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Chemical Storage and Transportation

Revised 11/2017


General Considerations for Chemical Storage 

Chemical Inventory

Chemical Storage Outside of the Lab

Primary Storage Locations 

Chemical Storage in Refrigerators and Freezers

Corrosive-liquids Storage

Storage of Strong Oxidizers

Flammable and Combustible Liquid Storage

Compressed Gas Storage

Secondary Storage Considerations:  Chemical Segregation 

 Segregation of Solids

 Segregation of Liquids

 Segregation of Gases

 Designated Areas

Chemical Stability



Explosive compounds

Transportation of Chemicals

General Guidelines

Flammable Liquids

Corrosives or Oxidizing Materials

Water-Reactive Chemicals

Pyrophoric Substances

Acutely Toxic Compounds


General Considerations for Chemical Storage

Chemical storage needs must be assessed before a chemical is purchased and delivered to the laboratory. This assessment includes determining the appropriate cabinet or shelving and ensuring that sufficient space will be available.  Determine chemical storage requirements by reviewing the information in this section of the Chemical Hygiene Plan and the safety data sheet for the chemical being purchased. 

This section of the Chemical Hygiene Plan does not address chemical security issues.  For information about securing chemicals from theft or misuse, contact EHRS.

The following general guidelines apply to all solid and liquid chemical storage areas:

  • Chemicals may not be stored in the lab if:
    • They have exceeded the manufacturer’s expiration date or the expiration intervals described in this section of the CHP or in any applicable SOPs.
    • The container is leaking, broken, or shows signs of vapor leakage and/or chemical reaction (e.g. salt formation around cap)
    • The chemical is highly hazardous and is not anticipated to be used in the next year.
Chemical Inventory

All chemicals in the laboratory must be entered into Penn’s Chemical Inventory System.  Information about the chemical inventory system can be found here

Chemical Storage Outside of the Lab

All storage cabinets located in hallways and equipment corridors must be placarded with the name of the principal investigator and also with identification of the cabinet’s contents. This information is critical for emergency personnel. The lab that owns the chemical storage cabinet must complete a Hallway Storage Sign Form (Appendix J) for each cabinet located in a hallway.  Chemicals stored in areas outside of the laboratory must be included in the lab’s chemical inventory records (see chemical inventory section above).

Primary Storage Locations

The primary storage location for a chemical is determined by the hazards of the material.  Chemical incompatibility (segregation) and chemical instability are discussed later in this section of the CHP. 

Primary storage locations include:

  • Refrigerator or freezer: Chemicals that must be stored at low temperature for safety or stability
  • Corrosive liquids storage cabinet:  Corrosive chemicals
  • Flammable liquids storage cabinet: Flammable chemicals and pyrophorics
  • Ventilated storage:  Chemicals with strong odors and/or low odor thresholds
  • Dry box or desiccator:  Moisture-sensitive chemicals
  • Glove box:  Air-sensitive chemicals
  • Open shelving or regular cabinets:  Chemicals with no specified storage requirements
Chemical Storage in Refrigerators and Freezers

Chemicals that must be stored at low temperature for safety or stability can be stored in laboratory refrigerators or freezers.  Flammable materials may only be stored in refrigerators/freezers if the equipment is designed for flammable material storage and UL-listed/labeled for this purpose.  Contact EHRS if you are unsure whether your lab refrigerator or freezer is approved for flammable liquids storage. 

Explosion-proof refrigerators/freezers are not the same as flammable-storage refrigerators/freezers.  Explosion-proof devices are only required in areas where a flammable atmosphere is anticipated.  In most lab situations, an explosion-proof refrigerator/freezer is not required.  If you are not sure whether the model of refrigerator/freezer you wish to purchase for your lab is appropriate, please contact EHRS for guidance.

Use of household-grade refrigerators/freezers in laboratories is discouraged.  Where household-grade refrigerators/freezers are used, the storage of flammable materials within them is prohibited.  The refrigerator/freezer must be labeled so that it is clear that both the storage of food/drink and the storage of flammable materials are prohibited within.

When ice accumulates in a laboratory freezer, the freezer must be defrosted.  The build-up of ice can cause a number of problems for chemical storage including:  uneven shelf surfaces, conditions making it difficult to remove or access chemical containers, and a higher likelihood of moisture entering chemical containers. Some newer freezers are designed to prevent ice build-up, but older equipment will need to be defrosted regularly. 

Hazardous chemicals must not be stored in cold rooms because cold rooms have recirculating ventilation systems.  Likewise, compressed gas cylinders, liquid nitrogen dewars, and dry ice are also prohibited in cold rooms.

