Views:11 Author:Alisa Chen Publish Time: 2017-10-19 Origin:Site
HOW DO I CHOOSE A SPINDLE?
The process of choosing a spindle and rotational speed for use with your Brookfield viscometer is ultimately one of trial and error. However, there are several means to narrowing the possibilities before any testing is performed. If a sample has historically been tested using a particular speed and spindle combination, the user should use that same combination. This will help to ensure test results are accurate and repeatable. The objective is to choose a spindle that will produce a dial or digital display reading between 10% and 100% torque.
WHY DO I NEED A VISCOSITY STANDARD?
Viscosity standards are used to check the accuracy of your Brookfield viscometer. Brookfield Silicone and Mineral Oil Standards provide you with a fluid viscosity value that is constant at 25°C, making calibration verification easy to establish. Standards are a traceable part of calibration verification - an important component of many certifying quality systems like ISO, ASHTO, etc.
HOW IS VISCOSITY AFFECTED BY TEMPERATURE?
Generally speaking, viscosity has an inverse relationship with temperature. As temperature increases, viscosity decreases. For this reason, it is critical to control the temperature of a sample during any viscosity measurement.
MY FLUID HAS A VISCOSITY THAT IS NOT PART OF YOUR STANDARD FLUIDS LISTING, WHAT SHOULD I DO?
The viscosity of your sample fluid is typically of little importance when checking the accuracy of your Brookfield Viscometer, because:
— your fluid may be non-Newtonian, so the viscosity will change; Brookfield Viscosity Standard fluids will not change with time or shear (rpm), making the calibration check more definable
— your Brookfield Viscometer is no more or less accurate at one range (rpm and spindle) than the next; if the Viscometer passes at one range, it can be considered to be calibrated throughout its entire range
HOW MANY VISCOSITY STANDARDS DO I NEED?
Generally one or two is sufficient. Select a fluid with a viscosity value that fits the measuring range of the spindle and speed that you use most often.
SHOULD I USE A DIGITAL VISCOMETER OR A DIAL READING (ANALOG) VISCOMETER?
Viscosity results obtained from Brookfield instruments are reproducible regardless of whether an instrument is a dial reading or digital. Assuming that all other conditions are identical - spindle, speed, temperature, container size, spring torque, etc., a reading produced on a dial reading viscometer is as valid, accurate, and reproducible as a reading produced on a digital viscometer.
HOW LONG SHOULD I WAIT FOR THERMAL EQUILIBRIUM?
Thermal equilibrium is the state at which every element of a viscosity measurement is at a unified temperature. These elements include, but are not limited to, the spindle, guard leg, sample container, sample, and temperature probe. Because temperature is critical to accurate readings, you should allow sufficient time to achieve equilibrium. In general, one hour is the minimum time to wait. The more viscous the material being measured, the longer you should wait.