ASTM D7321-21

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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
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Designation: D7321 − 18a D7321 − 21
Standard Test Method for
Particulate Contamination of Biodiesel B100 Blend Stock
Biodiesel Esters and Biodiesel Blends by Laboratory
Filtration
This standard is issued under the fixed designation D7321; 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 the determination of the mass of particulate contamination in B100 biodiesel in accordance with
Specification D6751 and BXX blends that are prepared against all No. 1 and No. 2 grade fuels allowed within Specifications D396
and D975.
NOTE 1—Middle distillate fuels with flash points less than 38 °C have been ignited by discharges of static electricity when the fuels have been filtered
through inadequately bonded or grounded glass fiber filter systems. See Guide D4865 for a more detailed discussion of static electricity formation and
discharge.
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
2.1 ASTM Standards:
D396 Specification for Fuel Oils
D975 Specification for Diesel Fuel
D1193 Specification for Reagent Water
D4057 Practice for Manual Sampling of Petroleum and Petroleum Products
D4865 Guide for Generation and Dissipation of Static Electricity in Petroleum Fuel Systems
D6751 Specification for Biodiesel Fuel Blend Stock (B100) for Middle Distillate Fuels
3. Terminology
3.1 Definitions:
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
D02.14 on Stability, Cleanliness and Compatibility of Liquid Fuels.
Current edition approved Oct. 1, 2018Oct. 15, 2021. Published October 2018November 2021. Originally approved in 2008. Last previous edition approved in 2018 as
D7321 – 18.D7321 – 18a. DOI: 10.1520/D7321-18A.10.1520/D7321-21.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. 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
D7321 − 21
3.1.1 biodiesel, n—fuel comprised of mono-alkyl esters of long chain fatty acids derived from vegetable oils or animal fats,
designated B100.
3.1.2 biodiesel blend, BXX, n—a fuel composed of biodiesel blendstock with hydrocarbon-based diesel fuel.homogeneous mixture
of hydrocarbon oils and mono-alkyl esters of long chain fatty acids.
3.1.2.1 Discussion—
In the abbreviation BXX, the XX represents the volume percentage of biodiesel fuel in the blend.
3.1.2.2 Discussion—
The mono-alkyl esters of long chain fatty acids (that is, biodiesel) used in the mixture shall meet the requirements of Specification
D6751.
3.1.2.3 Discussion—
Diesel fuel, fuel oil, and non-aviation gas turbine oil are examples of hydrocarbon oils.
3.1.2.4 Discussion—
B0 is synonymous with a hydrocarbon oil to which no biodiesel has been added.
3.1.3 bond, v—to connect two parts of a system electrically by means of a conductive wire to eliminate voltage differences.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 filtered flushing fluids, n—any of three solvents, methanol, propan-2-ol (isopropanol), or 2,2,4-trimethylpentane, filtered
through a nominal 0.45 μm filter.
3.2.2 glass fiber filter, n—glass fiber filter used in this test method.
4. Summary of Test Method
4.1 B100 Biodiesel Blend Stock Filtration:
4.1.1 A measured volume of 400 mL to 450 mL of biodiesel ester (B100) is vacuum filtered through one 0.7 μm glass fiber filter.
If upon visual inspection particulate contamination is observed, this may result in a high filtration time. In such cases, when the
contamination is high or of a nature that induces slow filtration rates, two or more filtrations using a fresh filter each time may be
required to complete filtration in a reasonable time.
4.1.2 After the filtration has been completed, the filter is washed with solvent, dried, and weighed. The particulate contamination
level is determined by the mass gained by the glass fiber filter, and is reported in units of grams per cubic metre or its equivalent
in milligrams per litre.
4.2 BXX Biodiesel Blend Filtration:
4.2.1 A measured volume of 800 mL to 900 mL of biodiesel blend (BXX) is vacuum filtered through one 0.7 μm glass fiber filter.
If upon visual inspection particulate contamination is observed, this may result in a high filtration time. In such cases, when the
contamination is high or of a nature that induces slow filtration rates, two or more filtrations using a fresh filter each time may be
required to complete filtration in a reasonable time.
4.2.2 After the filtration has been completed, the filter is washed with solvent, dried, and weighed. The particulate contamination
level is determined by the mass gained from the glass fiber filter, and is reported in units of grams per cubic metre or its equivalent
in milligrams per litre.
5. Significance and Use
5.1 The mass of particulates present in a fuel is a significant factor, along with the size and nature of the individual particles, in
the rapidity with which fuel system filters and other small orifices in fuel systems can become plugged. This test method provides
a means of assessing the mass of particulates present in a fuel sample.
5.2 The test method can be used in specifications and purchase documents as a means of controlling particulate contamination
levels in the fuels purchased.
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6. Apparatus
6.1 Filtration System—Arrange the following components as shown in Fig. 1.
6.1.1 Funnel and Funnel Base, with filter support for a 47 mm diameter glass fiber, and locking ring or spring action clip.
6.1.2 Ground/Bond Wire, 0.912 mm to 2.59 mm (No. 10 through No. 19) bare stranded flexible, stainless steel, or copper installed
in the flasks and grounded as shown in Fig. 1.
NOTE 2—The electrical bonding apparatus shown in Fig. 1 or other suitable means of electrical grounding that ensure safe operation of the filtration
apparatus and flask can be used. If the filtrate is to be subsequently tested for stability, it is advisable not to use copper since copper ions catalyze gum
formation during the stability test.
