ASTM E789-95(2001)
(Test Method)Standard Test Method for Dust Explosions in a 1.2-Litre Closed Cylindrical Vessel (Withdrawn 2007)
Standard Test Method for Dust Explosions in a 1.2-Litre Closed Cylindrical Vessel (Withdrawn 2007)
SCOPE
1.1 This test method covers the determination of the ignition of a dust dispersed in air, within a closed vessel.
1.2 This test method provides a measure of dust explosion pressure and rate of pressure rise. It does not provide a definitive determination of the flammability of a dust and has other severe limitations which are identified in Section 5. The preferred method for the design of safety equipment is Test Method E1226.
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 and health practices and determine the applicability of regulatory limitations prior to use. For specific safety precautions see Section 7.
1.4 The values stated in inch-pound units are to be regarded as the standard. The values in parentheses are for information only.
WITHDRAWN RATIONALE
This test method covers the determination of the ignition of a dust dispersed in air, within a closed vessel.
Formerly under the jurisdiction of Committee E27 on Hazard Potential of Chemicals, this test method was discontinued in July 2007 in accordance with section 10.5.3.1 of the Regulations Governing ASTM Technical Committees, which requires that standards shall be updated by the end of the sixth year since the last approval date.
General Information
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:E789–95 (Reapproved 2001)
Standard Test Method for
Dust Explosions in a 1.2-Litre Closed Cylindrical Vessel
This standard is issued under the fixed designation E 789; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope 3.2 Thepressureisdetectedbyatransducerandrecordedby
appropriatemeasuringequipmentfromwhichpressureandrate
1.1 Thistestmethodcoversthedeterminationoftheignition
of pressure rise may be determined.
of a dust dispersed in air, within a closed vessel.
1.2 This test method provides a measure of dust explosion
4. Significance and Use
pressure and rate of pressure rise. It does not provide a
4.1 This test method provides a procedure for measuring
definitive determination of the flammability of a dust and has
pressure and rate of pressure rise.
other severe limitations which are identified in Section 5. The
4.2 This test method may be used to determine whether a
preferred method for the design of safety equipment is Test
dust will ignite using an electric arc ignition source.
Method E 1226.
1.3 This standard does not purport to address all of the
5. Limitation
safety concerns, if any, associated with its use. It is the
5.1 Thevaluesdeterminedbythistestmethodarespecificto
responsibility of the user of this standard to establish appro-
the material tested and equipment and procedure used and are
priate safety and health practices and determine the applica-
not to be considered inherent, fundamental properties.
bility of regulatory limitations prior to use. For specific safety
5.2 Thesizeandshapeofthevesselhaveadirectbearingon
precautions see Section 7.
the data obtained. Extrapolation to vessels having a different
1.4 The values stated in inch-pound units are to be regarded
volume and shape should not be made.
as the standard. The values in parentheses are for information
5.3 The data cannot be used for direct calculation of
only.
explosion venting or containment.
5.4 Adustcloudthatdoesnotignitebythistestmethodmay
2. Referenced Documents
still be flammable. This test method does not provide a
2.1 ASTM Standards:
definitive determination of the flammability of a dust.
D 3173 Test Method for Moisture in theAnalysis Sample of
Coal and Coke
6. Apparatus
D 3175 Test Method for Volatile Matter in the Analysis
2 6.1 The equipment consists of a vertically mounted closed
Sample of Coal and Coke
steel combustion chamber (commonly known as the Hartmann
E 1226 Test Method for Pressure and Rate of Pressure Rise
3 tube), a dust dispersion system using clean air, ignition source,
for Combustible Dusts
pressure sensor, and recording system.
2.2 Other ASTM Document:
6.2 Fig. 1 is a schematic diagram of the apparatus.
STP 447A Manual on Test Sieving Methods
6.3 Construction details and tables are presented in the
3. Summary of Test Method annexes.
6.4 Thepressuretransducershouldbeinstalledandoperated
3.1 A dust cloud is formed in a closed steel combustion
according to the manufacturer’s recommendations.
chamber by a jet of clean compressed air and ignited by a
continuous electric arc.
7. Safety Precautions
7.1 Prior to handling a dust material, the toxicity of the
sample and its combustion products must be considered; this
This test method is under the jurisdiction ofASTM Committee E27 on Hazard
information is generally obtained from the manufacturer or
Potential of Chemicals and is the direct responsibility of Subcommittee E27.05 on
Dusts.
supplier. Appropriate safety precautions must be taken if the
Current edition approved Nov. 10, 1995. Published January 1996. Originally
material has toxic or irritating characteristics. Tests using this
published as E 789 – 81. Last previous edition E 789 – 89.
2 apparatus must be in a ventilated hood or other area having
Annual Book of ASTM Standards, Vol 05.05
Annual Book of ASTM Standards, Vol 14.02. adequate ventilation.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
E789
NOTE 1—Cam switch timer operates solenoid valve, spark ignition, and recording oscillograph.
