Principles of storage

Principles of safe storage

Key principles to provide safe storage of laboratory chemicals are:

·         Segregation  : allows incompatible chemicals to be sorted

·         Separation : separate chemicals due to characteristics such as toxicity, flammability, reactivity such as temperature, air, moisture, sunlight

·         Ventilation  : remove or dilute noxious, toxic or flammable vapors, prevent build up

 Basic Principles of Chemical Storage

·         Segregate incompatible substances to prevent dangerous interactions.

·         Ensure all the purchased chemicals are well labeled with their hazard category (e.g. flammable, corrosive, oxidizing, toxic etc.). A list of commonly used chemicals that should be segregated should be available to assist storage.

·         Store the minimum stock levels of hazardous chemicals in the laboratory

·         Dispose of hazardous chemicals that are no longer required

·         Store large breakable containers, particularly of liquids, below shoulder height

·         Ensure containers and bottle tops are sealed properly to avoid unnecessary leakage of fumes / vapors

·         Never carry a bottle containing chemicals by its top; instead carry in carriers or baskets that are capable of providing proper support, and support the base of the bottle in use.

Chemical classification

a)      Solids

·         oxidizing solids

·         flammable solids

·         water reactive solids

·         all other solids

Liquids

·         acid liquids

·         caustic liquids

·         oxidizing liquids

·         per-chloric acid solutions

·         flammable or combustible liquids

·         water reactive

·         all other liquids

 

 

Gases

·         toxic gases

·         flammable gases

·         oxidizing and inert gas

Flammable solvents

They include liquids with flashpoints < 100° F.

Flash point temperature: lowest temperature at which the vapor above the liquid can be ignited in air and have a high risk of catching fire. Substances with extremely low flash point temperatures are at extremely high risk of catching fire than those having a high flash point temperature.

Handling

·         Working volumes of flammable solvents (i.e. those kept on the bench) should not exceed 500 ml, and the solvent must be kept in a suitable closed vessel.

·         Before opening a bottle containing a flammable solvent, check that there is no open flame.

·         Do not light a match near a flammable solvent.

Storage

·         Stored in specialized metal flammable solvent containers (cabinets).

·         Clearly labeled, positioned away from doors or other means of escape from the laboratory.

·         No more than 50 liters of flammable material may be kept in any one laboratory room to reduce the risk of a serious laboratory fire.

·         Solvents such as iodine, hypochlorite flammable solvents must never be stored with oxidizing agents (e.g. sodium -and other halogens, hydrogen peroxide, nitric acid, potassium permanganate etc.) reducing agents or concentrated acids (e.g. concentrated sulfuric).

·         Flammable solvents should not be stored in fume hoods or vented cabinets, since the airflow will fan any fire and may also spread the fire to other parts of the building via the ventilation ducting.

·         Flammable solvents must never be stored in a refrigerator unless they are known to be spark proof.

Corrosive chemicals e.g. concentrated sulfuric acid, nitric acid, caustic soda, caustic potash.

Storage

Stored at a low level to avoid any serious injury and any knock off

Handling

·         Do not mouth pipette: accidental swallowing can lead to internal injury.

·         Pour corrosive chemicals at below eye level slowly avoiding eye splashes.

Toxic, harmful and irritating chemicals e.g. cyanide, formaldehyde

Storage:

·         Highly toxic chemicals must be kept in a locked cupboard.

·         Should be stored safely in a cupboard not an open shelf

Safe use/ handling:

·         Handle by wearing protective gloves.

·         Never mouth pipette.

 

Acid and alkali

Storage:

·         They can be sorted in a vented or metal cabinet so long as they are in a containment tray to prevent any spillages.

·         The use of ventilated cabinets are recommended where possible, allowing the removal of fumes at source.

·         All containers / bottle tops must be suitably sealed to avoid unnecessary leakage of fumes (NB parafilm can be used to seal container lids but should be checked / replaced at regular intervals).

