Chapter 16: Chemical Storage

General Storage Guidelines

The primary goals of safe chemical storage are to reduce risk by minimizing quantities of chemicals stored, avoiding contact between incompatible chemicals, and preventing hazardous storage conditions (for example, light and heat). Additionally, physical security of chemical storage areas is an increasing concern. Provide adequate security so that unauthorized personnel do not have access to chemicals. Chemical storage areas should be locked when authorized personnel are not present.

Selection of Chemicals

The overall risk associated with a particular laboratory is dependent in large part on the chemical inventory; chemical hazards, chemical volume, and storage conditions all influence risk. Whenever possible, choose chemicals that minimize hazards such as toxicity, flammability, and reactivity. In some cases, a less hazardous chemical can be used if laboratory procedures are modified. Ordering only the volume of chemical needed, or that will be used within the shelf life of the chemical, will minimize the chemical inventory within the laboratory. When only a small amount of a chemical is needed it can often be obtained from another laboratory on campus (the Chemical Hygiene Officer can be contacted for assistance). Additionally, determine if adequate storage conditions such as physical space and storage containers (such as flammable storage cabinets) are available prior to obtaining the chemical.

Chemical Inventory and Inspection

  • A chemical inventory must be maintained for all chemicals stored in the laboratory. EH&S maintains a chemical inventory of each lab on campus; however, laboratories are encouraged to keep their inventory current by adding and deleting chemicals as they are received or disposed. The chemical inventory database used at UNR is known as ChemTracker. Although ChemTracker is web-based, access to each laboratory inventory is secured to prevent unauthorized viewing. Each laboratory supervisor is granted access to his or her inventory; other laboratory personnel will be provided access only upon approval by the responsible laboratory supervisor. Laboratory supervisors wanting to allow other laboratory personnel to access their lab’s inventory will need to contact EH&S.
  • Empty chemical containers must be removed from the chemical inventory as they are disposed of. This can be accomplished by submitting a request for pickup of empty containers to EH&S using the chemical waste forms, or submitting UNR bar code numbers from empty containers to Luis Barthel-Rosa (luisbr@unr.edu). Alternatively, empty containers placed in a designated location will be removed by EH&S waste technicians when they dispose of full waste containers for which a request for disposal has been submitted.
  • Each laboratory should perform periodic (at least annually) inspections of their chemical inventory.
    • Chemicals that are no longer needed, or which meet any of the following conditions, should be disposed of through EH&S: i) safe shelf life has been exceeded, ii) evidence of chemical reaction, iii) identity of chemical is unknown, iv) container and/or cap corroded, leaking, or otherwise in poor condition.

General Storage Recommendations

  • It is recommended that chemical containers be labeled with the date of receipt and the date opened. This is especially important for peroxidizable chemicals and other chemicals with specific safe storage lifetimes.
  • It is recommended that higher risk chemicals (highly toxic, flammable, or reactive) be stored in secondary containment to reduce the likelihood of release.
    • For liquid chemicals, plastic tubs and trays can be used as secondary containment for larger containers or multiple containers, while sealed cans and plastic bags can be used for smaller, individual containers.
    • For solid chemicals, sealed containers or plastic bags can provide secondary containment.
  • Generally, chemicals should be stored in cabinets or on shelves.
    • Storage of chemicals in laboratory hoods should be minimized in order to maximize the hood ventilation performance.
    • Storage of chemicals on the floor should be avoided, and if required, glass chemical containers stored on the floor must be in secondary containment.
  • Chemical storage cabinets should be secured to a wall or other structure to avoid tipping over (especially likely in an earthquake).
    • Shelving should be secure and able to support the materials placed on them.
    • Shelves should have a barrier or lip to prevent chemical containers from falling off.

Segregation and Storage of Chemicals

In order to reduce the likelihood of incompatible mixing during storage, chemicals should be segregated and stored according to their hazard classification and compatibility (see appendix “Partial List of Chemical Incompatibilities”). Incompatible chemicals within hazard classes should also be separated.

The ChemTracker chemical inventory management system assigns chemicals to one of eleven storage groups as follows:
Storage Group Description
A Compatible Organic Bases
B Compatible Pyrophoric and Water Reactive Materials
C Compatible Inorganic Bases
D Compatible Organic Acids
E Compatible Oxidizers Including Peroxides
F Compatible Inorganic Acids Not Including Oxidizers or Combustibles
G Not Intrinsically Reactive or Flammable or Combustible
J* Poison Compressed Gases
K* Compatible Explosive Or Other Highly Unstable Materials
L Non-Reactive Flammables and Combustibles, Including Solvents
X* Incompatible With All Other Storage Groups

*Storage groups J, K, and X: Consult manufacturer and EH&S for specific storage guidance.

