ASTM D2158-21

Standard Test Method for Residues in Liquefied Petroleum (LP) Gases

SIGNIFICANCE AND USE
5.1 Control over the residue content (required by Specification D1835) is of considerable importance in end-use applications of LPG. In liquid feed systems, residues can lead to troublesome deposits and, in vapor withdrawal systems, residues that are carried over can foul regulating equipment. Residues that remain in vapor-withdrawal systems will accumulate, can be corrosive, and will contaminate subsequent product. Water, particularly if alkaline, can cause failure of regulating equipment and corrosion of metals.  
5.2 See Appendix X2 for information on the effect of temperature on the measurement of residue in LPG.
SCOPE
1.1 This test method covers the determination of extraneous materials weathering above 38 °C that are present in liquefied petroleum gases. The extraneous materials will generally be dissolved in the LPG, but may have phase-separated in some instances.  
1.2 Liquefied petroleum gases that contain certain anti-icing additives can give erroneous results by this test method.  
1.3 Although this test method has been used to verify cleanliness and lack of heavy contaminants in propane for many years, it might not be sensitive enough to protect some equipment from operational problems or increased maintenance. A more sensitive test, able to detect lower levels of dissolved contaminants, could be required for some applications.  
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-Jun-2021
• ICS: 75.160.30 - Gaseous fuels
• Technical Committee: D02 - Petroleum Products, Liquid Fuels, and Lubricants
• Drafting Committee: D02.H0 - Liquefied Petroleum Gas

Relations

• Refers: ASTM E2877-12(2019) - Standard Guide for Digital Contact Thermometers
• Effective Date: 01-May-2019
• Refers: ASTM D1835-13 - Standard Specification for Liquefied Petroleum (LP) Gases
• Effective Date: 01-May-2013
• Refers: ASTM D1835-12 - Standard Specification for Liquefied Petroleum (LP) Gases
• Effective Date: 01-Dec-2012
• Refers: ASTM E2877-12 - Standard Guide for Standard Guide for Digital Contact Thermometers
• Effective Date: 01-Nov-2012
• Refers: ASTM E2877-12e1 - Standard Guide for Digital Contact Thermometers
• Effective Date: 01-Nov-2012
• Refers: ASTM D7756-11 - Standard Test Method for Residues in Liquefied Petroleum (LP) Gases by Gas Chromatography with Liquid, On-Column Injection
• Effective Date: 01-Oct-2011
• Refers: ASTM D1835-11 - Standard Specification for Liquefied Petroleum (LP) Gases
• Effective Date: 01-May-2011
• Refers: ASTM E2251-11 - Standard Specification for Liquid-in-Glass ASTM Thermometers with Low-Hazard Precision Liquids
• Effective Date: 01-May-2011
• Refers: ASTM E2251-10 - Standard Specification for Liquid-in-Glass ASTM Thermometers with Low-Hazard Precision Liquids
• Effective Date: 01-Nov-2010
• Refers: ASTM D1796-04(2009) - Standard Test Method for Water and Sediment in Fuel Oils by the Centrifuge Method (Laboratory Procedure)
• Effective Date: 15-Apr-2009
• Refers: ASTM E2251-07 - Standard Specification for Liquid-in-Glass ASTM Thermometers with Low-Hazard Precision Liquids
• Effective Date: 01-Nov-2007
• Refers: ASTM D1835-05 - Standard Specification for Liquefied Petroleum (LP) Gases
• Effective Date: 01-Apr-2005
• Refers: ASTM D1796-04 - Standard Test Method for Water and Sediment in Fuel Oils by the Centrifuge Method (Laboratory Procedure)
• Effective Date: 01-Dec-2004
• Refers: ASTM D1835-03a - Standard Specification for Liquefied Petroleum (LP) Gases
• Effective Date: 01-Nov-2003
• Refers: ASTM E2251-03a - Standard Specification for Liquid-in-Glass ASTM Thermometers with Low-Hazard Precision Liquids
• Effective Date: 01-Nov-2003

Overview

ASTM D2158-21 - Standard Test Method for Residues in Liquefied Petroleum (LP) Gases provides a quantitative procedure for determining the presence and volume of extraneous material, known as residues, in liquefied petroleum gases (LPG) after evaporation above 38°C. Control over residue content is crucial for meeting quality standards, protecting equipment, and ensuring product performance, as required by Specification ASTM D1835. Residues, typically dissolved in LPG, can cause deposits, operational problems, and equipment damage in both liquid feed and vapor withdrawal systems.

