In testing facilities, capillaries must be changed out often in order to accommodate samples that differ widely in viscosity.

Qualified technicians are typically required to set up and run the test, and to clean up afterward. The main advantage of the capillary method is that it provides a high degree of accuracy, making it ideal for certain applications, such as measuring the viscosity of aviation fuel to determine its dollar value and expected performance.ĭespite that advantage, the capillary method is a demanding and expensive process. However, many of the methods in the petroleum industry are still based on the capillary method, which measures the time it takes for an oil product to flow through a narrow glass tube. These devices work by rotating a spindle at a defined speed and then measuring the amount of torque that the spindle senses as it tries to rotate, McGregor explains. Rotational viscometers have become a popular tool for measuring petroleum products, particularly for thicker products like lubricants and greases. This advance is particularly useful when conducting low-temperature tests, says McGregor, as the user can see graphically on the display how the viscosity of a lubricant increases as it cools. A few years ago, AMETEK Brookfield came out with a display on one of its rotational viscometers that shows a timeline of how viscosity changes with the rotation of the spindle.

Of chief concern are potential fluctuations in temperature, which, as evidenced by the above anecdote, can have real-world implications. Rather, the viscosity varies as a function of other parameters. The viscosity of an oil sample can be difficult to determine because it is not a single value. Yet viscosity testing is not always straightforward, and there are certain challenges that specifically arise when testing viscosity in oil. Of the many physical parameters that can be measured in oil, viscosity-defined as a fluid’s resistance to flow-is the most important, and most commonly measured, according to Dan Walsh, technical sales director at Spectro Scientific (Chelmsford, MA). That incident is a compelling example of the need for rigorous oil testing. Subsequent analysis revealed that the oil contained a component that had turned the lubricant into jelly, says Bob McGregor of AMETEK Brookfield (Middleboro, MA). By subscribing, you agree to receive email related to Lab Manager content and products.

Is there a way to test oil viscosity