Controlled drags requirements

Tar sand feed contains a certain portion of fine minerals that, if allowed to build up in concentration in the middlings, increases viscosity and eventually dismpts settling ia the separation cell. The drag stream is required as a purge in order to control the fines concentration in the middlings. The amounts of water that can enter with the feed and leave with the separation cell tailings and froth are relatively fixed. Thus, the size of the drag stream determines the makeup water requirement for the separation cell. 

If the process feed does not He in the Hquid—Hquid region it can be made to do so by dehberately feeding either pure or pure B to the decanter, as required. This may only be necessary during start-up or for control purposes because the recycled azeotrope has the beneficial effect of dragging the decanter composition further into the Hquid—Hquid region. 

Fhtients receiving warfarin for the first time often require daily adjustment of die dose, which is based on die daily PT/INR results. The nurse widiholds the drug and notifies die primary healdi care provider if the PT exceeds 1.2 to 1.5 times die control value or die INR ratio exceeds 3. A daily PT is performed until it stabilizes and when any otiier drag is added to or removed from die patient s drag regimen. After the PT has stabilized, it is monitored every 4 to 6 weeks. 

Another desirable physical property is high propellant density. One requirement for high propellant density has already been noted in the discussion of performance (Isd) requirements. The density of the propellant controls the size of the propellant tankage. Even in systems in which the volume of the vehicle is not critical, the smaller tankage results in a reduction in structural weight and aerodynamic drag of the vehicle. In addition, the change in density with temperature variation should be... 

Classical, macroscopic devices to measure friction forces under well-defined loads are called tribometers. To determine the dynamic friction coefficient, the most direct experiment is to slide one surface over the other using a defined load and measure the required drag force. Static friction coefficients can be measured by inclined plane tribometers, where the inclination angle of a plane is increased until a block on top of it starts to slide. There are numerous types of tribometers. One of the most common configurations is the pin-on-disk tribometer (Fig. 11.6). In the pin-on-disk tribometer, friction is measured between a pin and a rotating disk. The end of the pin can be flat or spherical. The load on the pin is controlled. The pin is mounted on a stiff lever and the friction force is determined by measuring the deflection of the lever. Wear coefficients can be calculated from the volume of material lost from the pin during the experiment. 

Sterilization by filtration is a major unit operation used in aseptic processes. Aseptic processes require the presterilization of all components of the drag product and its container. Then all of the components are brought together in a controlled aseptic environment to create the finished sterile product sealed within its container/closure system. The level of sterility attained by an aseptic procedure is a cumulative function of all the process steps involved in making the product. Therefore, the final level of sterility assurance for such a product cannot be greater than the step providing the lowest probability of sterility. Each step in the aseptic process must be validated to known levels of sterility assurance [43],... 

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