Section 173.128 - Class 5, Division 5.2-Definitions and types(a)Definition. For the purpose of this subchapter, oxidizer (Division 5.1) means a material that may, generally by yielding oxygen, cause or enhance the combustion of other materials. (1) A solid material is classed as a Division 5.1 material if, when tested in accordance with the UN Manual of Tests and Criteria (IBR, see §171.7 of this subchapter): (i) If test O.1 is used (UN Manual of Tests and Criteria, sub-section 34.4.1 ), the mean burning time is less than or equal to the burning time of a 3:7 potassium bromate/cellulose mixture; or(ii) If test O.3 is used (UN Manual of Tests and Criteria, sub-section 34.4.3 ), the mean burning rate is greater than or equal to the burning rate of a 1:2 calcium peroxide/cellulose mixture.(2) A liquid material is classed as a Division 5.1 material if, when tested in accordance with the UN Manual of Tests and Criteria, it spontaneously ignites or its mean time for a pressure rise from 690 kPa to 2070 kPa gauge is less then the time of a 1:1 nitric acid (65 percent)/cellulose mixture.(b)Assignment of packing groups.(1) The packing group of a Division 5.1 material which is a solid shall be assigned using the following criteria:(i) Packing Group I, for any material which, in either concentration tested: (A) If test O.1 is used (UN Manual of Tests and Criteria, sub-section 34.4.1 ), the mean burning time is less than the mean burning time of a 3:2 potassium bromate/cellulose mixture; or(B) If test O.3 is used (UN Manual of Tests and Criteria, sub-section 34.4.3 ), the mean burning rate is greater than the mean burning rate of a 3:1 calcium peroxide/cellulose mixture.(ii) Packing Group II, for any material which, in either concentration tested: (A) If test O.1 is used (UN Manual of Tests and Criteria, sub-section 34.4.1 ), the mean burning time is less than the mean burning time of a 2:3 potassium bromate/cellulose mixture and the criteria for Packing Group I are not met; or(B) If test O.3 is used (UN Manual of Tests and Criteria, sub-section 34.4.3 ), the mean burning rate is greater than the mean burning rate of a 1:1 calcium peroxide/cellulose mixture and the criteria for Packing Group I are not met.(iii) Packing Group III for any material which, in either concentration tested: (A) If test O.1 is used (UN Manual of Tests and Criteria, sub-section 34.4.1 ), the mean burning time is less than the mean burning time of a 3:7 potassium bromate/cellulose mixture and the criteria for Packing Groups I and II are not met; or(B) If test O.3 is used (UN Manual of Tests and Criteria, sub-section 34.4.3 ), the mean burning rate is greater than the mean burning rate of a 1:2 calcium peroxide/cellulose mixture and the criteria for Packing Groups I and II are not met.(iv) The materials is not classified as a Division 5.1 material if, in either concentration tested: (A) If test O.1 is used (UN Manual of Tests and Criteria, sub-section 34.4.1 ), the sample tested does not ignite and exhibit burn, or exhibits a mean burning time of greater than or equal to the mean burning time of a 3:7 potassium bromate/cellulose mixture.(B) If test O.3 is used (UN Manual of Tests and Criteria, sub-section 34.4.3 ), the sample tested does not ignite and exhibit burn, or exhibits a mean burning rate less than or equal to the mean burning rate of a 1:2 calcium peroxide/cellulose mixture.(2) The packing group of a Division 5.1 material which is a liquid shall be assigned using the following criteria:(i) Packing Group I for: (A) Any material which spontaneously ignites when mixed with cellulose in a 1:1 ratio; or(B) Any material which exhibits a mean pressure rise time less than the pressure rise time of a 1:1 perchloric acid (50 percent)/cellulose mixture.(ii) Packing Group II, any material which exhibits a mean pressure rise time less than or equal to the pressure rise time of a 1:1 aqueous sodium chlorate solution (40 percent)/cellulose mixture and the criteria for Packing Group I are not met.(iii) Packing Group III, any material which exhibits a mean pressure rise time less than or equal to the pressure rise time of a 1:1 nitric acid (65 percent)/cellulose mixture and the criteria for Packing Group I and II are not met.Amdt. 173-224, 55 FR 52634, 12/21/1990, as amended at 56 FR 66268, 12/20/1991; Amdt. 173-234, 58 FR 51532, 10/1/1993; Amdt. 173-241, 59 FR 67508, 12/29/1994; Amdt. 173-261, 62 FR 24732, 5/6/1997; 65 FR 58629, 9/29/2000; 66 FR 8647, 2/1/2001; 66 FR 45379, 8/28/2001; 68 FR 75744, 12/31/2003; 69 FR 76155, 12/20/2004; 80 FR 1156, 1/8/2015; 80 FR 72924, 11/23/2015