ASTM D4056-21

Standard Test Method for Estimation of Solubility of Water in Hydrocarbon and Aliphatic Ester Lubricants

SIGNIFICANCE AND USE
5.1 Knowledge of the water content is important in lubrication, as large amounts of water can cause corrosion fatigue in steel bearings, and the complete absence of water can cause metal scuffing.  
5.2 High water content has an accelerating effect on oxidation of lubricants, and can also contribute to foaming, especially at high altitude or temperature, or both.
SCOPE
1.1 This test method covers a procedure for estimating the equilibrium solubility of water and its vapor in hydrocarbon and aliphatic ester lubricants, at temperatures between 277 K and 373 K. The test method is limited to liquids of low to moderate polarity and hydrogen bonding, with predicted solubilities not over 1000 ppm by weight in hydrocarbons, or 30 000 ppm by weight in oxygenated compounds, at 298 K.  
1.2 Specifically excluded are olefins, nitriles, nitro compounds, and alcohols.  
1.3 This test method is recommended only for liquids not containing widely different chemical species. This excludes blends of esters with hydrocarbons, and lubricants containing detergents, dispersants, rust preventives, or load carrying additives.  
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.5 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.  
1.6 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-Nov-2021
• ICS: 75.100 - Lubricants, industrial oils and related products
• Technical Committee: D02 - Petroleum Products, Liquid Fuels, and Lubricants
• Drafting Committee: D02.L0.07 - Engineering Sciences of High Performance Fluids and Solids (Formally D02.1100)

Relations

• Refers: ASTM D4175-23a - Standard Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
• Effective Date: 15-Dec-2023
• Refers: ASTM D4175-23e1 - Standard Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
• Effective Date: 01-Jul-2023
• Refers: ASTM D2502-14(2019) - Standard Test Method for Estimation of Mean Relative Molecular Mass of Petroleum Oils from Viscosity Measurements
• Effective Date: 01-May-2019
• Refers: ASTM D2502-14(2019)e1 - Standard Test Method for Estimation of Mean Relative Molecular Mass of Petroleum Oils from Viscosity Measurements
• Effective Date: 01-May-2019
• Refers: ASTM D3238-17 - Standard Test Method for Calculation of Carbon Distribution and Structural Group Analysis of Petroleum Oils by the n-d-M Method
• Effective Date: 01-Jun-2017
• Refers: ASTM D3238-95(2015) - Standard Test Method for Calculation of Carbon Distribution and Structural Group Analysis of Petroleum Oils by the n-d-M Method
• Effective Date: 01-Oct-2015
• Refers: ASTM D94-07(2012) - Standard Test Methods for Saponification Number of Petroleum Products
• Effective Date: 01-Nov-2012
• Refers: ASTM D94-07(2012)e1 - Standard Test Methods for Saponification Number of Petroleum Products
• Effective Date: 01-Nov-2012
• Refers: ASTM D1298-12a - Standard Test Method for Density, Relative Density (Specific Gravity), or API Gravity of Crude Petroleum and Liquid Petroleum Products by Hydrometer Method
• Effective Date: 15-May-2012
• Refers: ASTM D1298-12 - Standard Test Method for Density, Relative Density (Specific Gravity), or API Gravity of Crude Petroleum and Liquid Petroleum Products by Hydrometer Method
• Effective Date: 01-Apr-2012
• Refers: ASTM D3238-95(2010) - Standard Test Method for Calculation of Carbon Distribution and Structural Group Analysis of Petroleum Oils by the n-d-M Method
• Effective Date: 01-Oct-2010
• Refers: ASTM D2502-04(2009) - Standard Test Method for Estimation of Molecular Weight (Relative Molecular Mass) of Petroleum Oils From Viscosity Measurements
• Effective Date: 01-Oct-2009
• Refers: ASTM D1218-02(2007) - Standard Test Method for Refractive Index and Refractive Dispersion of Hydrocarbon Liquids
• Effective Date: 01-Nov-2007
• Refers: ASTM D1298-99(2005) - Standard Test Method for Density, Relative Density (Specific Gravity), or API Gravity of Crude Petroleum and Liquid Petroleum Products by Hydrometer Method
• Effective Date: 01-Nov-2005
• Refers: ASTM D3238-95(2005) - Standard Test Method for Calculation of Carbon Distribution and Structural Group Analysis of Petroleum Oils by the n-d-M Method
• Effective Date: 01-Nov-2005

Overview

ASTM D4056-21: Standard Test Method for Estimation of Solubility of Water in Hydrocarbon and Aliphatic Ester Lubricants provides a reliable procedure to estimate the equilibrium solubility of water in hydrocarbon and aliphatic ester lubricants. This standard is essential for understanding how water interacts with lubricants, as water content directly influences performance, longevity, and safety of machinery and mechanical systems. The test covers a temperature range of 277 K to 373 K and is particularly useful for liquids of low to moderate polarity and hydrogen bonding, with specific solubility criteria.

