WO2009062379A1

WO2009062379A1 - A balanced orifice plate

Info

Publication number: WO2009062379A1
Application number: PCT/CN2008/001717
Authority: WO
Inventors: Paul D. Van Buskirk; William A. Heenan
Original assignee: Keyontechs Development Co., Ltd
Priority date: 2007-10-15
Filing date: 2008-10-10
Publication date: 2009-05-22
Also published as: RU2451908C2; CN101413626B; EG25408A; RU2010116060A; CN101413626A

Abstract

A balanced orifice plate includes a plate (4) which is suitable for installing in a pipe (1) and extends through the cross-section of the pipe (1). Said plate (4) has multiple through-holes (7, 8) which are formed so that the fluid passing through each through-hole has generally the same Reynolds number.

Description

Balanced orifice plate

The present invention relates to a flow control device, and more particularly to an orifice plate that balances or equalizes one or more process variables associated with fluids passing through the surface of the plate when inserted into the cross-section of the fluid. Background technique

In many applications where fluids in the pipeline are used, one or more fluid-related variables (such as pressure, temperature, flow, etc.) must be corrected or measured. Therefore, a variety of orifice plates have been developed for use as flow meters, flow controllers, flow restrictors or simply as flow regulators. The flow regulator can also correct the fluid in a manner suitable for process variable measurement. Three prior orifice designs are disclosed in U.S. Patent Nos. 5,295, No. 397, 5, 341, No. 848, and No. 5, 529, 093, the disclosure of which is incorporated herein by reference.

U.S. Patent No. 5,295,397, the disclosure of which is incorporated herein by reference to the entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire all Grooved holes of equal width and size are distributed in the central area. The number of slots in the area is proportional to the area occupied by the area relative to the overall area of the board.

A flow regulator (i.e., orifice plate) having a plurality of circular through holes is disclosed in US Patent No. 5,341,848. The holes are distributed over a plurality of annular arrays radially distributed around the central circular through holes. The holes in each annular array are equally spaced and arranged around the center of the plate, and all of the holes on any of the annular arrays have the same diameter. To match the flow rate profile associated with a fully deployed fluid, the size and number of holes is such that the flow impedance caused by the plates increases as the radius of the holes of a given array is placed.

U.S. Patent No. 5,529,093, the entire disclosure of which is incorporated herein by reference to the entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire entire portion The annular area of the central area is arranged in the same center. The fixed ratio determines the area of the hole on a region-to-area basis. The purpose of this design is to make the liquid fully deployed Disturbed structure and flow rate.

There is no prior art teaching to design orifice plates for balancing or equalizing one or more process variables through the entire surface of the panel. Often, variations in process variables flowing through the surface of the orifice cause inefficiencies in fluid flow. For example, existing orifices typically have a large pressure loss as fluid flows from one side of the orifice to the other. Unfortunately, the typical method of dealing with this large pressure loss is to use a more powerful and more expensive liquid pump. At the same time, the pressure profile of existing orifices is typically consumed by random and disordered vortex turbulence. These turbulent turbulences formed around the orifice plate reduce the linearity and repeatability of any process variable measurement, thus resulting in a reduction in measurement accuracy. The reduction in measurement accuracy results in variations in the process, which in turn increases the processing cost due to the higher equipment operating costs that must be maintained. However, random or unordered turbulent turbulence can be significantly reduced if the pressure across the surface of the orifice can be balanced or equalized. Therefore, by balancing the flow with respect to the measured process variable, the measurement accuracy of the process variable is increased while the cost of the measurement is reduced. Summary of the invention

Accordingly, it is an object of the present invention to provide an orifice plate for mounting within a conduit wherein a process variable associated with fluid passing through the orifice plate is balanced across the surface of the orifice plate, or a plurality of processes The surface of the variable across the orifice plate is set to an optimal equilibrium state.

Other objects and advantages of the present invention will become apparent from the following specification and drawings. According to the present invention, there is provided an orifice plate comprising: a plate adapted to be disposed in a pipe and extending through a cross section of the pipe, the plate having a plurality of through holes, the plurality of through holes being formed to pass The Reynolds number of the fluid in each through hole is equal.

Further, the plurality of through holes include: a central circular through hole located at a center of the plate; and a plurality of surrounding through holes located around the central circular through hole, the central circular through hole and the plurality of surrounding through holes satisfying the following

I is the distance from the center of the plate to the center of the surrounding through hole;

Vch is the fluid flow rate of the fluid within the pipe at the center of the surrounding through hole.

According to a further embodiment of the invention, each of the surrounding through holes is at an oblique angle at each surface of the plate.

The longitudinal axis of each of the surrounding through holes is parallel to the longitudinal axis of the pipe.

According to a further embodiment of the invention, each of the surrounding through holes is a circular hole. Optionally, each of the surrounding through holes is an arcuate groove.

According to a further embodiment of the invention, the plate is circular. Optionally the plate is rectangular. DRAWINGS

Other objects, features, and advantages of the present invention will be apparent from the description and appended claims appended claims

Figure 1 is a side view of a pipe with an orifice plate in a typical installation configuration;

Figure 2 is a plan view of one embodiment of an orifice plate in accordance with the present invention showing a conventional configuration for use in a pipe having a circular cross section;

Figure 3 is a plan view of another embodiment of an orifice plate in accordance with the present invention;

Figure 4 is a plan view of another orifice plate according to the present invention, wherein the orifice plate has a peripheral groove having a curved groove shape;

Figure 5 is a plan view of another embodiment of an orifice plate in accordance with the present invention showing a conventional configuration for use in a pipe having a rectangular cross section;

Figure 6 is a plan view of another embodiment of an orifice plate in accordance with the present invention;

Figure 7 is a plan view of another embodiment of an orifice plate in accordance with the present invention;

Figure 8 is a plan view of another embodiment of an orifice plate in accordance with the present invention;

Figure 9 is a plan view of another embodiment of an orifice plate in accordance with the present invention;

Figure 10 is a plan view of another embodiment of an orifice plate in accordance with the present invention;

Figure 11 is a plan view of another embodiment of an orifice plate in accordance with the present invention;

Figure 12 is a plan view of another embodiment of an orifice plate in accordance with the present invention;

Figure 13 is a partial cross-sectional view of the orifice plate showing the surface boundary of the inclined hole-plate Face

Figure 14 is a cross-sectional view of an orifice plate in which the orifices of the orifice plate are aligned parallel to the longitudinal axis of the pipe. detailed description

The present invention is an improved orifice plate. The term "orifice plate" as used herein includes any structural element (e.g., plate, disk, block, etc.) having a bore formed therethrough and to be mounted within a fluid for fluid to pass therethrough. The orifice plate can be used with a flow meter and can also be used simply as a flow regulator designed to change fluids in some way (e.g., DC, reduce noise associated with flow, reduce flow rate, etc.).

The use of the orifice plates of the present invention in flow meters provides more accurate process variable measurements and reduced costs. The orifice plates of the present invention reduce eddy currents, turbulent shear and fluid flow pressure. Additionally, the advantages of the orifice plate of the present invention over the prior art include improved repeatability, linearity, and reduced pressure loss. The orifice plate is also compatible with existing assembly and measurement systems, so no special piping, tools or calculations are required.

Figure 1 shows a typical mounting configuration using an orifice plate of the present invention. As previously mentioned, the orifice plate can easily control fluid flow or measure process variables of one or more fluid flows as part of a flow meter. The term "fluid" as used herein refers to any flowable material including steam or gas, homogenous or non-homogenous liquids and slurries.

In Fig. 1, the pipe 1 is joined at the joint 2 through the flanges 3 and 5. Pipes and connections are prior art and are not limited by the present invention. The orifice plate 4 is fixed between the flanges 3 and 5, and the orifice plate 4 controls the flow of fluid through the pipe 1 (in the direction of arrow 6). The orifice plate 4 is thus typically placed transversely or vertically in the stream 6 by known techniques.

The orifice plate 4 is sized and shaped to accommodate pipes of various sizes and shapes. For example, the orifice plate in Figure 2 is circular so that it is mounted to a cylindrical conduit. The orifice plate in Figure 6 is rectangular so that it fits into a rectangular pipe.

According to the orifice plate 4 of the present invention, when installed in the pipe, the flanges 3 and 5 sandwich the peripheral mounting area of the orifice plate 4, as shown in Fig. 14, the area inside the peripheral mounting region is the equilibrium flow zone 4C, flat The outside of the flow area is to the circumference 4D, and the through holes on the orifice 4 are distributed in the equilibrium flow zone. It should be noted that when there is no central circular through hole 7, the central area of the orifice plate 4 is the central circular area 7A and is indicated by a broken line, as shown in FIG. According to the invention, the peripheral through holes 8 in the orifice plate 4 are formed such that the Reynolds number of the fluid passing through each of the surrounding through holes 8 in the pipe is equal, so that a process variable associated with the fluid passing through the orifice plate spans the orifice plate. The surface is balanced, or the surface of multiple process variables across the orifice plate is set to an optimal equilibrium state.

