Viscosity & Rheology

Viscosity Glossary

3A
A U.S. industrial standard for process equipment design, often required for clean-in-place (CIP) certification
Absolute Viscosity
Viscosity value associated with a Newtonian material
ASTM
American Society for Testing and Materials. A U.S. organization responsible for establishing test standards
Autorange
A feature on standard Brookfield digital viscometers/rheometers that provides the maximum viscosity value measurable using a specific spindle at a designated RPM
Bob
A spindle used with the PVS Rheometer. Referred to as the "bob/stator" because it remains stationary while the sample cup rotates, causing the shearing action
Centipoise
A unit of measurement in the cgs system for viscosity, abbreviated as cP
Comm Port
Communications channel on a PC or computer through which data is transmitted
Concentric Cylinder
A cylinder within a cylinder. For viscosity measurement, a cylindrical spindle rotates inside a cylindrical chamber. Also known as "Coaxial Cylinder" because both cylinders share the same centerline
Cone Spindle
A spindle that has an almost flat circular shape with a small angle relative to the cup or plate on which it rotates
CP or C/P
Brookfield terminology for cone and plate geometry
Cylindrical Spindle
A spindle shaped like a cylinder
Disc Spindle
A spindle with a flat circular disc near the bottom of the rod. The shape of the disc spindle makes the calculation of shear rate an approximation or average across the surface of the disc
DIN
Deutsche Industrie Normung. A German organization responsible for establishing test standards, similar to ASTM in the U.S
Dyne-cm
A unit of measurement for torque
Fluid Ounce
A scientific unit of measurement for volume, abbreviated as oz
Footprint
Amount of bench space or area required for an item of equipment
Gap
Distance between the spindle and the chamber or cup in which the spindle rotates
Guard Leg
A protective bracket for spindles supplied with standard Brookfield LV and RV Viscometers/Rheometers
HA
Brookfield torque range appropriate for measuring medium to high viscosity materials. 100% torque = 14,374 dyne-cm
HB
Brookfield torque range appropriate for measuring high viscosity materials. 100% torque = 57,496 dyne-cm
5xHB
Brookfield torque range appropriate for measuring very high viscosity materials. Five times that of HB. 100% torque = 287,480 dyne-cm
Hz
A unit of measurement for frequency, expressed as "Hertz" or "cycles per second”
In-line
Refers to the placement of a process viscometer in a pipe
KREBS Unit
A unit of viscosity measurement obtained using a KREBS spindle rotating at 200 RPM; commonly used in the paint and coatings industry
LCD
Liquid crystal display
LV
Brookfield torque range appropriate for measuring low viscosity materials. 100% torque = 673.7 dyne-cm
mA
A scientific unit of measurement for current flow, expressed as "milliamp”
Micro Liter
A scientific unit of measurement for volume, abbreviated as µL
mMillipascal-Seconds (mPa·s)
A unit of measurement for viscosity, abbreviated as mPa·s
NIST
National Institute of Standards and Technology. A U.S. government organization responsible for establishing test standards
Newtonian
A material whose viscosity remains constant at all shear rates
Non-Newtonian
A material whose viscosity changes with varying shear rates
On-line
Use of a process viscometer to provide continuous viscosity measurement during material processing
pH
A measure of the concentration of hydrogen ion, indicating the degree of acidity or alkalinity in a material
Pint
A unit of measurement for volume, abbreviated as pt
Plate Spindle
A flat, circular spindle used to measure visco-elastic materials or materials containing particulate matter
Pneumatic
Operated by air pressure
Poise(P)
A unit of measurement for viscosity, abbreviated as P
PP
Brookfield terminology for plate and plate geometry
Relative Viscosity
Viscosity of a non-Newtonian material at a specific shear rate
Rheology
Science that studies the deformation and flow of materials
Rheometer
An instrument that measures the flow behavior of materials
RPM
Rotations per minute; a unit of measurement for spindle speed.
RS-232
A data transfer protocol used in computer systems
RTD
Resistance temperature detector; a type of sensor for measuring temperature
RV
Brookfield torque range appropriate for measuring medium viscosity materials. 100% torque = 7,187 dyne-cm
100% torque = 7,187 dyne-cm.
sec-1
Scientific unit of measurement for shear rate, expressed as "reciprocal seconds" or "inverse seconds”
Shear Rate
Velocity gradient in a flowing material; calculated based on spindle shape and rotational speed
Shear Stress
Force per unit area required to move a material
Spindle Geometry
Shape of a spindle. Brookfield spindles are available in various shapes, including disc, cylindrical, cone, plate, and KREBS
Time to Stop
BA Brookfield test procedure that measures the viscosity of a material after a specified time interval
Time to Torque
A Brookfield test procedure that measures the time required to reach a specified torque value
Torque Range
Torque measurement capability of a Brookfield viscometer or rheometer, measured in dyne-cm. Designations like LV, RV, HA, or HB define the torque range for specific instruments
Torque %
Amount of torque resistance measured by a rotating spindle immersed in a material
Volt(V)
A unit of measurement for electrical potential, abbreviated as V
Viscosity
Resistance of a material to flow. Viscosity = shear stress/shear rate
Viscosity Range
Operating range of a Brookfield instrument using specific spindles
Yield Stress
Amount of force required to cause a material to begin flowing

Conversion Tables

Viscosity

1 cP = 1 mPa·s
1 P = 100 cP
1 Pa·s = 1,000 mPa·s

Sample Volume

1 L = 1000 mL
1 gal = 3.7 L
1 pt = 16 oz.

Torque Range

LV = 673.7 dyne-cm
RV = 7,187 dyne-cm
HA = 14,374 dyne-cm
HB = 57,496 dyne-cm
5xHB = 287,480 dyne-cm

Temperature

°C = 5/9 (°F-32)