Concentric orifice

Orifice plates. Either the concentric orifice, eccentric orifice, or segmented orifice-type. Choice depends on the quality of the fluid handled. Venturi tubes. These consist of a well-rounded convergent section at the entrance, a throat of constant diameter, and a divergent section. Their accuracy is high however, installation, unless planned for in advance, is very difficult in the field. 

Concentric-orifice devices can be easily installed in high-pressure lenses. The high-end- and the low-end connection of such devices could be coupled with differential pressure transmitters, for example, with the before-mentioned devices of [54]. The devices are mounted in different ways. Mostly, the open pipe technique is used. Furthermore, both connected sides of the transmitter are fed with an inert gas, for example, nitrogen. For cases where the systems must separated, membrane devices can be arranged between them. All the mentioned orifice devices are technically proved and are applied in the high-pressure area. 

Ambrosius, E. E., and Spink, L. K., Coefficients of Discharge of Sharp-Edged Concentric Orifices in Commercial 2 in, 3 in, and 4 in Pipes for Low Reynolds Numbers Using Flange Taps, Trans. ASME 69 805, 1947. 

Segmental and eccentric orifice plates are functionally identical to the concentric orifice. The circular section of the segmental orifice is concentric with the pipe. The segmental portion of the orifice eliminates damming of foreign materials on the upstream side of the orifice when mounted in a horizontal pipe. Depending on the type of fluid, the segmental section is placed on either the top or bottom of the horizontal pipe to increase the accuracy of the measurement. 

Concentric orifice plates should not be used in slurry or other services, where solids may accumulate behind them. On erosive or corrosive fluids, the orifice plates should be made of resistant materials so that the sharp... 

Centrifugal extrusion encapsulation, or coaxial extrusion processing, is a liquid coextrusion process that uses an assembly of cylindrical nozzles consisting of concentric orifices located at the outer circumference of a rotating cylinder (Figure 24.3). 

Step-index fibers are manufactured using the rod/tube or the double crucible process, in which the core and cladding glasses are melted separately from ultrapure powders and transferred into two crucibles with concentric orifices at the bottom and drawn into a fiber. To obtain a semi graded refractive index profile, a diffusion process can be applied in a curing furnace. Step index fibers with a transmission loss of < 10 dB/km at a wavelength of 0.8. pm can be obtained. 

Co-extrusion processes. Liquid core and shell materials are pumped through concentric orifices, with the core material flowing in the central orifice, and the shell material flowing through the outer annulus. A compound drop forms that is composed of a droplet of core fluid encased in a layer of shell fluid. 

The concentric orifice plate is the least expensive and the simplest of the head meters. The orifice plate is a primary device that constricts the flow of a fluid to produce a differential pressure across the plate. The result is proportional to the square of the flow. Figure 2.14 shows a typical thin-plate orifice meter. 

The thin concentric orifice plate can be used with clean homogeneous fluids, which include liquids, vapours, or gases, whose viscosity does not exceed 65 cP (0.065 Pa s)... 

This arrangement provides a thin film of liquid sample solution flowing down to a narrow orifice (0.007-cm diameter) through which argon flows at high linear velocity (volume flow is about 0.5-1 1/min). A fine aerosol is produced. This particular nebulizer is efficient for solutions having a high concentration of analyte constituents. 

Fig. 6. Orifice plates (a) concentric, (b) eccentric, (c) segmental, (d) universal, and (e) quadrant-edge.

The orifice coefficient deviates from its value for sharp-edged orifices when the orifice wall thickness exceeds about 75 percent of the orifice diameter. Some pressure recovery occurs within the orifice and the orifice coefficient increases. Pressure drop across segmental ori-fiees is roughly 10 percent greater than that for concentric circular orifices of the same open area. 

Permanent pressure loss across a concentric circular orifice with radius or vena-contracta taps can be approximated for turbulent flow by... 

Segmental and eccentric orifices are frequently used for gas metering when there is a possibility that entrained liqiiids or solids would otherwise accumulate in front of a concentric circular orifice. This can be avoided if the opening is placed on the lower side of the pipe. For hquid flow with entrained gas, the opening is placed on the upper side. The pressure taps should be located on the opposite side of the pipe from the opening. 

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