Classification of DG Goods are made on their hazard and composition. Dangerous products are issued UN numbers and proper shipping names. The correct packing and packaging, paperwork, acceptance, and handling of risky commodities all require identification. Approximately 3,000 chemicals and commodities routinely carried by air are listed in the IATA DGR Classification of DG Goods
- Class 1-Explosives
- Class 2-Gasses
- Class 3-Flammable Liquids
- Class 4-Flammable Solids; Substance Liable to Spontaneous Combustion; Substances which, in Contact with Water, Emit Flammable Gases
- Class 5-Oxidizing Substances and Organic Peroxides
- Class 6-Toxic and Infectious Substances
- Class 7-Radioactive Material
- Class 8-Corrosives
- Class 9-Miscellaneous Dangerous Substances and Articles, Including Environmentally Hazardous Substances
Several classes are separated into sub-divisions due to the wide scope of the hazards within the class
Class 1-Explosives
Explosives are being classified as Class 1 DG goods
Why are explosives classified as hazardous materials?
To produce a sudden and dramatic physical effect, explosive molecules are intended to rapidly convert their (typically solid) state into a very hot gas.
This is accomplished by shocking them, which is accomplished in practise by discharging a small but highly sensitive charge (detonator) into direct contact with them. The shock forces the molecule to break down, causing a quick chemical change, which results in the explosion.
The transition from solid to gas occurs practically instantly, resulting in a rapid rise in volume as the solid converts to gas, as well as subsequent expansion due to a massive release of chemical energy in the form of heat – up to several thousand degrees. The desired physical impression is created by this sudden and dramatic increase in volume.
The effect of high explosives is to shatter and destroy anything close, whereas the effect of low explosives is to produce a large kinetic force. The energy release is the same, but the molecules in low explosives are engineered to shift fractionally slower, resulting in a forceful shove rather than a quick slice.
Explosives transport
Although explosives can be destructive when properly ignited, they are meant to be relatively stable and insensitive under typical settings. This means they can be handled and transported securely by land and sea as long as they are not subjected to intense shock, such as in a high-speed traffic accident, or allowed to become hot in a fire. Temperatures as low as 200o can ignite some high explosives.
In Class 1, there are six sections that indicate how the explosives will react and behave after they are detonated. The products are also assigned to one of 13 Compatibility Group letters, which basically indicate which categories can safely travel together.
When describing explosives in a transport document, the NEQ (Net Explosive Quantity) is disclosed separately from the gross weight.
1.1 Subclass
Contains explosives that can cause a large-scale explosion. A mass explosion is one that instantly affects practically the entire load.
1.2 Subclass
Consists of explosives with a projection risk but no mass explosion risk.
1.3 Subclass
Contains explosives with a fire hazard, a minor blast hazard, a minor projection hazard, or both, but no mass explosion hazard.
1.4 Subclass
Contains explosives that provide a slight threat of detonation. The explosive effects are mostly contained within the package, and no significant fragmentation of any size or range is expected. A fire from the outside must not produce a near-instantaneous explosion of the package’s contents.
1.5 subclass
Contains explosives that are extremely insensitive. This category includes compounds that provide a mass explosion risk but are so insensitive that initiation or transition from burning to detonation under normal transport conditions is extremely unlikely.
1.6 Subclass
Contains very insensitive articles that pose no threat of mass detonation. This category includes articles that contain only extremely insensitive detonating compounds and have a very low chance of inadvertent initiation or propagation.
Class 2-Gasses
Gases are usually transported and stored under pressure to minimise their volume and so save space.
If this pressure is quickly released, it might be dangerous. Unlike heat, which is transmitted to or from the surroundings until a constant temperature prevails, pressure never dissipates.
A high-pressure gas cylinder can hold a tremendous amount of force. If both ends of a breathing cylinder were cut off, then slit lengthwise and rolled out flat, the area would be 50 cms × 40 cms = 2000 cms2. The internal air pressure might be as high as 200 kg per cm2, resulting in a total force of 400 tonnes seeking to escape through the cylinder wall.
If a cylinder valve is damaged, the escaping gas is concentrated into a forceful jet, causing the cylinder to shoot off like a rocket and cause significant damage.
The majority of gases are denser than air. If they displace or dilute air in restricted places, they can induce asphyxia.
Applying pressure to gases reduces their volume, but converting them to liquid under pressure reduces the volume hundreds of times. Some gases, such as liquefied petroleum gases, chlorine, and ammonia, liquefy under pressure at normal temperatures. However, some permanent gases, such as liquid helium, will only liquefy if they are also cooled to extremely low (critical) temperatures.
