Classification Criteria (Section 3)
IATA DGR 67th Ed. Section 3 — Detailed classification criteria for all 9 hazard classes. Includes test methods, packing group assignment rules, division criteria, compatibility groups and classification decision flowcharts based on UN Manual of Tests and Criteria.
3.0 General Principles
3.0.1 Classifying Dangerous Goods: Dangerous goods are assigned to one of 9 hazard classes (some with divisions) and, where applicable, to a packing group (I, II or III) indicating the degree of danger.
3.0.3 Packing Groups: PG I = great danger, PG II = medium danger, PG III = minor danger. Classes 1, 2, 5.2, 6.2 and 7 have no packing groups.
3.0.4 Multiple Hazards: Substances with multiple hazards are classified according to Section 3.10 Precedence of Hazards Table.
3.0.5 Shipper's Responsibility: The shipper is responsible for correctly classifying, naming and packaging dangerous goods. If uncertain, the shipper must consult the relevant national authority.
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1
3.1 — Class 1: Explosives
Definition
Explosive substances and articles which have a mass explosion hazard, projection hazard, fire hazard, minor blast hazard, or are very insensitive with a mass explosion hazard.
Divisions
1.1Mass explosion hazard
1.2Projection hazard but not mass explosion
1.3Fire hazard, minor blast or projection — not mass explosion
1.4No significant hazard beyond the package
1.5Very insensitive substances with mass explosion hazard
1.6Extremely insensitive articles without mass explosion hazard
Air Transport Restrictions
- PAX aircraft: Only Division 1.4S permitted
- CAO aircraft: Division 1.3C/G and 1.4B/C/D/E/G/S permitted
- All other divisions/groups: FORBIDDEN in air transport
Test Criteria
- UN Series 1-8 tests (UN Manual of Tests and Criteria)
- Series 6: Assignment to division via thermal stability, impact, friction tests
- 3.1.7.4 exclusion criteria: no temperature rise, no rupture, no audible report, no flash/flame, no smoke/fumes beyond package
Table 3.1.A — Compatibility Groups (A-S)
| Group | Division(s) | Description |
|---|---|---|
| A | 1.1 | Primary explosive substance |
| B | 1.1/1.2/1.4 | Article containing primary explosive without two protective features |
| C | 1.1-1.4 | Propellant or deflagrating explosive substance/article |
| D | 1.1/1.2/1.4/1.5 | Secondary detonating explosive or black powder — no initiation means |
| E | 1.1/1.2/1.4 | Article with secondary detonating explosive + propelling charge, no initiation |
| F | 1.1-1.4 | Article with secondary detonating explosive + own initiation means |
| G | 1.1-1.4 | Pyrotechnic substance or article |
| H | 1.2/1.3 | Article containing explosive + white phosphorus |
| J | 1.1-1.3 | Article containing explosive + flammable liquid/gel |
| K | 1.2/1.3 | Article containing explosive + toxic agent |
| L | 1.1-1.3 | Explosive presenting special hazard (water-activated, hypergolic, pyrophoric) |
| N | 1.6 | Extremely insensitive articles |
| S | 1.4 | Packed/designed so hazardous effects confined within package |
Classification Flowchart
- Is the substance/article designed to produce explosive effect? -> Yes -> Proceed to test series
- Test Series 1-4: Can the substance detonate/deflagrate? -> Classify to appropriate division
- Test Series 5: Thermal stability -> Assign division (1.1-1.6)
- Test Series 6: Determine compatibility group (A-S)
- Division 1.4S test: Hazardous effects confined within package?
2
3.2 — Class 2: Gases
Definition
Substances with a vapour pressure > 300 kPa at 50°C, or completely gaseous at 20°C and 101.3 kPa. Transported as compressed, liquefied, refrigerated liquefied, dissolved, or adsorbed gas.
