Excerpted from Workplace Safety and Health Guidelines – Laboratory Handling Chemicals
As chemicals can be hazardous in different ways (e.g., flammable, corrosive, toxic, unstable), first inspect the chemical’s container label and SDS to understand the properties and characteristics of the chemical, and obtain specific storage guidance before determining the best way to store the chemical safely.
Proper storage of chemicals will protect flammable materials from ignition sources, minimize potential exposure to toxic substances and ensure segregation of incompatible chemicals, to prevent accidental mixing due to spillage or human error.
General Chemical Storage
- Do not store chemicals on the floor.
Exits, passageways, areas under tables and laboratory benches should be kept free from chemical containers, especially glass containers. If placed on the floor, the chemical containers risk being walked into, knocked over or hit with a chair or stool.
- Do not store chemicals above eye level.
If a chemical glass container falls and/ or breaks, its contents can splash on one’s face and upper body. Storing chemicals below eye level will protect eyes and faces from chemical spills from above. It will also prevent chemicals from being placed out of sight or put out of reach.
- Do not store chemicals on laboratory bench tops.
Laboratory benches are not the right place for storing chemicals (especially pure or concentrated chemicals) as incompatible chemicals may be inadvertently stored next to each other, chemical containers may be easily knocked over, and chemicals are not protected from a laboratory fire. Each chemical should have a proper designated storage location and be returned after use.
- Do not store chemicals in a fume cupboard, except for particularly odorous chemicals that require special ventilation.
Storing items (e.g., chemical containers, storage boxes, laboratory equipment) in a fume cupboard may severely disrupt its airflow, resulting in chemical vapors being drawn back into the laboratory atmosphere. Fume cupboards should be subject to good housekeeping and kept free of unnecessary items at all times.
- Store chemicals away from sources of heat.
Storing chemicals near heat sources (e.g., burners, ovens and steam pipes) will inevitably cause liquid vaporization rates to increase. This will cause pressure build up in the chemical container, possibly leading to container rupture. To reduce this risk, do not fill the container completely.
In particular, flammable and volatile liquids should be stored in a cool place, away from sunlight or direct heat. If placed next to a heat source, flammable substances can easily ignite, causing a laboratory fire. Storing a chemical in a cool location away from sunlight will also prevent its deterioration and prolong its shelf life.
- Store chemicals by compatibility, then by alphabetical order.
Storing chemicals by alphabetical order may lead to incompatible chemicals being stored next to one another. Instead, first segregate chemicals into inorganics and organics, and then into compatible groups based on their respective GHS hazard class, for example, flammables, oxidisers, reactive substances, corrosives, or toxics. Within the same compatible group, chemicals may be arranged alphabetically to facilitate easy retrieval.
- Only store chemical containers that are properly labelled.
The use of GHS-labelled containers ensures that the chemical can be immediately identified and its hazards communicated to the user at its point of use.
- Store chemicals in proper cabinets.
The use of proper cabinets specially designed for chemical storage is strongly recommended. These cabinets should be clearly labelled to indicate the hazardous nature of their contents (e.g., “flammable” or “corrosive”) together with the corresponding GHS hazard pictograms. In general, these cabinets are lockable and come with chemical resistant spill containment shelving with protective anti-roll edge guards that prevent containers from sliding off. Only authorized persons trained in chemicals handling should be allowed access to the chemicals inside the storage cabinets. No chemicals or equipment should be stored on top of a storage cabinet.
- Store breakable chemical containers in a secondary container.
A secondary container (e.g., a plastic or metal spill tray or a larger catch basin) will contain the chemical in the event of a spill, leak or container breakage.
- Date all chemical containers once received for storage and when opened.
This is a good practice to identify older chemicals which, when used first, help to reduce the amount of expired or deteriorated chemicals sent for disposal. Note that the expiration date set by the manufacturer indicates the shelf life of the unopened container, and does not imply that the chemical is safe for use up to the expiry date after the container has been opened.
- Do not store excessive amounts of chemicals.
Always order and store the smallest practical amount of a chemical. Though it may be cheaper (on a per unit cost basis) to buy chemicals in bulk quantities, the disadvantages often outweigh the initial price advantage. More chemicals mean that a larger storage space is required and a greater hazard exists. The cost of disposing unused chemicals can also be higher than their initial purchase cost.
- Equip chemical storage areas with facilities for emergency response.