Corrosive-liquids Storage

More information about safe use of corrosive liquids is available in the Corrosive Chemicals SOP.

Corrosive liquids must never be stored under sinks and may not be stored on shelves above eye-level.

The formation of crystals and residues around the caps of bottles of corrosive-liquids is an indication that the container is not properly sealed.  Containers that show these signs of leakage must be discarded by through an EHRS chemical waste pick-up.

Inorganic corrosives

Storage cabinets that are constructed of corrosion-resistant materials are the preferred storage location for most inorganic corrosive liquids.  The corrosive vapors that may escape from containers of concentrated acids and bases can damage cabinets, shelves, and brackets.  This can lead to costly repairs or replacement of cabinets, and may also cause shelf failure.  Thus, the storage of highly corrosive inorganic liquids in a flammable-liquids storage cabinet or in other cabinets that are not constructed of corrosion-resistant material is highly discouraged. 

See the chemical segregation section below for information about the storage of acids and bases in the same cabinet.

Mildly corrosive inorganic liquids such as dilute acids and bases (1.0 N HCl or 2.0 N NaOH, for example) may be stored in open shelving.  It is recommended that acids and bases stored in regular cabinets be kept on plastic trays or in plastic bins.


Amines are alkaline compounds that may be corrosive, but are generally weak bases.  Amines are also commonly flammable and tend to give off strong odors.  Amines do not need to be stored in a corrosion-resistant cabinet.  If they are flammable, they should be kept in a flammable-liquids storage cabinet.  It is usually best to store these strong-smelling chemicals in the flammable-liquids storage cabinet under the hood, as these are usually vented to the fumehood exhaust.

Organic acids and acid chlorides

Non-halogenated organic acids and acid chlorides (such as formic acid and acetic acid) are corrosive, but they are also flammable.  These should be stored in a flammable-liquids storage cabinet.  Keep the containers clean and tightly capped to avoid damage to the cabinet due to escaping corrosive vapor.  Halogenated organic acids such as trifluoroacetic acid are non-flammable and do not need to be kept in the flammable-liquids storage cabinet.

Oxidizing acids

More information about safe use of oxidizing chemicals is available in the Strong Oxidizers SOP.

Some acids such as nitric, perchloric, chromic, and sulfuric are strongly oxidizing in addition to being strongly corrosive.  These acids must be kept in a corrosion-resistant cabinet and must be stored separately from all reducing agents, organic chemicals, and cellulose containing materials.  Oxidizing acids must never be stored under sinks, on wooden shelves, or in wooden cabinets. They must also be kept away from paper products such as cardboard and paper towels.  Strong oxidizers are highly reactive and may release hazardous gases, ignite, or form explosive mixtures on contact with wood, paper, or other organic materials.

Storage of Strong Oxidizers

More information about safe use of oxidizing chemicals is available in the Strong Oxidizers SOP

See “Oxidizing acids” above.  This guidance applies to all strongly oxidizing chemicals.

Flammable and Combustible Liquid Storage

More information about the safe use of flammable liquids is available in the Flammable Liquids SOP.

The storage of flammable and combustible liquids in a laboratory, shop, or building area must be kept to the minimum needed for research and operations. Containers one liter and larger of flammable liquids must be stored in a flammable-liquids storage cabinet. Flammable-liquids storage cabinets are not intended for the storage of compressed gases or highly corrosive chemicals.  Flammable-liquids storage cabinets must meet the guidelines set forth in Lab Design & Equipment:  Flammable Liquids Storage Cabinets Specifications.Lab Design & Equipment:  Flammable Liquids Storage Cabinets Specifications.

Only compatible chemicals may be stored together inside of a single flammable-liquids storage cabinet.  See “Secondary Storage Considerations:  Chemical Segregation” below for details.

Flammable Liquids Storage in a refrigerator

See “Chemical Storage in Refrigerators and Freezers” section above.

Compressed Gas Storage

More information about the safe use of compressed gases is available in the Compressed Gases SOP and the Hazardous and Highly Toxic Gases SOP.

