PRINCIPLE OF OPERATION
The DVNext Wells-Brookfield Cone/Plate Rheometer is a precise torque meter which 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 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 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%. 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. One cone spindle is provided with the instrument and is calibrated for use with the sample cup. Additional cone spindles may be purchased and will be calibrated for use with the same sample cup.
VERSATILITY OF APPLICATION
The DVNext Wells-Brookfield Cone/Plate Rheometer provides a wide variety of shear rates and viscosity ranges, which can be further extended by the use of interchangeable cone spindles. Different models can be selected to meet the specific range of viscosities and shear rates required.
Shear rates as high as 1875 sec-1 (DVNextCP) can be achieved.
The small sample volume required permits rheological evaluations to be made on materials where sample availability is limited, such as biological fluids and thick film coatings that contain precious metals.
All wetted parts are stainless steel for corrosion resistance and ease of cleaning. Optional purge fitting, luer fitting, and embedded temperature probe available.
UPDATED GAP SETTINGS
The DVNext Wells-Brookfield Cone/Plate Rheometer is supplied with an advanced Electronic Gap Setting feature. This technology allows faster set-up time and minimizes the possibility of gap adjustment errors. A simple turn of the micrometer adjustment ring and the gap is set, reducing the time required associated with manual detection methods.
The new electronic gap setting system is now a standard feature on the DVNext Wells-Brookfield Cone/Plate Rheometer. This instrument provides precise shear profiles necessary to determine viscosity and develop rheological data.