Oxygen, nitrogen, hydrogen, helium, neon, and argon are among them. They must be kept in special, substantially insulated containers after liquefied to prevent them from warming up. If cold metal, for example, is mistakenly contacted without protection, it is clearly dangerous. Furthermore, an escape of very cold gas poses a respiratory hazard, resulting in direct lung damage or acute oxygen deprivation.
So far, all of these have been physical threats. However, combustible gases like butane and acetylene, as well as poisonous gases like chlorine and ammonia, pose chemical risks. As a result, the Class has three divisions:
Flammable Gas, Subclass 2.1
454 kilogrammes (1001 lbs) of any gas (a material with a boiling point of 20°C (68°F) or below at 101.3 kPa (14.7 psi) of pressure) which:
- Ignites at 101.3 kPa (14.7 psi) in a 13 percent or less by volume combination with air; or
- Has a flammable range of at least 12 percent air at 101.3 kPa (14.7 psi), regardless of the lower limit.
Non-flammable, non-poisonous Gas (Subclass 2.2)
Compressed gas, liquefied gas, pressured cryogenic gas, compressed gas in solution, asphyxiant gas, and oxidising gas are all included in this division. Any material (or mixture) that is not flammable or toxic when crushed (Division 2.2).
- At 20°C (68°F), exerts an absolute pressure of 280 kPa (40.6 psia) or greater in the packaging, and
- Does not meet Division 2.1 or 2.3 definitions.
Oxygen Gas Subclass 2.2
This is an add-on placard for compressed Oxygen in either a gas or a liquid state to the 2.2 Non-flammable Gas placard. Because oxygen does not burn, it is classified as a non-flammable gas. It is, nonetheless, necessary for combustion to occur. The rate and intensity of combustion are considerably increased when oxygen concentrations are high.
Poison Gas Subclasses 2.2
A material that is harmful by inhalation is one that is a gas at 20°C or less at a pressure of 101.3 kPa (one that has a boiling point of 20°C or less at 101.3 kPa (14.7 psi)) and that:
- is known to be so hazardous to people that it poses a health risk while being transported, or
- is presumed to be hazardous to people in the absence of adequate data on human toxicity because it has an LC50 value of less than 5000 ml/m3 when tested on laboratory animals.
Class 3-Flammable Liquids
Some flammable liquids, such as gasoline and kerosene, are made from petroleum. Alcohols, for example, can be produced naturally or artificially. The storage of flammable liquids is subject to strict regulations.
Vapours are created when some molecules in a liquid have enough energy and move rapidly enough to break away from the surface and into the air space above. In a heated liquid, the more molecules that reach this energy and velocity level, the faster vapours form.
The vapours are undetectable and thicker than air at all times. They’ll trickle down and clump together at the bottom. If the vapours are mixed with air and ignited, they will burn or explode if the mixture is within the material’s explosive limitations.
The flashpoint is the temperature at which a liquid releases just enough vapour to make an ignitable mixture with air, or when it reaches its lower explosive limit. Below the flashpoint, insufficient vapour develops to produce an ignitable combination. The lower the flash point, the more easily vapour can form at room temperature, and the bigger the risk.
Because gasoline has an FP of -40o C, it burns readily at room temperature. Because the FP of diesel is +65oC, it must be heated before it can burn. The UN maximum temperature for Class 3 is generally FP 60oC, after which the object is no longer deemed dangerous to transport. Diesel, on the other hand, has just recently been brought into full compliance with the Regulations. If a flammable liquid’s flash point (FP) is greater than 60°C and it is carried at a temperature higher than its FP, it is designated as Class 3. If it is carried at a temperature above 100o C but below its FP, it is classified as Class 9.
The auto-ignition temperature is the temperature at which a vapour will ignite in the absence of an ignition source. The AIT is much higher than the FP, for example, 300oC for gasoline; the effect is used in diesel engines that don’t use a spark plug.
Class 4: Flammable solids
Class 4.1: Flammable Solids or Substances.
Desensitized explosives that are explosives of Class 1 when dry and have been assigned a shipping name and danger class by the Associate Administrator.
Self-reactive materials that are thermally unstable and can decompose violently exothermically even without the presence of air.
Metal powders that can be ignited and react across the entire length of a sample in 10 minutes or less, or readily flammable materials that can generate a fire by friction and have a burning rate quicker than 2.2 mm (0.087 inches) per second.
Class 4.2: Flammable solids.
A pyrophoric material, which is a liquid or solid that can ignite within five (5) minutes after coming into contact with air, or a self-heating material that can self-heat while in contact with air and without an energy source, is a spontaneously combustible material.
Class 4.3 – Dangerous Get Wet.