All compressed gas cylinders, regardless of hazard class, must be stored as follows:

  • Store only the minimum amount of compressed gas required for immediate and near-term research needs.  Do not stockpile gas cylinders. Promptly return unneeded gas cylinders to the vendor.
  • Cylinders of hazardous compressed gases stored in common areas such as hallways must be clearly labeled with the name of the laboratory that is responsible for them.
  • Cylinders must be stored in an upright position and properly secured.  See Compressed Gases SOP. Compressed gas cylinders pose a crush hazard to hands and feet.
  • Always use the correct regulator. Do not use a regulator adapter.
  • Remove regulators when gas is not in use.  If the regulator fails, the entire contents of the gas cylinder may be discharged.
  • Cylinder caps must remain on the cylinder at all times unless a regulator is in place.
  • Cylinders must be stored in areas where they will not become overheated. Avoid storage near radiators, areas in direct sunlight, steam pipes and heat releasing equipment such as sterilizers.
  • Do not store compressed gas cylinders in cold rooms or other areas with recirculating ventilation.
  • Cylinders must be segregated as described below in the “Secondary Storage Considerations:  Chemical Segregation" section
  • Cylinders must be transported as described below in the “Chemical Transport” section

Toxic, flammable, and oxidizing gases have additional storage requirements and limits:

  • Cylinders of toxic and reactive gases must be stored and used in a fume hood or ventilated gas cabinet designed for this purpose.  See the Hazardous and Highly Toxic Gases SOP for additional requirements for the storage and use of these gases.  Certain gases may not be purchased and used on campus without EHRS review and approval.

Secondary Storage Considerations:  Chemical Segregation

Within each primary storage location (shelf, cabinet, etc.) incompatible materials may not be stored together without appropriate segregation.

Do not segregate chemical classes into separate rooms unless they will only be used in that room. Segregation that disrupts normal work flow or requires more frequent transport of chemicals between labs will increase the probability of a chemical spill.

Incompatible materials should be stored in separate cabinets whenever possible.  For example:  Acids and bases would be kept in separate corrosive liquids storage cabinets.  However, when that is not possible, secondary containment bins can be used to segregate the incompatible materials.  The secondary containment must be large enough to accommodate the volume of the largest container stored within.  Once separated into hazard classes, chemicals may be stored alphabetically or by other systems such as by carbon number.

Segregate solids as follows:

  • oxidizing solids
  • flammable solids
  • water reactive solids
  • all others solids

Segregate liquid reagents and solutions as follows:

  • *acid liquids
  • *alkaline liquids
  • *oxidizing liquids
  • perchloric acid solutions
  • *flammable or combustible liquids
  • pyrophoric & water-reactive liquids
  • all other liquids

*see primary storage section above for additional information about storing these classes of chemicals

Segregate compressed gases as follows:

  • toxic gases
  • flammable gases
  • oxidizing gases1
  • Empty cylinders must be stored separately from full or partially-full cylinders

1Oxidizing gas must be separated by a distance of at least 20 feet from fuel gas cylinders or a highly combustible material such as, but not limited to, oil, grease, flammable gas or a source of ignition, or be separated from the material by a noncombustible wall, not less than five feet high, having a fire resistance rating of one hour. All cylinders shall be stored away from heat in excess of 125° Fahrenheit. See above for more information about compressed gas cylinder storage.

Designated Areas

Designated Areas are a concept that applies to labs that mostly use non-hazardous or very low-hazard materials but may have one or two higher hazard chemicals. In these labs, PPE requirements and other chemical hygiene practices may not be uniform throughout the lab space.  In such labs, all locations within the laboratory where acutely toxic, carcinogenic, or reproductive hazards are handled must be demarcated with designated area caution tape. Preprinted tape is available from EHRS (see Appendix G). Alternately the lab worker may write “designated area” on yellow tape.  Areas that must be designated include all fume hoods, sinks, and bench tops where the acutely toxic, carcinogenic, or reproductive hazards are handled. The tape should be used in the same manner as radiation caution tape; the lab worker may designate an area only during the time the chemical is used and then remove it or may permanently designate an area and leave the tape in place.  

For labs where hazardous chemicals are routinely used throughout the room, the entire lab space may be deemed a “Designated Area”.  This is accomplished by including a “Designated Area” sticker on the lab room sign and by enforcing uniform practices for chemical-handling, PPE, housekeeping, and decontamination throughout the entire lab space.

(This information is also included, verbatim, in the Chemical Handling Section of the CHP)

Chemical Stability

The manner in which a chemical is stored and the length of time that it may remain stored in the laboratory is determined by the stability of the material.

Stability refers to the susceptibility of the chemical to undergo dangerous decomposition.  For the purposes of this section of the CHP, we are referring to the likelihood that chemicals will undergo decomposition or react (spontaneously or gradually) during normal storage in the lab.

Some chemicals are inherently unstable, while others may become more reactive in the presence of heat, air, water, light or other contaminants.  For this reason, it is important to understand which chemicals stored in your lab are, or may become, unstable and under what conditions this may occur. 

