SDS section 9 of 16
SDS Section 9: Physical and chemical properties
Section 9 gives the measurable physical and chemical properties of the product, such as appearance, odor, pH, boiling point, flash point, flammability limits, vapor pressure, density and solubility. These numbers are the evidence behind many hazard classifications and are what engineers use to size ventilation, choose storage and predict how a chemical will behave in a spill or fire.
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What OSHA requires in Section 9
OSHA enforces the content of Section 9 under the Hazard Communication Standard.
Appendix D, as revised in 2024, lists the following properties for Section 9. The preparer does not have to present them in this order.
- Physical state
- Color
- Odor (includes odor threshold)
- Melting point / freezing point
- Boiling point (or initial boiling point or boiling range)
- Flammability
- Lower and upper explosion limit / flammability limit
- Flash point
- Auto-ignition temperature
- Decomposition temperature
- pH
- Kinematic viscosity
- Solubility
- Partition coefficient n-octanol/water (log value)
- Vapor pressure (includes evaporation rate)
- Density and/or relative density
- Relative vapor density
- Particle characteristics
If no relevant information is found for a property, Appendix D requires the sheet to say so clearly. A property that does not apply (pH of a non-aqueous liquid) or has not been measured may be shown as "not applicable" or "no data available". Those two phrases mean different things.
GHS Annex 4 and international differences
GHS Annex 4 covers a similar set of properties, and sheets may add further data relevant to physical hazards, such as explosive or oxidizing properties. The GHS stresses stating the test method or temperature when a value depends on conditions (flash point by closed cup versus open cup, density at a given temperature).
EU sheets typically add "other information" such as miscibility or conductivity under Section 9. If you work with international suppliers, remember that units can differ (degrees Celsius or Fahrenheit, kPa versus mmHg), so check them before comparing sheets.
What to look for and red flags
What to look for
- Flash point and test method. The lower the flash point, the more readily the liquid gives off ignitable vapor. See flash point explained and the glossary entry.
- Flammability limits. The range between lower and upper limits is the vapor concentration in air that can burn.
- Vapor pressure and boiling point. Together they indicate how quickly the product enters the air.
- Vapor density. A value greater than 1 means vapors are heavier than air and can collect in low spots.
- Solubility and density. They indicate whether a spill floats, sinks or mixes with water.
- pH. Strongly acidic or alkaline products are corrosive.
Red flags
- "No data available" for most of the list on a product classified as flammable.
- A flash point given with no method or units.
- Values that clash with Section 2, for example a flash point of 60 degrees but a classification as a highly flammable liquid.
- A range so wide that it cannot be used to make a decision.
Worked example: typical fields
An illustrative layout. For compiled, sourced values for a real substance, see the properties section of the isopropanol page.
- Appearance
- Physical state and color, for example "clear colorless liquid"
- Odor / threshold
- Description; threshold if known
- pH
- Value at stated concentration and temperature, or "not applicable"
- Boiling point
- Value with unit and pressure
- Flash point
- Value with unit and method (closed cup or open cup)
- Flammability limits
- Lower and upper limits in percent by volume in air
- Vapor pressure / density
- Value with temperature; density relative to air
- Solubility
- In water and other solvents
See how this looks on a real page: isopropanol safety data, physical and chemical properties section. Every chemical page uses these 16 sections with the same anchors, so you can compare any substance.
Common mistakes
- Comparing flash points from different methods. Closed-cup and open-cup values are not interchangeable.
- Reading "not applicable" as "no data". The first means the property does not make sense for the product, the second means nobody knows.
- Ignoring temperature conditions. A vapor pressure measured at 20 degrees says little about a hot process.
- Assuming a high flash point means no fire risk. Heated liquids, mists and dusts can burn well below or above the nominal values.
- Forgetting the mixture effect. A mixture's properties are not the average of its ingredients' values. Use the figures for the actual product.
Frequently asked questions
What does Section 9 of an SDS contain?
Section 9 lists the product's physical and chemical properties, such as physical state and color, odor, pH, melting and boiling points, flammability, flash point, explosion or flammability limits, vapor pressure, density and relative vapor density, solubility, partition coefficient, auto-ignition and decomposition temperatures, kinematic viscosity and particle characteristics.
Where do I find the flash point on an SDS?
In Section 9. Look for the temperature and the test method used, such as closed cup. Section 5 then explains the fire-fighting consequences.
What is the difference between 'not applicable' and 'no data available'?
'Not applicable' means the property does not make sense for the product, for example pH for a dry solid insoluble in water. 'No data available' means the property is relevant but has not been determined.
Why does vapor density matter?
Vapors that are heavier than air collect in low areas such as pits, drains and basements, where they can reach flammable or toxic concentrations. Vapor density tells you where to ventilate and where to avoid ignition sources.