The flow time of hydraulic oil filter must be within the prescribed range
2018/5/17 Viewers:
Method stipulates that the flow time of the sample is within the range of 300 180S, the main purpose is to limit the velocity of liquid flow in the capillary, and to ensure that the liquid flow in the capillary is laminar flow. If the liquid velocity is too fast, it will become turbulent flow beyond a certain range. With the turbulence, the Poisson equation can not be applied to calculate the liquid viscosity. Moreover, due to the error of the outflow time reading, the error is large when the outflow time is too short. If the liquid flow rate is too slow, some high viscosity lubricants may get laminar flow. However, due to the difficulty of maintaining constant temperature during the determination time, the result of temperature measurement is often not allowed. However, when OC is used, the mixture of ice and water is easier to reach constant temperature. Therefore, when the viscosity of high viscosity lubricating oil is measured at OC, the flow time can be increased to 900S.
The following items should be paid attention to when measuring kinematic viscosity (1) strictly constant temperature. Strict constant temperature is stipulated. It is one of the important conditions to determine the viscosity of liquid oil. Because the viscosity of liquid oil decreases with the increase of temperature, it will increase with the decrease of temperature, and it is necessary to strictly keep the constant temperature in the measurement. Otherwise, there is a very small temperature fluctuation (over 01C), which will make the result of the measurement error. (2) the specimen shall be dehydrated and removed from the mechanical impurities. If the sample contains moisture and mechanical impurities, before measuring the viscosity, it must dehydrate and filter out mechanical impurities. Because the presence of impurities will affect the normal flow of oil in the viscometer, such as its door adheres to the inner wall of the capillary, the flow time will increase, the result is high, and the repeatability of the parallel determination results is poor; when there is water, it vaporizes in the case of higher temperature. At low temperature, it condenses and affects the oil in the viscometer. The normal flow affects the accuracy of the test results. (3) no bubbles are allowed in the sample. When the viscosity is measured, the bubble will affect the volume of the oil, and the gas plug may be formed after the entrance to the capillary, and the flow time is prolonged and the result is higher. (4) when the viscometer is adjusted to a vertical state and the kinematic viscosity is measured, the GB265 stripping method stipulates that the viscometer should be adjusted to a vertical state. Because if the capillary tube of the viscometer inclining, it will change the height of the liquid column, thus changing the static pressure and causing the error of the measurement result.
The following items should be paid attention to when measuring kinematic viscosity (1) strictly constant temperature. Strict constant temperature is stipulated. It is one of the important conditions to determine the viscosity of liquid oil. Because the viscosity of liquid oil decreases with the increase of temperature, it will increase with the decrease of temperature, and it is necessary to strictly keep the constant temperature in the measurement. Otherwise, there is a very small temperature fluctuation (over 01C), which will make the result of the measurement error. (2) the specimen shall be dehydrated and removed from the mechanical impurities. If the sample contains moisture and mechanical impurities, before measuring the viscosity, it must dehydrate and filter out mechanical impurities. Because the presence of impurities will affect the normal flow of oil in the viscometer, such as its door adheres to the inner wall of the capillary, the flow time will increase, the result is high, and the repeatability of the parallel determination results is poor; when there is water, it vaporizes in the case of higher temperature. At low temperature, it condenses and affects the oil in the viscometer. The normal flow affects the accuracy of the test results. (3) no bubbles are allowed in the sample. When the viscosity is measured, the bubble will affect the volume of the oil, and the gas plug may be formed after the entrance to the capillary, and the flow time is prolonged and the result is higher. (4) when the viscometer is adjusted to a vertical state and the kinematic viscosity is measured, the GB265 stripping method stipulates that the viscometer should be adjusted to a vertical state. Because if the capillary tube of the viscometer inclining, it will change the height of the liquid column, thus changing the static pressure and causing the error of the measurement result.
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