Orifice cycles through

Polyacrylamides are extremely sensitive to shear fields as pointed out in the literature (13,14) Any orifice mixing breaks up the chains of polyacrylamides. The viscosities of Pusher solutions are plotted against the number of cycles through an orifice in Figure 6. Even with a 1/16" orifice (which has less than a 10 psi pressure drop across it), the viscosity drops from 14.1 cp to 10.9 cp showing more sensitivity than the other polymers. Agitation with a propeller at low speeds (less than 500-600 rpm) is a proper mixing mode for polyacrylamides. 

Most mills control the cooking cycle by automatic time-temperature controllers and recorders. The rate of temperature rise to the conversion plateau must be slow to prevent hot pockets or cold areas. The rate of temperature increase to the inactivation plateau must be rapid to prevent excessive depolymerization in the intermediate temperature range. The viscometers operate according to different mechanisms time to expel paste from a sample device (Norcross) vibration of a probe in the paste (Dynatrol) torque readings (Brookfield) or pressure drop on passage through an orifice (Escher Wyss). Potential errors in viscosity can result from variations in starch solids due to differences in moisture content of the starch, errors in slurry preparation and the quantity of condensate added by the steam. The process yields a maximum paste concentration of about 32%. 

Extensive field testing determined that the most suitable and accurate pump for the dosimeter application was one designated "Accuhaler 808," which is manufactured by MDA Corporation. The principle of operation is based upon an aspiration cycle which draws a constant volume of sample air through a limiting type of orifice for each stroke of the pump. A counter reads out the pump strokes and the total sample volume is computed for a given sampling period. The dosimeter... 

Upon completion of the extraction cycle the internal portions of the citrus are located in the prefinisher tube. At this time, the orifice tube moves upward, placing pressure on the contents of the prefinisher tube. This causes the juice and the juice sacs, due to their small particle size, to flow through the holes of the prefinisher tube and into the juice manifold. Particles larger than the holes in the prefinisher tube are forced through an opening in the orifice tube and discharged out the bottom. 

Blood flow to the coronary arteries arises from orifices located immediately distal to the aorta valve. Perfusion pressure is equal to the difference between the aortic pressure at an instantaneous point in time minus the intramyocardial pressure. Coronary vascular resistance is influenced by phasic systolic compression of the vascular bed. The driving force for perfusion therefore is not constant throughout the cardiac cycle. Opening of the aortic valve also may lead to a Venturi effect, which can slightly decrease perfusion pressure. If perfusion pressure is elevated for a period of time, coronary vascular resistance declines, and blood flow increases however, continued perfusion pressure increases lead, within limits, to a return of coronary blood flow back toward baseline levels through autoregulation. 

FIGURE 2.3 Molding cycle of a pot-type transfer mold, (a) Molding compound is placed in the transfer pot and then (b) forced under pressure when hot through an orifice and into a closed mold, (c) When the mold opens, the sprue remains with the cull in the pot, and the molded part is lifted out of the cavity by ejector pins. (After Frados, J. ed. 1976. Plastics Engineering Handbook, 4th Ed., Van Nostrand Reinhold, New York.)... 

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