The viscosity of paint and other coatings materials with the KU value is determined by the help of a Stormer Viscometer. The device’s digital display can preset the KU value, CP value, room temperature, and load grams. It exhibits the measurement curve in real-time, and the test start and measurement time can be pre-specified.
How a Stormer Viscometer Works:
The instrument is primarily used for viscosity determination of coatings such as acrylic top coats, epoxy primers, chlorinated rubber paints, epoxy zinc-rich primers, and polyurethane topcoats. The conventional Stormer Viscometer determines the KU value of paint when the moment produced by the enamel quality is equivalent to the viscosity resistance of the paint, and the measurement value is within the 40–140KU range. The rotor blade of the instrument should be submerged in the sample till the mark of the rotating shaft. The knob should be loosened, and once the speed stabilizes itself at 200r/min, the measurement should be ceased.
The never-ending dedication toward enhancing the automation of the Stromer viscometer has enabled the instrument to display the viscosity KU and CP value directly. The improvements allow the user to work efficiently and give more accurate findings. Compared with the viscous moment obtained by the rotation rotor during rotational viscometer measurement. The results of viscosity resistance achieved by the blades of the stormer viscometer offer higher repeatability.
Why Choose a Digital Stormer Viscometer
The pros of using a digital Stormer viscometer are:
- Easy to operate.
- Easy to clean (Simple removal of the paddle allows better cleaning, which assists in simultaneous measurement of the drill degree.)
The environment of vibration and tide temperature tends to influence the accuracy, reducing the instrument’s service life. But the instrument has a precise structure and high environmental requirements.
The best thing about the Stromer Viscometer is that it does not require the stirring blade (or rotor) to be replaced during the whole measuring range. The Stirring blade rotates at a particular constant speed of 200r/min. The resistance torque collected by the stirring blade is converted to KU value by the computer to produce 200r. It’s a logarithm function representing the viscosity for brush and roller applications when rotated at minimum speed. The Stormer viscometer performs weighting and related data processing, automatically eliminating off-center data areas and improving the instrument’s measurement repeatability characteristics.
How to choose a rotational viscometer and a Stormer viscometer?
Viscosity which represents the relationship between internal frictions of the molecules of the coating fluid under the action of external force, qualifies as an essential physical property. It is associated with the chemical composition, and the majority of the non-Newtonian fluids and shear-thinning fluids exhibit an apparent viscosity decrease phenomenon due to an increase in shear stress.
The requirements for viscosity coatings are divided into two sections:
- Viscosity in Storage State ( Low Shear)
- Viscosity during production and construction application (Medium and High Shear).
The shelf-life of paints in storage is usually affected due to their viscosity. The solid particles will slowly sediment and some few days later delaminate, and agglomerate. As a result, the standard quality of the paint is affected which is not desired. High viscosity can prevent or minimize sedimentation and enhance the shelf life. Generally, a rotary digital viscometer measures the viscosity of stored paints. The basic principle of the instrument is that the rotor and mainspring spin at a fixed speed owing to the motor. The resistance the fluid offers to the rotor is displayed in the deformation of the mainspring. Because the torque is proportional to the resistance shown by the viscous drag of the rotor immersed in the sample fluid, it corresponds to the viscous drag of the rotor. Because viscosity is proportional, the viscosity value can be determined by measuring the torque generated by the rotor’s continuous revolution.
The rheological properties of coating material in the production or construction process are represented by the viscosity in the medium and high shear state. It mainly influences the difficulty of the coating construction, which is determined by the help of a Stormer Viscometer. The instrument is designed in such a way it precisely imitates the painters for pain construction. It judges the consistency to evaluate whether it’s as per the resistance offered or not. While the experiment is being performed, the paddle revolves at a fixed speed of 200rpm, determining the required load in grams. According to the formula, viscosity is measured in Krebs units (KU).
