Chemical Storage: Nine Compatible Storage Group System

This guide presents one compatible chemical storage method.  There are several appropriate chemical storage group methods available. They are each slightly different but have many overlapping similarities.  More detailed information on safe chemical storage can be found in the EHS Lab Chemical Storage Safety Course available through UI HR Self-Service.

Proper chemical storage controls health or physical hazards posed by chemical compounds during storage in the lab. It is designed to 1) protect flammables from ignition; 2) minimize the potential of exposure to poisons; and 3) segregate incompatible compounds to prevent their accidental mixing (via spills, residues, earthquakes, fires or human error). These guidelines include Part I - General rules of safe storage, Part II - Definition of storage groups and Part III - Illustrations of storage plans in lab facilities.

These guidelines were taken in part with permission and appreciation, from the Fred Hutchinson Cancer Research Center "Hazard Awareness and Management Manual" 

Part I: General and Principles of Safe Chemical Storage

  • A designated storage place for each compound.
  • Each stock container of a chemical compound should be returned to that location after each use. Storage locations can be marked on containers.
  • Not on the bench top.
  • Do not store stock supplies of chemicals on benchtops where they are unprotected from ignition sources and more easily knocked over. Only chemicals in use should be benchtops.
  • Not in the fumehood Do not keep stock supplies of chemicals in fumehoods they may, interfere with air flow in the hood, may provide fuel if there is a fire.
  • Not in alphabetical order except within "Chemical Storage Groups"
  • Do not store chemicals in alphabetical order except within "Chemical Storage Groups". Alphabetical arrangement of randomly collected chemicals often increases the likelihood of dangerous reactions by bringing incompatible materials into close proximity. 
  • Away from sun and heat
  • Storage areas should not be exposed to extremes of heat or sunlight. 
  • Not under the sink
  • Do not store any chemicals except bleach and compatible cleaning agents under the sink.
  • Label chemicals properly
  • All containers within the lab must be labeled. Suspect and known carcinogens must be labeled as such and segregated within trays to contain leaks and spills.
  • Safeguard against theft
  • This plan does not require security measures (i.e., locked cabinets) to prevent theft, but lab workers should make sure that lab doors are locked when unattended. Use of chemicals regulated by Drug Enforcement Agency may require registration and secured controlled storage.
  • Liquid chemicals
  • Storage of liquid chemicals is more hazardous than storage of solids and is subject to numerous and varied storage requirements.

Flammable liquids 

Peroxide formers

  • Peroxide formers must be stored in the flammable cabinets and must be regularly inventoried to track their age. See storage and testing guidelines for peroxide formers.


  • Store volatile poisons (evaporation rate above 1.0- ether=1.0) in a flammable cabinet.
  • Store non-volatile liquid poisons in a refrigerator or cabinet. Amounts less than 1 liter may be stored in a cabinet above bench level if the cabinet has sliding doors not swinging.

Acids and bases

  • Acids and bases should be physically separated.
  • All acids should be stored in a corrosive cabinet. Oxidizing acids (nitric, sulfuric, phosphoric, perchloric) should have secondary containment and, as a group, stored separately from other acids (organic and mineral).

Overview of the Chemical Storage Group

In this plan there are nine storage groups. Seven of these groups cover storage of liquids because of the wide variety of hazards posed by these chemicals. Specific instructions must be followed for metal hydrides (Group VIII) and certain individual compounds, but otherwise, dry solids are in Group IX. 

Many liquid chemicals pose hazards that correspond to more than one storage group. These chemicals should be stored in the lowest group number.

