Guide 104
Specification
Understanding Viscosity & Density
Two numbers that quietly drive transfer time, dosing accuracy, and whether a product will behave as expected in your equipment.
specs pumping QC dosing
Density (specific gravity)
- What it is: mass per volume (e.g., kg/L).
- Why it matters: converting between mass and volume dosing; filling drums/IBCs; freight calculations.
Viscosity
- What it is: “resistance to flow” (often in cP or mPa·s).
- Why it matters: pump selection, line pressure drop, mixing time, and whether you can dose through existing metering pumps.
Practical checks
- Confirm temperature of measurement (viscosity can change a lot with temperature).
- If dosing by volume, request density range on COA or TDS.
- For viscous liquids, ask about recommended transfer temperature or dilution procedure.
What to specify in an RFQ
- Target viscosity range at a stated temperature (e.g., “@ 25°C”).
- Density range (e.g., “@ 20°C”).
- Your dosing method: mass flow, volumetric pump, manual measurement, etc.