It is important that any area used for storing chemicals be sufficiently ventilated and equipped with the necessary firefighting, spill control, bodily decontamination and/ or first aid equipment so that in the event of an accident (e.g., a fire or a chemical spill), the laboratory can respond appropriately to the emergency.
Storage of Gaseous Chemicals
Storage of Highly Toxic Chemicals
Storage of Flammable Chemicals
Storage of Corrosive Chemicals
In general, a corrosive chemical is any substance that has either a very low pH (e.g., ≤ 2.0) or a very high pH (e.g., ≥ 11.5), and this includes many strong acids and alkalis (bases). Corrosive chemicals can destroy or irreversibly alter living tissue, and are particularly damaging to the skin and eyes. Also, as some chemicals become corrosive upon contact with water or moisture, inhaling a corrosive vapour or mist can cause severe irritation or damage to the respiratory tract.
Primary storage concerns:
- Prevent workers from inhaling chemicals, and/ or their eyes or skin from coming into contact with chemicals; and
- Prevent chemicals from coming into contact with incompatible substances (e.g., acids from coming into contact with alkalis).
The following applies when storing corrosive chemicals:
- Corrosive liquids should be stored in a storage cabinet designed for corrosives;
- Always store corrosives on a low shelf (the lower the better) and never above eye level. This will minimise the spread/ extent of the splash or spill should a container fall from the shelf. In particular, concentrated acids and bases should be stored as near the floor as possible;
- Corrosives should be stored in unbreakable plastic containers or in special safety-coated glass containers, preferably placed on a chemical resistant catch tray. These special glass containers are lined with a protective plastic coat that can prevent the glass from shattering and contain the corrosive substance in its original container long enough for proper disposal;
- Separate acids from alkalis as these can react violently when mixed. Store acids in a dedicated acid cabinet. Also, keep acids away from flammables as many acids are also strong oxidisers;
- Nitric acid (HNO3) should be stored in a dedicated secondary container (e.g., a plastic tub or basin) in the storage cabinet as it is incompatible with most other chemicals;
- Ensure that a spill control kit (equipped with acid and base neutralising agents) is readily available at each location where corrosive chemicals are stored; and
- Bodily decontamination facilities (e.g., an eyewash station and emergency shower) must be located near to or inside storage areas for immediate use upon accidental exposure (especially skin contact or contact with the eyes) to a corrosive chemical.
Hydrofluoric (HF) acid is extremely hazardous and needs special mention. HF acid is very corrosive – it readily penetrates the skin and damages underlying tissue and bones. When exposed to air, concentrated solutions of HF acid and anhydrous HF produce pungent fumes which, when inhaled, damage the respiratory system.
When storing HF acid, remember the following:
- Do not store HF acid in a glass container as it is incompatible with glass. Because of its high reactivity toward glass and moderate reactivity toward many metals, HF acid is usually stored in a plastic container; and
- Store HF acid separately from the other corrosives and keep only the minimum amount required for use in the laboratory. While HF acid may be stored with other acids in the same storage cabinet, it should be kept separate from other acids, for example, by storing it in a dedicated storage compartment or in a dedicated secondary container.
Storage of Oxidising Chemicals
Oxidizing chemicals readily yield oxygen or its equivalent, stimulating combustion. As such, oxidizing chemicals present a greater fire and explosion hazard. Oxidizers, while not necessarily combustible themselves, may cause spontaneous ignition or increase the burning rate of the combustible material they come into contact with.
Primary storage concern:
- Keep oxidising chemicals away from flammables and reducing agents.
Strong oxidising agents (e.g., chromic acid) should be stored in an inert, preferably unbreakable, container (e.g., glass or plastic), and capped tightly to prevent leaks.
Perchloric acid (as a solution) needs special mention as it is a very strong oxidising agent at higher concentrations or when heated. Perchloric acid should be substituted with a less hazardous chemical wherever possible. Also, never use perchloric acid in its anhydrous form, as it is unstable at room temperature and can spontaneously decompose resulting in a severe explosion. Anhydrous perchloric acid can also explode upon contact with wood or other organic materials.
The following applies if the use of perchloric acid is necessary:
- Procure only the minimum amount of perchloric acid needed for the laboratory work and store perchloric acid by itself;
- Store perchloric acid bottles in glass or ceramic trays in a metal cabinet away from organic or flammable materials. Alternatively, perchloric acid can be stored in a fume cupboard specially designed to handle perchloric acid; and
- Keep perchloric acid away from strong dehydrating agents like sulphuric acid as the dehydration of perchloric acid can lead to a fire and/ or explosion.