6.1.3 Receiving Flask, 1.5 L or larger borosilicate glass vacuum filter flask, into which the filtration apparatus fits, equipped with
a sidearm to connect to the safety flask.
6.1.4 Safety Flask, 1.5 L or larger borosilicate glass vacuum filter flask equipped with a sidearm to connect the vacuum system.
A fuel and solvent resistance rubber hose through which the grounding wire passes shall connect the sidearm of the receiving flask
to the tube passing through the rubber stopper in the top of the safety flask.
6.1.5 Vacuum System, either a water aspirated or a mechanical vacuum pump may be used if capable of producing a vacuum of
1 kPa to 100 kPa below atmospheric pressure when measured at the receiving flask.
6.2 Other Apparatus:
6.2.1 Air Ionizer, if used for the balance case. Air ionizers if used should be replaced annually.
NOTE 3—When using a solid-pan balance, the air ionizer may be omitted provided that, when weighing a glass fiber filter, it is placed on the pan so that
no part protrudes over the edge of the pan.
6.2.2 Analytical Balance, single- or double-pan, with the precision standard deviation of 0.07 mg or less.
6.2.3 Crucible Tongs, for handling clean sample container lids.
6.2.4 Drying Oven, naturally convected (without fan-assisted air circulation), controlling to 90 °C 6 5 °C.
6.2.5 Flushing Fluid Dispenser, an apparatus for dispensing flushing fluid through a nominal 0.45 μm filter.
6.2.6 Forceps, approximately 12 cm long, flat-bladed, with non-serrated, non-pointed tips.
FIG. 1 Schematic of Filtration System
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6.2.7 Graduated Cylinders, to contain at least 1 L of fluid and marked at 10 mL intervals. For samples that filter slowly, 100 mL
graduated cylinders may be required.
6.2.8 Petri Dishes, approximately 12.5 cm in diameter, with removable glass supports for glass fiber filters.
NOTE 4—Small watch glasses, approximately 5 cm to 7 cm in diameter, have also been found suitable to support the glass fiber filter.
7. Reagents and Materials
7.1 Purity of Reagents—Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all
reagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society, where
such specifications are available. Other grades may be used, provided it is first ascertained that the reagent is of sufficient purity
to permit its use without lessening the accuracy of the determination.
7.2 Purity of Water—Unless otherwise indicated, references to water mean reagent water as defined by Types I, II and III of
Specification D1193.
7.3 Flushing Fluids:
7.3.1 Methanol, (Warning—Flammable).
7.3.2 2,2,4-trimethylpentane (isooctane), (Warning—Flammable).
7.3.3 propan-2-ol (2-propanol; isopropyl alcohol), (Warning—Flammable).
7.4 Liquid or Powder Detergent, water-soluble, for cleaning glassware.
7.5 Glass Fiber Filter, plain, with a diameter of 47 mm and a nominal pore size of 0.7 μm.
7.6 Protective Cover, polyethylene film or clean aluminum foil.
8. Sampling
8.1 Sampling for Procedure for Biodiesel Blend Stock (B100):
8.1.1 The sample container should be 500 mL (615 mL) in volume and have a screw-on cap with an inert liner. Glass containers
are preferred to facilitate a visual inspection of the contents and the container before and after filling. Glass containers also allow
for visual inspection of the container, after the sample is emptied, to confirm complete rinsing of the container. Epoxy-lined sample
cans, polytetrafluoroethylene (PTFE) bottles, and high density linear polyethylene bottles have also been found suitable as sample
containers, but they are less desirable since visual inspection of the interior of the container is more difficult.
8.1.1.1 It is imperative that the entire contents of the sample container are filtered during the B100 filtration. This includes not
only all of the fuel but also all rinsings of the interior of the container with flushing fluid. Because of this, take care to protect the
sample from any external contamination.
8.1.2 If it is not possible to sample in a 500 mL bottle, or the sample has already been received in a 1 L bottle, follow 8.1.2.1.
8.1.2.1 Vigorously shake the sample for 1 min, and transfer 400 mL to 450 mL (615 mL) to a clean fresh 500 mL bottle. If a clean
fresh 500 mL bottle is not available, use a clean fresh 1 L bottle.
8.1.3 Precautions to avoid sample contamination shall include selection of an appropriate sampling point. Samples should
Reagent Chemicals, American Chemical Society Specifications,ACS Reagent Chemicals, Specifications and Procedures for Reagents and Standard-Grade Reference
Materials, American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed by the American Chemical Society, see Analar Standards for
Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC),
Rockville, MD.
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preferentially be obtained dynamically from a sampling loop in a distribution line, or from the flushing line of a field sampling
kit. Ensure that the line to be sampled is flushed with fuel before taking the sample.
8.1.3.1 Where it is desirable or only possible to obtain samples from static storage, follow the procedures given in Practice D4057
or equivalent, taking precautions for cleanliness of all equipment used. Ensure that the sample has not passed through intermediate
containers prior to placement in the prepared container.
NOTE 5—Samples obtained from static storage may give results that are not representative of the bulk contents of the tank because of particulate matter
settling. Where possible, the contents of the tank should be circulated or agitated before sampling, or the sampling should be performed shortly after a
tank has been filled.
8.1.4 Visually inspect the sample container before collecting the samples to verify that there are no visible particles present inside
the container. Collect 800 mL to 900 mL (615 mL), in a 1 L sample bottle or 400 mL to 500 mL (615 mL) in a 500 mL (615 mL)
sample bottle and ensure that there is an ullage (vapor space) of at least 10 % of the container volume to allow for liq
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