 

Handling:

·         Never mouth pipette concentrated acids or alkalis.

 

Storage of oxidizers (e.g. peroxides, perchlorates and nitrates)

Handling

Handle with care and most are dangerous to skin and eyes when in contact with reducing agents.

Storage

·         Oxidizing substances should be stored in a metal cabinet and never be sorted on organic matter such as wood and paper.

·         Oxidizing agents must never be stored with flammable solvents or reducing agents since fires and explosions can result

·         After any spillage, even without a naked flame or heat. Per-chloric acid is an extremely strong oxidizing agent (especially in the concentrated form), which can react explosively with organic materials. It should ideally be stored separately on a metal tray of sand within a cabinet, away from organic materials or dehydrating agents such as sulfuric acid.

Explosives e.g. dry picric acid

Storage

Stored under water in ground neck glass stoppered bottles

Avoid friction, shock and sudden heating which can initiate an explosion.

Storage containers should not have metal caps since it vigorously react with it.

 

Radioactive chemicals

Storage

Store in sealed lead container, placed in thick wood or concrete and kept in locked cupboard situated away from the main building.

 

Carcinogen

A chemical that causes cancer by ingestion, inhalation or by skin contact e.g. benzene

The risk is proportional to the length and frequency of the exposure and the concentration of the chemical.

Storage:

Should be kept in closed containers and labeled as carcinogenic handle with special precautions.

Safe use/handling:

Always wear protective plastic/rubber gloves and face mask when handling carcinogenic chemicals.

Avoid skin contact

 

Cryogens                  

Cryogenic liquids are liquefied gases that are kept in their liquid state at very low temperatures.

Handling:

·         Avoid all body contact with cryogens by wearing protective clothing.

·         Never mix different cryogens together.

·         Always use goggles, face shield and cold resistant gloves when handling cryogenic liquids.

Storage:

·         Ensure proper ventilation to avoid pressure build up

·         Use the right containers that can sustain and withstand rapid changes in temperature

·         Ban smoking in the immediate area

·         Never use oil/grease on the equipment containing liquid oxygen

·         Make sure the container used to hold cryogenic liquid is suitable for use in extreme cold.

 

 

 

Chemical Group	Primary Storage Concern	Facilities/Measures	Compatible storage groups
Flammables group e.g. alcohol, acetone	To protect from ignition.	Flammable Cabinet Flammable- or explosion-proof refrigerator	Volatile poisons may be in the same compartment of the flammable cabinet as flammables if bases are not present.
Volatile poisons e.g. chloroform, methylene chloride	To prevent inhalation exposures.	Flammable Cabinet Flammable- or explosion-proof refrigerator	Volatile poisons may be in the same compartment of the flammable cabinet as flammables if bases are not present.
Oxidizing acids e.g. nitric, sulfuric, perchloric	Preventing contact and reaction with each other and other substances and corrosive action on surfaces.	Corrosive Cabinet. Each oxidizing acid must be double-contained, i.e., the primary container must be kept inside canister, tray or tub.	Oxidizing acids must be double-contained and should be segregated in their own compartment in a corrosive cabinet. Small quantities may be double-contained and stored with organic and Mineral Acids. Store oxidizing acids on bottom shelf below organic acids.
Organic and Mineral Acids e.g. acetic, butyric, formic	To prevent contact and reaction with bases and oxidizing acids and corrosive action on surfaces.	Corrosive cabinet.	Small amounts of double-contained oxidizing acids can be stored in the same compartment with organic acids if the oxidizing acids are stored on the bottom shelf.
Liquid bases e.g. sodium hydroxide, ammonium hydroxide	Preventing contact and reaction with acids.	Corrosive cabinet	In tubs or trays in normal cabinet. Compatible Storage Groups: Liquid bases may be stored with flammables in the flammable cabinet if volatile poisons are not also stored there
Oxidizing agents  e.g. ammonium persulfate, hydrogen peroxide	To isolate from other materials.	Total quantities exceeding 3 liters should be kept in a cabinet housing no other chemicals.  Smaller quantities must be double-contained if kept near other chemicals, e.g., in a refrigerator.	-
Non-volatile liquid poisons e.g. acrylamide solutions, diethylpyrocarbonate,	To prevent contact and reaction with other substances.	Cabinet or refrigerator (i.e., must be enclosed) Do not store on open shelves in the lab or cold room. Liquid poisons in containers larger than 1 liter must be stored below bench level on shelves closest to the floor. Smaller container of liquid poison can be stored above bench level only if behind sliding doors.	Non-hazardous liquids (e.g., buffer solutions).
Reactives Metal Hydrides and Pyrophorics e.g. sodium borohydride, calcium hydride	To prevent contact and reaction with liquids and, in some cases, air.	Secure water-proof double-containment according to label instructions. Isolation from other storage groups.	If securely double-contained to prevent contact with water and/or air, metal hydrides may be stored in the same area as Dry Solids
Dry solids e.g. benzidine, cyanogen bromide	To prevent contact and potential reaction with liquids.	Cabinets are recommended, but if not available, open shelves are acceptable. Store above liquids. Warning labels on highly toxic powders should be inspected and highlighted or amended if they do not cause the containers to stand out against less toxic substances in this group. It is recommended that the most hazardous substances in this group be segregated. It is particularly important to keep liquid poisons below cyanide-or sulfide-containing poisons (solids). A spill of aqueous liquid onto cyanide - or sulfide - containing poisons would cause a reaction that would release poisonous gas.	Metal hydrides, if properly double-contained may be stored in the same area.

