balipax.blogg.se - Test for high viscosity paste

By knowing the FSR of the spindle/speed combination, you can determine whether that spindle/speed combination fits to the viscosity of the sample. The minimum viscosity that can be measured is one tenth of the full-scale range. In other words, the FSR is the maximum viscosity that can be measured with the chosen spindle/speed combination. The maximum measurable viscosity of the spindle at a given speed is called the full-scale range (FSR). For a better reproducibility, you should use the same spindle/speed combination for multiple tests. The highest viscosity range can be covered by measuring with the smallest spindle at the lowest speed. What does that mean? The lowest viscosity range can be covered by measuring with the biggest spindle at maximum speed. The flow resistance increases with the speed and size of the spindle. For a given viscosity, the flow resistance is related to the spindle’s speed of rotation and its shape and size. They are fixed on the coupling of the instrument. Usually, interchangeable spindles in the form of disks and cylinders are used. s, the dial reading has to be multiplied by the appropriate factor for the spindle and speed in use (Equation 1).įor each torque model, different spindles exist so that samples with different viscosities can be measured.To convert the torque % reading to viscosity in mPa

Dial reading: The torque value in % is shown by the pointer on the dial.There are two types of spring-type viscometers:

Spring type to measure high-viscosity substances (“H-type”).

Spring type to measure medium (regular)-viscosity samples ("R-type”).

Spring type to measure low-viscosity samples ("L-type").

There are three different rotational viscometer models: Different instrument models are available that have different spring types to cover a broad range of applications. In case of low-viscosity substances, the spring needs to be sufficiently sensitive, whereas for samples in the high-viscosity range, a more robust spring is required. The resulting driving torque depends on the rotational speed w, the spindle geometry, and the sample viscosity. The test sequence is the following: The user attaches a spindle to the rotational viscometer, sets a speed, and receives the dynamic viscosity and the torque (mostly in %). Optical sensors detect the deflection and the viscosity of the sample is then calculated from it. How do these work? The rotation of the spindle deflects a spring. Although there are two setups available to measure viscosity with a rotational viscometer – spring-type instruments and servo motor instruments – we only cover spring-type instruments here.