ASTM D445 Standard Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (Including Calculation of Dynamic Viscosity)

Developed by the American Society for Testing and Materials (ASTM),ASTM D445 Standard test method for kinematic viscosity of transparent and opaque liquids (including calculation of dynamic viscosity) The standard describes a test method for determining the kinematic viscosity of both clear and opaque liquid petroleum products by measuring the time it takes for a volume of liquid to flow under gravity through a calibrated glass capillary viscometer. Dynamic viscosity can be obtained by multiplying the kinematic viscosity by the density of the liquid.

ASTM D2170 and ASTM D2171 standards are also applicable for measuring the kinematic viscosity of bitumen. The test method described in ISO 3104 Petroleum products - Transparent and opaque liquids - Determination of kinematic viscosity and calculation of dynamic viscosity corresponds to this standard.

The results obtained from this test method depend on the behavior of the sample and are primarily intended for use in fluids where shear stress and shear rates are proportional (Newtonian flow behavior). However, if viscosity varies significantly with shear rate, different results may be obtained from viscometers with different capillary diameters. Procedure and sensitivity values ​​are included for residual fuel oils, which exhibit non-Newtonian behavior under certain conditions.

The kinematic viscosity range covered by this test method is from 0,2 mm2/s to 300.000 mm2/s at all temperatures. Accuracy is determined only for the materials, kinematic viscosity ranges, and temperatures shown in the footnotes to the accuracy section.

Mercury is designated by many regulatory agencies as a hazardous substance that can cause serious medical problems. Mercury and its vapors have been shown to be harmful to health and corrosive to materials. Caution is essential when handling mercury and mercury-containing products.

Many petroleum products and some non-petroleum materials are used as lubricants, and proper equipment operation depends on the appropriate viscosity of the fluid used. Furthermore, the viscosity of many petroleum fuels is important for predicting optimal storage, handling, and operating conditions. Therefore, accurate viscosity determination is crucial for many product specifications.

The measurement method described in this standard is based on monitoring the flow time of transparent or opaque liquids through a calibrated glass capillary.

The kinematic and dynamic viscosity of petroleum products is measured for the following reasons:

• Determining the quality of petroleum products
• Determine the applicability, operability and handling of petroleum
• Developing optimum storage conditions

Flow time is determined by duplicate measurements that include cleaning steps in between. To calculate kinematic viscosity, flow time is multiplied by the capillary constant obtained from the measurement of a certified viscosity reference material. This is an indirect viscosity determination because kinematic viscosity is calculated based on flow time.

For the calculation of dynamic viscosity ASTM: Additional density measurements are required according to standards D1217, ASTM D1480, ASTM D1481, or ASTM D4052.

The requirements for viscosity measurement according to the ASTM D445 standard are:

• Temperature control: Temperature is one of the most important factors affecting viscosity measurement. To meet the test requirements of the standard, a maximum temperature range of 15 degrees to 100 degrees plus/minus A temperature deviation of 0,02 degrees is allowed (outside this range, plus or minus 0,05 degrees). To meet this requirement, a temperature-controlled bath with an additional external thermometer is required. For adequate temperature compensation, the loaded capillary should be placed in the temperature bath before measurement. An equilibration time of approximately 30 minutes is recommended. However, the optimal equilibration time varies for each instrument and with different temperatures and kinematic viscosities. It needs to be determined more precisely experimentally.
• Timing device: According to this standard, timing devices providing plus/minus 0,07 percent accuracy and 0,1 second recording separation must be used.
• Sample filling and preparation: This test method is applicable to both clear and opaque liquids. Clear liquids must be homogenized and degassed in an ultrasonic bath. If the sample liquid contains fibers or particles, an additional filtration step is required. Residual fuel oils and opaque liquids are homogenized by several heating and mixing steps, and particles must be removed by a preheated filter. For opaque liquids, two counterflow capillaries are required to determine kinematic viscosity.

Particles are one of the most common sources of error. If the sample contains fibers or solid particles, filtration is required. The required filtration screen has a pore size of 75 µm, so particles larger than 75 µm must be filtered out. In addition to particles in the sample, dust particles inside the capillary can also cause erroneous measurements. Consequently, proper storage and careful cleaning of the capillaries are essential.

By default, petroleum samples can be measured with manual or automatic glass capillary viscometers. The Oswald-type, suspended-level, and counterflow capillaries specified in ASTM D445 can be used for various samples and viscosity ranges. These viscometers include glass capillaries, capillary holders, a temperature control unit, a temperature-controlled bath, a thermometer, a bath fluid suitable for the measurement temperature, and a time-measuring device that meets the required specifications of the standard.

According to the ASTM standard, kinematic viscosity and dynamic viscosity should be stated in millimeters per square second (mm2/s) and millipascal seconds (mPa·s).

The alternative standard for viscosity measurements is the standard “ASTM D7042 Standard test method for dynamic viscosity and density of liquids (and calculation of kinematic viscosity) by Stabinger viscometer”.

Our organization, which has been supporting businesses across all sectors for years through a wide range of testing, measurement, analysis, and evaluation activities, has a strong team of employees who closely follow global developments in science and technology and are constantly improving themselves. In this context, we also provide testing services in accordance with the "ASTM D445 Standard Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (Including Calculation of Dynamic Viscosity)" standard.