Division 4.3 products produce flammable gas when they react with water, either as a liquid or as a vapour. The heat of the reaction can ignite this. They must be kept in airtight containers that are hermetically sealed to prevent moisture or water vapour from entering.
Class 5
Class 5.1 – Oxidizing Agents
An oxidizer (Division 5.1) is a substance that can induce or increase the burning of other substances by releasing oxygen.
- A Division is a type of solid material. When evaluated according to the UN Manual of Tests and Criteria, 5.1 material has a mean burning time that is less than or equal to that of a 3:7 potassium bromate/cellulose mixture.
- A liquid material is classified as a Division 5.1 material if it spontaneously ignites or if its mean time for a pressure rise from 690 kPa to 2070 kPa gauge is less than that of a 1:1 nitric acid (65%)/cellulose mixture when evaluated according to the UN Manual of Tests and Criteria.
Class 5.2 – Organic peroxides
Unless one of the following lines applies, organic peroxide (Division 5.2) implies any organic compound having oxygen (O) in the bivalent -O-O- structure and that may be considered a derivative of hydrogen peroxide, where one or more hydrogen atoms have been replaced by organic radicals:
- The material fits the definition of an explosive as defined in this part’s subpart C, in which case it must be classified as such;
- According to this subchapter’s 49CFR 172.101 or 49CFR 173.21, the material may not be offered for transportation.
- The Associate Administrator for Hazardous Materials Safety has decided that the substance is not a Division 5.2 material
Class 6: Toxic and Infectious substances
Class 6.1 – Toxics
Poisonous and toxic substances classified under Class 6.1 DG goods
It is either known to be toxic to humans in enough to pose a health risk during transit, or it is suspected to be hazardous to humans based on laboratory animal testing.
Tear gas is an unpleasant substance that causes severe irritation, especially in tight spaces.
Class 6.2 – Infectious substances
Pathogens, or microorganisms that cause infectious disease in humans or animals, are present in Division 6.2 commodities. They are classified into one of three classes based on the risk of infectious transmission. Only the first two are deemed risky for travel.
Category A: Possibilities include lifelong handicap, life-threatening sickness, or death in humans or animals. These are classified as UN 2814, while infectious chemicals that exclusively affect animals are classified as UN 2900.
Class 7: Radioactive Substances.
It is either known to be toxic to humans in enough to pose a health risk during transit, or it is suspected to be hazardous to humans based on laboratory animal testing.
Any number of products with the marking RADIOACTIVE YELLOW III (LSA-III). The RADIOACTIVE placard is essential even if some radioactive items in “exclusive use” with low specific activity radioactive materials do not have the label.
A closed transport vehicle is a vehicle or conveyance with a securely fastened outside enclosure that prevents unauthorised personnel from entering the cargo space containing Class 7 (radioactive) items during normal transportation. The enclosure might be temporary or permanent, and it can be “see-through” in the case of packaged items. It must restrict access from the top, sides, and bottom.
A containment system is a collection of packing components designed to keep radioactive materials safe during transit.
Class 8: Corrosives
- A liquid or solid that causes full thickness deterioration of human skin at the place of contact within a certain length of time is defined as “corrosive materials” (Class 8) for the purposes of this subchapter. A corrosive liquid is one that has a high rate of corrosion on steel or aluminium.
- If the danger of a material is greater or less than the results of the tests provided in paragraph (a) of this section, RSPA may change its classification or determine that the substance is not subject to the provisions of this subchapter.
- For Class 8 skin corrosive materials, skin corrosion test data produced no later than September 30, 1995, using the procedures of 49CFR 173, Appendix A, in effect on September 30, 1995 (see 49CFR Part 173, Appendix A, revised as of October 1, 1994) for appropriate exposure times, may be used for classification and packing group assignment.
- A corrosive material with a gross weight of 454 kg (1001 lbs) or greater. Despite the fact that the corrosive class comprises both acids and bases, the hazardous materials load and segregation chart makes no mention of separating incompatible corrosive elements. Regardless, care should be taken while shipping corrosives to ensure that incompatible corrosive chemicals do not mix, as many corrosives react severely when mixed. When reacting to a transportation event involving corrosive materials (particularly corrosive mixtures), exercise caution.
Class 9: Miscellaneous dangerous substances and articles.
A material that poses a hazard during transportation but does not fit into any other hazard classification. This class consists of:
- Any item with anaesthetic, toxic, or other comparable properties that could cause a flight crew member considerable displeasure or suffering, preventing proper performance of assigned responsibilities; or
- Any material that is a hazardous substance, a hazardous waste, or a marine pollutant at elevated temperatures.