1、Designation: F2508 11Standard Practice forValidation and Calibration of Walkway Tribometers UsingReference Surfaces1This standard is issued under the fixed designation F2508; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year
2、 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.1. Scope1.1 This practice is intended to establish the parameters forvalidation and calibration of walkway tribometers.1.2 Thi
3、s practice provides a walkway tribometer supplierwith a procedure and suite of reference surfaces to validate hiswalkway tribometer by properly ranking and differentiating thesurfaces.1.3 This practice provides the user of a walkway tribometerwith a procedure and suite of reference surfaces to testc
4、alibration of his instrument.1.4 This practice describes the necessary materials, specifi-cations, and the cleaning process for reference materials, aswell as the requirements for the validation of a supplierswalkway tribometer and calibration of a users walkwaytribometer.1.5 This practice applies t
5、o walkway tribometers withoutreference to the nature of the scale of the readings produced bythem. The scale used in the reports of validation and calibrationmust be the same, and are to be those of the instrument ordefined for the instrument.1.6 The values stated in SI units are to be regarded asst
6、andard. The values given in parentheses are for informationonly and are not considered standard.1.7 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 p
7、ractices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D1349 Practice for RubberStandard Temperatures forTestingD3244 Practice for Utilization of Test Data to DetermineConformance with SpecificationsF1646 Terminology Relating to Sa
8、fety and Traction forFootwear3. Terminology3.1 DefinitionsFor terms used in this practice not identi-fied herein, refer to Terminology F1646.3.1.1 paired t-test, na test of statistical significance basedon the use of students t-distribution and used to compare twosample means (see Appendix X2).3.1.2
9、 supplier, nany individual, agent, company, manu-facturer, or organization responsible for the walkway tribom-eter prior to receipt by the user. D32443.1.3 test foot, nshoe bottom material or surrogatemounted on the walkway tribometer that comes into contactwith the surface being tested.3.1.4 walkwa
10、y tribometer, nany apparatus used to mea-sure the frictional forces acting at an interface between awalkway surface and shoe material.3.1.4.1 DiscussionA judgement of the adequacy of thesefrictional forces acting on a walkway surface/shoe surfaceinterface is the basis for an assessment of slip prope
11、rtiesrelative to human locomotion.3.2 Definitions of Terms Specific to This Standard:3.2.1 calibration, nthe set of operations that establishes,under specified conditions, the relationship between the valuesobtained by a walkway tribometer and the correspondingsupplier reference values.3.2.2 referen
12、ce surfaces (RSs), nspecified materials,identified in Section 7, that have an experimentally demon-strated slip properties for a select population of pedestrians andserve as references for walkway tribometer measurements.3.2.3 validation, nthe set of operations that establishes,under specified condi
13、tions, the proper ranking and differentia-tion of reference surfaces by a walkway tribometer.1This practice is under the jurisdiction of ASTM Committee F13 on Pedestrian/Walkway Safety and Footwear and is the direct responsibility of SubcommitteeF13.10 on Traction.Current edition approved March 15,
14、2011. Published March 2011. DOI:10.1520/F2508-11.2For referenced ASTM standards, visit the ASTM website, www.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 A
15、STM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4. Summary of Practice4.1 This practice establishes a procedure to: (1) validatewalkway tribometer models against a human gait-based refer-ence system, and (2) calibrate each individual walkway tri
16、bom-eters of a validated model against published suppliers refer-ence values (as defined in 9.1,Eq4).4.2 This practice provides for validation and calibration ofwalkway tribometers as a means of verifying their relationshipto reference surfaces and verifying a particular device contin-ues to produce
17、 consistent results.4.3 The method of ranking walkway surface slip propertiesusing a limited population of ambulating human subjects issupported by a peer-reviewed study.34.4 Validation consists of a series of 40 tests on eachreference surface from this practice. A walkway tribometermodel is conside
18、red valid if it ranks the four reference surfacesfrom this practice in the proper order with statistically signifi-cant differentiation between results obtained for each surface.Validation is intended to be accomplished for each walkwaytribometer model when it is initially introduced and is to beacc
