The charts used for this purpose are the ASTM Standard Viscosity-Temperature Charts for liquid Petroleum Products, available in 6 ranges. ![]() Because of the mathematical relationship that exists between these two variables, it is possible to predict graphically the viscosity of a petroleum fluid at any temperature within a limited range if the viscosities at two other temperatures are known. The manner in which the viscosity of a given fluid varies inversely with temperature. The absolute viscosity divided by the density of the fluid. The ration of the shearing stress to the shear rate of a fluid. Lubricant additive, usually a high molecular weight polymer, that reduces the tendency of an oil's viscosity to change with temperature. Multigrade oils, which provide effective lubrication over a broad temperature range, usually contain viscosity index improvers. Lubricant additive, usually a high molecular weight polymer, that reduces the tendency of an oil to change viscosity with temperature. In determining the viscosity index, two temperatures of viscosity are taken, one at 40☌ and the other at 100☌. The higher the viscosity index is on a particular fluid, the less of a change in viscosity there will be over a given temperature range. Heating tends to make lubricants thinner cooling makes them thicker. ![]() The measure of the rate of change of viscosity with temperature. The reduction of lubricant viscosity caused by contamination with water or other substances.Īny of a number of systems, which characterize lubricants according to viscosity for particular applications, such as industrial oils, gear oils, automotive engine oils, automotive gear oils, and aircraft piston, engine oils. ![]() Thin oils reduce friction in engines and help engines start quickly during cold weather. Thin oils have lower viscosity and pour more easily at low temperatures than thicker oils. it must be considered when selecting a pump and determining the friction losses in a fluid process system. So, we highly recommend giving our Combo package a try to enhance your knowledge on the subject.Engine oil viscosity refers to how easily oil pours at a specified temperature. Watching the videos will help you grasp the topic better and make learning more enjoyable. This package covers all the important details and presents them in an easy-to-understand format. It’s a great way to dive deeper into the subject through video explanations. If you want to learn more about this topic, we suggest checking out our Combo package with the given link . We want a higher viscosity index in lube oils because a good quality lube oil should not change its viscosity w.r.t change in temperature and a lower viscosity index in fuel oils because we want the viscosity to change w.r.t change with temperature. Lower viscosity index: more viscosity is affected with a change in temperature Higher viscosity index: less viscosity is affected with a change in temperature. It is the change in viscosity relative to temperature change. ![]() It can be measured by a device called a viscometer.ĭiagrams: Capillary type viscometer Falling ball-type viscometer Rotary type viscometer What is the Viscosity index? So viscosity is important in looking at how much is the clearance, if clearance is less, then we need less viscous lube oil otherwise it will not enter the between two surface clearances. We need to lubricate it so that it does not create friction and get wear and tear. When we have two metals, one is stationary and the other is moving up and down, the clearance between both metals is very less. So when fuel is heated, its viscosity reduces and proper injection takes place. It is very thick at 30° C so for burning it, we heat it to 130° C so that it can have a viscosity of 13 cst, the fuel we get on the ship has actual viscosity of 380 cst which is very thick at 50☌. The quality of fuel on the ship is third-grade quality. Viscosity ∝ 1/Temp (for liquid) Why is viscosity important onboard a ship? Example: honey when in very cold temp like 15° C is very thick and will not flow easily, raise it to 45° C then the flow will increase and at 80° C it will flow like water. Increasing the temperature of a substance decreases its viscosity which increases flow. All heavy oils and lube oils used on the ship are denoted by viscosity in cst at 50 ☌ Viscosity and its relation with temperature:
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |