Weights, types operating

The middle gauge cock is located at the boiler NOWL. Boilers operating at more than 250 psig have either two gauges or one gauge and an electric or electronic level indicator. Low water alarms are either float types or weight types. 

The apparent efficiency of the size reduction operation depends on the type of equipment used. Thus, for instance, a ball mill is rather less efficient than a drop weight type of crusher because of the ineffective collisions that take place in the ball mill. 

Light-Scattering Photometer. In one type, suspended particles are determined (counted). Another type is used to determine the molecular weight of macromolecules dispersed in solution. The former type operates on the basis of a nephelometer the latter is of much higher precision and uses monochromatic light. 

Separating a whole sample of a coal liquid or shale oil into classes poses special problems since these materials contain high concentrations of heteroatomic species compared with natural petroleums. Many of these compounds are quite polar and can cause emulsification, precipitation, and may even react to produce artifactual compounds at some stage during a separation procedure. Many liquid chromatographic techniques have been useful in class separations and analyses of petroleums. More often, these have been applied to particular analytical scale operations with fossil-derived liquids. The most common applications are for aromatic-aliphatic and molecular weight types of separations. 

Similar conclusions have been reached on the basis of studies with TiClj and amines (69). These catalysts polymerize propylene at a slow rate to highly isotactic polymers. The active site was long lived because polypropylene molecular weight increased with polymerization time over a long period. Mechanism studies (70) with the TiClj-Et N and Ziegler catalysts indicate a close resemblance and support the view that both catalyst types operate by propagation at a transition metal-carbon bond. 

Low-pressure Processes. Three processes for the polymerization of ethylene have recently been developed. The commercial process of the Phillips Petroleum Company for the polymerization of ethylene is carried out at relatively low pressures (100-500 psi) in either fixed-bed or slurry-type operations. The catalyst consists of 2-3 weight per cent chromium as oxide on silica alumina, and the reaction temperature varies from 90— 180°C. In fixed-bed operation, purified ethylene and hydrocarbon solvent streams are passed downflow, liquid phase over the catalsrst bpd. Solvent and polymer are collected, and the solvent is flashed overhead. Unreacted gases are removed from the solvent, taken overhead, and metered the solvent is recycled to the reactor. The solvent and polymer in the first receiver are cooled to room temperature to precipitate the polymer, which is then filtered and dried in a vacuum oven. In the slurry-type operation (indicated in Fig. 15-33 by a proposed flow diagram), solvent and a small... 

Some HALS act co-operatively with conventional flame retardants and there are high molecular weight types that are said to act as heat stabilisers. 

A thin film could lift a fairly heavy weight and operate reversibly for many cycles. The principle described made possible the construction of a continously working chemomechanical system. The operation was rather sluggish and the efficiency low, but it demonstrated the possibility of building a novel type of actuators made of water-swollen soft materials. Later, Tatara developed a chemomechanical piston... 

MSA part No. Output (A) Maximum voltage (V) Minimum voltage (V) Activation time (s) Duration Initiator type Operating temperature (°C) Weight (g) Height (mm) Diameter (mm)... 

Gel-permeation media are extremely versatile and may be used for separation of particles such as vimses (Fig. 11) as well as proteins (34). Separations of proteins and other particles having sizes equivalent to a molecular weight of 40 x 10 are possible using the agar-based Sepharose-type gel. This particular gel has a limited temperature range for operation, however. It melts upon heating to 40°C (34). 

Molecular Weight Distribution. In industry, the MWD of PE resins is often represented by the value of the melt flow ratio (MER) as defined in Table 2. The MER value of PE is primarilly a function of catalyst type. Phillips catalysts produce PE resins with a broad MWD and their MER usually exceeds 100 Ziegler catalysts provide resins with a MWD of a medium width (MFR = 25-50) and metallocene catalysts produce PE resins with a narrow MWD (MFR = 15-25). IfPE resins with especially broad molecular weight distributions are needed, they can be produced either by using special mixed catalysts or in a series of coimected polymerization reactors operating under different reaction conditions. 

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