19、omplished by or on behalf of the supplier and madeavailable to each user.4.5 Calibration for a specific walkway tribometer requires aseries of 16 tests on each of the reference surfaces from thispractice. A specific walkway tribometer is considered withincalibration if the bias of the mean test valu
20、es for each surfacefalls within the 95 % confidence interval for the walkwaytribometer model as established by the validation tests (asdefined in 9.1,Eq4).5. Significance and Use5.1 To be meaningful, walkway tribometer results mustcorrelate the slip characteristics of a surface or contaminant, orbot
21、h, to the actual propensity for human slips. To achieve thisgoal, walkway tribometer models must be validated against astandard with relevance to human ambulation.5.2 This practice prescribes a series of reference surfaceswith known relative slip potential ranging from very high tolow (as defined by
22、 laboratory conditions only) upon whichwalkway tribometer models can be validated. The relative slippotential of each reference surface was established from humansubject walking trials.35.3 The following should be considered in applying thevalidation and calibration obtained by this practice:5.3.1 T
23、he scientific study upon which the validation processis based was conducted with a select population of youngadults (mean age 26 years) who were free from gait deviationswhile walking in a straight path on a level surface with a meanwalking velocity of 2.18 m/s. This walking velocity is fasterthan t
24、he average walking velocity for the general populationwhich includes a much wider age range with greater variabil-ity; thus, the study sample population of pedestrians andconditions is not representative of the larger general populationof pedestrians.5.3.2 All subjects walked in Oxford-style shoes w
25、hose soleswere constructed of smooth styrene butadiene rubber (SBR)with 75A Shore hardness. The shoe style and sole material isnot representative of all combinations available in the market-place.5.3.3 The reference surfaces defined in this practice are notrepresentative of all walkway surfaces. The
26、 outcome of thevalidation practice reflects performance on the type of refer-ence surfaces and surface conditions defined in this practiceonly. Validation and calibration of a walkway tribometer asdefined by this practice does not imply validation and calibra-tion under all combinations of test foot
27、 materials and walkwaysurfaces.5.3.4 The validation and calibration procedure defined bythis practice is not intended to establish a “safe threshold”value for any walkway surface.6. Apparatus6.1 The walkway tribometer shall be free of defects andoperational throughout its range. Refer to the walkway
28、 tribom-eter instruction manual to ensure proper operation and instru-ment condition before the validation and calibration process.6.2 Test Foot Designation and Condition:6.2.1 The supplier must provide test foot material, dimen-sion, storage, and service life specifications. The specificationsshall
29、 be sufficient to permit procurement of an exemplar testfoot.6.2.2 A uniquely numbered test foot, meeting the suppliersmaterial and dimensional specifications shall be provided withthe walkway tribometer being tested.6.2.2.1 The calibration results shall apply only to the walk-way tribometer/test fo
30、ot combination tested.6.2.3 Prepare the test foot as prescribed by the walkwaytribometer supplier or by a fully documented procedure in-cluded in the validation or calibration report.7. Reference Surfaces (RSs)47.1 Reference Surfaces:7.1.1 RS APolished black granite whose surface beneaththe test foo
31、t is covered with a continuous film of 0.04 % byvolume solution of Triton X-1005(nonionic surfactant) indistilled water (that is, 200 L of Triton X-100 per 500 mL ofdistilled water).7.1.2 RS BPorcelain whose surface beneath the test foot iscovered with a continuous film of distilled water.7.1.3 RS C
32、Vinyl composition tile whose surface beneaththe test foot is covered with a continuous film of distilled water.7.1.4 RS DCeramic whose surface beneath the test foot iscovered with a continuous film of distilled water.7.2 Each RS shall be permanently marked to designate itsreference class (that is, “
33、A”, “B”, “C”, “D”).3Powers, C. M., Brault, J. R., Stefanou, M. A., Tsai, Y. J., Flynn J., andSiegmund, G. P., “Assessment of Walkway Tribometer Readings in Evaluating SlipResistance: a Gait-Based Approach,” Journal of Forensic Sciences, Vol. 52 , No.2, March 2007, pp. 400405.4Available from ASTM Int
34、ernational Headquarters. Order Adjunct No.ADJF2508. Original adjunct produced in 2011.5The sole source of supply of the apparatus known to the committee at this timeis Gallade Chemical, Santa Ana, CA. If you are aware of alternative suppliers,please provide this information to ASTM International Hea
