||Many "classic" chemical demonstrations involve exotic chemicals. A first class science curriculum does not really need to use these chemicals. With today's liability concerns, the more basic the chemicals used, the better.
Proper chemical storage controls health and physical hazards posed by chemical compounds during storage in the lab.
Chemical manufacturers are required to list all hazards on chemical containers and each chemical must be accompanied by a Material Safety Data Sheet (MSDS). The chemical label thus furnishes a quick method of determining whether the material is a fire hazard, health hazard or reactivity hazard. The MSDS furnishes more detailed information regarding toxicity exposure levels, flashpoints, required safety equipment and recommended procedures for spill containment.
There are simple systems and complex systems - good systems and bad systems. Randomly placing chemicals on a shelf is the worst system. Placing them in alphabetical order on shelves is only slightly better than no system at all. Chemicals should be stored by groups, either based on compatibility or incompatibility. A fairly simple system is explained on this page.
This system is designed to:
These guidelines include Part I general rules of safe storage and Part II definition of storage groups.
- Protect flammables from ignition;
- Minimize the potential of exposure to poisons;
- Segregate incompatible compounds to prevent their accidental mixing (by spills, residues, fires or human error).
Part I: General Rules of Safe Chemical Storage
- Safeguard against theft.
Locked cabinets are not required, but teachers should ALWAYS make sure that lab doors are locked when they are not in the room.
- 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.
- Not under the sink.
Do not store any chemicals except bleach and compatible cleaning agents under the sink.
- Away from sun and heat.
Storage areas should not be exposed to extremes of heat or sunlight.
- 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.
Overview of the Chemical Storage Groups:
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.
Poisons - volatile
Acids - Oxidizing
Acids - Organic and Mineral
Bases - Liquid
Oxidizer - Liquid
Poisons - Non-volatile
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
Group II: Volatile Poisons
Primary Storage Concern: To protect from ignition Recommended
Compatible Storage Groups: Volatile poisons may be in the same compartment of the flammable cabinet as flammables if bases are not present.
- Flammable cabinet
- Refrigerator: for containers less than 1 liter.
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, formal dehyde, halothane, mercaptoethanol, methylene chloride, phenol.
Group III: Oxidizing Acids
Primary Storage Concern: To prevent inhalation exposures.
Compatible Storage Groups: Volatile poisons may be in the same compartment of the flammable cabinet as flammable if bases are not present.
- Flammable cabinet
- Refrigerator: for containers less than 1 liter.
All oxidizing acids are highly reactive with most substances and each other. Examples: nitric, sulfuric, perchloric, phosphoric acids, and chromic acids.
Group IV: Organic and Mineral Acids
Primary Storage Concern: Preventing contact and reaction with each other and other substances and corrosive action on surfaces.
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.
- Safety Cabinet. Each oxidizing acid must be double-contained, i.e., the primary container must be kept inside canister, tray or tub.
Examples: acetic, butyric, formic, glacial acetic, hydrochloric, isobutyric, mercaptoproprionic, proprionic, trifluoroacetic acids.
Group V: Liquid Bases
Primary Storage Concern: To prevent contact and reaction with bases and oxidizing acids and corrosive action on surfaces.
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.
- Safety cabinet.
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.
Examples: sodium hydroxide, ammonium hydroxide, calcium hydroxide, glutaraldehyde
Group VI: Oxidizing Liquids
Primary Storage Concern: Preventing contact and reaction with acids.
Compatible Storage Groups: Liquid bases may be stored with flammables in the flammable cabinet if volatile poisons are not also stored there.
- Safety cabinet;
- In tubs or trays in normal cabinet.
Oxidizing liquids react with everything - potentially causing explosions or corrosion of surfaces.
Group VII: Non-Volatile Liquid Poisons
Examples: ammonium persulfate, hydrogen peroxide (if greater than or equal to 30%)
Primary Storage Concern: To isolate from other materials.
Compatible Storage Groups: None
- Total quantities exceeding 3 liters should be kept in a cabinet housing no other chemicals.
- Smaller quantities must be double-contained if kept near other chemicals, e.g., in a refrigerator.
Includes highly toxic (LD50 oral rat < 50 mg/kg) and toxic chemicals (LD50 oral rat < 500 mg/kg), known carcinogens, suspected carcinogens and mutagens.
Group VIII: Reactives Metal Hydrides and Pyrophorics
Examples: acrylamide solutions; diethylpyrocarbonate; diisopropyl fluorophosphate; uncured epoxy resins; ethidium bromide; triethanolamine
Primary Storage Concern: To prevent contact and reaction with other substances.
Compatible Storage Groups: Non-hazardous liquids (e.g., buffer solutions).
- Cabinet or refrigerator (i.e., must be enclosed)
- Do not store on open shelves in the lab or cold room.
- 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.
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.
Most metal hydrides react violently with water, some ignite spontaneously in air (pyrophoric).
Group IX: Dry Solids
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.
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.
- Secure, water-proof double-containment according to label instructions.
- Isolation from other storage groups.
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.
Compatible Storage Groups: Metal hydrides, if properly double-contained may be stored in the same area.
- 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.
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.