1、Designation: E582 07 (Reapproved 2013)1Standard Test Method forMinimum Ignition Energy and Quenching Distance inGaseous Mixtures1This standard is issued under the fixed designation E582; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revisi
2、on, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1NOTEWarning notes were editorially updated throughout in October 2013.1. Scope1.1 This test method covers the det
3、ermination of minimumenergy for ignition (initiation of deflagration) and associatedflat-plate ignition quenching distances.2The complete descrip-tion is specific to alkane or alkene fuels admixed with air atnormal ambient temperature and pressure. This method isapplicable to mixtures of the specifi
4、ed fuels with air, varyingfrom the most easily ignitable mixture to mixtures near to thelimit-of-flammability compositions.1.2 Extensions to other fuel-oxidizer combinations, and toother temperatures and pressures can be accomplished with allthe accuracy inherent in this method if certain additional
5、conditions are met: (a) mixture stability and compatibility withbomb, seal, and other materials is established through timetests described in Section 9;(b) the expected peak pressurefrom the test is within the pressure rating of the bomb(established as required by the particular research laboratory)
6、;(c) spark breakdown within the bomb is consistent withPaschens law for the distance being tested; (d) thetemperature, including that of the discharge electrodes, isuniform; and (e) if the temperature is other than ambient, theenergy storage capacitance required is less than about 9 pF.1.3 This meth
7、od is one of several being developed byCommittee E27 for determining the hazards of chemicals,including their vapors in air or other oxidant atmospheres. Themeasurements are useful in assessing fuel ignitability hazardsdue to static or other electrical sparks. However, the quenchingdistance data mus
8、t be used with great prudence since they areprimarily applicable to the ignition stage and therefore, repre-sent values for initial pressure and not the smaller valuesexisting at higher pressures.1.4 The values stated in inch-pound units are to be regardedas standard. The values given in parentheses
9、 are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.1.5 This standard should be used to measure and describethe properties of materials, products, or assemblies in responseto heat and flame under controlled laboratory conditions andshould no
10、t be used to describe or appraise the fire hazard orfire risk of materials, products, or assemblies under actual fireconditions. However, results of this test may be used aselements of a fire risk assessment which takes into account allof the factors which are pertinent to an assessment of the fireh
11、azard of a particular end use.1.6 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitation
12、s prior to use. Specific safetyprecautions are listed in Section 5.2. Terminology2.1 Definitions:2.1.1 ignition, nthe initiation of combustion.2.1.2 minimum ignition energy (MIE), nelectrical energydischarged from a capacitor, which is just sufficient to effectignition of the most easily ignitable c
13、oncentration of fuel in airunder the specific test conditions.2.2 Definitions of Terms Specific to This Standard:2.2.1 ignition quenching distance, nmaximum spacingbetween eletrode flanges that will not permit spark ignition andflame propagation beyond the flanges, when tested under thespecified tes
14、t conditions.3. Significance and Use3.1 The minimum energies provide a basis for comparingthe ease of ignition of gases. The flatplate ignition quenchingdistances provide an important verification of existing mini-mum ignition energy data and give approximate values of thepropagation quenching dista
15、nces of the various mixtures. It isemphasized that maximum safe experimental gaps, as from1This test method is under the jurisdiction of ASTM Committee E27 on HazardPotential of Chemicals and is the direct responsibility of Subcommittee E27.04 onFlammability and Ignitability of Chemicals.Current edi
16、tion approved Oct. 1, 2013. Published November 2013. Originallyapproved in 1976. Last previous edition approved in 2007 as E582 07. DOI:10.1520/E0582-07R13E01.2Litchfield, E. L., Hay, M. H., Kubala, T. S., and Monroe, J. S., “MinimumIgnition Energy and Quenching Distance in Gaseous Mixtures,” BuMine
17、s,R.L.7009, August 1967, p. 11.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1“flame-proof” or “explosion-proof” studies, are less than theflat-plate ignition quenching distances.4. Apparatus4.1 Reaction VesselThe recommended reactio
18、n vessel ismanufactured according to the specifications of Fig. 1 and Fig.2. This is a spherical vessel, manufactured of Type 304stainless steel, and passivated after machining. The sphericalgeometry maximizes the useable spark-gap length for a givenvessel volume. The reaction vessel provides for op
