1、Designation: F2866 10Standard Test Method forFlammability of a Membrane Switch in Defined Assembly1This standard is issued under the fixed designation F2866; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision
2、. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of the flam-mability characteristics of a membrane switch.1.2 This test method defines th
3、e MSB rating of a membraneswitch. Each character of the MSB rating represents a discretecharacteristic of a membrane switch performance under de-structive thermal loading.1.3 This test procedure will be destructive, but shouldprovide an insight into the relative performance flame-resistance characte
4、ristics of differing designs or assemblies, orboth.1.4 This test method will focus on the use of convectivecontact (burner flame) method for ignition, though othermethods of ignition are available.1.5 This test method is designed to determine if the mem-brane switch assembly will add (or detract) fr
5、om the flamepropagation from an exterior flame/fire source.1.6 If this test is intended to be used for an internalflammability source then set up the unit under test (UUT)appropriately and note it in the test scope and results.1.7 This standard does not purport to address all of thesafety concerns,
6、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 limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E906 Test Method for Heat and Visible Smoke R
7、eleaseRates for Materials and Products Using a ThermopileMethod3. Terminology3.1 Definitions:3.1.1 burn damagepercentage of the UUT that is dam-aged due to burn test. This is a visiual observation.3.1.2 flame propagationrefers to patterns in the flamefront that are examined (for example, uniform rat
8、e of advance,spotty ignition or charring, etc.). These observations arequalitative and should be noted in the data field.3.1.3 flame spread rate (FSR)described as the rate atwhich a flame front will travel along the surfaces of testedmaterials/assemblies. Typically measured in mm/s or in./min.3.1.4
9、flame target arearefers to the normalized target areaof a UUT that will be used for ignition location.Any variationsshould be noted.3.1.5 flame time (Ftime) or flame enduranceamount oftime, usually in seconds, that a self-sustaining flame willendure after removal of initial ignition source before fl
10、ame onUUT is extinguished.3.1.6 flame time of drippings (Ftime,drip)amount of timethat burning drippings, if any, remain burning. Typicallymeasured in seconds.3.1.7 gauze ignitionthis is a verification that UUT ignitesthe gauze.3.1.8 ignition sourcethe source that provides the heat-fluxto begin the
11、flammability test. This test method will recom-mend a convective flame for the ignition source, however, careshould be taken that any comparative tests should use the samemethod of ignition.3.1.9 mass-loss (mloss)the mass from a test specimen itlost to smoke, vaporization and char debris carried awa
12、y orfallen away, or both, during the flammability test cycle.Typically measured in grams (average).3.1.10 membrane switch assemblythe membrane switchshould not be tested in its unmounted state. The switch sampleshould be mounted onto the final end-use enclosure, panel,bezel, or agreed upon material.
13、1This test method is under the jurisdiction of ASTM Committee F01 onElectronics and is the direct responsibility of Subcommittee F01.18 on MembraneSwitches.Current edition approved Dec. 1, 2010. Published January 2011. DOI: 10.1520/F2866-10.2For referenced ASTM standards, visit the ASTM website, www
14、.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.1.1
15、0.1 DiscussionAssembly Specimen: This test methodis trying to provide a practical world analog for the resultsherein obtained. As a result, the unit under test (UUT) must inthe final mounted condition. The test is able to show flame-resistance in the final assembly as it interacts with themembrane s
16、witchs construction.3.1.11 MSBrating to quantify the burn characteristics of amembrane switch. Each character of the MSB rating representsa discrete characteristic of a membrane switch performanceunder destructive thermal loading. (see Table 1.)3.1.12 time-to-ignition (tign) the time it takes for a
17、targetspecimen to “ignite” under thermal loading with a self-standingflame front. The method for ignition (source) can be conduc-tive contact (super-heated filament), radiant energy (electricalor gas) or convective (free flame). Typically measured inseconds.3.1.12.1 DiscussionA “perfect” incombustib
18、le materialwill have infinite time to ignition; similarly a UUT with nosustained flame within the length of the ignition exposurewould be reported as “no ignition time observed”.3.1.12.2 DiscussionUsing a convective (free flame) igni-tion source the time to ignition may be difficult to determine(due