Difference between Rotational Viscometer and Stormer Viscometer
The Stormer Viscometer can be classified as a type of rotation viscometer in which there’s a pre-specified method, a particular rotor, and a container. Everything in the instrument is standard. However, when it comes to the rotational viscometer, the rotor, container, and method can be chosen as per the requirement. Hence, it’s not incorrect to state that Stormer Viscometer is a rotational viscometer except with some minute changes.
Making a choice can often be the most challenging thing to do. Therefore, if the user is mainly looking to determine the KU value, then the Stormer Viscometer is the ideal choice. In contrast, if they want to evaluate the viscosity of paint and ink, then a rotational viscometer with a temperature control system and multiple rotors should be preferred. However, the budget is also an important aspect for a rotational viscometer. Therefore, the instrument must be selected after doing extensive research and by being aware of the exact requirements.
If the choices are narrowed down to a rotational and a timer viscometer, then it primarily depends on what needs to be measured. The customers must make a decision based on the requirements. For any assistance, we’re available and can help you choose a viscometer based on your needs.
How to choose a Stormer viscometer?
- Measuring range
A Stormer viscometer has multiple models, each offering a different test range. Therefore, a viscometer should be purchased based on the sample’s viscosity.
- How much is the sample size?
Samples with low viscosity undergo testing more often than samples with high viscosity. The sample amount should be 200–450ml. If the sample amount is relatively more minor, a model which offers testing for smaller amounts should be preferred.
3) Auto-scan function
A higher degree of automation is required for samples that test unknown viscosity.
4) What is the speed?
Different models of viscometers may have different rotational speeds (divided into 4, 8, 9, and 18 gears).4th gear corresponds to 6, 12, 30, 60 rpm; 8th gear corresponds to 0.3, 0.6, 1.5, 3, 6, 12, 30, 60 rpm; 9th gear corresponds to 0.1, 0.3, 0.6 , 1.5, 3, 6, 12, 30, 60 rpm. The 18th gear corresponds to 0.3, 0.6, 1.5, 3, 6, 12, 30, 60 rpm and 0.5, 1, 2, 2.5, 4, 5, 10, 20, 50, 100 rpm.
In some instances, the speed of the 8th and 18th gears goes up to the range of 2 million.
However, the measurement relative error is also significant because the number of gears is small and the measurement range assigned to each gear is enormous. Different shear rates are observed due to multiple rotors which rotate at different rotational speeds. In case of non-newtonian liquids, the viscosity varies at every shear rate. Higher shear rates are observed when there are more gears in the rotation speed. It allows the user to get extra sample information.
How to use a Stromer viscometer?
- Place the lift on a steady and robust workbench. Make sure the weight lifting route is put outside the workbench outline.
- Slowly release the paddle break no. 8 to cease the rotation of paddle rotor 4.
- Blend the coating properly and shift it to the container (3). The coating level should be approximately 19mm away from the mouth of the container. The temperature of the coating and viscometer should be 23±0.2°C.
- Place the container on the container lifting tray (2). Re-arrange the placement of the tray and submerge the rotor (4) in the paint. The paint level should reach the mark of the rotor shaft.
- Turn the power on and choose an appropriate weight. The maximum weight should be 5g. Place it on a weight stand and release the brakes. The entire weight shifts to the blades, and the strobe start rotating. The line pattern on the moving strobe in the rotating direction of the blade indicates that the speed is higher than 200r/min. The speed is less than 200r/min if the line revolves against the paddle. In such cases, the weight should be increased. If the rate varies from 200r/min, various graphics will display in the strobe until the rotation speed reaches 200r/min and stable wide-line graphics appear.
- The measured value should be repeated until a consistent load value is achieved.
What does the Cp display on the Stromer Viscometer indicate?
CP is considered the smallest unit of dynamic velocity in centipoise.
1 centipoise is equal to 0.01poise which is equivalent to 0.001pa.s (pascal.sec) and 1 mpa.s (millipascal.sec)