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Chemical Storage Compatibility Guidelines

Quick Tips #181

Chemicals play an important role in many workplace applications. The inherent hazards of chemicals can be reduced by minimizing the quantity of chemicals on hand. However, when chemicals must be in-house, proper storage and handling can reduce or eliminate some of the associated risks.

Proper storage information can be obtained from Section 7 of the Safety Data Sheet (SDS). As required by 29 Code of Federal Regulations (CFR) 1910.1200, an SDS must be on hand for every hazardous chemical in your workplace. Sections 7, 9, and 10 of the SDS can also answer questions such as:

  • Is the chemical a flammable?
  • Is the chemical a corrosive?
  • Does the chemical need to be stored other than at ambient temperature?
  • Is the chemical an oxidizer or reducer?
  • Is the chemical light sensitive?
  • Does the chemical require any special handling procedures?

Typical storage considerations may include temperature, ignition control, ventilation, segregation and identification. Proper segregation is necessary to prevent incompatible materials from inadvertently coming into contact. If incompatible materials were to come into contact, fire, explosion, violent reactions or toxic gases could result.

When segregating chemicals, acids should not be stored with bases, and oxidizers should not be stored with organic materials or reducing agents. Physical barriers and/or distance are effective for proper segregation.

If cabinets are used to segregate chemicals, consider the compatibility of the chemicals with the cabinet. For example, corrosives, like strong acids and caustics, will corrode most metal cabinets. Non-metallic or epoxy-painted cabinets are available and will provide a better service life with these types of chemicals. Some acids and bases may damage the epoxy-painted surfaces of a cabinet if a spill occurs. Also, perchloric acid should not be stored in a wooden cabinet.

There are cabinets designed specifically to store flammable liquids. It is important to be aware of the maximum allowable container size and maximum quantities for storage in cabinets based on the category of the flammable. The category of a flammable is determined by its flash point and boiling point. The Occupational Safety and Health Administration (OSHA) has defined a flammable liquid as any liquid having a flash point of not more than 93° C or 199.4° F (29CFR 1910.106(a)(19)). OSHA further classifies flammables into four categories. 29 CFR 1910.106(a)(19)(i-v) and Table B.6.1 of 29 CFR 1910.1200 Appendix B provides the criteria for the four flammable liquid categories:

Category Criteria
1 Flash point < 73.4 °F and initial boiling point ≤ 95 °F
2 Flash point < 73.4 °F and initial boiling point > 95 °F
3 Flash point > 73.4 °F and ≤ 140 °F
4 Flash point > 140 °F and ≤ 199.4 °F

 

The following chart lists the maximum volume of flammables that can be stored in a single container type:

Maximum Allowable Size of Containers and Portable Tanks
Container Type
Category 1 Category 2 Category 3 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 spec.) 60 gallons 60 gallons 60 gallons 60 gallons
Approved Portable Tanks 660 gallons 660 gallons 660 gallons 660 gallons

 

The following chart lists the maximum volume of flammables that can be stored in a single flammable storage cabinet.

Maximum Storage Quantities for Cabinets
Liquid Class Maximum Storage Capacity
Category 1 60 Gallons
Category 2 60 Gallons
Category 3 60 Gallons
Category 4 120 Gallons*

*Not more than 60 gallons may be Category 1, 2, or 3 liquids. No more than 120 gallons of Category 4 liquids may be stored in a storage cabinet, according to OSHA 29 CFR 1910.106(d)(3)(i).

For ease of locating chemicals, many storerooms organize chemicals alphabetically. However, chemical storage based upon an alphabetical arrangement of chemicals may inadvertently locate incompatible materials in close proximity to one another. A few examples of this potentially dangerous storage method are demonstrated by the following pairs of incompatible materials:

Chemical Reaction
Acetic acid and acetaldehyde Polymerization of acetaldehyde
Copper (II) sulfide and cadmium chlorate Explosive reaction
Hydrogen peroxide and iron (II) sulfide Reacts vigorously
Sodium nitrite and sodium thiosulfate Explosive when heated

Other common examples of incompatible chemicals:

