Base Stock System

The advantages provided by a base stock system are twofold (17). 

Base stock requirements will vary dependent on the customer base served, which obviously dictates the hnished product mix. A wide variety of source oils are available that could be used for shortening base stocks, as illustrated by Table 1. The choices are narrowed by factors such as customer specihcations, costs, religious prohibitions, traditional preferences, crop economics, legislation, availability, transportation, and others. These factors have favored soybean oil in the United States for several decades. Therefore, most U.S. shortening processors have base stock systems dominated by soybean oil with only minor representation by the other source oils. The minor oils in most base stock systems serve as (3 promoters for plasticity, like cottonseed and palm oils, or those source oils required for specialty product preparation. 

The soybean oil base stock system in Table 7 uses both selective and nonselective conditions for the partially hydrogenated bases. Selectivity is not important for low-IV hard stocks because these reactions are continued to almost complete saturation. The main objective for these products is to reach maximum saturation as quickly as possible. Actual values for the hydrogenation conditions were not identihed because results vary from one converter to another due to design and other variables within each plant (20). It is necessary to develop conditions for each installation separately to meet the SFI, IV, and melting point relationships. 

In a base stock system the immediate signaling of aU demands to aU cells means that... 

TABLE 4 pifj, and E[A] for a Two-Cell Base Stock System with Zi = Z2 = 2... 

Classic Base Stock System is a push system because there is no limit on the amount of work in process in the system. 

The final periodic-review system we consider is actually the simplest, the base-stock system. In this system, we once again place an order at each review interval, but in this case, the review interval is set equal to the smallest discrete time unit covered by the system. Thus, for this inventory system, the period and the time unit are one-in-the-same. For example, if we manage the system using days as our time units—i.e., if lead time is specified in days—then in a base-stock system, we would review the inventory position X at the start of each day and place an order of size Q = S - x, to be received L days later. Thus, for this system, the review interval is T = 1 and the base-stock level is set to Sb = fr (CSL), where F is the cdf of the DLTR distribution, which in this case is the distribution of demand over L + 1 time units. If the demand rate per time unit, D, is normally distributed, then we can compute... 

Sometimes, the base-stock system is referred to as an (S - 1,S) system since the reorder point for this system is effectively s = S - 1, meaning that, as long as a non-zero demand (i.e., at least one unit of demand) occurs in the reorder interval of T = 1, we reorder to bring the inventory position back to S. 

The computations supporting this inventory policy are similar to those made in Example 3.9. In this case, Sb =110(1-+ 1) + ZcsrOoVb + l = (49.32)(5) + (1.282)(15)>/5 = 290. For the base-stock system, we know that an order will be placed every day, so each order needs to cover uncertain demand until the order placed at the next review arrives in stock L + 1 = 5 days later. 

Although lubricant base stocks have been subjected to dewaxing processes, they still contain large amounts of paraffins that result in a high pour point for the oil. In the paragraph on the cold behavior of diesel fuels, additives were mentioned that modify the paraffin crystalline system and oppose the precipitation of solids. 

The fluid is formulated from a premium mineral od-base stock that is blended with the required additive to provide antiwear, mst and corrosion resistance, oxidation stabdity, and resistance to bacteria or fungus. The formulated base stock is then emulsified with ca 40% water by volume to the desired viscosity. Unlike od-in-water emulsions the viscosity of this type of fluid is dependent on both the water content, the viscosity of the od, and the type of emulsifier utilized. If the water content of the invert emulsion decreases as a result of evaporation, the viscosity decreases likewise, an increase in water content causes an increase in the apparent viscosity of the invert emulsion at water contents near 50% by volume the fluid may become a viscous gel. A hydrauHc system using a water-in-od emulsion should be kept above the freezing point of water if the water phase does not contain an antifreeze. Even if freezing does not occur at low temperatures, the emulsion may thicken, or break apart with subsequent dysfunction of the hydrauHc system. 

Used oil disposal trends include waste minimisation such as by reclaiming used fluid on site, as well as recycling of mineral oil lubricants instead of disposing by incineration. The recycling effort involves a system where spent mineral oils are collected then shipped to specialty refineries where the materials are distilled, hydrofinished, and re-refined into fresh base stocks. These re-refined materials are virtually identical to virgin feedstocks. 

In order that your subcontractors can achieve 100% on-time delivery, you need to provide the same type of information and make the same commitments as your customer will to enable you to meet 100% on-time delivery to them (see Part 2 Chapter 15). You therefore need to inform your subcontractors of your production schedule and release orders to your subcontractors based on that schedule. If operating under a ship-to-stock system, you will need a means of notifying your subcontractor when stocks drop to the minimum level. Under such arrangements, you do not need a purchase order for every delivery as one order specifying the shipment rate will suffice. A good maxim to work by is ... 

Small firm used about 4,000 gallons of TCA to clean metal stock Firm converted to a water-based cleaning system... 

Figure 16.4 Map of the North Padfic Ocean basin showing several important features of the trades biome. (A) Dynamic topography of the sea surface in dyn-cm relative to 1000 dbar based on historical hydrographic observations. Arrows show the direction of geostrophic flow. From Wyrtki (1975). (B) Sea surface distributions of chlorophyll (mg m for the Pacific Ocean in 2003 from 15°S to 65°N latitude as derived from the AQUA MODIS satellite-based sensor system (4 km resolution). Superimposed on ocean color, in white contour lines, is the mean annual surface nitrate concentration (mmol NO m ) based on the World Ocean Atlas (2001) Ocean Climate Laboratory/NODC. Areas of high NOs (and presumably NOs flux) correspond to areas that are enriched in chlorophyll as a result of net plant growth. The North Pacific trades biome is the central region of low standing stocks of plants (<0.1 mg m blue-purple areas) and low ambient NOT concentrations (<1 mmol m ).

Usually, steam is added to the preheat system, either as velocity steam or after the preheater as dilution steam to get deeper volatilization. Each product is steam stripped as in crude oil distillation. In the case of naphthenic crude oils, the bottom product may be directed to asphalt specialties rather than being treated to make lubricating oil base stock. 

One of the most critical and often overlooked problems in oil condition monitoring is the introduction of an incorrect lubricant into machinery lubrication systems. Incorrect oil addition ranges from the introduction of foreign materials such as glycol or different base stock fluids to the introduction of similar oil of a different type or viscosity grade. Whilst incorrect oil is not a lubricant failure mode per se, it can be the root cause of real lubrication problems. 

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