Divisions
2.1Flammable gas: ignitable at 20°C/101.3 kPa in a mixture of ≤13% with air, or has a flammable range with air of ≥12 percentage points
2.2Non-flammable, non-toxic gas: transported at ≥200 kPa or as refrigerated liquid, not meeting 2.1 or 2.3 criteria
2.3Toxic gas: known to be toxic/corrosive to humans, or LC₅₀ ≤5,000 mL/m³ (ppm)
Air Transport Restrictions
- Division 2.3 (toxic gases): FORBIDDEN on PAX aircraft
- Division 2.1 flammable gases: quantity-limited on PAX
- Aerosols (UN 1950): classified as 2.1 or 2.2 based on flammability test
Test Criteria
- Flammability: ISO 10156 test method for gas/gas mixture ignitability
- Toxicity: LC₅₀ ≤ 5,000 mL/m³ for 1-hour rat inhalation exposure
- Gas mixture classification: LC₅₀(mix) = 1 / Σ(fᵢ / LC₅₀ᵢ) formula
- Corrosive gas mixtures: similar summation formula with TLCi values
- Hazard precedence: Div 2.3 > Div 2.1 > Div 2.2
Packing Group
Gases are NOT assigned packing groups. Transport conditions (compressed, liquefied, etc.) determine packaging requirements.
Classification Flowchart
- Is vapour pressure > 300 kPa at 50°C or completely gaseous at 20°C/101.3 kPa? -> Yes -> Class 2
- Is it toxic (LC₅₀ ≤ 5,000 ppm)? -> Yes -> Division 2.3
- Is it flammable (≤13% lower limit or ≥12% range)? -> Yes -> Division 2.1
- Otherwise -> Division 2.2
3
3.3 — Class 3: Flammable Liquids
Definition
Liquids having a flash point of not more than 60°C (closed-cup test), or offered for transport at temperatures at or above their flash point. Also includes liquid desensitized explosives.
Air Transport Restrictions
- PG I (flash point any, boiling point ≤35°C): FORBIDDEN on PAX aircraft
- PG II/III: permitted with quantity limits
- Viscous liquids (3.3.3): may be exempt from Class 3 if specific viscosity criteria met
Test Criteria
- Flash point determination (Table 3.3.B): ISO 1516/1523/2719/13736, ASTM D56/3278/3828/93
- Closed-cup test is the primary method; open-cup only as screening
Packing Group Assignment
| Packing Group | Flash Point (closed-cup) | Initial Boiling Point |
|---|---|---|
| I | — | ≤ 35°C |
| II | < 23°C | > 35°C |
| III | ≥ 23°C but ≤ 60°C | > 35°C |
Classification Flowchart
- Is the liquid's flash point ≤ 60°C (closed-cup)? -> Yes -> Class 3
- Initial boiling point ≤ 35°C? -> Yes -> PG I (FORBIDDEN PAX)
- Flash point < 23°C and boiling point > 35°C? -> Yes -> PG II
- Flash point ≥ 23°C and ≤ 60°C and boiling point > 35°C? -> Yes -> PG III
4
3.4 — Class 4: Flammable Solids; Spontaneous Combustion; Water-Reactive
Definition
Substances presenting flammable solid hazards (4.1), spontaneous combustion hazards (4.2), or emitting flammable gases on contact with water (4.3).
Divisions
4.1Flammable solids, self-reactive substances, solid desensitized explosives, polymerizing substances
4.2Substances liable to spontaneous combustion — pyrophoric (ignite within 5 min in air) and self-heating
4.3Substances which, in contact with water, emit flammable gases at a dangerous rate
Air Transport Restrictions
- Division 4.1: Self-reactive Type A FORBIDDEN; Type B CAO only
- Division 4.2 PG I (pyrophoric): FORBIDDEN on PAX and CAO
- Division 4.3 PG I: generally FORBIDDEN
Test Criteria
- 4.1 Flammable solids: burning rate test (UN N.1) — burns faster than reference substance, metal powders ignite within 10 min
- 4.1 Self-reactive: Types A-G classification per SADT and detonation/deflagration tests
- 4.1 Desensitized explosives: UN 1310-3474, phlegmatized with water or alcohol
- 4.2 Pyrophoric: spontaneous ignition within 5 minutes when exposed to air (L.1/L.2 test)
- 4.2 Self-heating: self-heating test (H.1-H.4) — sample temperature exceeds oven temperature by 60°C
- 4.3 Water-reactive: rate of flammable gas emission test (N.5) — ≥1 L/kg/h
Self-Reactive Substances — Types A-G (3.4.1.2.4)
ADetonates or deflagrates rapidly as packaged -> FORBIDDEN
BThermal explosion or rapid deflagration/detonation in package -> CAO only, temperature control may be required
CNeither detonation nor deflagration, but thermal explosion in confined space
DDetonates partially, no rapid deflagration, no violent effect when heated under confinement
ENeither detonation nor rapid deflagration; low or no effect when heated under confinement
FNo detonation in cavitated state, no deflagration, low or no effect when heated; low explosive power