  • The ChemTracker storage groups can be used to assist laboratory workers in segregating chemicals; however, incompatible chemicals may still end up grouped together so laboratory personnel will need to evaluate the compatibility of stored chemicals.
  • When a chemical fits in more than one hazard category, store the chemical according to the highest risk (based on severity of consequences and likelihood) hazard criteria.
    • Fire is generally considered to be the highest risk category and flammability/combustibility should be used as the major storage criteria.

General Chemical Storage (Storage Group G)

General chemical storage includes low risk chemicals not assigned to another specific hazard group (such as salts, amino acids, buffers, etc.). Store these chemicals using general storage recommendations.

  • It is recommended that general chemicals be separated into liquids and solids, and then further segregated into organic and inorganic sections.

Acids

  • Store oxidizing acids (such as nitric acid, perchloric, and chromic acid) away from organic acids, and organic solvents.
    • Concentrated perchloric acid should be stored in glass or plastic (polyethylene or polypropylene) secondary containers away from combustible materials (such as wooden shelves and paper).
    Note: Glacial acetic acid has a flash point of approximately 102 °F (39 °C) and is classified as a combustible liquid.
  • Store inorganic acids separately from organic acids.
  • Concentrated acids should be stored in an acid storage cabinet.
  • Separate acids from active metals (such as sodium, magnesium, and potassium) and chemicals that generate toxic gases on contact with acids (such as inorganic cyanides and sulfides).
  • Separate acids from bases.
    • If necessary, acids and bases can be stored in the same cabinet; however, they should be physically separated by storing in secondary containers (such as bus tubs).

Bases

  • Separate bases from acids.

Flammable and Combustible Liquids

Maximum Flammable and Combustible Liquid Container Size

The maximum allowable (by OSHA) sizes for flammable and combustible liquid storage containers are as follows:
Container Type Flammable Liquid Category 1 Flammable Liquid Category 2 Flammable Liquid Category 3 Flammable Liquid Category 4
Glass or approved plastic 1 pint 1 quart 1 gallon 1 gallon
Metal (other than DOT drums) 1 gallon 5 gallons 5 gallons 5 gallons
Safety cans 2 gallons 5 gallons 5 gallons 5 gallons
Metal drums (DOT specifications) 60 gallons 60 gallons 60 gallons 60 gallons
Approved portable tanks 660 gallons 660 gallons 660 gallons 660 gallons

Exceptions:Glass or plastic containers up to one gallon capacity can be used for a Category 1 or 2 flammable liquid if the stored liquid would be rendered unfit for its intended use by contact with metal, or would excessively corrode a metal container so as to create a leak hazard. See 29 CFR 1910.106(d)(2)(iii)(a)(1)-(2) for complete exception.

OSHA Flammable Liquid Categories

Category 1 - Flash point < 23°C (73.4°F) and initial boiling point ≤ 35°C (95°F)

Category 2 - Flash point < 23°C (73.4°F) and initial boiling point > 35°C (95°F)

Category 3 - Flash point ≥ 23°C (73.4°F) and ≤ 60°C (140°F)

Category 4 - Flash point > 60°C (140°F) and ≤ 93°C (199.4°F)

Maximum Allowable Quantities in Laboratory Buildings

Contemporary laboratory safety practice dictates that the volume of flammable and combustible liquids stored and used in the laboratory be minimized. Flammable liquids, and to a lesser extent combustible liquids, should always be stored in flammable liquid storage cabinets and safety cans to minimize the risk of fire.

The Nevada State Fire Marshall, through incorporation of the International Fire Code (IFC), regulates maximum storage quantities for flammable and combustible liquids per fire control area. The IFC also limits the number of control areas per building and per floor.

The maximum allowable quantities of flammable and combustible liquids per control area (including chemical waste) are:
Class Quantity – Storage Quantity – In Use, Closed System Quantity – In Use, Open System
1A 30 gallons 30 gallons 10 gallons
1A, 1B, and 1C combined* 120 gallons 120 gallons 30 gallons
II 120 gallons 120 gallons 30 gallons
IIA 330 gallons 330 gallons 80 gallons

* Quantity limits for Class 1A may not be exceeded.

