Environment, Health and Safety

Appendix L - EHS Segregation Scheme

Appendix L - EHS Segregation Scheme

Proper chemical segregation is essential for preventing dangerous reactions, fires, explosions, and toxic exposures in laboratory and storage environments. This guide provides a systematic approach to organizing chemicals based on their primary hazard classifications to minimize risks and ensure regulatory compliance.

Understanding Segregation Requirements

Segregation Hierarchy

  • Hazard Class: Must be segregated from all other hazard classes (highest priority)
  • Class: Must be segregated from other classes within the same hazard class
  • Group: Recommended segregation from other groups within the same class (best practice)

General Principles

  • Always segregate by most severe hazard when chemicals have multiple classifications
  • Maintain adequate separation distances (minimum 8 feet or use approved separation barriers)
  • Use secondary containment for liquid chemicals
  • Ensure compatible fire suppression systems for each storage area
  • Provide appropriate ventilation for each hazard class

HAZARD CLASS 1: EXPLOSIVES

Risk: Potential for detonation, deflagration, or violent reaction

Storage: Segregate from all other hazard classes. Store in approved storage cabinets. Limit quantities to minimum needed

HAZARD CLASS 2: COMPRESSED GASES

Risk: Physical hazards from pressure release, asphyxiation, flammability, toxicity

Class 2.1: Flammable Gases

Examples: Hydrogen, methane, acetylene, propane

Storage: Segregate from oxidizers and heat sources. Store upright and secured. Provide adequate ventilation.

Class 2.2: Non-Flammable Gases

Examples: Nitrogen, argon, carbon dioxide, helium

Storage: Segregate from flammable and toxic gases. Monitor for asphyxiation hazards in enclosed spaces.

Class 2.3: Poisonous Gases

Examples: Ammonia, chlorine, hydrogen sulfide, carbon monoxide

Storage: Segregate from all other gases. Require specialized ventilation and detection systems.

Special Gas Categories:

Oxidizing Gases

Examples: Oxygen, nitrous oxide, fluorine

Storage: Segregate from all other gases. Minimum 20 feet from flammables.

Corrosive Gases

Acids: Hydrogen chloride, hydrogen fluoride

Bases: Ammonia 

Storage: Segregate by pH compatibility

Cryogenic Gases

Examples: Liquid nitrogen, liquid helium

Storage: Specialized cryogenic storage with pressure relief systems

Pyrophoric Gases

Examples: Silane, phosphine

Storage: Inert atmosphere storage, segregate from all other materials

HAZARD CLASS 3: FLAMMABLE LIQUIDS

Risk: Fire and explosion hazards

Flammable Liquids (Flash Point <100°F)

Examples: Ethanol, acetone, diethyl ether, hexane

Storage: Use approved flammable storage cabinets. Segregate from oxidizers and heat sources.

Combustible Liquids (Flash Point 100-200°F)

Examples: Mineral oil, some cooking oils

Storage: May be stored with flammable liquids if no other hazards present. Keep away from heat sources and oxidizers.

HAZARD CLASS 4: FLAMMABLE SOLIDS

Risk: Fire hazards from friction, heat, or moisture contact

Class 4.1: Flammable Solids

Examples: Magnesium powder, sulfur, aluminum powder

Storage: Keep dry and away from heat sources

Class 4.2: Spontaneously Combustible

Examples: White phosphorus, sodium sulfide

Storage: Segregate from all other classes. May require inert atmosphere.

Class 4.3: Dangerous When Wet

Examples: Sodium, potassium, calcium carbide

Storage: Segregate from all moisture sources. Use desiccants, waterproof containers

HAZARD CLASS 5: OXIDIZERS

Risk: Enhance combustion, may cause violent reactions with organics

Class 5.1: Oxidizers

Liquid Oxidizers 

Examples: Hydrogen peroxide (>8%), sodium hypochlorite solutions

Storage: Segregate from all flammables and combustibles.

Solid Oxidizers 

Examples: Potassium permanganate, sodium nitrate, ammonium nitrate

Storage: Segregate from flammables, combustibles, and reducing agents. Store in original containers. Keep dry to prevent decomposition.

Class 5.2: Organic Peroxides

Examples: Benzoyl peroxide, cumene hydroperoxide

Storage: Segregate from all other chemicals. Refrigerated storage often required.  Monitor expiration dates closely.  Never store near heat sources. 

HAZARD CLASS 6: POISONS/TOXIC SUBSTANCES

Risk: Acute or chronic health effects from exposure

Class 6.1: Poisons

Poison Liquids

Examples: Mercury, carbon tetrachloride, methanol

Storage: Ventilated storage with secondary containment

Poison Solids

Examples: Arsenic compounds, lead compounds, nickel compounds

Storage: Sealed containers in ventilated areas

Special Toxic Categories:

Carcinogens

Examples: Benzene, formaldehyde, asbestos

Storage: Segregate from other chemicals. Designated storage areas with restricted access. Special labeling and inventory requirements.

Reproductive Hazards

Examples: Lead compounds, mercury, certain solvents

Poisonous Inhalation Hazards (PIH)

Examples: Hydrogen fluoride, phosgene

Storage: Segregate from all other chemicals. Specialized ventilation and detection systems.

Cyanides

Examples: Sodium cyanide, potassium cyanide

Storage: Segregate from acids (prevents hydrogen cyanide gas formation).  Locked storage with restricted access. 

HAZARD CLASS 7: RADIOACTIVES

Risk: Ionizing radiation exposure

Storage:  Segregate from all other chemicals.  Licensed radioactive material storage areas.  Radiation monitoring and security.  Follow NRC regulations. 

HAZARD CLASS 8: CORROSIVES

Risk: Chemical burns, material degradation

Inorganic Acids

Examples: Hydrochloric, sulfuric, phosphoric acid

Storage: Segregate from bases to prevent violent neutralization.  Secondary containment required.  Corrosion-resistant shelving. 

Oxidizing Acids

Examples: Nitric acid, perchloric acid

Storage: Segregate from organics and other acids.  Special ventilation requirements.  Non-combustible, non-metallic storage. 

Hydrofluoric Acid

Storage: Segregate from all other acids. Polyethylene containers only. Special emergency procedures required.

Organic Acids (Liquid)

Examples: Acetic acid, formic acid

Storage:Stored in flammable cabinets if concentration at or above 80%.  Segregate from strong bases. 

Bases

Examples: Sodium hydroxide, potassium hydroxide, ammonium hydroxide

Liquid Bases Storage: Secondary containment, segregate from acids

Solid Bases Storage: Keep dry, segregate from acids and moisture-sensitive materials

Incompatible Chemical Combinations

Never Store Together:

  • Oxidizers + Flammables/Combustibles
  • Acids + Bases
  • Acids + Cyanides
  • Water-reactive chemicals + any moisture source
  • Organic peroxides + heat sources or metals

If you need further information, call EHS at 607-255-8200, or send an e-mail to askEHS@cornell.edu.