The DVNext Wells-Brookfield Cone/Plate Rheometer, now with an easy-to-change magnetic cone/plate, gives researchers a sophisticated instrument for routinely determining the absolute viscosity of fluids in small sample volumes. Its cone and plate geometry provides the precision necessary for the development of complete rheological data.
FEATURES AND BENEFITS
- Determine the absolute viscosity of small samples (0.5–2.0 mL)
- Precise shear rates for determining a material’s flow curve behavior
- Rapid temperature control due to small sample size
- Magnetic coupling attachment for simplified spindle attachment and removal
- Electronic gap adjustment for simplified setup and increased throughput
- Touch Screen Display available on DVNext Rheometers
- Auto-zero function to ensure precision torque measurement
- Auto-range function to define full-scale-range (FSR) for all spindle/speed combinations
- Torque measurement accuracy: 1% of full-scale range
- Repeatability: 0.2% of full-scale range
PRINCIPLE OF OPERATION
The DVNext Wells-Brookfield Cone/Plate Rheometer is a precise torque meter that is driven at discrete rotational speeds. The torque measuring system, which consists of a calibrated beryllium-copper spring connecting the drive mechanism to a rotating cone, senses the resistance to rotation caused by the presence of sample fluid between the cone and a stationary flat plate.
The resistance to the rotation of the cone produces a torque that is proportional to the shear stress in the fluid. This reading is easily converted to absolute centipoise units (mPa·s) from pre-calculated range charts. Alternatively, viscosity can be calculated from the known geometric constants of the cone, the rate of rotation, and the stress-related torque.
The correct relative position of the cone and plate is obtained by following a simple mechanical procedure without the need for external gauges or supplementary instrumentation.
The stationary plate forms the bottom of a sample cup which can be removed, filled with 0.5 ml to 2.0 ml of sample fluid (depending on the cone in use), and remounted without disturbing the calibration. The sample cup is jacketed and has tube fittings for connection to a constant temperature circulating bath.
The system is accurate to within ±1.0% of full-scale range. Reproducibility is to within ±0.2%. The working temperature range is from 0°C to 100°C.
Various cone spindles are available for use with the DVNext Wells-Brookfield Cone/Plate Rheometer. Cone spindles may be purchased and will be calibrated for use with the same sample cup.