  • Group I Flammable Liquids 
  • Group II  Poisons - volatile
  • Group III Acids - Oxidizing
  • Group IV Acids - Organic and Mineral
  • Group V Bases - Liquid
  • Group VI Oxidizer - Liquid
  • Group VII Poisons - Non-volatile
  • Group VIII Reactives
  • Group IX  Solids

Part II: Storage Group Definitions

Group I: Flammable Liquids

Includes liquids with flashpoints < 100 F. Examples: all alcohols, acetone, acetaldehyde, acetonitrile, amyl acetate, benzene, cyclohexane, dimethyldichlorosilane, dioxane, ether, ethyl acetate, histoclad, hexane, hydrazine, methyl butane, picolene, piperidine, propanol, pyridine, scintillation liquids, all silanes, tetrahydrofuran, toluene, triethylamine, xylene Primary Storage Concern: To protect from ignition 

Recommended Facilities/Measures:  
 1.  Flammable Cabinet
 2.  Refrigerator: for containers less than 1 liter.

Compatible Storage Groups: Volatile poisons may be in the same compartment of the flammable cabinet as flammables if bases are not present.

Group II: Volatile Poisons

Includes poisons toxics and known and suspected carcinogens with strong odor or evaporation rate greater than 1 (butyl acetate = 1): Examples: carbon tetrachloride, chloroform, dimethylformamide, dimethyl sulfate, formamide, formaldehyde, halothane, mercaptoethanol, methylene chloride, phenol. Primary Storage Concern: To prevent inhalation exposures.  Recommended Facilities/Measures:   1. Flammable cabinet   2. Refrigerator: for containers less than 1 liter.  Compatible Storage Groups: Volatile poisons may be in the same compartment of the flammable cabinet as flammable if bases are not present. 

Group III: Oxidizing Acids

All oxidizing acids are highly reactive with most substances and each other. Examples: nitric, sulfuric, perchloric, phosphoric acids, and chromic acids. Primary Storage Concern: Preventing contact and reaction with each other and other substances and corrosive action on surfaces. 

Recommended Facilities/Measures:
  1. Safety Cabinet.  Each oxidizing acid must be double-contained, i.e., the primary container must be kept inside canister, tray or tub. 

Compatible Storage Groups:  Oxidizing acids must be double-contained and should be segregated in their own compartment in a safety cabinet. When quantities are small (e.g., 1 or 2 bottles) they do not warrant a separate compartment. Small quantities may be double-contained and stored with Group 4 Organic and Mineral Acids. Store oxidizing acids on bottom shelf below Group 4. 

Group IV: Organic and Mineral Acids

Examples: acetic, butyric, formic, glacial acetic, hydrochloric, isobutyric, mercaptoproprionic, proprionic, trifluoroacetic acids. 

Primary Storage Concern: To prevent contact and reaction with bases and oxidizing acids and corrosive action on surfaces.  

Recommended Facilities/Measures:  
  1. Safety cabinet. 

Compatible Storage Groups: Small amount of double-contained oxidizing acids can be stored in the same compartment with organic acids if the oxidizing acids are stored on the bottom shelf. Exceptions: acetic anhydride and trichloroacetic anhydride are corrosive. These acids are very reactive with other acids and should not be stored in this group. It is better to store these with organic compounds as in Group 7 Non-volatile Liquid Poisons. 

Group V: Liquid Bases

Examples: sodium hydroxide, ammonium hydroxide, calcium hydroxide, glutaraldehyde Primary Storage Concern: Preventing contact and reaction with acids.  Recommended Facilities/Measures:   1. Safety cabinet;   2. In tubs or trays in normal cabinet.  Compatible Storage Groups: Liquid bases may be stored with flammables in the flammable cabinet if volatile poisons are not also stored there.   

Group VI: Oxidizing Liquids

Oxidizing liquids react with everything potentially causing explosions or corrosion of surfaces. Examples: ammonium persulfate, hydrogen peroxide (if greater than or equal to 30%) Primary Storage Concern: To isolate from other materials. 

Recommended Facilities/Measures:  
  1. Total quantities exceeding 3 liters should be kept in a cabinet housing no other chemicals.  
  2. Smaller quantities must be double-contained if kept near other chemicals, e.g., in a refrigerator. 