GThermally stable (SADT ≥ 75°C for 50 kg package); not a self-reactive substance -> Not Class 4.1
Packing Group Criteria — Division 4.1 (Flammable Solids)
PG INot applicable for flammable solids (PG II or III only)
PG IIBurning rate test: burning time < 45 sec or flame passes wetted zone; metal powders: ≤ 5 min reaction zone
PG IIIBurning rate test: burning time < 45 sec and wetted zone stops flame for ≥ 4 min; metal powders: > 5 min reaction zone
Packing Group Criteria — Division 4.2 (Spontaneous Combustion)
PG IPyrophoric: liquid/solid ignites within 5 min of exposure to air
PG IISelf-heating: positive result with 25 mm cube sample at 140°C
PG IIISelf-heating: positive result with 100 mm cube at 140°C, negative with 25 mm cube
Packing Group Criteria — Division 4.3 (Water-Reactive)
PG IVigorous reaction with water at ambient temperature; gas spontaneously ignites; gas evolution rate ≥ 10 L/kg/h
PG IIGas evolution rate ≥ 20 L/kg/h over any 7-hour period, gas does not spontaneously ignite
PG IIIGas evolution rate ≥ 1 L/kg/h but does not meet PG I or II criteria
Classification Flowchart
- Is the substance a solid that can sustain combustion? -> Burning rate test -> 4.1
- Is it self-reactive? -> SADT + detonation tests -> Type A-G classification
- Does it ignite spontaneously in air within 5 min? -> Yes -> 4.2 PG I (pyrophoric)
- Does it self-heat beyond 60°C above oven temp? -> Yes -> 4.2 PG II/III
- Does it emit flammable gas on contact with water (≥1 L/kg/h)? -> Yes -> 4.3
5
3.5 — Class 5: Oxidizing Substances and Organic Peroxides
Definition
Division 5.1 substances that may cause or intensify combustion by providing oxygen. Division 5.2 organic compounds with the bivalent -O-O- structure that are thermally unstable.
Divisions
5.1Oxidizing substances: may cause/intensify combustion of other materials by yielding oxygen
5.2Organic peroxides: thermally unstable organic compounds with -O-O- structure, may decompose explosively
Air Transport Restrictions
- Division 5.2 Type A: FORBIDDEN
- Division 5.2 Type B: CAO only, temperature control required
- Division 5.1 PG I: restricted quantities on PAX
Test Criteria
- 5.1 Solids: UN O.1 test — mean burning time compared to 3:7 potassium bromate/cellulose mixture
- 5.1 Liquids: UN O.2 test — pressure rise and time-to-pressure compared to 1:1 65% nitric acid/cellulose mixture
- 5.1 Available oxygen: O_A = 16 × Σ(n_i × C_i / m_i)
- 5.2 SADT (Self-Accelerating Decomposition Temperature): UN H.1-H.4 tests
- 5.2 Temperature control: Types B-F with SADT ≤ 45-50°C require temperature control in transport
Packing Group Criteria — Division 5.1 (Oxidizers)
PG ISolids: mean burning time < 3:7 potassium bromate/cellulose reference; Liquids: spontaneously ignites or pressure rise/time ratio ≥ reference with 1:1 nitric acid/cellulose
PG IISolids: mean burning time ≤ 3:2 potassium bromate/cellulose reference; Liquids: pressure rise/time ratio ≥ reference with 1:1 nitric acid/cellulose (but not PG I)
PG IIISolids: mean burning time ≤ 2:3 potassium bromate/cellulose reference; Liquids: other criteria met but not PG I or II
Organic Peroxide Types A-G (3.5.2.3)
ACan detonate or deflagrate rapidly as packaged -> FORBIDDEN
BExplosive properties — neither rapid detonation nor deflagration; thermal explosion in package
CExplosive properties but cannot detonate or deflagrate rapidly or thermal explode
DDetonates only partially; no rapid deflagration; medium effect when heated under confinement
ENeither detonation nor deflagration; low or no effect when heated under confinement
FNo detonation in cavitated state; low or no explosive power; low or no effect when heated
GThermally stable (SADT ≥ 75°C) and/or available oxygen ≤ 0.5% -> Not Division 5.2
Classification Flowchart
- Does the substance yield oxygen to enhance combustion? -> Oxidizer test -> 5.1
- PG assignment: compare burning time/pressure to reference standards -> PG I/II/III
- Is it an organic compound with -O-O- structure? -> Yes -> 5.2 candidate
- SADT + explosion tests -> Assign Type A-G
- Type A -> FORBIDDEN; Type G -> Not Division 5.2
6
3.6 — Class 6: Toxic and Infectious Substances
Definition
Division 6.1: substances liable to cause death, injury or harm by ingestion, inhalation or skin contact. Division 6.2: substances containing viable micro-organisms known to cause disease in humans or animals.