By following this method, industries can ensure that lubricant formulations and operational environments remain within safe and efficient parameters, avoiding issues caused by too much or too little water.

Key Topics

• Scope of Application:
  ASTM D4056-21 is designed for estimating the solubility of water in hydrocarbon and aliphatic ester lubricants, excluding substances like olefins, nitriles, nitro compounds, and alcohols.

• Significance of Water Content:

  • Too much water may lead to corrosion fatigue in steel bearings.
  • Absence of water may cause metal scuffing.
  • Excess water accelerates oxidation and promotes foaming at high temperatures or altitudes.

• Test Method Parameters:

  • Applicable for lubricants where predicted solubility does not exceed 1000 ppm by weight in hydrocarbons, or 30,000 ppm by weight in oxygenated compounds.
  • Intended for single-component liquids, not complex blends or formulations containing additives such as detergents or dispersants.

• Data Requirements:
  The standard utilizes measurements such as:

  • Density (obtained via ASTM D1298)
  • Refractive index (ASTM D1218)
  • Molecular weight (ASTM D2502)
  • Saponification number for esters (ASTM D94)
  • Carbon distribution for hydrocarbons (ASTM D3238)

• Calculation Methodology:
  Solubility parameters are calculated using physical property data to estimate the amount of water that can dissolve in the lubricant at specified conditions.

• Safety and Compliance:
  Users are responsible for implementing the necessary health, safety, and environmental practices and for determining applicable regulatory limitations.

Applications

Industrial and Engineering Relevance:

• Used in quality assurance for lubricant manufacturers.
• Helps maintenance teams in automotive, aviation, and energy sectors monitor and control water content in lubricants.
• Supports the design of lubricant systems for high-reliability applications, especially where precise water control is critical.

Operational Benefits:

• Prevents corrosion fatigue and metal scuffing by maintaining appropriate water levels.
• Extends the lifespan of bearings, gears, and other moving components.
• Reduces the risk of lubricant oxidation and foaming, optimizing equipment performance.

Limitations:

• Not suitable for multi-component systems or lubricants with additives.
• Specific to non-polar and moderately polar liquids; does not cover all types of lubricants.

Related Standards

• ASTM D94 - Test Methods for Saponification Number of Petroleum Products
• ASTM D1218 - Test Method for Refractive Index and Refractive Dispersion of Hydrocarbon Liquids
• ASTM D1298 - Test Method for Density, Relative Density, or API Gravity of Crude Petroleum and Liquid Petroleum Products by Hydrometer Method
• ASTM D2502 - Test Method for Estimation of Mean Relative Molecular Mass of Petroleum Oils from Viscosity Measurements
• ASTM D3238 - Test Method for Calculation of Carbon Distribution and Structural Group Analysis of Petroleum Oils by the n-d-M Method
• ASTM D4175 - Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants

These related standards support the accurate measurement and analysis required for implementing ASTM D4056-21 effectively and are commonly referenced in lubricant test protocols.

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Keywords: ASTM D4056-21, solubility of water in lubricants, hydrocarbon lubricants, aliphatic ester lubricants, water content, lubricant performance, oxidation, corrosion fatigue, lubricant testing standards.