Chemical Is Incompatible and Should Not Be Mixed or Stored With
Acetic acid Chromic acid, nitric acid, hydroxyl compounds, ethylene glycol, perchloric acid, peroxides, permanganates
Acetylene Chlorine, bromine, copper, fluorine, silver, mercury
Acetone Concentrated nitric and sulfuric acid mixtures
Alkali and alkaline earth metals (such as powdered aluminum or magnesium, calcium, lithium, sodium, potassium) Water, carbon tetrachloride or other chlorinated hydrocarbons, carbon dioxide, halogens
Ammonia (anhydrous) Mercury, chlorine, calcium hypochlorite, iodine, bromine, hydrofluoric acid (anhydrous)
Ammonium nitrate Acids, powdered metals, flammable liquids, chlorates, nitrates, sulfur, finely divided organic or combustible materials
Aniline Nitric acid, hydrogen peroxide
Arsenical materials Any reducing agent
Azides Acids
Bromine See Chlorine
Calcium oxide Water
Carbon (activated) Calcium hypochlorite, all oxidizing agents
Carbon tetrachloride Sodium
Chlorates Ammonium salts, acids, powdered metals, sulfur, finely divided organic or combustible materials
Chromic acid and chromium trioxide Acetic acid, naphthalene, camphor, glycerol, alcohol, flammable liquids in general
Chlorine Ammonia, acetylene, butadiene, butane, methane, propane (or other petroleum gases), hydrogen, sodium carbide, benzene, finely divided metals, turpentine
Chlorine dioxide Ammonia, methane, phosphine, hydrogen sulfide
Copper Acetylene, hydrogen peroxide
Cumene hydroperoxide Acids (organic or inorganic)
Cyanides Acids
Flammable liquids Ammonium nitrate, chromic acid, hydrogen peroxide, nitric acid, sodium peroxide, halogens
Fluorine Everything
Hydrocarbons (such as butane, propane, benzene) Fluorine, chlorine, bromine, chromic acid, sodium peroxide
Hydrocyanic acid Nitric acid, alkali
Hydrofluoric acid (anhydrous) Ammonia (aqueous or anhydrous)
Hydrogen peroxide Copper, chromium, iron, most metals or their salts, alcohols, acetone, organic materials, aniline, nitromethane, combustible materials
Hydrogen sulfide Fuming nitric acid, oxidizing gases
Hypochlorites Acids, activated carbon
Iodine Acetylene, ammonia (aqueous or anhydrous), hydrogen
Mercury Acetylene, fulminic acid, ammonia
Nitrates Sulfuric acid
Nitric acid (concentrated) Acetic acid, aniline, chromic acid, hydrocyanic acid, hydrogen sulfide, flammable liquids, flammable gases, copper, brass, any heavy metals
Nitrites Acids
Nitroparaffins Inorganic bases, amines
Oxalic acid Silver, mercury
Oxygen Oils, grease, hydrogen, flammable liquids, solids or gases
Perchloric acid Acetic anhydride, bismuth and its alloys, alcohol, paper, wood, grease, oils
Peroxide, organic Acids (organic or mineral), avoid friction, store cold
Phosphorus (white) Air, oxygen, alkalis, reducing agents
Potassium Carbon tetrachloride, carbon dioxide, water
Potassium chlorate Sulfuric and other acids
Potassium perchlorate (see also chlorates) Sulfuric and other acids
Potassium permanganate Glycerol, ethylene glycol, benzaldehyde, sulfuric acid
Selenides Reducing agents
Silver Acetylene, oxalic acid, tartartic acid, ammonium compounds, fulminic acid
Sodium Carbon tetrachloride, carbon dioxide, water
Sodium nitrate Ammonium nitrate and other ammonium salts
Sodium peroxide Ethyl or methyl alcohol, glacial acetic acid, acetic anhydrite, benzaldehyde, carbon disulfide, glycerin, ethylene glycol, ethyl acetate, methyl acetate, furfural
Sulfides Acids
Sulfuric acid Potassium chlorate, potassium perchlorate, potassium permanganate (similar compounds of light metals, such as sodium, lithium)
Tellurides Reducing agents

 

General Incompatibilities by Chemical Groups
Acids Alkalines, Combustibles, Flammables, Cyanides, Nitrates and Reactive Sulfides
Oxidizers Organics
Nitrates Acids
Ammoniated Compounds Hypochlorites / Bleach
Organics Nitrates Perchlorates / Oxidizers / Metals

 

In addition to chemical compatibility concerns, safe chemical handling requires regular inspections of chemical storage areas and maintenance of stringent inventory control.

Commonly Asked Questions
 
Q. What are some things to look for when inspecting a chemical storage area?
A. All chemicals should be properly labeled. Chemicals should have their caps secured at all times. No chemicals should be stored on bench tops, fume hoods, on the floor or extending into traffic aisles. Chemical shelves should not be over crowded. Chemicals should not be stored above eye level.
 
Q. What should we do if we have old, unlabeled chemicals in house?
A. Hire a hazardous waste contractor to come in and evaluate the situation and properly dispose of the materials.
 
Q. What emergency equipment should be located near the chemical storage area?
A. First aid supplies, emergency phone numbers, eyewash and shower facilities, fire extinguishers, spill cleanup supplies and personal protective equipment should be readily available.
 

 

Sources

Prudent Practices for Handling Hazardous Chemicals in Laboratories. National Academy Press, Washington D.C.
2011.

29 CFR 1910.106, Flammable Liquids

29 CFR 1910.1200 Hazard Communication

Fire Protection Guide to Hazardous Materials. National Fire Protection Association, Quincy, MA. 2010.

CRC Handbook of Chemistry and Physics, 96th edition, CRC Press. 2016

(Rev. 4/2016)


Find even more information you can use to help make informed decisions about the regulatory issues you face in your workplace every day. View all Quick Tips Technical Resources at www.grainger.com/quicktips.

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Please Note:
The information contained in this publication is intended for general information purposes only and is based on information available as of the initial date of publication. No representation is made that the information or references are complete or remain current. This publication is not a substitute for review of the current applicable government regulations and standards specific to your location and business activity, and should not be construed as legal advice or opinion. Readers with specific questions should refer to the applicable standards or consult with an attorney.


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