Pour Point and Viscosity

Viscosity and pour point determinations are performed principally to ascertain the handling (flow) characteristics of petroleum at low temperatures. 

There are, however, some general relationships of crude oil composition that can be derived from pour point and viscosity data. Commonly, the lower the pour point of a crude oil the more aromatic it is, and the higher the pour point the more paraffinic it is. 

Viscosity is usually determined at different temperatures (e.g., 25°C/77°F, and 100°C/212°F) by measuring the time for a volume of liquid to flow under gravity through a calibrated glass capillary viscometer (ASTM D-445). 

In the test, the time for a fixed volume of liquid to flow under gravity through the capillary of a calibrated viscometer under a reproducible driving head and at a closely controlled temperature is measured in seconds. The kinematic viscosity is the product of the measured flow time and the calibration constant of the viscometer. Conversion of the kinematic viscosity in centistokes (cSt) at any temperature to Saybolt Universal viscosity in Saybolt Universal seconds (SUS) at the same temperature and for converting kinematic viscosity in centistokes at 122 and 210°F to Saybolt Furol viscosity in Saybolt Furol seconds (SFS) at the same temperatures (ASTM D-2161) is avaibale through formulae. 

The viscosity index (ASTM D-2270, IP 226) is a widely used measure of the variation in kinematic viscosity due to changes in the temperature of petroleum between 40°C and 100°C (104°F and 212°F). For crude oils of similar kinematic viscosity, the higher the viscosity index the smaller is the effect of temperature on its kinematic viscosity. The accuracy of the calculated viscosity index is dependent only on the accuracy of the original viscosity determination. 

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Poly-a-olefins (PAOs) are biodegradable and nontoxic to marine organisms they also meet viscosity and pour point specifications for formulation into oil-based muds [78]. 

The other thermal cracking process is visbreaking. This is a milder thermal process and is mainly used to reduce the viscosities and pour points of vacuum residues to... 

Yields and properties for high-severity desulfurization of Kuwait atmospheric tower bottoms are contained in Table XV. Residuum conversion to lighter products is apparent by the higher distillate yields relative to low-severity yields indicated in Table XIV. The LSFO product properties affected to the greatest extent with increasing severity are sulfur, viscosity, and pour point. 

The low viscosity and pour point characteristics of the SRC-II distillates are also attractive in industrial boiler and industrial cogeneration applications substituting for No. 2 fuel oil or natural gas. Demonstration burn programs in industrial boilers are being planned. 

Visbreaking is a thermal cracking process in which the thermal reactions are not allowed to proceed to completion. It is used for partial conversion of the higher boiling fractions, usually the residua, fisbreaking, unlike the coking processes (Table 13.3), is a relatively mild thermal cracking operation mainly used to reduce the viscosity and pour point... 

VISCOSITIES, POUR POINTS, AND OXIDATIVE DEGRADATION TENDENCIES 273 TABLE 8. Viscosities and Pour Points of Major Lubricating Basestocks. 

In any determination of the pour point, petroleum that contains wax produces an irregular flow behavior when the wax begins to separate. Such petroleum possesses viscosity relationships that are difficult to predict in pipeline operation. In addition, some waxy petroleum is sensitive to heat treatment that can also affect the viscosity characteristics. This complex behavior limits the value of viscosity and pour point tests on waxy petroleum. However, laboratory pumpabUity tests (ASTM D-3245, IP 230) are available that give an estimate of minimum handling temperature and minimum line or storage temperature. 

In viscosity breaking only a mild decomposition take place, the oil is decomposed just enough to lower the viscosity and pour point, so it can be pumped more easily. Little or no gasoline is produced. 

Notes There are six common grades or varieties of this oil, marketed under the name Fluorolube. The properties listed above that are marked with an asterisk depend upon the grade that is used. The primary physical differences between the grades are the viscosities and pour points. 

Often, the inhibitor may be diluted just prior to injection to improve its mobility. Pour point is related to viscosity and is mainly important during cold weather. The inhibitor must flow at the lowest temperature expected at the location of use. Often the active ingredient of an inhibitor formulation is only 20% of the bulk, in order that the proper viscosity and pour point can be achieved through dilution. 

Ease of starting, according to Shoemaker and Gadebusch, depends mainly upon ignition quality but also upon viscosity and pour point. 

Uses Surfactant intermediate, engine oil lubricant additive, viscosity and pour-point improver, plasticizer, epoxy, antifreeze lubricant, control for leather goods and corrosion inhibitor sizing agent in the alkaline production of paper Features Good thermal stability melt processable cost effective Properties Cl, amber liq, sp, gr, 0,955 vise, 250 cs b.p. 235 5 mm Hg flash pt. (PM-CC)195C... 

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