Determination pour point

Pour point n. Temperature at which materials posses a defined degree of fluidity. One particular method of determining pour point involves recording the times of efflux of a specified volume of the molten product through an orifice of standard dimensions. From the figures thus obtained it is... 

Pour Point n Temperature at which materials posses a defined degree of fluidity. One particular method of determining pour point involves recording the times... 

At lower temperatures, the crystals increase in size, and form networks that trap the liquid and hinder its ability to flow. The pour point is attained which can, depending on the diesel fuel, vary between -15 and -30°C. This characteristic (NF T 60-105) is determined, like the cloud point, with a very rudimentary device (maintaining a test tube in the horizontal position without apparent movement of the diesel fuel inside). 

Other terms relating to physical properties include viscosity refractive index pour point, ie, the lowest temperature at which the oil flows flash point, ie, the temperature at which the oil ignites and aniline point, ie, the minimum temperature at which equal volumes of oil and aniline are completely miscible. These are determined under defined conditions estabHshed by ASTM. 

Certain properties of a liquid fuel are measured routinely in a laboratory for characterization purposes. Besides density and viscosity, these properties include the pour point, the cloud point, and the flash point. Standard ASTM (American Society for Testing Materials) procedures are available for their determination. 

The pour point represents the lowest temperature at which the liquid fuel will pour. This is a useful consideration in the transport of fuels through pipelines. To determine the pour point, an oil sample contained in a test tube is heated up to 115°F (46°C) until the paraffin waxes have melted. The tube is then cooled in a bath kept at about 20°F (11°C) below the estimated pour point. The temperature at which the oil does not flow when the tube is horizontally positioned is termed the pour point. 

As oil enters the environment, it begins to spread immediately. The viscosity of the oil, its pour point, and the ambient temperature will determine how rapidly the oil will spread, but light oils typically spread more rapidly than heavy oils. The rate of spreading and ultimate thickness of the oil slick will affect the rates of the other weathering processes. For example, discharges that occur in geographically contained areas (such as a pond or slow-moving stream) will evaporate more slowly than if the oil were allowed to spread. Most of this process occurs within the first week after the spill. 

It is recommended that any higher-viscosity product such as residual oil or heavy distillate fuel be evaluated for changes in low-temperature handling properties over time. Testing for reversion in pour point by the Shell Amsterdam Reversion Test or the British Admiralty Pour Point Reversion Test are recommended. Also, viscosity increase versus temperature decrease determinations are recommended for products stored at low temperatures for extended periods of time. 

If shearing has destroyed the loosely formed wax lattice network of gelled crude oil so that the oil flows below its natural pour point, heating can restore the oil to its original pour point. By heating the crude oil to temperatures 20°F to 30°F (11.1 °C to 16.7°C) above the cloud point, waxes can be melted, solubilized and redistributed into the oil. When the pour point is then determined for this heated oil, the result obtained may be higher than the result obtained for the same oil which was not heated prior to pour point testing. All wax must be melted and solubilized into... 

When determining the pour point of certain heavy residual products such as 6 fuel oils, bunker fuels, vacuum gas oils, vacuum resids, atmospheric resids, and visbreaker bottoms, it is important to pay close attention to the temperature applied to the oil prior to pour point testing. In some cases, preheating an oil to temperatures greater than 212°F (100°C) prior to pour point testing can result in a pour point value which is lower than the value obtained for the same oil preheated to 110°F (43.3°C). 

The pour point test is used to determine the lowest temperature at which a fuel can be effectively pumped. However, the pour point value can be misleading, especially when it is used to determine the low-temperature handling characteristics of residual fuel oil and other heavy fuels. Low-temperature viscosity measurements are considered more reliable than pour point values for determining the flow properties and pumpability of these oils. 

This procedure can be utilized to determine whether heavy fuel wax crystal modifiers will lose their performance properties after long-term storage at fluctuating temperatures. Daily heating and overnight cooling may interfere with the ability of some wax crystal modifiers to maintain their performance properties in some residual oils and crude oils. This loss of performance is frequently termed pour point reversion. The British Admiralty Pour Point Test can be utilized to help predict these reversion tendencies. 

Compare the pour point obtained with the value determined from a standard ASTM D-97 pour point test. If the pour point temperature obtained is higher than the standard ASTM D-97 value, a reversion in pour point has occurred. 

This method describes a procedure for determining the critical pour point of residual fuel oils. 

Determine the ASTM D-97 pour point of each sample. 

Utilize low-temperature viscosity determinations rather than pour point values to establish low-temperature handling limits on oils possessing this characteristic phenomenon. 

STMCS. 1963. Method for determination of Amsterdam maximum pour point. 

Fuel Oils, Analytical. The following determinations were made at US War Planes during WWII 1) Specific Gravity 2) Moisture 3) Insolubles 4) Flash Point and 5) Pour Point Tests... 

The denormal oils recovered from the experiments were separated from the solvent by batch distillation. Vacuum and nitrogen stripping were applied towards the end, stopping when the oil temperature in the reboiler reached 473 K. Cloud and pour points were determined on the oil products. 

The oil yields calculated from the analyses of the denormal products in Table III are plotted versus denormal product pour point in Figure 12. It is seen that 60% of the ii-paraffins must be removed before the pour point begins to decrease. Further extraction of the ti-paraffins to 88% of the theoretical (maximum) yield of 16.7 wt % n-paraffins then reduces the pour point from 294 K to 266 K. It appears that extraction of the remaining n-paraffins may lower the pour point to the desirable range of 261-255 K. It would be interesting to determine the effect of pour point depressants on the denormal oil product. 

The products obtained were analyzed for composition using high-performance liquid chromatography (HPLC) (LC -10AT Shimadzu, Kyoto, Japan), which consisted of a column (STR ODS-II, 25 cm in length x 4.6 mm in id Shinwa Chemical, Osaka, Japan) operated at 40°C at a flow rate of 1.0 mL/min with methanol as a carrier solvent. The column was packed with silica particles (5-pm particle diameter and 12-nm pore diameter). The cloud and pour points of the obtained biodiesel were then determined by a mini-cloud/pour point tester (Model MPC-102 Tanaka Scientific, Tokyo, Japan) based on ASTM D2500 for cloud point and ASTM D6749 for pour point (14). 

Table 6 tabulates the pour point values for selected vegetable oils and synthetic fluids. It must be noted that some of the fluids may actually still pour after being held for significant durations at slightly lower temperatures than their determined PP. A good example is castor oU, which pours after more than 24 hours when stored at —25°C, although its PP has been determined to be —24°C in triplicate runs. 

Initially, kinematic viscosities at 40°C and pour points of the fluids were determined (results shown in Table 8). It appears that low-temperature properties of vegetable oils are much more inferior to those of synthetic basestocks or even mineral oil. Cold storage properties of vegetable oils do not appreciably respond to the pour point depressants (PPD), as opposed to mineral oils. This is consistent with earlier observations (35). Oxidative stabilities of the oils are compared in Table 9. 

During the cooling process, the response to diluents and PPD molecules is dependent on the vegetable oils FA composition and its geometry to a certain extent. Pour point determinations (65) of safflower, high oleic safflower, and high linoleic safflower in the presence of diluent and additive molecules are presented in Table 10 (68). 

Parameters Determining Selectivity. We believe that the peculiar selectivity of Pt-H-mordenite for hydrocracking normal and near-normal paraflSns in high-boiling feedstocks could not have been predicted from the known adsorption and diffusion properties of mordenites loc. cit.). However, extensive catalytic studies on the preparation of low-pour-point petroleum fractions have suggested to us that catalyst selectivity depends... 

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