A rheometer is a device that was developed to measure how a liquid’s suspensions or slurries flow when force is applied to it. Many fluids can be tested with a rheometer when a single numerical viscosity value cannot determine them due to their components. A rheometer can also be used to discover the additional parameters and values that a viscometer can correctly measure. In other words, the rheometer tests a fluid’s rheology.
There are two types of rheometers that test a liquid’s rheology. There is an applied shear stress/strain option that is known as a rotational/shear rheometer. It is designed to measure native strain and can provide valuable data for measuring the liquid’s shear stress. The other type is a native stress controlled rheometer. It is used to control the application of a defined stress/shear that measures the strain of the shear as a result. But we only talk about shear rheometer series in this article.
What does Rheometer Mean?
The word Rheometer comes from a Greek word that means “measuring flow.” Therefore, the device created for this task was dubbed the rheometer. The word rheometer has historically been used to refer to different types of measurement devices. First, it was the name of the device that measured electric current until a new word was created to replace it (the galvanometer or ammeter). It was also the name of the medical tool used to measure blood flow. Rheometer was also the name of the civil engineering tool used to measure water flow. After the term rheology was defined, the tools previously referred to as rheometers were renamed.
Rheometers that Measure Shear
There are a wide variety of rheometers that measure shear in different ways. Though these have slight differences, they generally offer the same kind of information. The following are the available shear rheometers:
Pipe or Capillary – The pipe or capillary rheometer is designed to measure a liquid that is forced through a tube. This makes it possible to measure a constant cross section and dimensions that define the laminar flow of the fluid. Shear rate can be determined via the dimensions measured from the liquid’s flow rate and pressure drop, which are converted into the proper shear stress measurement.
Rotational cylinder – This is a cylinder and a one-plate measuring system, where the liquid is placed within the small ring space of a cylinder that is inside another. The cylinder is then rotated at a speed that makes the shear rate measurable. The torque of the force that is needed to turn the other cylinder is then used to convert the shear rate into shear stress. A modern day rotational cylinder apparatus may be able to spin at 600, 300, 200, 100, 6 & 3 RPM to measure the shear stress of fluids. Modern day options can also be programmed to measure these values at changing intervals, which can measure important time based readings.
Cone and plate – Here, a liquid is placed on a flat plate as well as a short, shallow cone that is placed on top. The cone is typically at a one degree slant. The plate is rotated and the force exerted on the cone is measured. Oscillating versions of this rheometer can measure additional values such as elasticity.
Ektron Tek Co., Ltd. is a rheometer manufacturer which has professional research and maintenance team. With more than 30 years of experience and technology, we have marketed our products worldwide with our brand EKTRON TEK. Thanks to continuous efforts and innovation, we have gained the trust and compliments as a world-reputed company from our customers and have maintained the leading position of rubber testing instruments industry in Asia. If you need more information about rheometer series, welcome to visit our website and feel free to contact Ektron Tek.
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