

This practice is essential for maintaining the integrity of results produced by moisture analyzers, which are commonly used in applications such as quality control, process monitoring, and various analyses in the chemical and petroleum industries. The standard supports compliance with internationally recognized principles for laboratory calibration and test equipment reliability.

Key Topics

• Preparation of Water Content Standards:
  The calibration technique described in ASTM D4178-23 relies on generating standards of known water content within the range of 20 cm³/m³ to 2000 cm³/m³. This ensures that moisture analyzers can be calibrated to accurately measure low and high levels of water vapor.

• Calibration Procedure:
  The method involves using a carrier gas passed through a molecular sieve saturated with water and equilibrated at controlled temperature and pressure conditions. By adjusting the flow of both wet and dry carrier gas, gas mixtures with precise water concentrations are created for calibration.

• Apparatus Requirements:
  Detailed requirements are specified for the calibration apparatus, including an ice bath primary standard moisture apparatus, wet test meter, bubble meter, pressure gauge, and molecular sieve material.

• Safety Considerations:
  Users are advised to establish safety, health, and environmental protocols prior to conducting calibration activities. Special attention is recommended for LPG safety training when this method is applied in relevant environments.

Applications

• Laboratory Calibration:
  Calibration of benchtop moisture analyzers used in research, quality control, and materials testing.

• On-Stream Process Analysis:
  Ensures reliable and accurate moisture measurements in continuous industry processes, including oil refining, petrochemical production, and natural gas processing.

• Quality Control:
  Guarantees the validity of results provided by moisture analyzers, supporting product consistency and regulatory compliance.

• Equipment Maintenance:
  Provides a method for verifying analyzer performance, identifying drift, and supporting troubleshooting activities, including sensor replacement and adjustment.

Related Standards

• ASTM D6304 - Test Method for Determination of Water in Petroleum Products, Lubricating Oils, and Additives
• ASTM E104 - Practice for Maintaining Constant Relative Humidity by Means of Aqueous Solutions
• ASTM D5530 - Practice for Estimating and Measuring Water Vapor Transmission Rate of Materials Using an Infrared Detection Technique
• International Organization for Standardization (ISO) guides on calibration and equipment management

---

By following ASTM D4178-23, organizations benefit from standardized procedures to ensure moisture measurement accuracy, repeatability, and traceability, crucial for both laboratory calibration and robust process control. This standard supports compliance with national and international quality assurance practices, making it integral to laboratories and industries where measurement of water content is critical. For the most up-to-date and official procedures, always refer to the current version of the standard as published by ASTM International.

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: D4178 − 23
Standard Practice for
Calibrating Moisture Analyzers
This standard is issued under the fixed designation D4178; 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* 2.1.1 A carrier gas at a constant gauge pressure of 207 kPa
is passed through a molecular sieve drier and then routed over
1.1 This practice covers a calibration technique based on the
a molecular sieve support saturated with water and equilibrated
preparation of standards of known water content. This tech-
at 0 °C.
nique is applicable to the production of standards between
3 3 3 3 2.1.2 By blending different volumes of the wet carrier gas
20 cm /m and 2000 cm /m water.
with dried carrier gas, gas standards of known water concen-
1.2 The values stated in SI units are to be regarded as
tration can be prepared.
standard.
2.2 The moisture analyzer to be calibrated is then connected
1.2.1 Exception—The values given in parentheses are for
to the source of the gas standard of known water concentration.
information only.
1.3 This standard does not purport to address all of the
3. Significance and Use
safety concerns, if any, associated with its use. It is the
3.1 This practice is intended to provide a method to cali-
responsibility of the user of this standard to establish appro-
brate moisture analyzers used on-stream or in the laboratory.
priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use.
4. Apparatus
1.3.1 The user is advised to obtain LPG safety training for
4.1 Ice Bath Primary Standard Moisture Apparatus—Fig. 1
the safe operation of this test method procedure and related
illustrates a typical system.
activities.
4.2 Wet Test Meter, 1 L divisions.
1.4 This international standard was developed in accor-
dance with internationally recognized principles on standard- 4.3 Bubble Meter, graduated in cubic centimetres.
ization established in the Decision on Principles for the
4.4 Pressure Gauge—A Bourdon-type spring gauge of test
Development of International Standards, Guides and Recom-
gauge quality, 100 mm to 250 mm in diameter, with a scale
mendations issued by the World Trade Organization Technical
range from 0 kPa to 400 kPa (0 psi to 60 psi), maximum
Barriers to Trade (TBT) Committee.
intermediate graduations of 1.5 kPa (0.25 psi).
4.5 Wet Mole Sieve 5A, 60/80 mesh (other mesh sizes may
2. Summary of Practice
be used, except powder).
2.1 The practice is based on the principle that ice has a
vapor pressure of 0.611 kPa at 0 °C. Therefore, when a carrier
5. Preparation of Apparatus
gas at a constant gauge pressure of 207 kPa (30 psig) is passed
5.1 Saturate mole sieve with water.
through a molecular sieve saturated with water and held at
5.1.1 Cover in beaker enough mole sieve to fill the wet mole
0 °C, the total pressure is equal to 207 kPa plus 98 kPa (one
sieve container. Add water to cover mole sieve. Let stand
atmosphere) and the water concentration of the gas leaving the
6 overnight.
molecular sieve is [0.611/(207 + 98)] × 10 ppm or 2000 ppm
5.1.2 Drain the excess water by pouring the mole sieve
volume water, regardless of flow.
slurry into a filtering funnel and letting all the free water drain
out.
This practice is under the jurisdiction of ASTM Committee D02 on Petroleum
NOTE 1—The useful lifetime of the wet mole sieve is not known. It is
Products, Liquid Fuels, and Lubricants and is the direct responsibility of Subcom-
recommended that the procedure described in 5.1.1 and 5.1.2 be followed
mittee D02.D0 on Hydrocarbons for Chemical and Special Uses.
prior to each calibration.
Current edition approved Oct. 1, 2023. Published October 2023. Originally
approved in 1982. Last previous edition approved in 2017 as D4178 – 82 (2017).
6. Procedure
DOI: 10.1520/D4178-23.
For a more complete discussion of this procedure, see Mator, R. T., “Trace
6.1 Fill the ice bath bucket for the primary standard appa-
Moisture Analyzers and Their Calibration,” Proceedings of the 20th Annual ISA
ratus one third full of water; then add ice to bring the level to
Analysis Instrumentation Symposium, May 12-15, 1974, Pittsburgh, PA, “Session:
Sampling and Calibration Systems,” 1974, p. 125. full.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, Wes
...