 

Proper storage equipment

Cupboard

It should be able to:

·         Strong enough to carry the equipment

·         Compatible with the material stored

·         Supported with the shelves to support the load

·         Secure or can control access especially for materials such as toxic, poisonous, radioactive etc.

·         Easily cleanable

Cabinets

N/B: Cabinets are recommended, but if not available, open shelves are acceptable.

·         Acid Cabinets: made up of acid resistant materials and should contain a tray, to contain any leakage or spillage.

·         Flammable Solvent Cabinets: made up of fire resistant material. A metal spill tray is used to contain spillages.

·         Ventilated Cabinets: cabinets fitted with forced ventilation and may be free-standing with their own extract system or positioned beneath a fume cupboard and attached to its duct.

Ventilated cabinets are designed to safely store chemicals that give off noxious fumes and smells. These fumes are sucked away by forced ventilation. If you do not have a ventilated cabinet, these noxious chemicals can be stored in sealed secondary containers that should only be opened in a fume cupboard.

*Fume cupboards are not designed or intended for the storage of chemicals. The working surfaces of fume cupboards should therefore be kept clear of materials and containers when these are not needed for the ongoing work activities. Excess storage of chemicals in fume cupboards disrupts the airflow resulting in a lower level of protection to users.

The following are unsuitable conditions for chemical storage areas: Leaking or deteriorating containers; spilled chemicals; lack of or low lighting levels; blocked exits or aisles; doors blocked open, lack of security; trash accumulation; open lights or matches; fire equipment blocked, broken or missing; lack of information or warning signs ("Flammable liquids", "Acids", "Corrosives", "Poisons", etc.) Temperature extremes (too hot or cold in storage area)

REFERENCE

1.0   Proper Handling and Storage of Chemicals by Professor Dr. Ibtisam Kamal, HDR – Process Engineering.Faculty of Engineering-Soran University

2.0   https://ehs.research.uiowa.edu/chemical-storage-information

 

 

Question:

Determine the chemical storage plan for the school’s lab

Describe the storage of photosensitive chemicals

Answer:

·         Store in dark brown bottles

·         Bottles should have tightly fitting glass stoppers

·         Place them in dark cupboards

·         Place them in dark rooms