This internationally recognized test supports manufacturers, distributors, and end-users in evaluating LPG cleanliness and suitability for various applications.

Key Topics

• Residue Determination: Specifies the process for measuring the volume of nonvolatile materials that remain after LPG samples are evaporated at 38°C, including procedures for detecting visible and non-visible oil stains.
• Significance in Practice: Residue levels in LPG are linked to risks such as system fouling, corrosion, contamination of subsequent product, and regulator failures due to both organic and water-based contaminants.
• Test Limitations: The standard notes potential issues when testing LPG containing certain anti-icing additives and recognizes situations where more sensitive analytical methods may be needed for very low residue levels.
• Apparatus and Reagents: Outlines requirements for precision laboratory equipment, such as centrifuge tubes, temperature measuring devices, solvents (typically HPLC-grade pentane or cyclopentane), and filter paper to accurately conduct the test.
• Safety and Handling: Emphasizes safety practices due to LPG’s flammability and potential for cold burns, along with recommendations for preventing static discharge and handling pressurized samples.
• Reporting Results: Provides details for reporting residue volume to the nearest 0.05 mL and oil stain observations to the nearest 0.1 mL, as well as "Pass/Fail" designations according to application-specific requirements.

Applications

• Quality Control: Used routinely by LPG producers, refiners, and distributors to ensure LPG products meet regulatory and contractual specifications concerning residues.
• Operational Safety: Identifies potential contaminants that could impact downstream equipment, such as vapor regulators, burners, and engines, helping to prevent fouling, corrosion, and failures that can compromise safety and reliability.
• Maintenance Planning: Allows operators of LPG-fueled systems-like heating, grain drying, and automotive applications-to anticipate and mitigate deposit-related maintenance needs.
• Regulatory Compliance: Supports conformance to legally mandated standards, helping facilities pass inspections and avoid penalties or shutdowns.
• Product Selection: Aids end-users in selecting the appropriate LPG source for sensitive or critical applications, especially where minimal residue content is vital.

Related Standards

• ASTM D1835: Specification for Liquefied Petroleum (LP) Gases, which mandates residue limits for LPG products.
• ASTM D7756: Test Method for Residues in LP Gases by Gas Chromatography-provides a more sensitive alternative for detecting lower levels of dissolved contaminants.
• ISO 13757: Method for determining oily residues in LPG at higher temperatures.
• EN 15470 / EN 15471 / EN 16423: European standards for residue determination using high temperature and gas chromatographic methods, suitable for applications requiring detection of different residue ranges and origins.
• ASTM E2251, E1137, E2877: Related standards for temperature measurement instrumentation used in precision residue testing.

By referencing ASTM D2158-21, organizations demonstrate commitment to LPG product quality, operational integrity, and international best practices for testing and safety in the handling of liquefied petroleum gases.

