2.1.2. Signboards on containers and pipes must be placed as laid down in Part III.
2.1.3. Places where there is a risk of colliding with obstacles or of falling must be permanently marked with a safety colour and/or with signboards.
2.1.4. Traffic routes must be permanently marked with a safety colour.
2.2. Occasional signs
2.2.1. Illuminated signs, acoustic signals and/or verbal communication must be used where the occasion requires, taking into account the possibilities for interchanging and combining signs set out in paragraph 3, to signal danger, to call persons to take a specific course of action and for the emergency evacuation of persons.
2.2.2. Hand signals and/or verbal communication must be used where the occasion requires, to guide persons carrying out hazardous or dangerous manoeuvres.
3. Interchanging and combining signs
3.1. Any one of the following may be used if equally effective:
—a safety colour or a signboard to mark places where there is an obstacle or a drop,
—illuminated signs, acoustic signals or verbal communication,
—hand signals or verbal communication.
3.2. Some types of signs may be used together:
—illuminated signs and acoustic signals,
—illuminated signs and verbal communication,
—hand signals and verbal communication.
4. The instructions in the table below apply to all signs incorporating a safety colour.
| Colour | Meaning or purpose | Instructions and information |
| Red— | Prohibition sign | Dangerous behaviour |
| Danger alarm | Stop, shutdown, emergency cut out devices Evacuate | |
| Fire-fighting equipment | Identification and location | |
| Yellow— or Amber |
Warning sign | Be careful, take precautions Examine |
| Blue — | Mandatory sign | Specific behaviour or action Wear personal protective equipment |
| Green — | Emergency escape, first aid sign | Doors, exits, routes, equipment, facilities |
| No danger | Return to normal |
5. The effectiveness of a sign must not be adversely affected by:
5.1. the presence of another emission source of the same type which interferes with visibility or audibility; therefore, in particular,
5.1.1. the placing of too many signs too close together should be avoided;
5.1.2. two illuminated signs which are likely to be confused are not to be used at the same time;
5.1.3. an illuminated sign is not to be used in the proximity of another similar illuminated source;
5.1.4. two acoustic signals are not to be used at the same time;
5.1.5. an acoustic signal is not to be used if there is too much ambient noise;
5.2. poor design, insufficient number, incorrect positioning, poor state of repair or incorrect functioning of the signs or signalling devices.
6. Depending on requirements, signs and signalling devices must be cleaned, maintained, checked, repaired, and if necessary replaced on a regular basis to ensure that they retain their intrinsic and/or functional qualities.
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