1、 Tentative Interim Amendment NFPA69 Standard on Explosion Prevention Systems 2014 Edition Reference: 7.2.3.1.2, 7.2.3.1.1(new), A.3.3.25, and Table C.1(a) TIA 14-1 (SC 16-4-9 / TIA Log #1211) Pursuant to Section 5 of the NFPA Regulations Governing the Development of NFPA Standards, the National Fire
2、 Protection Association has issued the following Tentative Interim Amendment to NFPA 69, Standard on Explosion Prevention Systems, 2014 edition. The TIA was processed by the Technical Committee on Explosion Protection, and was issued by the Standards Council on April 6, 2016, with an effective date
3、of April 26, 2016. A Tentative Interim Amendment is tentative because it has not been processed through the entire standards-making procedures. It is interim because it is effective only between editions of the standard. A TIA automatically becomes a public input of the proponent for the next editio
4、n of the standard; as such, it then is subject to all of the procedures of the standards-making process. 1. Revise Subparagraph 7.2.3.1.2 to read as follows: 7.2.3.1.2 For gases and vapors, if the LOC values according to ASTM E 2079 are not available, then the LOC values obtained in flammability tub
5、es shall be used after adjustment by subtracting 1.5 2 percent by volume oxidant for LOC values of 10 percent or greater and by multiplying by a factor of 0.85 for LOC values less than 10 percent, as indicated in the adjusted columns in Table C.1(a). 2. Add new Subparagraph 7.2.3.1.3 to read as foll
6、ows: 7.2.3.1.3 In no case shall the adjusted LOC value for carbon dioxide inerting result in a value lower than that required for nitrogen inerting. 3. Revise Annex A.3.3.25 to read as follows: A.3.3.25 Limiting Oxidant Concentration (LOC). Materials other than oxygen can act as oxidants. The LOC de
7、pends upon the temperature, pressure, and fuel concentration as well as the type of diluent. Preliminary results of the ASTM E 2079, Standard Test Methods for Limiting Oxygen (Oxidant) Concentration in Gases and Vapors, round robin tests for gases and vapors revealed that the LOC data that were obta
8、ined using different test methods and that are listed in a majority of reference publications are nonconservative. The old Bureau of Mines data were obtained mostly in a 50 mm diameter flammability tube. This diameter might be too small to mitigate the flame-quenching influence, thereby impeding acc
9、urate determination of the LOC of most fuels. The 4 L minimum volume specified in ASTM E 2079 would correspond to a diameter of at least 200 mm (7.9 in.). As a result, some LOC values determined using this standard are approximately 1 percent by volume oxygen lower than the previous values measured
10、in the flammability tube, and a few are even up to 1.5 2 percent by volume lower. The lower LOC values obtained in larger chambers are more appropriate for use in fire and explosion hazard assessment studies. A data comparison can be found in Table A.3.3.25. 4. Replace Table C.1(a) and associated notes with the following: Issue Date: April 6, 2016 Effective Date: April 26, 2016 (Note: For further information on NFPA Codes and Standards, please see www.nfpa.org/codelist) Copyright 2016 All Rights Reserve NATIONAL FIRE PROTECTION ASSOCIATION