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: D2158 −21
Standard Test Method for
Residues in Liquefied Petroleum (LP) Gases
This standard is issued under the fixed designation D2158; 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* D96Test Method for Water and Sediment in Crude Oil by
Centrifuge Method (Field Procedure) (Withdrawn 2000)
1.1 This test method covers the determination of extraneous
D1796Test Method for Water and Sediment in Fuel Oils by
materials weathering above 38°C that are present in liquefied
the Centrifuge Method (Laboratory Procedure)
petroleum gases. The extraneous materials will generally be
D1835Specification for Liquefied Petroleum (LP) Gases
dissolved in the LPG, but may have phase-separated in some
D7756Test Method for Residues in Liquefied Petroleum
instances.
(LP) Gases by Gas Chromatography with Liquid, On-
1.2 Liquefiedpetroleumgasesthatcontaincertainanti-icing
Column Injection
additives can give erroneous results by this test method.
E1137SpecificationforIndustrialPlatinumResistanceTher-
mometers
1.3 Although this test method has been used to verify
cleanliness and lack of heavy contaminants in propane for E2251Specification for Liquid-in-Glass ASTM Thermom-
eters with Low-Hazard Precision Liquids
many years, it might not be sensitive enough to protect some
equipment from operational problems or increased mainte- E2877Guide for Digital Contact Thermometers
nance. A more sensitive test, able to detect lower levels of
2.2 Other Standards:
dissolved contaminants, could be required for some applica-
EN 15470Liquefied petroleum gases – Determination of
tions.
dissolved residues – High temperature gas chromato-
graphic method
1.4 The values stated in SI units are to be regarded as
EN 15471Liquefied petroleum gases – Determination of
standard. No other units of measurement are included in this
dissolved residues – High temperature gravimetric
standard.
method
1.5 This standard does not purport to address all of the
EN 16423Liquefied petroleum gases – Determination of
safety concerns, if any, associated with its use. It is the
dissolved residue – Gas chromatographic method using
responsibility of the user of this standard to establish appro-
liquid, on-column injection
priate safety, health, and environmental practices and deter-
EN ISO 6246Petroleum products – Gum content of fuels –
mine the applicability of regulatory limitations prior to use.
Jet evaporation method
1.6 This international standard was developed in accor-
ISO 13757Liquefied petroleum gases – Determination of
dance with internationally recognized principles on standard-
oily residues – High-temperature method
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
3. Terminology
mendations issued by the World Trade Organization Technical
3.1 Definitions of Terms Specific to This Standard:
Barriers to Trade (TBT) Committee.
3.1.1 oil stain observation, n—the volume of solvent-
residue mixture required to yield an oil stain or ring that
2. Referenced Documents
persists for 2min under specified conditions on absorbent
2.1 ASTM Standards:
paper.
3.1.2 residue, n—the volume, measured to the nearest
0.05mL, of the residual material boiling above 38°C resulting
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.H0 on Liquefied Petroleum Gas.
CurrenteditionapprovedJuly1,2021.PublishedJuly2021.Originallyapproved The last approved version of this historical standard is referenced on
ɛ1
in 1963. Last previous edition approved in 2016 as D2158–16a . DOI: 10.1520/ www.astm.org.
D2158-21. Available from European Committee for Standardization (CEN), Avenue
For referenced ASTM standards, visit the ASTM website, www.astm.org, or Marnix 17, B-1000, Brussels, Belgium, http://www.cen.eu.
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Available from International Organization for Standardization (ISO), ISO
Standards volume information, refer to the standard’s Document Summary page on Central Secretariat, Chemin de Blandonnet 8, CP 401, 1214 Vernier, Geneva,
the ASTM website. Switzerland, https://www.iso.org.
*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
D2158 − 21
from the evaporation of 100mL of sample under the specified 7.3 Syringe, 2mLgraduated in 0.1 mLand equipped with a
conditions of this test method. needle200mm 65mmlong.Theneedlemaybeeitherasharp
needle (ordinary medical syringe needle) or a safe, non-sharp
3.1.3 solvent-residue mixture, n—a mixture (solution) of
syringe needle to avoid a puncture hazard. Alternatively, an
10mL of solvent with any residue remaining in the centrifuge
