A safety data sheet has sixteen sections and almost nobody reads all of them. For GHS dangerous goods classification and transport purposes you need four. Knowing which four, and knowing which one quietly lies to you, is most of the skill.
The other half of the skill is knowing that GHS dangerous goods classification and transport classification are two different systems wearing similar clothes, which is where most of the expensive errors start.
This guide walks through the sections that matter, shows what to extract from each, and explains the mismatch between GHS and transport classification that catches out even careful teams.
GHS dangerous goods classification versus transport classification
First, clear up the confusion at the root of most SDS misreadings. There are two classification systems in play and they are not the same thing.
GHS (the Globally Harmonised System) governs hazard communication for workplaces and consumers. It produces the orange diamond pictograms, the signal words, and the H-statements on your retail label. It answers: what does this do to a person handling it?
Transport classification (49 CFR, IATA DGR, IMDG) governs movement. It produces UN numbers, hazard classes and packing groups. It answers: what does this do inside a vehicle, in bulk, under stress?
They overlap enormously, which is exactly why they get conflated. A GHS "flammable liquid, category 2" is very likely a transport Class 3, but the categories do not map one-to-one onto packing groups. Read across from one to the other and you will be right often enough to build false confidence, and wrong often enough to get caught.
Section 2 — hazard identification
Your smoke alarm. Pictograms, signal word, hazard statements.
You are not classifying from this section; you are deciding whether to keep reading. A flame, a corrosion symbol, a gas cylinder or an exploding bomb means the transport question is live. An exclamation mark alone often does not.
Section 3 — composition
This is what you actually classify. Constituents with CAS numbers and concentration ranges.
Two things to watch. First, concentration is usually given as a range ("10–25 %"), and for a concentration-dependent classification like Class 8, the top of the range is the safe assumption. Second, the sheet lists hazardous constituents, not everything in the bottle. A 60 % "other" balance is normal and is not a gap in the data.
Section 9 — physical and chemical properties
The most valuable section on the sheet for transport, and the one most people skip past to get to 14.
Section 9 carries the measured numbers that decide the packing group:
- Flash point — and, critically, the test method. Closed cup and open cup are not interchangeable, and the transport criteria want closed cup.
- Initial boiling point — needed alongside flash point to separate packing group I from II for Class 3.
- pH — a first indicator for corrosivity, though not itself the criterion.
- Physical state and density — solid or liquid changes the applicable entries entirely.
If section 9 gives a flash point range rather than a value, or omits the test method, you do not have enough to assign a packing group with confidence. Say so and get the number.
Section 14 — transport information, and why to be sceptical
Section 14 gives you UN number, proper shipping name, transport hazard class, packing group and environmental hazard flags. It looks like the answer. Frequently it is. But it is the supplier's classification for the supplier's shipment, and four things routinely differ between theirs and yours.
| Difference | What the supplier assumed | What applies to you |
|---|---|---|
| Pack size | 200 L drum, fully regulated | 50 ml retail bottle, possibly limited quantity |
| Concentration | Neat or technical grade | Diluted finished product, maybe unregulated |
| Mode | Road freight only | Air, where limits are far tighter |
| Edition | The regulation current when written | The edition in force on your ship date |
Section 14 is evidence, not a verdict. It tells you how a competent chemist classified a material under one set of assumptions. Your job is to check whether those assumptions are yours.
Classify7 ruleset team, on why the engine treats supplied transport data as an input to verify rather than an answer to accept
Reading one properly
Suppose a supplier sends the sheet for a citrus degreaser you intend to sell in 500 ml bottles. Working the four sections in order:
- Section 2 shows a flame pictogram and H226, flammable liquid and vapour. Keep going.
- Section 3 shows d-limonene at 30–60 % and isopropanol at 10–25 %. Take the top of each range.
- Section 9 gives a closed-cup flash point of 21 °C and an initial boiling point above 35 °C. Below 23 °C means packing group II, not III.
- Section 14 says UN1993, Class 3, packing group III. That contradicts section 9.
The likely explanation is that section 14 was written against an earlier formulation or a different grade. Either way, you now know not to copy it. The measured value in section 9 governs, and the correct entry for your product is packing group II — with the tighter air quantity limits and the Y-rated packaging that come with it.
That internal contradiction is more common than you would hope. It is worth checking every sheet for it as a matter of routine, because it takes thirty seconds and it is the single highest-yield check on the document.
- Copying section 14 without checking it against section 9.
- Mistaking a GHS category for a transport packing group.
- Using an open-cup flash point against closed-cup criteria.
- Taking the bottom of a concentration range for a concentration-dependent class.
- Filing the SDS but not recording which revision a determination was based on, so you cannot tell later what changed.
Where GHS dangerous goods classification does and does not map across
Because the two systems share vocabulary, it is worth being explicit about where a GHS category is a useful signal and where reading across will mislead you.
| GHS element on the label | Useful transport signal | What it does not tell you |
|---|---|---|
| Flame pictogram, H224–H226 | Very likely Class 3 or Class 4 | The packing group — that needs the flash point value |
| Corrosion pictogram, H314 | Likely Class 8 | Whether the concentration you ship is regulated at all |
| Gas cylinder pictogram | Likely Class 2 | Which division — 2.1, 2.2 and 2.3 differ sharply |
| Environment pictogram, H410–H412 | Possible marine pollutant for ocean | Nothing about road or air classification |
| Skull and crossbones, H300–H301 | Possible Division 6.1 | The packing group — that needs LD50 data |
| No pictogram at all | Weak evidence of non-regulation | Lithium batteries carry no GHS pictogram and are Class 9 |
That last row deserves emphasis. A sealed lithium battery presents no workplace chemical hazard, so it carries no GHS pictogram and its SDS may barely mention transport. It is nonetheless Class 9, and among the most restricted things in the air network. Any screening process built on GHS dangerous goods classification alone will miss it entirely — see PI965, PI966 and PI967 for what it does require.
The GHS itself is maintained by UNECE, who also publish the UN Model Regulations that transport classification derives from — which is exactly why the two look so similar and behave so differently.
Feeding an SDS to a classifier
All of the above is mechanical enough to automate, provided the tool reads the measured properties rather than just lifting section 14. Classify7 accepts SDS text directly at POST /api/classify through the sdsText field, and on the site the classifier has a collapsed Paste SDS text field beneath the description box.
It uses section 9 values to resolve the packing group where the class depends on one, and returns needs_review rather than a guess when the sheet does not carry the property it needs. Where a supplied transport entry conflicts with the measured properties, you get told, rather than having the contradiction quietly resolved in one direction.
For what to do with the resulting numbers, see packing groups I, II and III and the UN number lookup reference. The GHS system itself is documented by the UNECE, who maintain both it and the UN Model Regulations that transport classification is built on.