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: D4056 − 21
Standard Test Method for
Estimation of Solubility of Water in Hydrocarbon and
Aliphatic Ester Lubricants
This standard is issued under the fixed designation D4056; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope* 2. Referenced Documents
1.1 This test method covers a procedure for estimating the 2.1 ASTM Standards:
equilibrium solubility of water and its vapor in hydrocarbon D94Test Methods for Saponification Number of Petroleum
and aliphatic ester lubricants, at temperatures between 277K Products
and 373K. The test method is limited to liquids of low to D1218Test Method for Refractive Index and Refractive
moderate polarity and hydrogen bonding, with predicted solu- Dispersion of Hydrocarbon Liquids
bilities not over 1000ppm by weight in hydrocarbons, or D1298Test Method for Density, Relative Density, or API
30000ppm by weight in oxygenated compounds, at 298K. Gravity of Crude Petroleum and Liquid Petroleum Prod-
ucts by Hydrometer Method
1.2 Specifically excluded are olefins, nitriles, nitro
D2502Test Method for Estimation of Mean Relative Mo-
compounds, and alcohols.
lecular Mass of Petroleum Oils from Viscosity Measure-
1.3 This test method is recommended only for liquids not
ments
containing widely different chemical species. This excludes
D3238Test Method for Calculation of Carbon Distribution
blends of esters with hydrocarbons, and lubricants containing
and Structural Group Analysis of Petroleum Oils by the
detergents, dispersants, rust preventives, or load carrying
n-d-M Method
additives.
D4175Terminology Relating to Petroleum Products, Liquid
1.4 The values stated in SI units are to be regarded as Fuels, and Lubricants
standard. No other units of measurement are included in this
3. Terminology
standard.
3.1 Definitions of Terms Specific to This Standard:
1.5 This standard does not purport to address all of the
3.1.1 For definitions of terms used in this test method, refer
safety concerns, if any, associated with its use. It is the
to Terminology D4175.
responsibility of the user of this standard to establish appro-
3.1.2 charge transfer parameter, n—the portion of the
priate safety, health, and environmental practices and deter-
solubility parameter not attributed to London or Keesom
mine the applicability of regulatory limitations prior to use.
forces.
1.6 This international standard was developed in accor-
3.1.2.1 Discussion—It includes hydrogen bonds, induced
dance with internationally recognized principles on standard-
dipoles, and other quasichemical forces.
ization established in the Decision on Principles for the
3.1.2.2 Discussion—The square of the solubility parameter
Development of International Standards, Guides and Recom-
equals the sum of the squares of the three partial parameters.
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee. 3.1.3 dispersion parameter, n—the portion of the solubility
parameter attributed to London forces.
3.1.4 polar parameter, n—the portion of the solubility
This test method is under the jurisdiction of ASTM Committee D02 on parameter attributed to Keesom (permanent dipole) forces.
Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of
SubcommitteeD02.L0.07onEngineeringSciencesofHighPerformanceFluidsand
Solids (Formally D02.1100). For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Dec. 1, 2021. Published February 2022. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 1981. Last previous edition approved in 2016 as D4056–16. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/D4056-21. 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
D4056 − 21
3.1.5 solubility parameter, n—the square root of the cohe- If a value at 293 K is known (as required for Test Method
sive energy density (heat of vaporization minus work of D3238) multiply it by 0.998 to obtain n with sufficient
D
vaporization, per unit volume of liquid), at 298K. accuracy.
6.2.2 Calculate the refractivity function as follows:
3.2 Symbols:
2 2
y 5 n 21 / n 12 (2)
~ ! ~ !
D D
C = percentage of aromatic carbons,
A
6.2.3 Calculate the parameter as follows:
C = percentage of naphthenic carbons,
N
3 2
d = density of lubricant at 298K, g/mL,
δ 545 2119 1108 y 24.58 (3)
d y y
G = solubility by weight, mg/kg (ppm),
6.3 For hydrocarbons, calculate δ and P as follows:
M = molecular weight of lubricant, g/mol, d
6.3.1 Determine C and C by Test Method D3238.
n = refractive index of lubricant at 298K, A N
D
6.3.2 Calculate the parameters as follows:
RH = relative humidity,%,
S = saponification number, mg of KOH/g of lubricant,
P 50.0143C and (4)
A
T = system temperature, K,
H 50.0286C 10.0143C (5)
A N
V = molar volume of lubricant, mL/mol,
x = mole fraction of water in equilibrium mixture,
6.4 For esters, calculate P and H as follows:
y = Lorentz-Lorenz refractivity function,
6.4.1 DeterminethesaponificationnumberbyTestMethods
0.5
δ = dispersion parameter, (MPa) ,
d D94.
0.5
P = polar parameter, (MPa) ,
6.4.2 Calculate the parameter as follows:
0.5
H = charge transfer parameter, (MPa) ,
P 50.00815 Sdand (6)
φ = volume fraction of lubricant in equilibrium mixture,
0.5
and H 50.00173 SM/V (7)
φ = volume fraction of water in equilibrium mixture.
6.5 Calculate the volume fraction of water at 298K and
saturation as follows:
4. Summary of Test Method
2 2
1⁄φ 5exp 0.00726 φ 18.00 2δ 1 2.39 15.55
@ ~~ ! ~
2 1 d
4.1 Data required are the density, refractive index, and
2 2
2P) 12.39 16.27 2 H )1 1 218/V φ ] (8)
~ ! ~ !
molecularweightofahydrocarbon.Thesaponificationnumber
NOTE 1—For hydrocarbons, it may be safely assumed that φ =1.00.
is also required for an ester. From these are calculated the
However, that can introduce a significant error for some esters, so
carbon distribution for a hydrocarbon, and then the partial
calculate φ stepwise. Start with φ =1.00, next step φ =1−φ from the
2 1 1 2
solubility parameters. These in turn are used to calculate the
first step, and so on until no further significant change is noted.
...