equivalent liquid dispensing device capable of delivering
tube at the conclusion of the first step in this test method.
0.1mL increments may be used, such as a 0.1mL pipet.
4. Summary of Test Method 7.4 Temperature Measuring Device, that is intrinsically
safe, with accuracy equal to or better than liquid-in-glass
4.1 A 100mL sample of liquefied petroleum gas is weath-
thermometer ASTM S5C described in Specification E2251.
ered in a 100mL centrifuge tube. The volume of residue
Guide E2877 and Specification E1137 may be useful for
remaining after heating the tube to 38°C is measured and
selecting a digital contact thermometer.
recorded.
7.4.1 For routine testing, a general purpose thermometer or
4.2 Todissolveanyresidue,10mLofsolventisaddedtothe
a digital contact thermometer with 0.5°C subdivisions or
centrifuge tube. Small, measured volumes of solvent-residue
displayresolutionandamaximumerrorof0.5°Cmaybeused.
mixture are deposited on an absorbent paper in a specified
NOTE 1—When a thermometer or a water bath, or both, are not
manner. The appearance of the absorbent paper to which the
available, for example when conducting a field test, a satisfactory
residue solution has been added in measured increments is
alternative for screening purposes is to warm the tip of the centrifuge tube
observed and recorded.
with the hand.
7.5 Absorbent Paper, white, at least 100mm diameter.
5. Significance and Use
Medium grade or rapid filter paper has been found to be
5.1 Control over the residue content (required by Specifica-
satisfactory. In this test method, the paper will be referred to as
tion D1835) is of considerable importance in end-use applica-
“filter paper.”
tions of LPG. In liquid feed systems, residues can lead to
7.6 Solvent Wash Bottle, typically polyethylene.
troublesome deposits and, in vapor withdrawal systems, resi-
dues that are carried over can foul regulating equipment. 7.7 Water Bath, controlled at 38°C 6 2°C.
Residues that remain in vapor-withdrawal systems will
7.8 Copper Wire, 1mm to 2mm diameter, at least 10mm
accumulate, can be corrosive, and will contaminate subsequent
longer than the centrifuge tube’s height.
product. Water, particularly if alkaline, can cause failure of
7.9 Clamp, suitable for holding the centrifuge tube during
regulating equipment and corrosion of metals.
weathering.
5.2 See Appendix X2 for information on the effect of
temperature on the measurement of residue in LPG.
8. Reagents and Materials
8.1 Solvent—HPLC-grade pentane or cyclopentane. An-
6. Interferences
other grade of solvent may be used provided that it meets the
6.1 Solid contaminants such as rust, scale or dirt can
requirements of 10.2.
interfere with this test method, which is not intended for
8.1.1 Although pentane is the preferred solvent for use in
representative measurement of solid, undissolved contami-
this test method, cyclopentane may be substituted for pentane
nants. However, the presence of solids in the centrifuge tube
whenever the ambient temperature or altitude is too high to
should be reported.
enable the convenient handling of pentane.
8.1.2 Storage of solvent in a polyethylene wash bottle for
7. Apparatus
several days contaminates the solvent. Therefore, do not use
7.1 Centrifuge Tube, 100mL graduated, conforming to
anysolventthathasremainedinapolyethylenewashbottlefor
dimensions given in Fig. 1.The first 0.5mLshall be graduated
more than one day.
in 0.05mL increments. The shape of the lower tip of the tube
is especially important. The taper shall be uniform and the
9. Hazards
bottom shall be rounded as shown in Fig. 1. Tubes shall be
9.1 Note that there is a significant fire hazard from LPG
made of thoroughly annealed heat-resistant glass. Volumetric
vapors, and since the boiling point of LPG can be as low as
graduation tolerances, based on air-free water at 20°C, are
−41°C, there is a risk of freezing “burns.” Take appropriate
given in Table 1. Detailed requirements for centrifuge tubes
safety precautions to prevent ignition or fire, and wear suitable
appear in Test Methods D96 and D1796.
protectiveequipmenttoprotectagainstskincontactwithliquid
7.2 Cooling Coil and Cooling Bath, a minimum length of
or vaporizing LPG.
6mof5mmto7mmoutsidediametercoppertubingwoundto
9.2 Operators should wear a grounded antistatic wrist strap.
a diameter of 63.5mm 6 1.5mm outside diameter, and
The use of an antistatic floor mat and grounding the sample
assembled in a suitable cooling bath. (See Fig. 2 as an
cylinder are also advised.
example.)
7.2.1 Mechanical refrigeration is permitted provided that 9.3 When using a cooling bath of dry ice and hydrocarbon
