IATA DGR 67th Ed. Section 3.10 — Rules for determining primary/subsidiary hazards and packing groups (PG) for substances with multiple hazardous properties, Table 3.10.A Precedence of Hazards, Section 3.11 transport of samples, and Section 3.12 classification of articles containing dangerous goods.
3.10 Classification of Substances with Multiple Hazards
If a substance is not specifically listed by name in Subsection 4.2 Dangerous Goods List and possesses more than one hazard, the primary and subsidiary hazards must be determined according to the criteria in this section.
Class 1 (explosives), 2 (gases) and 7 (radioactive), as well as Division 5.2 (organic peroxides) and 6.2 (infectious), are outside the scope of Table 3.10.A — these classes always take precedence.
3.10.1 Using the Precedence of Hazards Table
3.10.1.1 Application
- Identify the two (or more) hazards of the substance.
- Find the relevant row (primary candidate) and column (secondary candidate) in Table 3.10.A.
- The class/division at the intersection point = primary hazard. The other = subsidiary hazard.
- PG: the Roman numeral at the intersection (I, II, III) = the most stringent PG applies.
- Proper shipping name: select the most appropriate n.o.s. entry under the primary hazard class/division from Table 4.1.A.
3.10.1.2 Packing Group (PG)
The most stringent PG applies — the lowest value among the PG values from the substance's different hazards (PG I > PG II > PG III) prevails.
3.10.1.3 Proper Shipping Name
Once the primary hazard is determined via Table 3.10.A, the proper shipping name should be the most appropriate n.o.s. entry under the relevant class/division in Table 4.1.A (see 4.1.3.2).
3.10.2 Exceptions — Outside the Scope of Table 3.10.A
The following classes/divisions are not covered by Table 3.10.A — they always take precedence:
Explosives, gases, radioactive — always take precedence (except 3.10.3)
Organic peroxides and infectious substances (see also 3.10.5)
Division 4.1 self-reactive + solid desensitized explosives
Substances spontaneously combustible in air
Highly toxic by inhalation — however, when intersecting with Class 8, LC50 and PG rules apply
Liquid desensitized explosives
Table 3.10.A — Precedence of Hazards and Packing Groups
This table covers multiple-hazard cross-references between Class 3, 4, 5.1, 6.1, and 8.
- Row = primary hazard candidate (class + PG)
- Column = subsidiary hazard candidate (class)
- Intersection = primary hazard class/division + applicable PG (Roman numeral I/II/III)
- "—" = impossible combination
- l = liquid, s = solid, i = inhalation, d = dermal, o = oral
- * = excluding Division 4.1 self-reactive; excluding Class 3 desensitized explosives
- ** = for pesticides, the primary hazard must be Division 6.1
Full table: DGR 67th Ed. p.197 (PNG Page 0229). This table is based on the UN Model Regulations Precedence of Hazards Table.
Special Rules (3.10.3-3.10.5)
3.10.3 — Radioactive Material
Radioactive material with additional hazardous properties is always classified as Class 7, and the additional hazard must also be identified. Excepted packages are excluded. Special Provision A130 applies to UN 3507 (Uranium hexafluoride).
3.10.4 — Magnetized Material
If a substance also meets the magnetic criteria (UN 2807), it must be identified both under its primary hazard class and as 'magnetized material'.
3.10.5 — Infectious Substances
Infectious substances (Division 6.2) with additional hazardous properties are always classified as Division 6.2; the most significant subsidiary hazard must also be identified.
3.11 Transport of Samples for Further Testing
3.11.1 Classification: If the exact hazard class is not known, a tentative hazard class, proper shipping name, and UN number must be assigned. This assignment is based on the shipper's knowledge and the Subsection 3.10 precedence table.
3.11.2 Proper Shipping Name: Where possible, the most appropriate n.o.s. entry supplemented by the word "sample" should be used (e.g. Flammable liquid, n.o.s., sample). If no n.o.s. entry is suitable, UN 3167 (gas sample, non-pressurized) from Table 4.1.A may be used.
3.11.3 Restrictions: The sample must not be classified as Class 1, or as an infectious substance under Division 6.2, or as radioactive material. Combined packaging net weight must not exceed 2.5 kg.
3.12 Classification of Articles Containing Dangerous Goods (n.o.s.)
3.12.1 Under UN 3537-3548, machinery/equipment that does not have its own proper shipping name and contains dangerous goods as residue or an integral part may be classified as Article containing dangerous goods.
Conditions:
- (a) The quantity of dangerous goods does not exceed Packing Instruction 860 limits or is in limited quantities.
- (b) The contents meet the definitions of the relevant dangerous goods class (Subsection 3.10 precedence table applies).
3.12.4 Articles containing Class 1, Division 6.2, Class 7, or radioactive material are not covered by this section. However, articles containing explosives excluded from Class 1 under 3.1.7.4 are subject to this section.
3.12.5 Articles must be assigned to the class/division of the dangerous goods they contain. The precedence of each dangerous good is determined using Table 3.10.A. Class 9 contents should be considered as a higher hazard.
3.12.6 The subsidiary hazard must cover other dangerous goods represented by the primary hazard. Column C (Table 4.2) identifies subsidiary hazard only when a single dangerous good is present. If an article contains multiple dangerous goods that could react dangerously with each other, each must be separately packaged (see 5.0.2.11(a)).
Source: IATA DGR 67th Ed., Section 3.10 (p.196-197), Section 3.11 (p.198), Section 3.12 (p.198-199). PNG Page 0228-0231.