Saybolt Seconds Universal units

The viscosity of syrups is usually reported in either centipoises (mPa s) or SSU (Saybolt Seconds Universal) units. SSU units are related to centipoises by the following equation 61... 

A dry sump design should be employed. The gear unit for a train with a central lube oil system should be designed for the turbine grade oils of the system. Typically, 150 Saybolt Seconds Universal (SSU) oils at 100°F (ISO 32) with an inlet temperature of 110°F to 120°F are adequate. 

A 1.1 The calculation of viscosity-gravity constant (VGC) can also be calculated from viscosity in units of Saybolt seconds universal (SUS) and relative density (specific gravity). 

SUs Saybolt Universal seconds USDA United States Department... 

The following formulas may be used to convert centis-tokes (cSt units) to approximate Saybolt universal seconds (SUS units). For SUS values between 32 and 100 ... 

Liquid viscosity is usually measured by the amount of time it takes for a given volume of liquid to flow through an orifice. The Saybolt universal viscometer is the most widely used device in the United States for the determination of the viscosity of fuel oils and liquids. It should be stressed that Saybolt viscosities, which are expressed in Saybolt seconds SSU), are not even approximately proportional to absolute viscosities except in the range above 200 SSU hence, converting units fiom Saybolt seconds to other units requires the use of special conversion tables. As the... 

A number of arbitrary viscosity units have also been used. The most common has been the Saybolt Universal second (SUs) which is simply the time in seconds required for 60 mL of oil to empty out of the cup in a Saybolt viscometer through a carefully specified opening. Detailed conversion tables appear in ASTM D2161, approximation of kinematic viscosity V in mm /s(= cSt) can be made from the relation shown in equation 8 ... 

Viscosity. Although traditionally of Httle importance in the evaluation of vegetable and insect waxes, viscosity is an important test for mineral and synthetic waxes. One of the most frequently used tests, ASTM D88, is used to measure the time in seconds required for a specified quantity of wax at a specified temperature to flow by gravity through an orifice of specified dimensions. This viscosity is expressed in Saybolt Universal Seconds (SUS) at the temperature of the test. The SI unit for kinematic viscosity is mm /s (=cSt). 

In the SI system, the theoretical unit of v is m2/s or the commonly used Stoke (St) where 1 St = 0.0001 m2/s = 100 cSt = 100 centiStoke. Similarly, 1 centiStoke = 1 cSt = 0.000001 m2/s = 0.01 Stoke = 0.01 st. The specific gravity of water at 20.2°C (68.4°F) is almost 1. The kinematic viscosity of water at 20.2°C (68.4°F) is for all practical purposes equal to 1 cSt. For a liquid, the kinematic viscosity will decrease with higher temperature. For a gas, the kinematic viscosity will increase with higher temperature. Another commonly used kinematic viscosity unit is Saybolt universal seconds (SUS), which is the efflux time required for 60 mL of petroleum product to flow through the calibrated orifice of a Saybolt universal viscometer, as described by ASTM-D88. Therefore, the relationship between dynamic viscosity and kinematic viscosity can be expressed as... 

Kinematic viscosity is measured by timing the flow of a fixed volume of material through a calibrated capillary at a selected temperature (ASTM D-445, IP 71). The unit of kinematic viscosity is the stokes, and kinematic viscosities of waxes are usually reported in centistokes. Saybolt Universal seconds can be derived from centistokes (ASTM D-2161) ... 

The typical characteristics of the variation of viscosity with temperature can be seen in a plot of hydrocarbon viscosities at two temperatures. Figure 3.1 shows the relationship for n-paraffins,1-3 and when both axes are converted to logarithms a linear relationship results. Figure 3.2 (the temperatures employed for this type of diagram are now usually 40°C and 100°C, whereas in the past 100°F and 210°F were used correspondingly, units for viscosity were originally in Saybolt universal seconds (SUS) they are now in centistokes. Distillation fractions through base stocks show similar behavior. 

One unit for kinematic viscosity used in the oil industry (but of limit use in the mining industry) is the seconds Saybolt universal (or SSU). For values of kinematic viscosity larger than 70 centistokes (cst), the following formula is recommended by the Hydraulic Institute (1990) ... 

Saybolt viscometer A type of instrument used to determine the viscosity of petroleum oils. It is based on the time in seconds for a given volume of oil to pass through an aperture at a controlled temperature and collect in a container with a volume of 60 millilitres. The Saybolt universal second is the unit used as a measure of the ldnemaUc viscosity. 

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