FIG. 1 Schematic of Apparatus for Determining Pressure and Rate of Pressure in a Dust Explosion
as-received state it should be recognized that the test results may not
7.2 Before initiating a test check and secure the Hartmann
represent the most severe dust explosion possible. Any process change
apparatus, fittings, and gaskets to prevent leakage.
resulting in a higher fraction of fines than normal or drier product than
7.3 All testing should start using 0.1 g of sample to prevent
normal will increase the potential hazard from dust explosions.
over-pressurization due to high-energy materials. No experi-
8.3 To achieve this particle fineness ($95 % minus 200
ments should be run so that the explosion pressure exceeds 175
mesh) the sample may be ground or pulverized or it may be
psig (1.21 MPa).
sieved.
7.4 In assembling the electrical circuitry for this apparatus,
standard wiring and grounding procedures must be followed.
NOTE 2—The operator should consider the thermal stability of the dust
Since the high-voltage spark circuit presents an electric shock
during any grinding or pulverizing. In sieving the material, the operator
hazard, adequate interlock and shielding must be employed to must verify that there is no selective separation of components in a dust
that is not a pure substance.
prevent contact.
7.5 All enclosures containing electrical equipment should
8.4 The moisture content of the test sample should not
be connected to a common ground, and shielded cables should
exceed 5 % in order to avoid test results being noticeably
be used.
influenced.
7.6 The operator should work from a protected location in
NOTE 3—There is no single method for determining the moisture
case of vessel or electrical failure.
content or for drying the sample.ASTM lists many methods for moisture
determination in the Annual Book of ASTM Standards. Sample drying is
8. Sampling and Test Specimen
equally complex due to the presence of volatiles, lack of or varying
porosity such as coal (see Test Methods D 3173 and D 3175), and
8.1 It is not practical to specify a single method of sampling
sensitivity of the sample to heat. Therefore, each must be dried in a
dust for test purposes since the character of the material and its
manner that will not modify or destroy the integrity of the sample.
available form affect selection of the sampling procedure.
Hygroscopic materials must be desiccated.
Generally accepted sampling procedures should be used as
described in STP 447A.
9. Calibration and Standardization
8.2 Tests may be run on an as-received sample. However,
9.1 Calibration of the air dispersion system should be made
due to possible accumulation of fines at some location in a
to establish proper air flow into the dispersion cup and
processing system, it is recommended that the test sample be at
combustion bomb. A cylindrical calibration chamber as de-
least 95 % minus 200 mesh (74 µm).
tailed in Fig.A1.13 is secured to the combustion chamber base
NOTE 1—It may be desirable in certain instances to conduct dust after setting the mushroom four turns counterclockwise from
explosion tests on materials as sampled from a process, since (a) process
its closed position. A pressure transducer is connected to the
dust streams may contain a wide range of particle sizes or have a
calibration chamber. The air (100 psig, 690 kPa) in the
well-defined specific moisture content making it desirable to test the
dispersion reservoir is then released and a pressure-time record
material in the as-received state, (b) materials consisting of a mixture of
of the event is obtained from the appropriate measuring
chemicals may be selectively separated on sieves making it desirable to
equipment. The maximum pressure and rate of pressure rise
test the as-received material, (c) certain fibrous materials which may not
determined from this record should be within the following
pass through a relatively coarse screen may produce dust explosions if
tested in the as-received state, ( d) when a material is tested in the limits:
E789
9.1.1 Maximum Pressure: 256 2 psig (172 6 14 kPa)
9.1.2 Maximum Rate of Pressure Rise: 975 6 50 psi/s
(6.726 0.34 MPa/s).
9.2 A standardization of the equipment before starting the
3 3
testing and at the end of the day with 0.75 oz/ft (kg/m )of
lycopodium is necessary. The test equipment must read a
pressure of 100 6 12 psig (690 6 83 kPa) and rate of 6300
psi/s 6 20 % before using.
10. Procedure
10.1 Separate the steel combustion chamber from the dis-
persion cup base. Clear the dispersion system with several
blasts of air. Remove the spark electrodes and insulators from
the tube and dry clean them with sandpaper, steel wool, emery
cloth,orsimilarmaterial.Rechecktheelectrodesandrepointas
necessary. Clean the inside of the tube with a wire brush or
similar device and remove the loosened residue from the
preceding test with a blast of high-pressure air or a vacuum
cleaner. Thoroughly clean the dispersion cup, mushroom, and
FIG. 2 Pressure Versus Time—Data Analysis
pressure transducer.
10.2 Remove the mushroom and check the mushroom insert
(Fig. A1.7) making sure it is flush with the top of the air
11.3 It is important that the captured waveform is free from
dispersion cup (A1.6). Reinsert the mushroom by turning it
noise and spikes which could cause errors during the analysis.
clockwise until the cap is snug against the dispersion cup; then
Filtering techniques in the data capture hardware should be
turn the mushroom counterclockwise four complete turns.
employed and additionally some software smoothing of the
10.3 Spread a weighed amount of dust into a uniformly thin
data can be undertaken.
layer around the bottom of the dispersion cup. Determine
concentration by dividing the weight of dust used by the
12. Report
3 3
volume of the steel combustion chamber 75 in. (0.00123 m ).
