Understanding Chemical Class Labels: A Comprehensive Guide

When shipping laboratory chemicals, safety and compliance are top priorities. Whether you're transporting small reagent bottles or bulk industrial solvents, every package must be properly labeled to indicate the hazards associated with its contents. These labels — known as hazard class labels — help ensure safe handling, transport, and storage of dangerous goods.

In this guide, we’ll break down the chemical class labels that commonly appear on shipping boxes for chemicals, including the meaning of each class, visual identifiers, and key examples.

---

? Why Chemical Class Labels Matter

Chemical hazard class labels are part of the international regulations enforced by:

• U.S. Department of Transportation (DOT)

• United Nations (UN Model Regulations)

• Occupational Safety and Health Administration (OSHA)

• International Air Transport Association (IATA)

• Globally Harmonized System (GHS)

These labels:

• Alert handlers and transporters to chemical dangers

• Prevent accidents like spills, fires, or exposure

• Ensure proper emergency response

• Comply with legal regulations to avoid fines

---

? Major Hazard Classes Used in Shipping Chemicals

Chemicals are grouped into 9 hazard classes, each with a specific label design. Below is a breakdown of these classes with visual descriptions and real-world examples:

Class 1: Explosives

Label: Orange background with a bursting ball icon
Subdivisions: 1.1 – 1.6 (based on type and level of hazard)

Description: Materials capable of causing explosions by chemical reaction. Rare in laboratories but may apply to certain reactive metal azides or blasting agents.

Examples:

• Trinitrotoluene (TNT)

• Nitroglycerin

• Some pyrotechnic compounds

Handling Tips:

• Avoid friction, heat, and impact

• Use specially approved containers

• Restricted transport methods

Class 2: Gases

Label Variants:

• 2.1 (Flammable Gas): Red flame symbol

• 2.2 (Non-Flammable, Non-Toxic Gas): Green cylinder symbol

• 2.3 (Toxic Gas): White skull and crossbones

Description: Compressed gases, liquefied gases, dissolved gases, or refrigerated liquefied gases.

Examples:

• 2.1: Propane, Hydrogen

• 2.2: Nitrogen, Helium, Argon

• 2.3: Chlorine gas, Hydrogen sulfide

Handling Tips:

• Secure cylinders upright

• Use appropriate regulators

• Monitor for leaks

Class 3: Flammable Liquids

Label: Red background with a white flame

Description: Liquids with a flash point below 60°C (140°F), which can ignite under normal transport conditions.

Examples:

• Acetone

• Ethanol

• Toluene

• Methanol

Handling Tips:

• Keep away from heat, sparks, and flames

• Use flame-proof storage cabinets

• Ground containers when dispensing

Class 4: Flammable Solids

Label Variants:

• 4.1: Flammable Solid (Red and white stripes)

• 4.2: Spontaneously Combustible (Red top, white bottom)

• 4.3: Dangerous When Wet (Blue background)

Description:

• 4.1: Solids prone to ignition through friction

• 4.2: Ignite spontaneously in air

• 4.3: React with water to release flammable gas

Examples:

• 4.1: Naphthalene, magnesium powder

• 4.2: White phosphorus

• 4.3: Sodium metal, potassium

Handling Tips:

• Store in inert atmospheres

• Avoid exposure to air or water

• Handle with dry tools

Class 5: Oxidizers and Organic Peroxides

Label Variants:

• 5.1: Oxidizer (Yellow flame over circle)

• 5.2: Organic Peroxide (Half red, half yellow)

Description:

• Oxidizers release oxygen to support combustion

• Organic peroxides are thermally unstable and may explode

Examples:

• 5.1: Potassium nitrate, Hydrogen peroxide

• 5.2: Benzoyl peroxide

Handling Tips:

• Keep away from flammable materials

• Avoid heat and contamination

• Store in vented containers

Class 6: Toxic and Infectious Substances

Label Variants:

• 6.1: Toxic substances (White label, skull and crossbones)

• 6.2: Infectious substances (White label with biohazard symbol)

Description:

• 6.1: Can cause death or serious harm by ingestion, inhalation, or skin contact

• 6.2: Contain pathogens

Examples:

• 6.1: Cyanide compounds, arsenic trioxide

• 6.2: Clinical lab specimens, viruses

Handling Tips:

• Use full PPE (gloves, mask, eye protection)

• Ensure spill containment

• Special shipping protocols apply

Class 7: Radioactive Materials

Label: Yellow/white with radiation trefoil symbol

Description: Materials that emit ionizing radiation, measured by activity level.

Examples:

• Uranium compounds

• Cobalt-60

• Iodine-131

Handling Tips:

• Requires shielding (lead)

• Limit exposure time

• Must be transported by licensed carriers

Class 8: Corrosives

Label: Black and white with substance spilling on hand and metal

Description: Substances that cause severe skin burns, destroy living tissue, or corrode metals.

Examples:

• Hydrochloric acid

• Sodium hydroxide

• Sulfuric acid

• Nitric acid

Handling Tips:

• Use acid/base resistant gloves and eye protection

• Avoid skin or inhalation exposure

• Store in corrosion-proof cabinets

Class 9: Miscellaneous Dangerous Goods

Label: Black and white vertical stripes on top, blank bottom

Description: Hazardous materials not covered by other classes but still pose risks.

Examples:

• Lithium batteries

• Dry ice (solid CO₂)

• Genetically modified organisms

Handling Tips:

• Check carrier-specific restrictions

• Use proper packaging

• Include handling documentation

?️ How to Read a Chemical Shipping Box Label

Each label on a chemical shipping box includes:

• Hazard class symbol (as described above)

• UN number (e.g., UN 1993 for flammable liquids)

• Proper shipping name

• Packing group (I, II, III) – indicates degree of hazard

• Handling instructions and precautionary statements

Final Thoughts

Understanding and applying the correct chemical class labels is not just a legal requirement — it’s a crucial part of ensuring safety during chemical transportation. Whether you’re shipping within San Diego or across international borders, proper labeling prevents accidents and keeps your team, partners, and community safe.

At 949 Chemical, we help labs across California stay compliant by providing not only high-purity chemicals but also packaging, labeling, and shipping solutions tailored for hazardous materials.