Displacement devices, positive

Counterrotating intermesning screws provide a dispersive milling action between the screws and behave like a positive displacement device with the ability to generate pressure more efficiently than any other extruder. 

The down-comer from the gas/liquid separator that collects the liquid slurry product is connected to the suction side of a moyno-type (Liberty progressive cavity) pump. The pump discharge is connected to a primary separation device (an inertial separator similar to a hydrocyclone). Since the slurry pump is a positive displacement device (i.e., no slurry slippage inside the pump), the total flow... 

An extrusion is comprised of a basket (cylinder) to contain the mix and a hydraulically actuated piston to press the mass through multiple extrusion dies. The baskets are jacketed for temperature control and contain internal screens to retain large agglomerates. Since the casting powder strands are unperforated, the dies are simple cylindrical barrels with conical lead-in sections. Extrusion rates are normally controlled by orifices in the hydraulic supply line however, constant-rate positive displacement devices are also used. As they extrude, the strands are collected separately in suitable containers. 

The cholestane and taurocholate serve as internal standards. They should be dispensed with a Hamilton syringe or other positive displacement device to insure accurate delivery to each sample. Let solvents evaporate before proceeding. The exact amount of taurocholate used should also be dispensed into a scintillation vial to accurately determine the number of dpm added to each sample. 

Several typologies of blowers or compressors are potentially suitable for fuel cell application. In Fig. 4.4 a flow diagram of all compressor types is reported, distinguishing two main classes (dynamic and positive displacement) and different typologies for each (reciprocating and rotary as positive displacement devices, and centrifugal and axial as dynamic machines). 

The flow rate for pressurized delivery is determined by the difference in the source and destination pressures and any impedance to flow in the delivery path. The flow rates for a positive displacement device are generally quite accurate and reliable and should not change significantly with small variations in the blanketing pressure and the flow impedance of the system. 

Metering pump n. A positive displacement device that pumps a measured amount of polymer solution to the spinnerets. 

Ram or plunger extruders are simple in design, rugged, and discontinuous in their mode of operation. Ram extruders are essentially positive displacement devices and are able to generate very high pressures. Because of the intermittent operation of... 

These are positive displacement devices — also called fixed displacement pumps . That means that the volume of movement within the pump is the volume of fluid which will be removed from the work chamber during every revolution of the pump. 

Variations in pressure and volume demands have a serious impact on blower reliability. Since blowers are positive-displacement devices, they generate a constant volume and a variable pressure that is dependent on the downstream system s back-pressure. If demand decreases, the blower s discharge pressure continues to increase until (1) a downstream component fails and reduces the back-pressure, or (2) the brake horsepower required to drive the blower is greater than the motor s locked rotor rating. Either of these results in failure of the blower system. The former may result in a reportable release, while the latter will cause the motor to trip or burn out. 

Metering Pump n A positive displacement device that... 

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