Class 4 labels (Flammable Solid label – 4.1)

Class 4 labels are used for marking and identifying Flammable Solid substances during transportation.

class 4 labels flammable solid label

WHAT ARE CLASS 4 Dangerous Goods?

Class 4 deals with substances, other than those classified as explosives, which under conditions of transport, are readily combustile or may cause or contribute to a fire through friction.

There are 3 divisions for Class 4 dangerous goods:

  • 4.1 Flammable solids
  • 4.2 Substances liable to spontaneous combustion
  • 4.3 Substances which, in contact with water, emit flammable gases

Division 4.1 contains:
Flammable Solids (readily combustible solids and solids which may cause fire through friction)

Self-reactive Substances  (thermally unstable substances liable to undergo a strongly exothermic decomposition even without the participation of oxygen)

Solid Desensitized Explosives (substances wetted with water or alcohol, or diluted with other substances, to form a solid mixture to suppress their explosive properties)

Polymerizing Substances (such as celluloid, which may evolve toxic and flammable gases when on fire)

Examples of commonly transported Flammable Solids include

  • Naphthalene (mothballs)
  • Hay / Straw
  • Metal powders
  • Seed cake (oil bearing seeds after the oil has been extracted)
  • Safety matches
  • Solid Firelighters


class 4 labels flammable solid label

The ADR (European agreement concerning the international carriage of dangerous goods by road) regulations, state that all packages containing dangerous goods should have a warning label and that the label shall be in the form of a square at an angle of 45° (diamond shaped).

The Class 4.1 labels for packages must be at least 100 x 100mm, from edge to edge, and set at an angle of 45°. The label must show a black flame in the top corner and have seven red vertical stripes on a white background. A dotted outer boundary must indicate the edges of the labels (unless it is being applied on a background of contrasting colour).  The labels must show an inner 2mm border that is 5mm away from the edge of the labels. The class number ‘4’ must be shown in the bottom corner and be in text at least 12mm high.

If the size of the package is too small to fit a 100mmx100mm warning label, then the dimensions may be reduced provided the symbols and other elements remain clearly visible. However, the inner line must remain 2mm thick and must remain 5mm from the edge of the label.


the Class 4.1 PLACARD

The Class 4.1 placard is used for cargo transport units such as freight containers and road/rail tanker vehicles.

class 4 labels flammable solid label

Class 4.1 placards must be at least 250mm x 250mm, from edge to edge, and set at an angle of 45°. The placard must show a dotted outer boundary line (unless it is being applied on a background of contrasting colour).  The class number ‘4.1’ must be shown in the bottom corner and be in text at least 25mm high.

There is no specification for the thickness of the inner line, as yet, but there must be a gap of 12.5mm between this and the outer dotted border or the outer edge of the label.  The upper half of the label must the exploding bomb-burst and the Class 1 must be shown in the bottom corner.

This article should not be used in substitute for checking the exact requirements in the applicable modal regulations.


We manufacture Class 4 labels at 101mm x 101mm on rolls of 250, and our Class 4 placards, for use in international transportation, are supplied at 250x250mm.  All labels are fully compatibe with IATA/ ICAO, UN ADR/RID and IMDG/IMO requirements.

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