Dynamic viscosity, kinematic viscosity and condition viscosity three kinds of measurement methods.

(1) power viscosity: ηt is two liquid layers 1 cm apart, its area is 1 (square centimeter) relative to the speed of movement of 1 cm / s when the resistance generated, the unit is grams / lm? sec. 1 g/cm? sec = 1 poe general: industrial power viscosity unit with poe to express.

(2) kinematic viscosity: at the temperature t ℃, kinematic viscosity with the symbol γ, in the unit system, kinematic viscosity units for s, that is, square meters per second (m2 / s), the actual determination of commonly used centile, (cst) said centile unit of square millimeters per second (that is, 1cst = 1mm2 / s). Kinematic viscosity is widely used to determine the viscosity of jet fuel oil, diesel oil, lubricating oil and other liquid petroleum products dark petroleum products, lubricating oil after use, crude oil, etc. The determination of kinematic viscosity uses the countercurrent method.

(3) condition viscosity: refers to the viscosity expressed in condition units measured by using different specific viscometer, the condition viscosity usually used in various countries are the following three kinds.

① En's viscosity is also called Engler (Engler) viscosity. Is a certain amount of specimens, in the prescribed temperature (such as: 50 ℃, 80 ℃, 100 ℃), from the Engler viscometer out of 200 ml of specimens required time and distilled water at 20 ℃ out of the same volume of time required (seconds) ratio. Temperature t? when the En's viscosity with the symbol Et, the unit of En's viscosity for the condition degree.

② Sai viscosity, that is, Sai Porter (sagbolt) viscosity. Is a certain amount of specimens, in the prescribed temperature (such as 100?F, F210?F or 122?F, etc.) from the Sai viscometer outflow 200 ml of the number of seconds required to "seconds" unit. Sai viscosity is also divided into Sai general viscosity and Sai heavy oil viscosity (or Sai Furol (Furol) viscosity) of two kinds.

③ Ray's viscosity that Redwood (Redwood) viscosity. Is a certain amount of specimens, in the prescribed temperature, from the Raytheon meter out of 50 ml of the number of seconds required to "seconds" as a unit. Ray viscosity is also divided into Ray 1 (Rt said) and Ray 2 (with RAt said) two kinds.

The above three conditions viscosity determination method, commonly used in Europe and the United States, China in addition to the use of the En viscometer to determine the dark colored lubricating oil and residual oil, the other two viscometers are rarely used. Three kinds of conditions viscosity expression method and unit are different, but the relationship between them can be converted through the chart. At the same time, the En's viscosity and kinematic viscosity can also be converted, so it is much more convenient and flexible.

The nature of internal friction between fluids, known as the viscosity of the fluid.

Dynamic viscosity is the ratio of the internal friction force per unit contact area of the fluid and the rate of change of flow velocity perpendicular to the direction of motion.

Kinematic viscosity is the ratio of kinetic viscosity to the density of the fluid at the same temperature. The ratio of the density of the fluid at the same pressure.