Most fluids maintain a constant viscosity regardless of the pace at which the fluid is forced to move. Q: Does a fluid’s viscosity change in relation to the rate of shear stress (i.e., how rapidly or slowly the fluid is stirred, pumped or otherwise forced to move), or is the viscosity constant?Ī: The answer depends on the specific fluid. For example, if you were to tip over open containers of honey and water, the honey would pour out more slowly because its kinematic viscosity is higher. The slower the fluid’s flow in relation to gravity, the higher its viscosity. Kinematic viscosity, in simple terms, measures a fluid’s resistance to flow under the force of gravity. For example, it takes more force to mix yogurt in a blender than to mix fruit juice because yogurt has a higher absolute viscosity. The more force required to move the fluid, the greater the fluid’s absolute viscosity. Q: What are absolute viscosity and kinematic viscosity, and what is the difference between them?Ī: Absolute and kinematic represent the two methods for measuring and reporting viscosity.Ībsolute (also known as dynamic) viscosity measures a fluid’s resistance to flow when the fluid is subjected to a controlled force, such as a moving machine part, pressurized air or a pump. The greater the resistance to flow, the higher the fluid’s viscosity. Below are answers to some common questions about viscosity that may shed some light on this complex yet vital aspect of lubrication.Ī: Viscosity is a fluid’s resistance to flow at a given temperature. Understanding viscosity is important for proper lubricant selection and management, and ultimately for maximizing the performance, efficiency and life span of your equipment. This may lead to significant damage and possibly equipment failure. It really is that simple, and the potential gains are substantial.A lubricant’s viscosity is generally considered one of its most important properties, and with good reason: If the viscosity of a lubricant is even modestly different from what is needed for a particular component and application, the lubricant will not be able to lubricate the component effectively. Perhaps you’re over-cooling and could increase the efficiency by optimising your machine settings? If you lubricate with grease, you simply need to change to the right kind, with the right viscosity. There are several ways of changing viscosity: you can change your lubricant, dilute the existing lubricant, and you can review your routines. They even often lubricate better than thicker lubricants, since they move more quickly through the system and don’t heat up as much. But thinner lubricants also work well in heavier machinery and in systems that operate under high pressure, such as hydraulic systems. They make the biggest difference in machines that stay outside all year round and are subject to large temperature variations. Synthetic lubricants have lower viscosity and reduce energy loss, thus saving money, because they flow more easily and retain their lubrication properties even at lower temperatures. Pre-heating is of course an option, but the downside is higher energy consumption and the lubricant spoils more quickly. Mineral oils for instance become more viscous, or thicker, at lower temperatures. Viscosity is also very much affected by temperature. Lubricants with too high a viscosity are heavier to push around the system, which leads to direct energy losses and poorer lubrication.

All you need to do is make sure your lubricants are of the right viscosity.įundamentally, viscosity is about how ‘thick’ or ‘thin’ a lubricant is. And the necessary actions are simple the simplest one doesn’t even cost any extra. This means that smarter lubrication can make a big difference.

And lower energy consumption means lower carbon dioxide emissions. Greater energy efficiency leads to lower costs. Just as optimum viscosity is a simple key to greater energy efficiency, energy efficiency is a key to better finances and environmental performance. INCREASE ENERGY EFFICIENCY – WITHOUT NEW INVESTMENT A lot of people believe that finances and the environment are conflicting issues, but that doesn’t have to be the case. Energy efficiency is an integral issue in many companies today, both to reduce costs and to meet the latest energy directives and environmental requirements.

Low vs high viscosity