Rapid Determination Of Absolute Viscosity for Small Samples

The Wells-Brookfield Cone/Plate Viscometer/Rheometer gives researchers a sophisticated instrument for routinely determining absolute viscosity of fluids in small sample volumes. Its cone and plate geometry provides the precision necessary for development of complete rheological data.

PRINCIPLE OF OPERATION

The Wells-Brookfield Cone/Plate Viscometer/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. The amount of torque is indicated either on a dial or digital display, depending on model. 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 .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 the working 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 Wells-Brookfield Cone/Plate instruments. 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 Wells-Brookfield Cone/Plate Viscometer/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 (DV3TCP) 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.

ELECTRONIC GAP SETTING

Wells-Brookfield Cone/Plate Digital Viscometers/Rheometers are now supplied with an advanced Electronic Gap Setting feature. This technology allows faster set-up time and minimizes the possibility of gap adjustment errors. With the enhanced system, a bright LED lights up when a hit point is achieved. 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 our complete line of Wells-Brookfield Cone/Plate Digital Viscometers/Rheometers. These instruments provide precise shear profiles necessary to determine viscosity and develop rheological data.

FEATURES & BENEFITS

·Determine 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
·Electronic gap adjustment for simplified setup and increased throughput
·Touch Screen Display available on DV3T Rheometers and DV2T Viscometers
·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

SPECIFICATIONS