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: D4056 − 16 D4056 − 21
Standard Test Method for
Estimation of Solubility of Water in Hydrocarbon and
Aliphatic Ester Lubricants
This standard is issued under the fixed designation D4056; 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*
1.1 This test method covers a procedure for estimating the equilibrium solubility of water and its vapor in hydrocarbon and
aliphatic ester lubricants, at temperatures between 277 K and 373 K. The test method is limited to liquids of low to moderate
polarity and hydrogen bonding, with predicted solubilities not over 1000 ppm by weight in hydrocarbons, or 30 000 ppm by weight
in oxygenated compounds, at 298 K.
1.2 Specifically excluded are olefins, nitriles, nitro compounds, and alcohols.
1.3 This test method is recommended only for liquids not containing widely different chemical species. This excludes blends of
esters with hydrocarbons, and lubricants containing detergents, dispersants, rust preventives, or load carrying additives.
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.5 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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.6 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
2.1 ASTM Standards:
D94 Test Methods for Saponification Number of Petroleum Products
D1218 Test Method for Refractive Index and Refractive Dispersion of Hydrocarbon Liquids
D1298 Test Method for Density, Relative Density, or API Gravity of Crude Petroleum and Liquid Petroleum Products by
Hydrometer Method
D2502 Test Method for Estimation of Mean Relative Molecular Mass of Petroleum Oils from Viscosity Measurements
D3238 Test Method for Calculation of Carbon Distribution and Structural Group Analysis of Petroleum Oils by the n-d-M
Method
D4175 Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
This test method is under the jurisdiction of ASTM Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of Subcommittee
D02.L0.07 on Engineering Sciences of High Performance Fluids and Solids (Formally D02.1100).
Current edition approved Jan. 1, 2016Dec. 1, 2021. Published March 2016February 2022. Originally approved in 1981. Last previous edition approved in 20102016 as
D4056 – 01 (2010).D4056 – 16. DOI: 10.1520/D4056-16.10.1520/D4056-21.
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
D4056 − 21
3. Terminology
3.1 Definitions of Terms Specific to This Standard:
3.1.1 For definitions of terms used in this test method, refer to Terminology D4175.
3.1.2 charge transfer parameter—parameter, n—the portion of the solubility parameter not attributed to London or Keesom forces.
3.1.2.1 Discussion—
It includes hydrogen bonds, induced dipoles, and other quasichemical forces.
3.1.2.2 Discussion—
The square of the solubility parameter equals the sum of the squares of the three partial parameters.
3.1.3 dispersion parameter—parameter, n—the portion of the solubility parameter attributed to London forces.
3.1.4 polar parameter—parameter, n—the portion of the solubility parameter attributed to Keesom (permanent dipole) forces.
3.1.5 solubility parameter—parameter, n—the square root of the cohesive energy density (heat of vaporization minus work of
vaporization, per unit volume of liquid), at 298 K.
3.2 Symbols:
C = percentage of aromatic carbons,
A
C = percentage of naphthenic carbons,
N
d = density of lubricant at 298 K, g/mL,
G = solubility by weight, mg/kg (ppm),
M = molecular weight of lubricant, g/mol,
n = refractive index of lubricant at 298 K,
D
RH = relative humidity, %,
S = saponification number, mg of KOH/g of lubricant,
T = system temperature, K,
V = molar volume of lubricant, mL/mol,
x = mole fraction of water in equilibrium mixture,
y = Lorentz-Lorenz refractivity function,
0.5
δ = dispersion parameter, (MPa) ,
d
0.5
P = polar parameter, (MPa) ,
0.5
H = charge transfer parameter, (MPa) ,
φ = volume fraction of lubricant in equilibrium mixture, and
φ = volume fraction of water in equilibrium mixture.
4. Summary of Test Method
4.1 Data required are the density, refractive index, and molecular weight of a hydrocarbon. The saponification number is also
required for an ester. From these are calculated the carbon distribution for a hydrocarbon, and then the partial solubility parameters.
These in turn are used to calculate the volume fraction of water dissolved at 298 K at saturation. This is converted to mole fraction,
and adjusted to system temperature. The mole fraction is then converted to solubility by weight. If the system atmosphere is not
saturated, the solubility is multiplied by the relative humidity.
5. Significance and Use
5.1 Knowledge of the water content is important in lubrication, as large amounts of water can cause corrosion fatigue in steel
bearings, and the complete absence of water can cause metal scuffing.
5.2 High water content has an accelerating effect on oxidation of lubricants, and can also contribute to foaming, especially at high
altitude or temperature, or both.
6. Procedure
6.1 Calculate the molar volume of the lubricant as follows:
D4056 − 21
6.1.1 Determine the density at 298 K by Test Method D1298 or equivalent. If the density at 293 K is known (as required for Test
Method D3238) multiply it by 0.996 to obtain d with sufficient accuracy.
6.1.2 Determine the molecular weight by Test Method D2502.
6.1.3 Calculate the molar volume as follows:
V 5 M/d (1)
6.2 Calculate the dispersion parameter
...