19、 to the fact that there is interference between the ignitionsource and the ignition of the UUT).4. Significance and Use4.1 There are numerous flammability ratings and tests.Almost without fail, these standards and tests are focused onvery specific industries or results, many of which are notapplicab
20、le to the membrane switch/human machine interfaceassembly. This test is designed to provide relative resultsbetween membrane switches that have been assembled to theunits final enclosure, housing, etc.4.2 In addition to the tests measurement of the rate of burn,a laboratory can also observe the effe
21、cts of burning materialfalling from the test specimen onto other materials (typically agauze test area) not directly part of the test specimen. Theindirect burning is an issue of interest to see if the testspecimen will be able to act as an initiator for a far greater andmore damaging flame event (f
22、ire). Observations should benoted, as qualitative descriptions, as appropriate.4.3 This test can measure the flammability via the use ofhigh-speed photographic or video equipment.4.4 Temperature of the ignition source can be measured viaa calibrated thermocouple pyrometer, calorimeter or IR ther-mom
23、eter with an appropriate range.4.5 This test is not designed to provide a PASS or NO PASSstatus for a switch, rather, it is designed to provide a “grade”for the level of flammability of a membrane switch assembly(as defined in 3.1.10). The end user should make the finaldetermination if the level of
24、flammability is acceptable for theparticular application.5. Interferences5.1 Method of IgnitionResults compared between differ-ent methods of ignition (radiant versus convective) mayprovide different results for tign. Therefore any comparativesamples should use the same calibrated method of ignition
25、.5.2 Mounted in Final AssemblyMounting the membraneswitch to the end use substrate or enclosure will account for thethermal heat sink effect provided by the mounting substrate orenclosure.5.3 Rigid Fixture SupportThe membrane switch assemblyshould have rigid fixture support in order to allow remotet
26、esting during the burn cycle. UUT should be mounted toinsure that the parts to do not fall while under test.5.4 Venting of the FPA Test BoothThe type and placementof venting and exhausting for airflow in test booth should benoted or documented by photos or drawings, or both. Dupli-cation of test res
27、ults may be achieved only with the sameamount of air-flow and air-to-fuel mixture in the test booth.5.5 Oxygen ConcentrationThe concentration of the oxy-gen in the FPA chamber atmosphere (normal air, concentratedO2, pressurized, etc.) during the test or oxidizers, or both,found in the test material(
28、s) will affect the results.5.6 Duration of IgnitionThe longer the ignition burn testthe greater the chance the part will ignite and begin to exhibitflame propagation.5.7 Relative Humidity in FPAIt is thought this will havesome effect on the results, however the extent of which is to bedetermined.6.
29、Apparatus6.1 Fire Propagation Apparatus (FPA)Draft-free boothmade of non-flammable material (high-temp Pyrex, ceramic orsteel) rectangular or cylindrical space with proper: (1) ventila-tion for exhaust fumes, smoke, etc., (2) free empty area formounting rigs and UUT and (3) appropriate fixings andmo
30、unts, as needed for ignition source and (4) vent holes orventilation, or both, for inflow of fresh air.6.1.1 FPAmay also provide oxygen in standard sea-levelnormal air concentration, 40 % oxygen, air with pure nitrogenTABLE 1 MSB RatingModel t(ign)Time to ignition FSR Flame Spread Rate F(time)Contin
31、uation of burn m(loss)Mass loss Burn Damage % Gauze IgnitionThe following 0 = no ignition 0 = no burn 0 = self extinguishing 0 = no loss 0=0%damage 0 = noshould be 1 = 10 s 1=1mm/s 1=1s 1=10%loss 1=10%damageconsidered 2=9s 2=2mm/s 2=2s 2=20%loss 2=20%damagewhen deciding 3=8s 3=3mm/s 3=3s 3=30%loss 3
32、=30%damageonaswitch 4=7s 4=4mm/s 4=4s 4=40%loss 4=40%damageMSBrating 5=6s 5=5mm/s 5=5s 5=50%loss 5=50%damage6=5s 6=6mm/s 6=6s 6=60%loss 6=60%damage7=4s 7=7mm/s 7=7s 7=70%loss 7=70%damage8=3s 8=8mm/s 8=8s 8=80%loss 8=80%damage9=2sorless 9=veryveryfastburn 9=9s 9=90% 9=90%ormore 9=yesF2866 102or mixtu
33、res of gaseous suppression agents. These are alloptional and should be recorded.6.1.1.1 Example FPA Test BoothOhio State University(OSU) rate of release apparatus may be used for radiant fluxignition tests, as described below. This is a modified version ofthe rate of heat release apparatus standardi
34、zed by Test MethodE906. See Fig. 1.6.2 Mounting DeviceSteel mount stand to hold measuringprobe securely and provide orthogonal (for horizontal andvertical) and angled (45 or defined angle from vertical)mounting of UUT with respect to ignition source. See 5.3 ifneeded.6.3 Ignition SourceTo provide th