12.1 Report the following information:
Explosion tests are normally made at calculated dust concen-
3 3
12.1.1 Completeidentificationofthematerialtested,includ-
trations of 0.1, 0.2, 0.5, 1.0, and 2.0 oz/ft (or kg/m ).
ing source, code numbers, forms, color, previous history.
NOTE 4—To convert gram weight per 75 in. to ounces per cubic feet
12.1.2 Size distribution (sieve analysis) of the sample as
multiply by 0.813.
received and as tested.
10.4 Secure the electrodes in the steel combustion chamber
12.1.3 Moisture content of the as-received and as-tested
and adjust to a ⁄4-in. (6.4-mm) gap. material.
10.5 Place the O-ring on top of the dispersion cup, and lock
12.1.4 Maximum pressure for all concentrations and par-
the steel combustion chamber in place with the hinged bolts.
ticle sizes tested. Curves showing these data may also be
10.6 Secure the O-ring and top assembly to the combustion included (see Fig. 3).
chamber by hand-tightening the locking ring handle.
10.7 Adjust the air dispersing pressure in the 3-in.
(0.00005-m ) reservoir to 100 psig (690 kPa).
10.8 Ensure that the dispersion system is airtight.
10.9 Attachtheelectricalsourcetotheelectrodesandsetthe
desired recorder speed.
10.10 Put shield in place.
10.11 Actuate the firing circuit to conduct the test (seeA1.6
for a description of the sequence of events following activation
of the firing circuit).
11. Calculation
11.1 A pressure versus time trace for an explosion is
typicallyoftheformgiveninFig.2,fromwhich( 1)maximum
pressure and (2) maximum rate of pressure rise can be
deduced.
11.2 The data points constituting the above curve can be
captured using high-speed analog to digital data capture
FIG. 3 Maximum Pressure and Rates of Pressure Rise Developed
techniques and then the logged data can be analyzed. by Explosions of Zirconium Dust in the Hartmann Equipment
E789
NOTE 5—Precision is based on lycopodium reported in ASTM. Other
13. Precision
materials may give results outside the above criteria.
13.1 The following criteria should be used for judging the
acceptability of results.
14. Keywords
13.1.1 Maximum Pressure:
14.1 dust explosion; dust ignition
13.1.1.1 Repeatability—The average of duplicate tests
should be considered suspect if they differ by more than 20 %.
13.1.1.2 Reproducibility—The average of duplicate tests
obtained by each of several laboratories should be considered
suspect if they differ by more than 22 %.
ANNEXES
(Mandatory Information)
A1. METHOD OF OPERATION OF HARTMANN EQUIPMENT AND DETAILED DRAWINGS
A1.1 Fig. 1 is a schematic of the test apparatus and nearly hemispherical in shape. Air flows into the chamber and
associated electronic instrumentation. Detailed constructional impinges on a mushroom-shaped deflector in the bottom of the
drawings of each part of the apparatus are shown in Figs. dispersion cup. Total volume of the combustion chamber is 75
3 3
A1.1-A1.13. Part numbers and the figure for the drawings of in. (0.00123 m )
each part are listed inTableA1.1.To serve as a guide, auxiliary
TABLE A1.1 Listing of Constructional Drawings for the Hartmann Apparatus
NOTE 1—Make combustion chamber base, six of one piece.
NOTE 2—Combustion chamber assembly, Parts 1, 12, 16, and 6, may be chromium-plated inside and outside except threads of Parts 12 and 16.
NOTE 3—All sliding fits shall be Class 3 medium fit ASA classification of fits. Nominal allowances are indicated.
Fig. Part Number To Fit Method of
Nomenclature Material
No. No. Required Part No. Assembling
Fig. A1.1 1 Hartmann combustion chamber 1 Seamless carbon mechanical steel . .
tubing
Fig. A1.2 . Hartmann base support and air control system 1 . 1 .
Fig. A1.3 2 Pressure transducer adapter ring 1 brass 1 slide fit
Fig. A1.3 3 Locking ring 1 brass 1 12 threads per inch
Fig. A1.3 4 Locking ring handle 3 brass 3 silver solder
Fig. A1.3 5 Electrode holder locknut wrench 1 steel 18 .
Fig. A1.4 6 Combustion chamber base 1 steel 1 12 threads per inch
Fig. A1.5 7 Holding lug screws 4 hardened steel 8 ⁄4-20 thread
Fig. A1.5 8 Holding lug base 4 steel 10 slide fit
Fig. A1.6 9A Dispersion cup 1 brass 6 slide fit
Fig. A1.7 9B Mushroom 1 brass 9C 2-56 thread
Fig. A1.7 9C Mushroom insert 1 brass 9A snug fit
Fig. A1.8 10 Dispersion cup base 1 brass 9A 6-32 screws
Fig. A1.2 11 Base support 1 aluminum 10 8-32 screws
Fig. A1.9 12 Viewing port 2 brass 1 silver solder
Fig. A1.9 13 Viewing port adapter 2 brass 12 14 threads per inch
Fig. A1.9 14 Viewing window 2 glass 13 Loose slide fit
Fig. A1.10 15 View
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