35、dquarters. Your com-ments will receive careful consideration at a meeting of the responsible technicalcommittee,1which you may attend.F2508 1127.3 Reference surfaces shall be stored in a manner thatprevents deformation and contamination.7.4 Reference surfaces should not be used for validation orcali
36、bration testing after 5 years from date of purchase.8. Procedure8.1 EnvironmentThe validation and calibration test shallbe performed at a humidity level of 50 6 5 % and atemperature range of 23 6 2C (73.4 6 3.6F) (derived fromPractice D1349).8.2 Reference Surface PreparationThe reference surfaceshal
37、l be free from visible dents, cracks, voids, or othersignificant blemishes.8.2.1 Cleaning:8.2.1.1 No surface treatment except as specified in thissection is permitted.8.2.1.2 Prepare a 0.05 % by volume solution of liquidsodium lauryl sulfate in distilled water (that is, 250 L ofsodium lauryl sulfate
38、 per 500 mL of distilled water).8.2.1.3 Dip a clean soft-bristled nylon brush in the cleaningsolution and gently scrub in a circular pattern the entirereference surface for a minimum of 10 s. Reapply the cleaningsolution and repeat the minimum 10-s scrubbing two times.8.2.1.4 Rinse the surface thoro
39、ughly with distilled water,ensuring that no visible suds or soap residues remain.8.2.1.5 Dry the surface with dry and oil-free compressed airor air dry if compressed air is not available. The referencesurface shall exhibit no visible moisture film or droplets.8.2.1.6 Prepare an ethanol solution cont
40、aining equal partsdenatured ethanol in distilled water.8.2.1.7 Dip a clean soft-bristled nylon brush, different fromthat used in 8.2.1.3, in the ethanol solution and gently scrub thereference surface for 10 s.8.2.1.8 Dry the reference surface with dry and oil-freecompressed air or air dry if compres
41、sed air is not available.Any visible contamination remaining after this step willdisqualify the reference surface for use.8.2.1.9 Ensure that handling of the reference surface doesnot introduce contaminants to the surfaces, including exposingthe surfaces to contact of human skin.8.2.1.10 The cleanin
42、g procedure should be performed be-fore each testing session.8.3 Reference Surface MountingMount the reference sur-face onto a flat and rigid substrate that prevents movement ofthe reference surface parallel to the test plane of the walkwaytribometer during testing. Select a substrate that will notd
43、eform during wet testing.8.4 Walkway Tribometer Validation TestingUsing thewalkway tribometer being validated and the test foot preparedin 6.2.3, perform 40 tests in accordance with a uniquelyidentifiable version of the walkway tribometer suppliers op-erating instructions or any other formal procedu
44、re in the testarea of each of the four reference surfaces that have beenprepared in accordance with 8.2. Of the 40 tests, perform 10 ineach of 4 orthogonal directions, that is, at 0, 90, 180, and 270relative to an arbitrarily defined direction on the referencesurface. Record the results of all tests
45、 as specified in Section10.9. Analysis of Results and Walkway TribometerValidation9.1 For the 40 tests on each reference surface, calculate themean ( X ), standard deviation (SD), standard error (SE)ofthemean, and 95th percentile confidence interval (CI) for thewalkway tribometer test results for ea
46、ch reference surfaceusing Eq 1 through Eq 4, respectively:X 51n(i51nxi! (1)where:n = number of measurements (40), andxi= test resultSD 51n 1(i51nxi x!2(2)SE 5SD=n(3)95th percentile CI 5 X 6 1.96 3 SE!5 X 1.96 3 SE! to X 1 1.96 3 SE! (4)9.2 A valid walkway tribometer must properly rank thefriction be
47、tween the test foot and reference surfaces andprovide a statistically unique slip resistance measure for eachsurface. A valid walkway tribometer model shall satisfy thefollowing two compliance criteria:9.2.1 Rank OrderThe rank order of the mean walkwaytribometer results for each reference surface sh
48、all be the sameas shown in Appendix X1.9.2.2 DifferentiationUsing the mean and standard devia-tion, paired t-tests as described in Appendix X2 shall producesignificantly different results (p 0.05) for all adjacentlyranked reference surfaces (that is, between RS A and RS B, RSB and RS C, and RS C and
49、 RS D).9.3 Failure to meet the two validation criteria shall beconsidered an unsatisfactory result. The suppliers guidelinesfor troubleshooting shall be followed, and the walkway tribom-eter validation repeated. If the results are still not satisfactory,the walkway tribometer fails the validation.10. Walkway Tribometer Validation Report10.1 The report shall include information about the walk-way tribometer, test foot, reference surfaces, test procedure,and analysis method to allow the validation testing to bereproduced. The report shall i