the coolant temperature is below −43°C. If dry ice is used, a solvent, be aware that the bath can ‘bump’ or splatter cold
non-glass dewar or vessel is recommended. liquid when LPG is passed through the tubing.
D2158 − 21
FIG. 1 Cone-Shaped Centrifuge Tube, 203 mm
TABLE 1 Centrifuge Tube Graduation Tolerances
10.2 Verification of cleanliness of glassware and solvent.
Scale, Division, Limit of Error,
10.2.1 Add 10 mL of a new sample of solvent to the
Range, mL
mL mL
centrifuge tube.
0.0 to 0.1 0.05 0.02
0.1 to 0.3 0.05 0.03 10.2.2 Mark the center of the filter paper with a pencil or
0.3 to 0.5 0.05 0.05
other non-pentane-soluble writing tool.
0.5 to 1.0 0.1 0.05
1.0to3.0 0.1 0.1
10.2.3 Fill the syringe or equivalent liquid dispensing de-
3.0to5.0 0.5 0.2
vice (see 7.3) with a portion of the solvent drawn from the
5.0 to 25.0 1.0 0.5
centrifuge tube and direct 0.1mLportions of the solvent to the
25.0 to 100.0 1.0 1.0
mark on the paper.
10.2.3.1 The solvent is added in 0.1mL increments to
10. Preparation of Apparatus
confine the solvent ring to a circle about 30mm to 35mm in
diameter. The filter paper should be held level during the
10.1 Wash all glassware that is to be used in the test in the
selected solvent. solventaddition.Onemethodistoplaceitona250mLbeaker.
D2158 − 21
11.1.4 Immediately insert the copper wire through a clean,
slotted cork or a clean, loose-fitting plug of cotton or cleansing
tissue in the mouth of the centrifuge tube. The wire helps to
prevent superheating and resulting bumping (erratic or exces-
sive boiling), and the cork (or plug) will keep out air or
moisture while the sample is weathering.
11.1.5 If more than 10 mL of the sample is lost because of
bumping, obtain a new sample and repeat the test.
11.1.6 Allow the sample to weather, using artificial heating
if the ambient temperature or type of sample requires it. If,
when weathering has ceased and the tube has reached ambient
temperature, a visible residue remains, place the tip of the tube
in a water bath at 38°C for 5min.
NOTE 2—Residues that are volatile at 38°C, such as most gasoline
components and lighter diesel fuel components, will evaporate at this
temperature and not contribute to residue by Test Method D2158.
However, materials that have low vapor pressure at 38°C, such as higher
boiling components of diesel fuel, lubricating oils, heavy greases and
plasticizers, will remain and be measured as ‘residues.’ See 11.4.
11.1.7 Record the volume of any remaining residue to the
nearest 0.05mL, and the presence of extraneous matter, if
observed.
11.1.8 Perform the oil stain observation described in 11.2
even if there is no apparent or visible residue in the centrifuge
tube. Experience has shown that there can be a thin film of oil
ontheinnersurfaceofthecentrifugetubethatisdifficulttosee
anddoesnotgiveameasurablevolume,butcanstillgivearing
or stain in the Oil Stain Observation procedure.
11.2 Oil Stain Observation:
NOTE 1—Coils in the drawing are extended for clarity.
11.2.1 Add sufficient solvent to the centrifuge tube contain-
FIG. 2 Precooling Equipment
ing the residue described in 11.1.6 to restore the volume to
10mL. Add the solvent from the wash bottle and carefully
wash down the sides of the tube. Stir well so that any residue
10.2.4 Allow the solvent to evaporate for 2min, and note
at the bottom of the tube is dissolved uniformly in the solvent.
the persistence of an oil ring.
Stirring with the syringe needle (see 7.3) or pipette has been
10.2.4.1 The presence of an oil ring shall be observed by
found satisfactory. This mixture will be referred to as the
holding the dry filter paper between the eye and a bright
solvent-residue mixture.
incandescent light or strong daylight.
11.2.2 Mark the center of a clean white filter paper.
10.2.4.2 If no oil ring appears after 1.5mL of solvent has
11.2.3 Fill the syringe or equivalent liquid dispensing de-
been added, the solvent and glassware are satisfactory.
vice(see7.3),anddirect1.5mLofthesolvent-residuemixture
10.2.4.3 The appearance of an oil ring indicates either
at the center of the paper at an appropriate rate such that the
improperly cleaned glassware or contaminated solvent.
wetted circle is maintained at about 30mm to 35 mm in
11. Procedure
diameter. If desired, steps 11.2.3 and 11.2.4 may be omitted,
and the test continued according to 11.2.5.
11.1 Residue Measurement:
11.2.4 After directing the entire 1.5mL of residue solution
11.1.1 If the LPG sample is expected to be clean, with no
onto the filter paper and at the end of a 2min waiting period,
residues or contamina
...

