![]() ![]() The difference is when the viscosity is tested at a much colder temperature. In other words, a SAE 30 motor oil is the same viscosity as a 10w-30 or 5W-30 at 210° (100° C). The numbers without the W are all tested at 210° F or 100° C which is considered an approximation of engine operating temperature. When you see a W on a viscosity rating it means that this oil viscosity has been tested at a Colder temperature. What does a 5W-30 do that an SAE 30 won’t? These are translated into the easier to understand SAE viscosity numbers you see on an oil bottle. You will see oil viscosity measurement in lube articles stated in kinematic (kv) and absolute (cSt) terms. The thicker (higher viscosity) of an oil, the slower it will flow. Simply put, viscosity is the oil’s resistance to flow or, for the layman, an oil’s speed of flow as measured through a device known as a viscometer. This leaves them still wondering what the viscosity numbers really mean on a bottle of motor oil. Most of the time when viscosity is explained words are used that are too technical for the average person to quickly grasp. As a rule of thumb, multiply the specific gravity of a liquid by 8.34 to find the weight of a gallon of that liquid.What does the SAE Viscosity rating on your Motoroil bottle mean? In our table below, we have given various liquids' characteristics with the temperature modified to one of more of a real world value. You can observe the little balls floating in the tube. Another version will determine the concentration of anti-freeze in an automobile radiator. This is the same instrument that we use to tell if your automobile battery is fully charged. ![]() The float is calibrated to float on fresh water so if the fluid you are testing has a higher specific gravity, the float will raise in the liquid and at a lower specific gravity it will sink lower in the liquid. It consist of a glass cylinder with a rubber bulb on top, and a float positioned inside the glass tube. We measure specific gravity with a hydrometer. The really important thing to keep in mind is that there is no correlation between viscosity and specific gravity. Like specific gravity, viscosity can be altered by a change in temperature, but unlike specific gravity it can also be altered by agitation. Thick liquids are said to have a high viscosity and thin liquids a low viscosity. It is important that you do not confuse specific gravity with viscosity which is a measurement of a fluids resistance to pouring, though there is often what is perceived to be an obvious relationship. As you have already guessed fresh water at 4☌ (39° F) has been assigned a value of one (1). If it sinks into the fresh water the specific gravity is more than one. If the liquid you are comparing will float on this water it has a specific gravity of less than one (1). In relationship to liquids, the term specific gravity is used to describe the weight or density of a liquid compared to an equal volume of fresh water at 4☌ (39° F). Its density is 7.85 grams per cubic centimeter, or 7.85 kilograms per liter, or 7.85 metric tons per cubic meter. If something is 7.85 times as heavy as an equal volume of water (such as iron is) its specific gravity is 7.85. In the metric system specific gravity is the same as in the English system. Specific gravity is the heaviness of a substance compared to that of water, and it is expressed without units. Specific Gravity And Viscosity Of Liquids ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |