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Chemical Compatibility Concerns in Storage
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 associated risks.
Proper storage information can usually be obtained from the Safety Data Sheet (SDS), label or other chemical reference material. As required by 29 CFR 1910.1200, an SDS must be on hand for every chemical in your workplace. The SDS and chemical label can be consulted for information on special storage requirements. 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. A physical barrier and/or distance is 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. However, it is recommended that hydrochloric acid not be stored in any metal cabinet. Some other acids and bases may damage the painted surfaces of a cabinet if a spill occurs. Also, perchloric acid should not be stored in a wooden cabinet.
There are cabinets available specifically for flammable materials. It is important to be aware of maximum allowable container size and maximum quantities for storage in cabinets based on the category of the flammable. The class of a flammable is determined by its flash point and boiling point.
|MAXIMUM ALLOWABLE SIZE OF CONTAINERS AND PORTABLE TANKS|
|Category 1||Category 2||Category 3||Category 4|
|Glass or approved plastic||1 pt.||1 qt.||1 gal.||1 gal.|
|Metal (other than DOT drums)||1 gal.||5 gal.||5 gal.||5 gal.|
|Safety Cans||2 gal.||5 gal.||5 gal.||5 gal.|
|Metal Drums (DOT spec.)||60 gal.||60 gal.||60 gal.||60 gal.|
|Approved Portable Tanks||660 gal.||660 gal.||660 gal.||660 gal.|
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 |
|Category 1||60 Gal.|
|Category 2||60 Gal.|
|Category 3||60 Gal.|
|Category 4||120 Gal.*|
*Not more than 60 gallons may be Category 1, 2, or 3liquids. 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) and NFPA 30 Section 4-3.1.
NOTE: Not more than three such cabinets may be located in a single fire area, according to NFPA 30 Section 4-3.1.
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. A few examples of this potentially dangerous storage method are demonstrated by the following pairs of incompatible materials:
|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|
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|
|Carbon (activated)||Calcium hypochlorite, all oxidizing agents|
|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)|
|Flammable liquids||Ammonium nitrate, chromic acid, hydrogen peroxide, nitric acid, sodium peroxide, halogens|
|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|
|Nitric acid (concentrated)||Acetic acid, aniline, chromic acid, hydrocyanic acid, hydrogen sulfide, flammable liquids, flammable gases, copper, brass, any heavy metals|
|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|
|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|
|Sulfuric acid||Potassium chlorate, potassium perchlorate, potassium permanganate (similar compounds of light metals, such as sodium, lithium)|
Source: Introduction to Safety in the Chemical Laboratory, Academic Press.
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 an expert to come in and evaluate the situation and properly dispose of the materials.|
|Q.||What are some things to consider when planning a chemical store room?|
|A.||The chemical store room should have a cool, dry atmosphere, sufficient lighting in all areas, a ventilation system that exhausts to the outside, secure and sufficient shelving and unobstructed aisles with no blind areas.|
|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.|
29 CFR 1910.1450, Occupational Exposure to Hazardous Chemicals in Laboratories
CHRIS Manual. U.S. Coast Guard
Prudent Practices for Handling Hazardous Chemicals in Laboratories. National Academy Press, Washington D.C.
29 CFR 1910.106, Flammable Liquids
Fire Protection Guide to Hazardous Materials. National Fire Protection Association, Quincy, MA. 1994.
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The information contained in this publication is intended for general information purposes only. This publication is not a substitute for review of the applicable government regulations and standards, and should not be construed as legal advice or opinion. Readers with specific questions should refer to the cited regulation or consult with an attorney.