Compatible Storage Groups: None

Group VII: Non-Volatile Liquid Poisons

Includes highly toxic (LD50 oral rat < 50 mg/kg) and toxic chemicals (LD50 oral rat < 500 mg/kg), known carcinogens, suspected carcinogens and mutagens Examples: acrylamide solutions; diethylpyrocarbonate; diisopropyl fluorophosphate; uncured epoxy resins; ethidium bromide; triethanolamine
Primary Storage Concern: To prevent contact and reaction with other substances.
Recommended Facilities/Measures:

  1.  Cabinet or refrigerator (i.e., must be enclosed)
  2.  Do not store on open shelves in the lab or cold room.
  3.  Liquid poisons in containers larger than 1 liter must be stored below bench level on shelves closest to the floor. 
       Smaller container of liquid poison can be stored above bench level only if behind sliding (non-swinging) doors.

Compatible Storage Groups: Non-hazardous liquids (e.g., buffer solutions). Exceptions: Anhydrides, e.g., acetic and trichloroacetic are organic acids, however it is better to store with this group than with Group 4 Organic Acids, since they are highly reactive with other organic or mineral acids.

Group VIII: Reactives Metal Hydrides and Pyrophorics

Most metal hydrides react violently with water, some ignite spontaneously in air (pyrophoric).  Examples of metal hydrides, are sodium borohydride, calcium hydride, lithium aluminum hydride. Other pyrophorics are boron, diborane, dichloroborane, 2-Furaldehyde, diethyl aluminum chloride, lithium, white or yellow phosphorus and trimethyl aluminum. Other water reactives include aluminum chloride-anhydrous, calcium carbide, acetyl chloride, chlorosulonic acid, sodium, potassium, phosphorous pentachloride calcium, aluminum tribromide, calcium oxide, and acid anhydrides.
Primary Storage Concern: To prevent contact and reaction with liquids and, in some cases, air. 

Recommended Facilities/Measures:  
  1. Secure, water-proof double-containment according to label instructions.  
  2. Isolation from other storage groups. 

Compatible Storage Groups: If securely double-contained to prevent contact with water and/or air, metal hydrides may be stored in the same area as Group 9 Dry Solids.  

Group IX: Dry Solids

Includes all powders, hazardous and non-hazardous. Examples: benzidine, cyanogen bromide, ethylmaleimide, oxalic acid, potassium cyanide, sodium cyanide

Primary Storage Concern: To prevent contact and potential reaction with liquids. Recommended Facilities/Measures: 

  • Cabinets are recommended, but if not available, open shelves are acceptable. 
  • Store above liquids. 
  • Warning labels on highly toxic powders should be inspected and highlighted or amended if they do not cause the containers to stand out against less toxic substances in this group.
  • It is recommended that the most hazardous substances in this group be segregated. 
  • It is particularly important to keep liquid poisons below cyanide-or sulfide-containing poisons (solids). A spill of aqueous liquid onto cyanide - or sulfide - containing poisons would cause a reaction that would release poisonous gas.
  • Compatible Storage Groups: Metal hydrides, if properly double-contained may be stored in the same area.
  • Exceptions: Solid picric or picricsulfonic acid can be stored with this group, but should be checked regularly for dryness. When completely dry, picric acid is explosive and may detonate upon shock or friction. Picric acid in contact with some metals may form explosive metal picrates. Use non-metal caps. 

Part III: Storage Plan Variations for Different Lab Facilities

On the following pages are illustrations of possible chemical storage arrangements for two types of lab facilities. They are provided merely as examples of arrangements which satisfy the recommendations of the chemical storage plan. They are not intended to restrict storage designers to the particular arrangements and facilities depicted.  

Variation 1: Chemical storage plan for lab with minimal facilities and chemicals in all 9 storage groups.
Sample Chemical Storage for a Lab Variation 1

 Variation 2: Chemical storage plan for lab with freestanding acid cabinet.

Sample Chemical Storage for a Lab Variation 2

Updated 07/17/12