Refer to the safety data sheet or ask your supervisor or EHRS for help determining whether a chemical may be unstable.


All potentially unstable chemicals must be dated upon receipt and upon opening, and they must be discarded through EHRS immediately whenever any of these conditions exist:

  • The chemical is no longer needed for current research needs
  • The expiration date specified by the manufacturer on the chemical label has been reached
  • The storage duration specified for this chemical in Penn’s Chemical Hygiene plan has been reached.  (Varies depending on hazard , see below)
  • The purity of the material becomes suspect due to known contamination or changes in the physical appearance or activity of the chemical are observed
  • The chemical container or cap is damaged
  • The chemical is discovered in the lab with no “received” or “opened” date on the label

For specific storage limitations and expiration intervals for peroxide-formers and explosive compounds see the following SOPs and sections in Penn’s Chemical Hygiene Plan:

Peroxide-Forming Chemicals SOP

  • Peroxide-formers (including THF, diethyl ether, potassium metal, etc.)
  • Auto-polymerizing (vigorously condensing) compounds

Explosive (and Potentially Explosive) Compounds SOP

  • Shock-sensitive materials
  • Air, water, and light sensitive materials
  • Organic peroxides
  • Azides
  • Nitrates
  • Explosive salts
  • Perchlorates
  • Fulminates
  • Picrates
  • And others (see SOP)

Transportation of Chemicals

The transportation of hazardous chemicals in laboratory buildings provides the greatest potential for chemical exposure to the building occupants. Spills occurring outside storerooms and laboratories may lead to hazardous concentrations of vapors and gases being distributed throughout the building.  Always use a carrier when transporting reagent containers by hand.

General Chemical Transport Guidelines:
  1. Chemicals, substances and research materials must be clearly labeled with the correct chemical name when transported. Hand-written labels are acceptable; chemical formulas and structural formulas are not acceptable (except for small quantities of compounds synthesized in the laboratory).
  2. Persons transporting chemicals outside of the laboratory must wear safety glasses and one disposable glove for handling the chemical container and carrier.  One hand must remain ungloved for operating door handles and elevator buttons.
  3. An appropriate chemical cart must be used whenever chemicals cannot easily be transported in a carrier using one hand. The cart must have sides, on each shelf, that are high enough to retain the containers. Cart wheels must be large enough to prevent the carts from being caught in floor cracks and door and elevator thresholds.
  4. If two gloves are worn while operating a chemical cart, one glove must be removed before operating door handles and elevator buttons or a second person who is not wearing gloves must accompany the person operating the cart. 
  5. Freight elevators shall be used where available to transport hazardous materials. Under no circumstances are passenger elevators to be used for the transportation of hazardous materials if freight elevators are available.

The following guidelines apply for the transport of specific classes of hazardous chemicals:

Flammable Liquids Transport
  • Original containers of flammable liquids shall be placed in a secondary container or acid-carrying bucket.
  • No more than 5 gallons of flammable liquids in glass containers shall be transported on the freight elevator unless the original shipping carton (box) is used and the materials are on an appropriate cart.

More information about the safe use of flammable liquids is available in the Flammable Liquids SOP.

Corrosives or Oxidizing Materials Transport
  • Original glass shipping containers holding liquid acids and bases must be placed in a secondary container or acid-carrying bucket.
  • Incompatible chemicals, for example chromic acid (oxidizing acid) and ethyl acetate (organic solvent), may not be transported on the same cart unless they are in original shipping cartons and physically separated.

More information about safe use of corrosive liquids is available in the Corrosive Chemicals SOP.

More information about safe use of oxidizing chemicals is available in the Strong Oxidizers SOP.

Water-Reactive, Pyrophoric, and Acutely Toxic Substances Transport
  • Wherever possible, use the original outside shipping containers (packaging) when transporting water-reactive, pyrophoric, or acutely toxic chemicals.
  • Once opened, water-reactive, pyrophoric, and acutely toxic chemicals must be placed in a rigid secondary container or acid carrying bucket for transporting.

More information about safe use of these materials is available in the following SOPs:  Water-Reactive Chemicals SOP, Pyrophoric Chemicals SOP, Acutely Toxic Chemicals SOP

Compressed Gases Transport

  • Transport compressed gas cylinders using only equipment designed for this function.  Regular hand trucks may not be used for cylinder transport.
  • Never lift, carry, or "walk" cylinders by hand.
  • The protective valve cap must be in place during transport.
  • Never transport a cylinder with a regulator in place.

More information about the safe use of compressed gases is available in the Compressed Gases SOP and the Hazardous and Highly Toxic Gases SOP.


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