Divisions
6.1Toxic substances: LD₅₀/LC₅₀-based classification by oral, dermal and inhalation routes
6.2Infectious substances: Category A (life-threatening) and Category B (does not meet Cat A criteria)
Air Transport Restrictions
- Division 6.1 PG I inhalation toxicity (vapour): FORBIDDEN on PAX and CAO
- Division 6.2 Category A: special requirements; Category B (UN 3373): exempted from full DGR with PI 650
Test Criteria
- Oral toxicity: LD₅₀ (mg/kg body weight, rat, 14-day observation)
- Dermal toxicity: LD₅₀ (mg/kg body weight, rabbit, 24-hour exposure, 14-day observation)
- Inhalation (dust/mist): LC₅₀ (mg/L air, rat, 4-hour or 1-hour converted exposure)
- Inhalation (vapour): LC₅₀ (mL/m³) with saturated vapour concentration V at 20°C
- Liquid mixture inhalation: LC₅₀(mix) formula using volatility ratio R
Table 3.6.A — Division 6.1 PG Criteria (Oral, Dermal, Dust/Mist)
| Packing Group | Oral LD₅₀ (mg/kg) | Dermal LD₅₀ (mg/kg) | Inhalation LC₅₀ dust/mist (mg/L) |
|---|---|---|---|
| I | ≤ 5.0 | ≤ 50 | ≤ 0.2 |
| II | > 5.0 to ≤ 50 | > 50 to ≤ 200 | > 0.2 to ≤ 2.0 |
| III | > 50 to ≤ 300 | > 200 to ≤ 1,000 | > 2.0 to ≤ 4.0 |
Table 3.6.B — Division 6.1 Vapour Inhalation PG Criteria
| Packing Group | Vapour Inhalation Criteria |
|---|---|
| I | LC₅₀ ≤ 1,000 mL/m³ and V ≥ 10 × LC₅₀ |
| II | LC₅₀ ≤ 3,000 mL/m³ and V ≥ LC₅₀ (not PG I) |
| III | LC₅₀ ≤ 5,000 mL/m³ and V ≥ 0.2 × LC₅₀ (not PG I/II) |
Division 6.2 — Infectious Substance Categories
Category A: Capable of causing permanent disability, life-threatening or fatal disease in otherwise healthy humans/animals on exposure. UN 2814 (human) / UN 2900 (animal).
Category B: Does not meet Category A criteria. UN 3373 — Biological Substance, Category B. Packed per PI 650.
Classification Flowchart
- Does the substance cause death/injury by ingestion, inhalation or skin contact? -> Check LD₅₀/LC₅₀ -> 6.1
- Apply Table 3.6.A (oral/dermal/dust) and Table 3.6.B (vapour) criteria -> PG I/II/III
- If PG I inhalation vapour -> FORBIDDEN (PAX + CAO)
- Contains viable pathogenic micro-organisms? -> 6.2
- Category A (life-threatening)? -> UN 2814/2900, PI 620; Category B -> UN 3373, PI 650
7
3.7 — Class 7: Radioactive Material
Definition
Material containing radionuclides where both the activity concentration and total activity exceed the values specified in Tables 2-7.2.2.1 (Columns 3-5). Based on A₁/A₂ activity values per radionuclide.
Air Transport Restrictions
- Transport Index (TI) limits: PAX max TI per package varies by aircraft type
- Criticality Safety Index (CSI) limits apply for fissile material
- Type B(M) packages require multilateral approval for air transport
Test Criteria
- A₁ value: activity limit for special form radioactive material
- A₂ value: activity limit for other forms of radioactive material
- Transport Index (TI): max radiation level at 1 m from package surface (mSv/h × 100)
- Package types: Excepted, Industrial (IP-1/2/3), Type A, Type B(U), Type B(M), Type C
- Label categories: I-WHITE (TI=0, surface ≤ 0.005 mSv/h), II-YELLOW (TI ≤ 1), III-YELLOW (TI ≤ 10)
Packing Group
Radioactive materials are NOT assigned packing groups. Package type and TI/CSI determine transport requirements.