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.
´1
Designation: D2158 − 16a D2158 − 21
Standard Test Method for
Residues in Liquefied Petroleum (LP) Gases
This standard is issued under the fixed designation D2158; 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.
ε NOTE—The IP designation was removed editorially in February 2018.
1. Scope*
1.1 This test method covers the determination of extraneous materials weathering above 38 °C that are present in liquefied
petroleum gases. The extraneous materials will generally be dissolved in the LPG, but may have phase-separated in some instances.
1.2 Liquefied petroleum gases that contain certain anti-icing additives can give erroneous results by this test method.
1.3 Although this test method has been used to verify cleanliness and lack of heavy contaminants in propane for many years, it
might not be sensitive enough to protect some equipment from operational problems or increased maintenance. A more sensitive
test, able to detect lower levels of dissolved contaminants, could be required for some applications.
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.
2. Referenced Documents
2.1 ASTM Standards:
D96 Test Method for Water and Sediment in Crude Oil by Centrifuge Method (Field Procedure) (Withdrawn 2000)
D1796 Test Method for Water and Sediment in Fuel Oils by the Centrifuge Method (Laboratory Procedure)
D1835 Specification for Liquefied Petroleum (LP) Gases
D7756 Test Method for Residues in Liquefied Petroleum (LP) Gases by Gas Chromatography with Liquid, On-Column Injection
E1137 Specification for Industrial Platinum Resistance Thermometers
E2251 Specification for Liquid-in-Glass ASTM Thermometers with Low-Hazard Precision Liquids
E2877 Guide for Digital Contact Thermometers
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.H0 on Liquefied Petroleum Gas.
Current edition approved Dec. 15, 2016July 1, 2021. Published January 2017July 2021. Originally approved in 1963. Last previous edition approved in 2016 as
ɛ1
D2158 – 16.D2158 – 16a . DOI: 10.1520/D2158-16AE01.10.1520/D2158-21.
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.
The last approved version of this historical standard is referenced on www.astm.org.
*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
D2158 − 21
2.2 Other Standards:
EN 15470 Liquefied petroleum gases – Determination of dissolved residues – High temperature gas chromatographic method
EN 15471 Liquefied petroleum gases – Determination of dissolved residues – High temperature gravimetric method
EN 16423 Liquefied petroleum gases – Determination of dissolved residue – Gas chromatographic method using liquid,
on-column injection
EN ISO 6246 Petroleum products – Gum content of fuels – Jet evaporation method
ISO 13757 Liquefied petroleum gases – Determination of oily residues – High-temperature method
3. Terminology
3.1 Definitions of Terms Specific to This Standard:
3.1.1 oil stain observation, n—the volume of solvent-residue mixture required to yield an oil stain or ring that persists for 2 min
under specified conditions on absorbent paper.
3.1.2 residue, n—the volume, measured to the nearest 0.05 mL, of the residual material boiling above 38 °C resulting from the
evaporation of 100 mL of sample under the specified conditions of this test method.
3.1.3 solvent-residue mixture, n—a mixture (solution) of 10 mL of solvent with any residue remaining in the centrifuge tube at the
conclusion of the first step in this test method.
4. Summary of Test Method
4.1 A 100 mL sample of liquefied petroleum gas is weathered in a 100 mL centrifuge tube. The volume of residue remaining after
heating the tube to 38 °C is measured and recorded.
4.2 To dissolve any residue, 10 mL of solvent is added to the centrifuge tube. Small, measured volumes of solvent-residue mixture
are deposited on an absorbent paper in a specified manner. The appearance of the absorbent paper to which the residue solution
has been added in measured increments is observed and recorded.
5. Significance and Use
5.1 Control over the residue content (required by Specification D1835) is of considerable importance in end-use applications of
LPG. In liquid feed systems, residues can lead to troublesome deposits and, in vapor withdrawal systems, residues that are carried
over can foul regulating equipment. Residues that remain in vapor-withdrawal systems will accumulate, can be corrosive, and will
contaminate subsequent product. Water, particularly if alkaline, can cause failure of regulating equipment and corrosion of metals.
5.2 See Appendix X2 for information on the effect of temperature on the measurement of residue in LPG.
