Viscosity
Little Pro on 2016-01-13
Viscosity is the measure of a liquid’s resistance to flow. There are two types of viscosity: Dynamic viscosity and Kinematic viscosity. You can often find it in the section 9 of a safety data sheet (SDS).
Dynamic Viscosity [Pa.s = 1 kg/m?s] is a measure of a liquid’s resistance to its shearing flows, where adjacent layers move parallel to each other with different speeds.
Kinematic Viscosity is a measure of the resistive flow of a fluid under the influence of gravity. The kinematic viscosity [m2/s] is the ratio between the dynamic viscosity [Pa.s = 1 kg/m?s] and the density of a fluid [kg/m3]. The SI unit of the kinematic viscosity is m2/s. Other units used include St and cSt.
1 St (Stoke) = 1 cm2/s = 10^(?4) m2/s
1 cSt (centiStoke) = 1 mm2/s = 10^(?6)m2/s
Water at 20 °C has a kinematic viscosity of about 1 cSt.
Regulatory Implications of Viscosity
Liquids with lower viscosity are generally more hazardous because they can spread more quickly. Usually, increased temperature reduces the viscosity of a liquid and makes it more hazardous.
Under GHS, a hydrocarbon shall be classified as aspiration toxicity hazard category 1 if its kinematic viscosity is less than 20.5mm2/s (20 cSts) at 40 °C .
More Physicochemical Properties
- Physical State, Appearance & Odour;
- Melting point;
- Boiling Point;
- Relative Density;
- Flash Point;
- Vapor Pressure;
- Henry's Law Constant;
- Surface Tension;
- Water Solubility;
- n-Octanol/Water Partition Coefficient;
- pH;
- Flammability;
- Oxidising Properties;
- Explosive Properties;
- Granulometry;
- Explosive Limits;
- Viscosity;
- Dissociation Constant;
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Tags: Topics - CRA, Physiochemical Property