When a delivery arrives, the person unpacking it rarely has time to read sixteen sections of a safety data sheet for every bottle. The GHS pictograms on the label give a quick visual cue. Used well, they help you put each container in the right cabinet. Used carelessly, they can put two incompatible chemicals side by side because they share the same symbol.
The nine pictograms at a glance
- GHS01, exploding bomb: explosives, self-reactive substances and some organic peroxides.
- GHS02, flame: flammable gases, liquids and solids, pyrophorics, substances that emit flammable gas with water, and self-heating materials.
- GHS03, flame over circle: oxidisers.
- GHS04, gas cylinder: gases under pressure.
- GHS05, corrosion: corrosive to metals, skin corrosion and serious eye damage.
- GHS06, skull and crossbones: acute toxicity in the higher categories.
- GHS07, exclamation mark: lower category acute toxicity, irritation, skin sensitisation and some other hazards.
- GHS08, health hazard: carcinogens, mutagens, reproductive toxicants, respiratory sensitisers, target organ toxicity and aspiration hazards.
- GHS09, environment: hazardous to the aquatic environment.
Turning pictograms into storage zones
A simple scheme for a laboratory store might look like this:
- Flame: a ventilated flammables cabinet, with quantity limits set by local rules. Keep away from heat, sparks and oxidisers.
- Flame over circle: a separate cabinet or shelf away from flammables, organics and reducing agents.
- Corrosion: a corrosion-resistant cabinet with trays, but with acids and bases kept apart.
- Skull and crossbones: a lockable cabinet with restricted access and an inventory log.
- Health hazard: a designated area for carcinogens and reproductive toxicants, clearly labelled, with access limited to trained users.
- Gas cylinder: secured upright, away from heat, with flammable and oxidising gases separated.
- Exclamation mark and environment only: general chemical shelving, with spill trays for liquids.
Where pictograms are not enough
Same symbol, incompatible chemicals
The corrosion pictogram appears on hydrochloric acid and on sodium hydroxide. Storing them together risks a violent reaction if both leak. Within the corrosives zone, separate acids from bases with distinct trays or shelves.
Similarly, nitric acid carries both the corrosion and the oxidiser pictograms. It should not share a tray with acetic acid or other organic acids, even though all of them are corrosive acids, because concentrated nitric acid can oxidise organics vigorously.
Reactivity that has no pictogram
Some important incompatibilities are not obvious from the symbols:
- Cyanides and sulfides with acids, which release toxic hydrogen cyanide or hydrogen sulfide.
- Water-reactive metals such as sodium or lithium, which need dry storage away from aqueous solutions and sprinklers where possible.
- Peroxide formers such as diethyl ether, THF and 1,4-dioxane, which may carry only the flame pictogram but require dating and periodic testing.
- Hypochlorites with acids or ammonia, which liberate chlorine or chloramines.
Multiple pictograms
A chemical with several pictograms must be stored according to its most demanding combination. Methanol carries flame, skull and crossbones, and health hazard. It belongs in the flammables cabinet, with access controlled like other toxic materials.
A worked example: unpacking a mixed delivery
Imagine a single delivery containing acetonitrile, 65 percent nitric acid, sodium hydroxide pellets, potassium cyanide, dichloromethane and a box of sodium chloride. Here is how the pictograms guide the first decisions, and where extra thought is needed.
- Acetonitrile shows the flame and exclamation mark. It goes into the flammables cabinet.
- Nitric acid shows the flame over circle and corrosion. It goes into the acid section of the corrosives cabinet, on its own tray, away from organic acids and well away from acetonitrile.
- Sodium hydroxide shows corrosion. It shares the corrosives cabinet, but on the base side, separated from all acids.
- Potassium cyanide shows the skull and crossbones and the environment pictogram. It goes into the locked toxics cabinet, and must never be stored near acids, since contact releases hydrogen cyanide.
- Dichloromethane shows the health hazard and exclamation mark. It is not flammable under normal conditions, but it should be kept away from reactive metals such as aluminium powder and from strong bases.
- Sodium chloride carries no pictogram and goes on general shelving.
Five of the six decisions follow from the pictograms. The cyanide and acid separation, and the nitric acid and organic acid separation, come from the reactivity section of the SDS rather than from the symbols.
Transport labels are not GHS pictograms
The diamond labels on an outer shipping box follow transport regulations and look different, for example a red flame label with a class number at the bottom. A box may show transport labels while the inner bottle shows GHS pictograms. Use the bottle label and the safety data sheet for storage decisions.
Temperature-controlled storage adds one more layer. A laboratory refrigerator used for flammable solvents should be a model designed for that purpose, without internal ignition sources. Ordinary domestic refrigerators have caused fires when vapours from a loosely capped bottle reached the thermostat.
Practical habits for the store
- Check section 7 (handling and storage) and section 10 (stability and reactivity) of the SDS for any new chemical before shelving it.
- Keep an up-to-date inventory with hazard classes, so you can see quantity build-up in each zone.
- Label shelves by zone and post a simple incompatibility chart on the store door.
- Use secondary containment for liquids, especially corrosives and flammables.
- Review the store when a new chemical class arrives, not only at annual inspection.
Documentation from Zemixal
Every Zemixal product ships with a certificate of analysis and a 16-section GHS safety data sheet, and labels carry the relevant pictograms and hazard statements. Product pages show hazard information before you order, which helps when planning storage space for a new project. Browse Lab Reagents or the full catalogue, and see the chemistry terms glossary for hazard class definitions.