6. Interferences
6.1 Solid contaminants such as rust, scale or dirt can interfere with this test method, which is not intended for representative
measurement of solid, undissolved contaminants. However, the presence of solids in the centrifuge tube should be reported.
7. Apparatus
7.1 Centrifuge Tube, 100 mL graduated, conforming to dimensions given in Fig. 1. The first 0.5 mL shall be graduated in 0.05 mL
increments. The shape of the lower tip of the tube is especially important. The taper shall be uniform and the bottom shall be
rounded as shown in Fig. 1. Tubes shall be made of thoroughly annealed heat-resistant glass. Volumetric graduation tolerances,
based on air-free water at 20 °C, are given in Table 1. Detailed requirements for centrifuge tubes appear in Test Methods D96 and
D1796.
7.2 Cooling Coil and Cooling Bath, a minimum length of 6 m of 5 mm to 7 mm outside diameter copper tubing wound to a
diameter of 63.5 mm 6 1.5 mm outside diameter, and assembled in a suitable cooling bath. (See Fig. 2 as an example.)
Available from European Committee for Standardization (CEN), Avenue Marnix 17, B-1000, Brussels, Belgium, http://www.cen.eu.
Available from International Organization for Standardization (ISO), ISO Central Secretariat, Chemin de Blandonnet 8, CP 401, 1214 Vernier, Geneva, Switzerland,
https://www.iso.org.
D2158 − 21
FIG. 1 Cone-Shaped Centrifuge Tube, 203 mm
TABLE 1 Centrifuge Tube Graduation Tolerances
Scale, Division, Limit of Error,
Range, mL
mL mL
0.0 to 0.1 0.05 0.02
0.1 to 0.3 0.05 0.03
0.3 to 0.5 0.05 0.05
0.5 to 1.0 0.1 0.05
1.0 to 3.0 0.1 0.1
3.0 to 5.0 0.5 0.2
5.0 to 25.0 1.0 0.5
25.0 to 100.0 1.0 1.0
7.2.1 Mechanical refrigeration is permitted provided that the coolant temperature is below −43 °C. If dry ice is used, a non-glass
dewar or vessel is recommended.
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NOTE 1—Coils in the drawing are extended for clarity.
FIG. 2 Precooling Equipment
7.3 Syringe, 2 mL graduated in 0.1 mL and equipped with a needle 200 mm 6 5 mm long. The needle may be either a sharp needle
(ordinary medical syringe needle) or a safe, non-sharp syringe needle to avoid a puncture hazard. Alternatively, an equivalent liquid
dispensing device capable of delivering 0.1 mL increments may be used, such as a 0.1 mL pipet.
7.4 Temperature Measuring Device, that is intrinsically safe, with accuracy equal to or better than liquid-in-glass thermometer
ASTM S5C described in Specification E2251. Guide E2877 and Specification E1137 may be useful for selecting a digital contact
thermometer.
7.4.1 For routine testing, a general purpose thermometer or a digital contact thermometer with 0.5 °C subdivisions or display
resolution and a maximum error of 0.5 °C may be used.
NOTE 1—When a thermometer or a water bath, or both, are not available, for example when conducting a field test, a satisfactory alternative for screening
purposes is to warm the tip of the centrifuge tube with the hand.
7.5 Absorbent Paper, white, at least 100 mm diameter. Medium grade or rapid filter paper has been found to be satisfactory. In
this test method, the paper will be referred to as “filter paper.”
7.6 Solvent Wash Bottle, typically polyethylene.
7.7 Water Bath, controlled at 38 °C 6 2 °C.
7.8 Copper Wire, 1 mm to 2 mm diameter, at least 10 mm longer than the centrifuge tube’s height.
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7.9 Clamp, suitable for holding the centrifuge tube during weathering.
8. Reagents and Materials
8.1 Solvent—HPLC-grade pentane or cyclopentane. Another grade of solvent may be used provided that it meets the requirements
of 10.2.
8.1.1 Although pentane is the preferred solvent for use in this test method, cyclopentane may be substituted for pentane whenever
the ambient temperature or altitude is too high to enable the convenient handling of pentane.
8.1.2 Storage of solvent in a polyethylene wash bottle for several days contaminates the solvent. Therefore, do not use any solvent
that has remained in a polyethylene wash bottle for more than one day.
9. Hazards
9.1 Note that there is a significant fire hazard from LPG vapors, and since the boiling point of LPG can be as low as −41 °C, there
is a risk of freezing “burns.” Take appropriate safety precautions to prevent ignition or fire, and wear suitable protective equipment
to protect against skin contact with liquid or vaporizing LPG.
9.2 Operators should wear a grounded antistatic wrist strap. The use of an antistatic floor mat and grounding the sample cylinder
are also advised.
9.3 When using a cooling bath of dry ice and hydrocarbon solvent, be aware that the bath can ‘bump’ or splatter cold liquid when