19、posedmounting of the spark electrodes which permits rapid andconvenient variation of the gap length without the necessity foropening the vessel. The input orifice (Fig. 2, Section A-A)islocated so that the gases are introduced approximately tangen-tially to the vessel walls, thus providing a turbule
20、nt swirlingmotion that facilitates mixing. A sight glass permits directobservation of flame initiation and propagation throughout thereaction volume.NOTE 1Tolerance is 60.010 in., unless noted.NOTE 2Break all sharp edges.NOTE 3Material is Type 304 stainless steel.NOTE 4Thread depth is 75 to 80 %.NOT
21、E 51 in. = 25.4 mm.FIG. 1 Electrode Assembly (I)E582 07 (2013)124.2 Electrode Assembly:4.2.1 The electrodes (Fig. 1) have metal tips flanged withglass plates. The tips screw into18-in. stainless steel rodswhich extend through inserts in the bomb walls to permitexternal electrical connections. Gas se
22、als are provided betweenthe reaction vessel and the inserts and between the inserts andthe18-in. rods by O-ring seals (see Fig. 2, Assembly). Theglass flange material should be either borosilicate or high silicaand the flanges should be fastened to the stainless steel tipswith a thin layer of epoxy
23、cement. The facing surfaces shouldbe planar and coplanar to 0.001 in. (0.025 mm) or 1 % of theintended test gap, whichever is larger.4.2.2 Two inserts are required to carry the18-in. rodsthrough the walls of the reaction vessel. At least one of theseinserts must be made of high-electrical resistivit
24、y insulatingmaterial. Hard rubber, phenolic plastic, poly(methyl methacry-alate) (PMMA), and many other materials are suitable for usewith the alkane and alkene fuels. In the excepted cases (othersimilarly energetic fuels), the insulating material must not reactwith or absorb the fuel being tested.N
25、OTE 1Tolerance is 60.010 in., unless noted.NOTE 2Break all sharp edges.NOTE 3Material is Type 304 stainless steel.NOTE 4Thread depth is 75 to 80 %.NOTE 51 in. = 25.4 mm.FIG. 2 Electrode Assembly (II).E582 07 (2013)134.2.3 Where the test arrangement is optimized through theuse of a “double-ended powe
26、r supply, (see Fig. 3(b) twoinsulating inserts are required. Otherwise, one of the insertsmay be machined from Type 304 stainless steel.4.2.4 Insulation between the two electrodes should exceed1012 as discussed in 4.3.3.4.2.5 Measurement of the gap width is made by availabletechniques and implements
27、 most suitable for the gap distancebeing measured. Calibrated leaf gages, inside micrometers, orvernier calipers are suitable, depending upon the gap distance.The measurements should be made with a repeatability of60.001 in. (0.025 mm) or 1 %, whichever is most conserva-tive. To facilitate such meas
28、urements, it is helpful to have leafgages of known thicknesses for frequently used gap distances.High-quality machinists micrometers will generally provideadequate accuracy.4.3 Power Supply and Electrical Circuit:4.3.1 The power supply should be of the oscillator type, sothat its filter condensers w
29、ill be electrically small. The maxi-mum output current should be about 1 mA. (WarningWithsuch a power supply, the probability of lethal shock to theoperator from the high-voltage circuits becomes negligible.However, all usual and normal hazards to personnel will existon the 60-Hz supply, main-side o
30、f the power supply.)4.3.2 The power supply can be single-side with one high-voltage output terminal and one low-voltage, neutral, or groundterminal (see Fig. 3(a).Alternatively, the power supply may bedouble-ended with two high-voltage output terminals, onenegative and one positive, together with a
31、center-tappedgrounding or neutral connection (see Fig. 3(b). For maximumtesting flexibility, the power supply should deliver variable oradjustable output voltage differences between 1 and 30 kV.NOTE 1The double-ended power supply should be used only inconjunction with two insulating inserts. The met
32、al bomb structure mustthen be connected to the power supply center point and connected tosystem ground. The double-ended power supply gives somewhat highergap breakdown voltages at larger spark gaps and, thus, somewhat lowerignition energies. This consideration should be of importance only if thever
33、y highest quality data are required.4.3.3 The output filter capacitors of the power supply mustbe isolated from the discharge energy storage capacitance byan isolating resistor. The resistive-capacitive time constant ofthe charging circuit containing the energy storage capacitanceshould be several s
34、econds; 1012 is a desirable value for themost easily ignitable mixture (energy storage capacitance of 8to 12 pF) with the value reduced inversely as the energystorage capacitance is increased for less easily ignitable mix-tures. Two resistors should be used in series, four with thedouble-ended suppl
