SDS Section 5: Firefighting measures

The section read by someone who did not choose to read it

Every other heading on a safety data sheet is found by someone who went looking for it. Section 5 is read at a gate, at night, by a fire officer deciding whether to put water on what is inside. That reader cannot interpolate, cannot telephone the author, and the cost of a wrong answer is not a fine.

Two small things about the heading before the substance. The three texts spell it differently — REACH Annex II prints Firefighting measures as one word, while OSHA’s Appendix D and UN GHS Annex 4 both print Fire-fighting measures with a hyphen. Nothing legal turns on it; it tells you which text the author worked from. And REACH opens the section with a scope sentence the US text does not have: section 5 shall describe the requirements for fighting a fire caused by the substance or mixture, or arising in its vicinity. That final clause does real work. A drum of something non-combustible sitting inside a warehouse fire is squarely in scope. The question is not only “how does this burn” but “what happens if this is in a fire”.

5.1 — one number, two answers, and only one of them usually written

Subsection 5.1 is a single number carrying two separately captioned fields. REACH prints Suitable extinguishing media and Unsuitable extinguishing media as distinct entries. OSHA compresses them into one item and signals the same duty in parentheses: “Suitable (and unsuitable) extinguishing media.” UN Annex 4 heads its paragraph Suitable extinguishing media and puts the unsuitable requirement in the second sentence — which is the structural reason it is so easily lost.

The regulation names no agent

This surprises people. Search all three texts for foam, carbon dioxide, dry powder or sand and you will not find them. Neither the EU, the US nor the UN text prescribes an extinguishing agent for anything. The choice is entirely the supplier’s, made from the classification in section 2 and the measured data in section 9. A consequence worth knowing: when two suppliers’ sheets for the same chemical recommend different media, neither is quoting a legal value. Both are publishing an assessment, and assessments can be wrong.

The unsuitable half is the one that matters

Only one worked example appears anywhere in section 5’s extinguishing-media text, and it is a negative one: avoid high-pressure media that could cause the formation of a potentially explosible dust-air mixture. Both REACH 5.1 and UN A4.3.5.1 print it. That the drafters spent their single example on what not to do says how the risk is distributed.

The reason is simple. Water is the default. It is what the appliance is filled with and what will be applied unless someone says otherwise in time. So a blank unsuitable field is not neutral — it reads, to a person under time pressure, as permission. On a water-reactive substance that is the difference between a contained fire and a violent one. The same asymmetry runs through the other physical classes: smothering an oxidiser does less than expected because the material carries its own oxygen, and a straight jet on a burning flammable liquid spreads the pool rather than covering it.

5.2 — what the fire makes that the product was not

Subsection 5.2 is headed Special hazards arising from the substance or mixture in the EU text and Specific hazards arising from the chemical in the US and UN texts. All three point at the same idea: the hazards created by the fire, as distinct from the hazards the product already had.

The principal case is hazardous combustion products. A material can be unremarkable in a sealed drum and produce something acutely harmful in the plume, and the sheet has to say which. UN Annex 4 supplies two model phrasings — “may produce toxic fumes of carbon monoxide if burning” and “produces oxides of sulphur and nitrogen on combustion” — and OSHA names “nature of any hazardous combustion products” as its example of what 5(b) is for.

Two consistency tests follow immediately. The products listed here are the same molecules that section 10 has to list as hazardous decomposition products; a sheet that declares none in section 10 while naming oxides of nitrogen in 5.2 has not been read as one document. And whoever inhales that plume becomes a case for section 4, so the effects described in the two places should recognisably match.

5.3 — actions first, then equipment

Subsection 5.3 carries two obligations that are easy to collapse into one. It requires advice on protective actions to be taken during firefighting — the regulator’s own example is keeping containers cool with water spray — and separately, special protective equipment for firefighters.

On the equipment, the EU text is markedly more prescriptive than the US one. REACH 5.3 enumerates: boots, overalls, gloves, eye and face protection and breathing apparatus. OSHA’s 5(c) says “special protective equipment and precautions for fire-fighters” and stops. Neither text sets a performance standard for the garment inside section 5, which is why an entry naming a type is more useful than one naming a category.

The actions half is the part most often reduced to a single line about breathing apparatus. It should cover what is done to the scene: cooling containers still in the heat, withdrawing rather than approaching where the container may fail, and keeping contaminated fire-water out of the drain — the last of which is the point where section 5 hands over to section 6 and to the environmental duties further down the sheet.

Fire PPE lives here, and nowhere else

This is worth stating flatly because sheets get it wrong in both directions. REACH subsection 8.2.2.1 says that where appropriate, section 5 shall be referred to for specific fire and chemical personal protective equipment advice. The pointer runs from section 8 to section 5. Section 8 describes protection for routine work held at or below an exposure limit; a fire is an uncontrolled release with a different exposure profile and different kit. A section 5 that says “see section 8” inverts the regulation’s own cross-reference and leaves the fire equipment unstated in the only place it belongs.

How section 5 connects to the rest of the sheet

• The classification in section 2 decides whether section 5 is a formality or the most consequential page in the document — flammable, pyrophoric, self-heating, oxidising and water-reactive classes all change the answer.
• Section 9 supplies the numbers that make section 5 checkable: the Annex requires the flash point, and for flammable liquids at least the lower explosion limit.
• Section 10 must list the same hazardous decomposition products that 5.2 lists as combustion products.
• Section 7 determines what a fire will actually involve. Section 5 describes one product; a store contains several, and the segregation rules are what stop the incident becoming a mixture.
• Section 6 is the same material before it ignites, and takes over again for the fire-water run-off afterwards.
• Section 8 points here for fire equipment under 8.2.2.1 and should not duplicate it.

What a good section 5 looks like

1. Is the unsuitable-media field an answer or a dash? A named medium with a reason attached — “do not use water jet: spreads burning liquid” — is an answer. An empty field is a decision handed to whoever arrives first.
2. Does 5.2 name actual products of combustion, and does section 10 name the same ones? Carbon monoxide, oxides of nitrogen, hydrogen chloride — named substances, not the phrase “toxic gases”. Then check they reappear further down the sheet.
3. Could a crew act on 5.3 without reading anything else? One protective action for the scene and one specified set of equipment. If the entry contains only a garment, or only a cross-reference, half the subsection is missing.