IFC Flammable and Combustible Liquid Definitions

Class IA – Liquids having a flashpoint below 73 °F (23 °C), and having a boiling point below 100 °F (38 °C).

Class IB – Liquids having a flashpoint below 73 °F (23 °C), and having a boiling point at or above 100 °F (38 °C).

Class IC – Liquids having a flashpoint at or above 73 °F (23 °C), and below 100 °F (38 °C).

Combustible Liquids

Class II – Liquids having a flashpoint at or above 100 °F (23 °C), but below 140 °F (60 °C).

Class IIIA – Liquids having a flashpoint at or above 140 °F (60 °C), but below 200 °F (93 °C).

Additionally, the number of allowable control areas, and the percentage of the maximum allowable quantity per control area is limited by the floor level within the building as listed below.
Floor Level % of Max. Allowable Quantity Per Control Area Number Control Areas Per Floor
Above Grade 9 5 1
Above grade 7 - 9 5 2
Above Grade 6 12.5 2
Above Grade 5 12.5 2
Above Grade 4 12.5 2
Above Grade 3 50 2
Above Grade 2 75 3
Above Grade 1 100 4
Below Grade 1 75 3
Below Grade 2 50 2
Lower than grade 2 Not Allowed Not Allowed

Note 1: A single control area may be composed of multiple laboratory rooms; thus, the maximum allowable quantity of flammable and combustible liquids in an individual laboratory room will usually be less than the above control area values.

Note 2: The maximum allowable limits for flammable and combustible liquids can be doubled if stored in an approved flammable liquid storage cabinet or approved safety cans, and can be doubled again if the rooms comprising the control area are equipped with automatic fire suppression sprinklers.

It is recommended that quantities of flammable liquids stored outside of a flammable storage cabinet or safety can be limited as follows

  • The maximum quantity of flammable liquids (Class I) and Class II combustible liquids, combined, that can be stored outside of a flammable storage cabinet is 10 gallons; however, this total can be increased to 25 gallons if the flammable and combustible liquids are stored in safety cans.
  • All 5 gallon flammable liquid containers should be stored in a flammable liquid storage cabinet.

Storage in Flammable Liquid Cabinets

Maximum Storage Quantities

  • Maximum storage quantities per individual flammable liquid storage cabinet are:
    • 60 gallons of flammable or combustible liquid.
    • 120 gallons of flammable and combustible liquid combined.

Ventilation of Flammable Liquid Cabinets

  • Flammable storage cabinets should not be vented for fire protection purposes.
  • Ventilation of cabinets must be in accordance with fire protection requirements found in NFPA 30, Flammable and Combustible Liquids Code and approved by the State Fire Marshall’s Office.
    • Do not remove vent bungs from storage cabinets unless the cabinets are properly ventilated.

Additional information on venting flammable liquid storage cabinets is available from Grainger.

Labeling of Flammable Liquid Cabinets

  • Storage cabinets must be labeled “Flammable-Keep Fire Away.”

Storage in Refrigerators and Freezers

Refrigerators and freezers designed for domestic use contain interior spark sources and should not be used for storage of flammable liquids.

  • Do not use a domestic refrigerator or freezer for storage of flammable liquids; use only an approved “laboratory safe” unit (no spark sources in the interior of the unit).
    • The quantity of flammable liquid stored in refrigerators is included in the maximum amount that can be stored outside of an approved flammable liquid cabinet.

Non-Flammable/Combustible Organic Liquids

  • Store in a cabinet separated from oxidizing materials.
    • These chemicals can be stored with flammable and combustible liquids.

Oxidizers

  • Separate oxidizers from flammable and combustible materials, and reducing agents.

Highly Reactive Chemicals

  • Store water reactive chemicals in a secondary container or other protective barrier against accidental exposure to water.
    • Do not store under sinks or near other locations with potential water exposure.
  • Store pyrophoric chemicals in an inert atmosphere in accordance with the manufacturer’s (SDS) recommendations or other recognized laboratory safety practices, and away from flammable chemicals and heat sources. Additional information on pyrophoric chemicals is available in Chapter 5.
  • Many organic chemicals can undergo autooxidation upon exposure to air and form shock sensitive peroxides. Chapter 6 has information on the proper handling and storage of peroxide forming chemicals.