Classification Flowchart
- Activity > exemption values (Table 2-7.2.2.1)? -> Yes -> Class 7
- Determine A₁/A₂ values for the radionuclide(s)
- Select package type based on activity content (Excepted / Type A / Type B)
- Calculate Transport Index (TI) and assign label category (I-WHITE / II-YELLOW / III-YELLOW)
- Fissile? -> Calculate CSI and apply fissile package limits
8
3.8 — Class 8: Corrosives
Definition
Substances that cause irreversible damage to living tissue (skin destruction / visible necrosis through the epidermis into the dermis) or materially damage other goods or means of transport.
Air Transport Restrictions
- PG I: restricted quantities on PAX aircraft
- Substances meeting Class 8 + PG I inhalation toxicity of 6.1 follow special precedence rules (3.8.2.3)
Test Criteria
- In vivo skin test: OECD Guideline 404 — apply substance to intact albino rabbit skin
- In vitro alternatives accepted per UN GHS criteria
- Metal corrosion: corrosion rate on steel (S235JR) or aluminium (7075-T6) > 6.25 mm/year at 55°C
Packing Group Assignment
| Packing Group | Exposure Time | Observation Time | Effect |
|---|---|---|---|
| I | ≤ 3 min | ≤ 60 min | Irreversible damage to intact skin |
| II | > 3 min to ≤ 60 min | ≤ 14 days | Irreversible damage to intact skin |
| III | > 60 min to ≤ 4 h | ≤ 14 days | Irreversible damage to intact skin |
| III | — | — | Metal corrosion rate > 6.25 mm/year at 55°C |
Classification Flowchart
- Does the substance destroy living skin tissue? -> In vivo or in vitro test -> Class 8
- Exposure ≤ 3 min + observation ≤ 60 min with irreversible damage? -> PG I
- Exposure ≤ 60 min + observation ≤ 14 d? -> PG II
- Exposure ≤ 4 h + observation ≤ 14 d or metal corrosion > 6.25 mm/y? -> PG III
- 3.8.5: Substances destroying intact skin within 3 min with exposure to intact and abraded skin -> FORBIDDEN
9
3.9 — Class 9: Miscellaneous Dangerous Goods
Definition
Substances and articles presenting hazards during air transport not covered by other classes. Includes lithium batteries, environmentally hazardous substances, magnetized material, and elevated temperature substances.
Air Transport Restrictions
- Lithium batteries (UN 3090/3091/3480/3481): special provisions per PI 965-970
- Magnetized material (UN 2807): compass deviation > 2 degrees at 4.6 m
- Environmentally hazardous (UN 3077/3082): marine pollutant criteria apply
Test Criteria
- Aviation regulated solid/liquid (UN 3334/3335): ICAO TI criteria for substances not meeting other class criteria but posing aviation hazard
- Magnetized material: field strength > 0.00525 gauss at 2.1 m or > 0.002 gauss at 4.6 m from any surface
- Elevated temperature: liquid at ≥ 100°C or solid at ≥ 240°C (UN 3257/3258)
- Environmentally hazardous: LC₅₀ ≤ 1 mg/L (96 h fish) or EC₅₀ ≤ 1 mg/L (48 h crustacea) + logPₒw ≥ 4
- Lithium batteries: UN 38.3 test series (T.1-T.8) required
Packing Group
Class 9 substances are NOT assigned packing groups (although some entries show PG III in the DG List for packaging purposes).
Classification Flowchart
- Does it meet any Class 1-8 criteria? -> No -> Consider Class 9
- Is it a lithium battery? -> UN 38.3 tests passed? -> UN 3090/3091/3480/3481
- Is it magnetized (compass deviation > 2° at 4.6 m)? -> UN 2807
- Is it environmentally hazardous? -> UN 3077 (solid) / UN 3082 (liquid)
- Is it an elevated temperature substance? -> UN 3257/3258
Source: IATA DGR 67th Ed. Section 3 (Classification), pp. 161-198. Chunk references: docs/extracted/iata-dgr/65-png/chunks/page_0193-page_0230. Classification test procedures: UN Manual of Tests and Criteria, 8th Revised Edition.
Related Pages
Hazard Classes OverviewQuick overview of all 9 classes with PAX/CAO status.Multiple Hazards (Section 3.10-3.12)Precedence of hazards table and primary/subsidiary determination.Dangerous Goods ListSearchable DG List by UN number (Table 4.2).Packing InstructionsPI lookup for all classes and divisions.