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Chemical accidents can easily occur when incompatible chemicals are stored too closely together in a chemical store. Storing incompatible chemicals closely together creates a risk of chemical reactions – such as fires, explosions and toxic release.

Incompatible chemicals should always be stored at least 3 metres apart, or at least 5 metres apart if there is a risk of a violent reaction. If you’re looking for information about responding quickly to a chemical incident, read this post.

The below list includes 10 commonly used chemicals and the incompatible chemicals which should never be stored close by:


1. Chlorine

Chlorine is a common disinfectant that is widely used in swimming pools and leisure centres. Chlorine should not be stored with ammonia, acetylene, benzene, butadiene, hydrogen, any petroleum gases, sodium carbide or turpentine.


2. Acetone

Acetone is often used to clean down surfaces in laboratories and manufacturing plants. Acetone should not be stored in the same chemical store as bromine, chlorine, nitric acid, sulfuric acid, or hydrogen peroxide.


3. Iodine

Iodine has a number of uses in schools, universities and several workplaces. Its primary uses are to test for the presence of starch and to serve as a disinfectant. It should not be stored with acetylene, ammonia or hydrogen.


4. H20 (Water)

Water is a compound of two chemical substances – hydrogen and oxygen. While it is a very commonly used substance, there are several incompatible chemicals which cannot be stored near water. These include, but are not limited to, acetyl chloride, alkaline and alkaline earth metals, barium peroxide, carbides, chromic acid, phosphorous oxychloride, phosphorous pentachloride, phosphorous pentoxide, sulfuric acid and sulfur trioxide.


5. Caustic Soda

Caustic soda (sodium hydroxide) is commonly used in farming to treat feeds. It can also be used as a cleaning agent in households, and has several uses within a manufacturing facility. Caustic soda should not be stored near any chemical acid in a chemical store.


6. Nitric Acid

Nitric acid has several different purposes but is commonly used in manufacturing and chemical laboratories to etch metal, as well as being a component of explosives and fertilisers. Nitric acid should be stored in a chemical store away from substances such as acetone, acetic acid, alcohol, chromic acid, aniline, hydrocyanic acid, hydrogen sulfide and any flammable substances.


7. Hydrogen Peroxide

Hydrogen peroxide has several different use cases – in the household, this chemical can be used as a cleaner and in the treatment of wounds, while in manufacturing it can be used in pulp and paper bleaching, and the manufacture of laundry detergents. Hydrogen peroxide should never be stored with copper, chromium, iron, most metals or their salts, alcohols, acetone, organic materials, aniline, nitromethane, flammable liquids, ammonia or oxidizing gases.


8. Zinc Powder

This substance is widely used in the manufacturing of many products including paint, cosmetics and batteries. It is also used as a reducing agent and for casting moulds. Zinc powder should not be stored near sulphur.


9. Mercury

Mercury is used in products such as thermometers and barometers, as well as in fluorescent lamps and dental amalgams.  Compounds of mercury are also used to develop certain medicines. Mercury should never be stored near acetylene, fulminic acid or ammonia.


10. Oxygen

Oxygen is used in metal cutting, to facilitate oxy-acetylene welding. It is also heavily used in the iron and steel industries, to smelt iron ores into steel. Oxygen is also used for a host of purposes in chemical manufacturing, such as the creation of antifreeze and polyester primers and in several medical applications and in water treatment. Oxygen should be stored away from substances such as oils, grease and hydrogen and any flammable liquids, solids, or gases in a chemical store.


Ensuring Safe Storage of Chemicals

This list covers only some of the most commonly used chemicals and is not meant as a definitive list. To ensure safe storage of substances in your chemical store, also refer to the Material Safety Data Sheet. In addition to manufacturer guidelines, always be sure to follow local regulations and applicable laws regarding chemical storage requirements, including building, fire and electric codes. Our previous article, “Hazards Associated With Handling and Storing Flammable Materials”, can also be an invaluable resource in learning to correctly store chemicals. Discover more about best practices and other in-depth content discussing storing chemicals in the workplace and ensuring chemical safety, through our blog section, or contact our expert team for any particular enquiries.

Updated April 2022.