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: D4178 − 82 (Reapproved 2017) D4178 − 23
Standard Practice for
Calibrating Moisture Analyzers
This standard is issued under the fixed designation D4178; 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 This practice covers a calibration technique based on the preparation of standards of known water content. This technique is
3 3 3 3
applicable to the production of standards between 20 cm /m and 2000 cm /m water.
1.2 The values stated in SI units are to be regarded as standard.
1.2.1 Exception—The values given in parentheses are for information only.
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.
1.3 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.
1.3.1 The user is advised to obtain LPG safety training for the safe operation of this test method procedure and related activities.
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. Summary of Practice
2.1 The practice is based on the principle that ice has a vapor pressure of 0.611 kPa at 0 °C. Therefore, when a carrier gas at a
constant gauge pressure of 207 kPa (30 psig) is passed through a molecular sieve saturated with water and held at 0 °C, the total
pressure is equal to 207 kPa plus 98 kPa (one atmosphere) and the water concentration of the gas leaving the molecular sieve is
[0.611/(207 + 98)] × 10 ppm or 2000 ppm volume water, regardless of flow.
2.1.1 A carrier gas at a constant gauge pressure of 207 kPa is passed through a molecular sieve drier and then routed over a
molecular sieve support saturated with water and equilibrated at 0 °C.
2.1.2 By blending different volumes of the wet carrier gas with dried carrier gas, gas standards of known water concentration can
be prepared.
This practice is under the jurisdiction of ASTM Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of Subcommittee
D02.D0 on Hydrocarbons for Chemical and Special Uses.
Current edition approved Oct. 1, 2017Oct. 1, 2023. Published November 2017October 2023. Originally approved in 1982. Last previous edition approved in 20122017
as D4178 – 82 (2012).(2017). DOI: 10.1520/D4178-82R17.10.1520/D4178-23.
For a more complete discussion of this procedure, see Mator, R. T., “Trace Moisture Analyzers and Their Calibration,” Proceedings of the 20th Annual ISA Analysis
Instrumentation Symposium, May 12-15, 1974, Pittsburgh, PA, “Session: Sampling and Calibration Systems,” 1974, p. 125.
*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
D4178 − 23
2.2 The moisture analyzer to be calibrated is then connected to the source of the gas standard of known water concentration.
3. Significance and Use
3.1 This practice is intended to provide a method to calibrate moisture analyzers used on-stream or in the laboratory.
4. Apparatus
4.1 Ice Bath Primary Standard Moisture Apparatus—Fig. 1 illustrates a typical system.
4.2 Wet Test Meter, 1 L divisions.
4.3 Bubble Meter, graduated in cubic centimetres.
4.4 Pressure Gauge—A Bourdon-type spring gauge of test gauge quality, 100 mm to 250 mm in diameter, with a scale range from
0 kPa to 400 kPa (0 psi to 60 psi), maximum intermediate graduations of 1.5 kPa (0.25 psi).
4.5 Wet Mole Sieve 5A, 60/80 mesh (other mesh sizes may be used, except powder).
5. Preparation of Apparatus
5.1 Saturate mole sieve with water.
5.1.1 Cover in beaker enough mole sieve to fill the wet mole sieve container. Add water to cover mole sieve. Let stand overnight.
5.1.2 Drain the excess water by pouring the mole sieve slurry into a filtering funnel and letting all the free
...