LPG is passed through the tubing.
10. Preparation of Apparatus
10.1 Wash all glassware that is to be used in the test in the selected solvent.
10.2 Verification of cleanliness of glassware and solvent.
10.2.1 Add 10 mL of a new sample of solvent to the centrifuge tube.
10.2.2 Mark the center of the filter paper with a pencil or other non-pentane-soluble writing tool.
10.2.3 Fill the syringe or equivalent liquid dispensing device (see 7.3) with a portion of the solvent drawn from the centrifuge tube
and direct 0.1 mL portions of the solvent to the mark on the paper.
10.2.3.1 The solvent is added in 0.1 mL increments to confine the solvent ring to a circle about 30 mm to 35 mm in diameter. The
filter paper should be held level during the solvent addition. One method is to place it on a 250 mL beaker.
10.2.4 Allow the solvent to evaporate for 2 min, and note the persistence of an oil ring.
10.2.4.1 The presence of an oil ring shall be observed by holding the dry filter paper between the eye and a bright incandescent
light or strong daylight.
10.2.4.2 If no oil ring appears after 1.5 mL of solvent has been added, the solvent and glassware are satisfactory.
10.2.4.3 The appearance of an oil ring indicates either improperly cleaned glassware or contaminated solvent.
11. Procedure
11.1 Residue Measurement:
11.1.1 If the LPG sample is expected to be clean, with no residues or contaminants that could result in an oil stain, the procedure
may be performed without a cooling coil. However, if a residue or oil stain is detected using this screening procedure (that is, a
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residue is measured at greater than or equal to 0.05 mL in 11.1.7, or an oil stain is generated with 1.5 mL of test solution in 11.2.4),
the test shall be repeated using a cooling coil.
11.1.2 Attach the cooling coil to the LPG sample source, cool the coil to below the boiling point of the sample, and flush the coil
and sampling line.
11.1.3 Rinse and cool the centrifuge tube with the material to be sampled and then fill it to the 100 mL mark with a representative
sample of LPG.
11.1.4 Immediately insert the copper wire through a clean, slotted cork or a clean, loose-fitting plug of cotton or cleansing tissue
in the mouth of the centrifuge tube. The wire helps to prevent superheating and resulting bumping (erratic or excessive boiling),
and the cork (or plug) will keep out air or moisture while the sample is weathering.
11.1.5 If more than 10 mL of the sample is lost because of bumping, obtain a new sample and repeat the test.
11.1.6 Allow the sample to weather, using artificial heating if the ambient temperature or type of sample requires it. If, when
weathering has ceased and the tube has reached ambient temperature, a visible residue remains, place the tip of the tube in a water
bath at 38 °C for 5 min.
NOTE 2—Residues that are volatile at 38 °C, such as most gasoline components and lighter diesel fuel components, will evaporate at this temperature and
not contribute to residue by Test Method D2158. However, materials that have low vapor pressure at 38 °C, such as higher boiling components of diesel
fuel, lubricating oils, heavy greases and plasticizers, will remain and be measured as ‘residues.’ See 11.4.
11.1.7 Record the volume of any remaining residue to the nearest 0.05 mL, and the presence of extraneous matter, if observed.
11.1.8 Perform the oil stain observation described in 11.2 even if there is no apparent or visible residue in the centrifuge tube.
Experience has shown that there can be a thin film of oil on the inner surface of the centrifuge tube that is difficult to see and does
not give a measurable volume, but can still give a ring or stain in the Oil Stain Observation procedure.
11.2 Oil Stain Observation:
11.2.1 Add sufficient solvent to the centrifuge tube containing the residue described in 11.1.6 to restore the volume to 10 mL. Add
the solvent from the wash bottle and carefully wash down the sides of the tube. Stir well so that any residue at the bottom of the
tube is dissolved uniformly in the solvent. Stirring with the syringe needle (see 7.3) or pipette has been found satisfactory. This
mixture will be referred to as the solvent-residue mixture.
11.2.2 Mark the center of a clean white filter paper.
11.2.3 Fill the syringe or equivalent liquid dispensing device (see 7.3), and direct 1.5 mL of the solvent-residue mixture at the
center of the paper at an appropriate rate such that the wetted circle is maintained at about 30 mm to 35 mm in diameter. If desired,
steps 1
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