User Guide to Thresholds and Classification - Environmental ...

51User Guide for Thresholds and Classifications6.1.2. Classification criteria for flammable solids subclass 4.1.1There are two classification categories to subclass 4.1.1, easily ignitable, readily combustible flammablesolids and solids that may cause fire through friction. The criteria for inclusion in these categories are asfollows.Category A (medium hazard) – classification 4.1.1A (equivalent to UN PG II)a. Any readily combustible solid (other than a metal powder) that, when tested in accordance withsection 33.2.1.4 (burning rate test of Test Series N.1) of the UN Manual of Tests and Criteria, has aburning time of less than 45 seconds and the flame passes the wetted zone.b. Any metal powder or metal alloy powder for which the zone of reaction spreads over the wholelength of the sample in five minutes or less, when tested in accordance with section 33.2.1.4(burning rate test of Test Series N.1) of the UN Manual of Tests and Criteria.c. A substance listed in the Dangerous Goods List in chapter 3.2 of the UN Model Regulationsnumbered UN 1343 (phosphorus trisulphide).d. Any other substance that may cause fire through friction, and has a similar degree of flammability tothe foregoing UN numbered substances in (c) above (that is, where the amount of friction required tocause ignition, when tested in accordance with Test Series 3(b) (para 13.5, UN Manual of Tests andCriteria), is less than 120% of that for any of the substances in the preceding paragraph).Category B (low hazard) – classification 4.1.1B (equivalent to UN PG III)a. Any readily combustible solid (other than a metal powder) which, when tested in accordance withpara 33.2.1.4 (burning rate test of Test Series N.1) of the UN Manual of Tests and Criteria, has aburning time of less than 45 seconds and the wetted zone stops the flame propagation for at least 4minutes.b. Any metal powder or metal alloy powder for which the reaction spreads over the whole length of thesample in more than 5 minutes but not more than 10 minutes, when tested in accordance withsection 33.2.1.4 (burning rate test of Test Series N.1) of the UN Manual of Tests and Criteria.c. Any substance listed in the Dangerous Goods List, chapter 3.2, UN Model Regulations andnumbered UN 1331, 1944, 1945, or 2254.d. Any other solid that may cause fire through friction, and has a similar degree of flammability to theforegoing UN numbered substances in (c) above (that is, where the amount of friction required tocause ignition, when tested in accordance with Test Series 3(b) (para 13.5, UN Manual of Tests andCriteria), is less than 120% of that for any of the substances in the preceding paragraph).6.1.3. DiscussionThreshold for flammable solidsThe HSNO Act threshold criteria are equivalent to those for UN division 4.1(a) as set out in the UN ModelRegulations and UN Manual of Tests and Criteria.Correlation with United Nations Packing GroupsJanuary 2012 EPA0109