35、y. One resistor shall be immediately at thepower supply terminal, the other at the bomb energy storagecapacitance. Supply-line electrical insulation needs to begreater than 1014 to be consistent with 1012 seriesresistance. Such resistance is most easily achieved through airinsulation with appropriat
36、ely rounded corners to reduce coronalosses.4.4 Measurement of Energy Storage CapacitanceThe en-ergy storage capacitance may be measured with a high-qualitycapacitance meter capable of accurate measurement in therange of 5 pF, or greater, capacity. Lower frequency instru-ments are generally preferred
37、, since problems of lead lengthNOTE 1Distributed capacitance must be considered as part of the energy storage capacitance.NOTE 2See 4.3 for component value guidelines.FIG. 3 Connections of Single and Double-Sided Power Supply in Circuit.E582 07 (2013)14and spurious readings are minimized. If the cap
38、acitance meteris nulled with the test probe at some distance from the bomb,proximity effects will be observed as the test probe is broughtcloser to the bomb and energy-storage capacitance. Theseproximity effects must be nulled out to achieve accurate energystorage capacitance determinations.4.5 Meas
39、urement of Energy Storage VoltageEnergy stor-age voltage cannot ordinarily be measured with an electrostaticvoltmeter for the most easily ignitable mixtures, since themeter capacitance will probably exceed the desired energystorage capacitance. In these instances, energy storage voltagemust be measu
40、red with an electrometer voltmeter used inconjunction with a voltage divider network. Total resistance ofthe divider network should be at least 1014.4.6 Gas-Handling SystemPlumbing for the gas-handlingsystem should be of stainless steel. A vacuum gage in thesystem is necessary and access to ambient
41、temperature andbarometric data is desirable. Gas shut-off valves should be ofgood quality and suitable to the service.5. Safety Precautions5.1 If the recommendations of 4.3 are followed, there are nohigh-voltage hazards. The normal 60-Hz supply line hazardsexist as always when equipment is operated
42、from such lines. Inthe interest of stability, it is desirable to have the high-voltagepower supply and electrometer voltmeter turned-on continu-ously during a normal working period. In this case, the voltageoutput control of the power supply should be turned to itsminimum value except during the act
43、ual test. The two sparkelectrodes should be shorted together by two clips and a shortpiece of flexible braid. If two insulating inserts are used (4.2),the center of the braid should be connected to the metal of thereaction vessel.5.2 Normal pressure vessel problems exist, therefore, thesight glass m
44、ust be in good condition and adequately seated;and the bolts holding the two parts of the bomb together andthe insert-retaining rings must be in place and tightened. Caremust be given to the preparation of the gas mixture. The twocomponents must not be permitted to mix in the supply lines,both for r
45、easons of personnel safety and to ensure a mixture ofknown composition.6. Preparation of Apparatus6.1 Clean the test vessel to remove residues from previoustests or if required by 6.2.6.2 Verify that the insulation resistance of high-voltageelectrode(s) to the reaction vessel walls is at least 1012
46、.Disassemble and clean if required.6.3 Set up the desired test gap in the reaction vessel.6.4 Determine the desired energy storage capacitance (seeSection 8) and set up this value with calibrated electricalcapacitors rated for the anticipated test voltage. The smallervalues of capacitance should be
47、trimmed with lengths of wireor metal rods.7. Procedure7.1 Evacuate the reaction vessel to absolute pressures below10 mmHg (13.33 Pa).7.2 Load the desired gas mixture, as determined from thecalculations, observing the necessary safety considerations ofSection 5. First, add the minor constituent (fuel
48、) to the desiredpartial pressure of fuel. Close the main valve to the reactionvessel and evacuate the supply lines. Introduce the majorcomponent (air) into the supply lines to a pressure greater thanthat of the fuel in the reaction vessel. Open the main valve andfill the reaction vessel to the desir
49、ed total pressure, then closethe main valve.NOTE 2This method of mixing, in conjunction with the mixing orificein the reaction vessel of Section A-A of Fig. 2, offers maximum uniformityand accuracy in the prepared gas mixture. When used to preparevapor-oxidizer mixtures, this method minimizes the possibility of vaporcondensation.NOTE 3Experimenters desiring to use other techniques of mixturepreparation and sample injection should bear the responsibility of estab-lishing the adequacy of those techniques.7.3 Remove the electrode shunting
copyright@ 2008-2019 麦多课文库（www.mydoc123.com）网站版权所有
备案/许可证编号：苏ICP备17064731号-1