Displacement devices

Head Devices A variety of devices utilize hydrostatic head as a measure of level. As in the case of displacer devices, accurate level measurement by hydrostatic head requires an accurate knowledge of the densities of both heavier-phase and lighter-phase fluids. The majority of this class of systems utilize standard-pressure and differential-pressure measuring devices. 

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 velocity readings are carried out by four probes whose radial and longitudinal position can be established at will inside the contactor by means of a displacement device controlled by computer, which established the coordinates... 

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. 

The relative displacement devices (high-speed evenness meters) can be response-type device accelerometers mounted to a vehicle or wheel trailer. Such devices are as follows TRRL Bump Integrator (BI), Mays ride meter, NAASRA roughness meter, Road meter PCA, ROMDAS bump integrator, all response-type devices, Canadian ARAN, Road Surface Tester (RST-SAAB) and accelerometer-type devices. When these devices are used, proper calibration of the equipment is vital and the output is best expressed in IRI (International Roughness Index). 

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. 

In vacuum filters, vacuum can be easily produced either by the suction of an ordinary liquid pump or by a gas displacement device, such as a rotary vacuum pump or steam ejector. Depending upon the device, the effect is to find a driving force of up to about 12 p.s.i. (0.81 bar), which in many instances is sufficient to give vastly improved rates of filtration with all except the finest solids. 

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