35、e heat flux needed toinitiate flame propagation. The source may be conductive,convective or radiant and should be mounted on a swing-outstand so that the ignition source (such as a burner) may beswung out of position for warm up prior to the test under theUUT.6.3.1 Conductive Ignition SourceExample:
36、 Tungsten wirefilament, AWG #20 or greater, with proper electrical input toachieve a 3000K (4940.3F) surface temperature.6.3.2 Convective Ignition SourceExample: Bunsen burnerwith a nominal 0.375 in. (9.5 mm) inside diameter tubeadjusted to give a free-standing flame 1.5 in. (38.1 mm) high.The minim
37、um flame temperature measured by a calibratedthermocouple pyrometer in the center of the flame must be1120K (1556F).6.3.3 Radiant Ignition SourceExample: A radiant heatsource incorporating four (4) Type LLsilicon carbide elements,20 in. (508 mm) long by 0.63 in. (16 mm) outside diameter.The heat sou
38、rce should have a nominal resistance of 1.4 V andbe capable of generating a radiant flux of $100 kW/m2,oratungsten-quartz external isolated heat element that can providea radiant flux of $65 kW/m2.6.4 Photographic / Video Monitoring Equipment capableof making visual recording of the burn test. A cal
39、ibration stripor grid should be mounted in the visual focal plane so that therate of flame advance or flame spread-rate, (flammability) canbe measured in mm/s or in./min.6.5 Timing DeviceStop watch or other timing device inseconds or minutes of elapsed test time for UUT. It must beused to measure th
40、e time of application of burner flame to UUTand self-extinguishing time or test duration, or both.6.6 Temperature Measuring Device, radiant flux meter,calorimeter, thermocouple pyrometer or IR pyrometer of suit-able ranges, as required depending on ignition source set upused.6.6.1 Thermocouple Pyrom
41、etersThermocouples suitablefor testing the thermal output of the ignition flame. Theseshould be 0.0625 in. (1.6 mm) to 0.125 in. (3.18 mm) metalsheathed, ceramic packed, type K, grounded thermocoupleswith a nominal 22 to 30 AWG conductors.6.6.2 CalorimeterCalorimeter must be a 0-17.0 W/cm2(0-15.0 BT
42、U/ft2-s) calorimeter, accurate to within 63%.6.7 Data RecordingSuitable calibrated instrument with anappropriate range to measure and record the outputs of thecalorimeter and thermocouples.6.8 Weight ScaleWeighing device, capable of measuringthe mass (weight) of the UUT. The part may be weighed befo
43、reand after flammability test or a continual weighing system maybe used to provide real-time mass changes during test. Thescale should be accurate to 61g.6.9 GauzeCotton, a supply of (absorbent) 100 % un-treated cotton. First Aid Steri Pad (4 by 4 in. 12 ply sterile 100% cotton pad constructed of fi
44、ne mesh USP Type VII gauze).7. Procedure7.1 Pre-Test Setup:7.1.1 Precondition membrane switch assembly until ap-proximation of steady-state condition is achieved. UTT mustbe conditioned at 77 6 20F (25 6 10C) 55 % 6 10relative humidity for a minimum of 24 h before testing. UUTshall remain in this co
45、nditioned state up to being placed in FPAfor flammability testing.7.1.2 Weigh UUT just prior to test.7.1.3 Calibrate ignition source with NIST traceable measur-ing devices, as appropriate: radiant flux meter, calorimeter,thermocouple pyrometer or IR pyrometer.FIG. 1 Typical FPA Test BoothF2866 1037.
46、1.4 Ensure that the test specimen (unit under test, UUT) ismounted securely onto the rigid substrate or enclosure. It willbe mounted on the final application using the same manner andmaterial(s) of attachment as the final product. The entireassembly should then be securely fixed into position by mea
47、nsof nonflammable clamps or spring grips.7.1.4.1 Vertical TestUUT should be mounted verticallyabove ignition source; see Fig. 2.7.1.4.2 Horizontal TestUUT should be mounted horizon-tally (90 orthogonal plane) directly above ignition source; seeFig. 3.7.1.4.3 Angle TestUUT should be mounted at the de
48、finedangle from the direction of the ignition source; see Fig. 4. Allangles are approximate.7.1.5 Clamp UUT in test fixture and position desired.7.1.6 Position test Bunsen burner under center of the des-ignated flame target area of UUT switch assembly (X-Ylocation). Burner is in “off” (cold) state.7
49、.1.7 Position Bunsen burner at the appropriate height(Z-direction) under flame target area of the UUT. Burner is in“off” (cold) state.7.1.8 Swing the Bunsen burner out of position from underUUT and ignite. Burn for approximately 2 min to allow it tocome up to steady state.NOTE 1Calorimeter should read 11.9 6 0.6 W/cm2(10.5 6 0.5BTU/ft2-s). Thermocouple should read 1556 6 36F.7.1.9 Position clean white gauze below UUT for target onburn drippings, as applicable.7.2 In-Process Test:7.2.1 Vertical, Horizontal or Angle Test:7.2.1.1 A