For any surrounding through hole on the orifice plate 4, the Reynolds number N of the fluid passing through the peripheral through hole is proportional to the product R of the distance from the center of the surrounding through hole to the center of the orifice plate and the flow velocity V of the fluid at R, that is, N It is directly proportional to RXV. For example, as shown in FIGS. 3 and 14, for the peripheral through hole 8 whose center is the center of the orifice plate 4, which is _Reh , the Reynolds number of the fluid flowing through the peripheral through hole 8 is N _rchl , and the flow velocity is V _chl , therefore, N _rchl and! ^^ ^ is proportional. Similarly, for the surrounding through hole 8 whose center is the center of the orifice plate 4, R _ch2 , the Reynolds number of the fluid flowing through the surrounding through hole 8 is N _{rch 2} , and the flow velocity is V _ch2 , therefore, N _{rch 2} and ! ^^ ^ is proportional.

Therefore, according to the present invention, the surrounding through hole 8 on the orifice plate 4 is designed to satisfy:

Rchl X _c hl = _c h2 X _c h2 ( 1

The Reynolds number of fluid flowing through each of the surrounding through holes is equal such that a process variable associated with the fluid passing through the orifice is balanced across the surface of the orifice, or a plurality of process variables are placed across the surface of the orifice The optimum balance state is set, and the accuracy of measurement using the orifice plate 4 is improved.

It should be noted that, for the central circular through hole 7 located at the center of the orifice plate 4, the Reynolds number N _{rcl of the} fluid flowing through the central circular through hole 7 and the radius RP of the central circular through hole 7 flow rate V _cl flowing through the center of the orifice plate V _cl In direct proportion.

Therefore, as long as the through hole design on the orifice plate 4 of the present invention satisfies R _cl XV _cl = R _ch XV _ch =

It is possible to make the Reynolds number of the fluid flowing through each through hole substantially equal, as shown in Fig. 2.

The orifice plate 4 according to the first embodiment of the present invention will be described below with reference to Fig. 2 .

As shown in FIG. 2, the orifice plate 4 according to the first embodiment of the present invention is formed with a central circular through hole 7 at the center and a plurality of peripheral through holes 8 located around the central circular through hole 7, as shown in FIG. In the embodiment, the number of the surrounding through holes 8 is 4 and both are circular holes, however, the present invention is not limited thereto. According to the first embodiment of the present invention, the through hole on the orifice plate 4 (the center circular through hole and the surrounding through hole)

8) The distribution in the equilibrium flow zone 4C satisfies the following basic relationships:

RciV _c i ⁼ Rch _C h (2 )

among them:

R _cl is the radius of the central circular through hole;

v _cl is the flow rate of the fluid in the pipe at the center of the central circular through hole (ie, the center of the orifice);

Vc _h is the fluid flow rate of the fluid in the pipe at the center of the surrounding through hole. The radial velocity of the fluid in the pipe is calculated as:

V/V _cl =((lR)/R _w ) ^1/m (3)

among them:

The flow rate of the pipe in the center of the pipe for the fluid inside the pipe,

! ^ is the inner diameter of the pipe,

M is a function of the Reynolds number f (N), which is an empirical function, depending on the fluid and so on.

Therefore, the relationship between the radius of the central circular through hole and the distance from the surrounding through hole to the center of the plate is satisfied.

= (V _c i((l-Rci)/ R _w ) ^1/m ) / (V _cl ((lR _ch )/ RJ ^1/m )

= (l-Rci) ^{1 / m} / (1 - Rch) ^{1 / m} ) (4) According to the first embodiment of the present invention, when the design of the center circular through hole and the surrounding through hole satisfy that their Reynolds numbers are equal, The area of the central circular through hole and the surrounding through hole and the pipe satisfy the following relationship:

among them: ^ is the radius of the pipe;

n is the number of surrounding through holes whose center is I from the center of the orifice plate.

β = (ΑAll holes/Α pipes) ^1/2 (5 )

A is the area and sum of all the through holes on the orifice plate.

Α« is the cross-sectional area of the pipe

From this derived:

1 + n (R _ch /R _cl ) ² - β ² (R _w /R _cl ) ² = 0 (6 )

Fig. 3 shows a plan view of an orifice plate 4 according to another embodiment of the present invention.

In Fig. 3, the orifice plate 4 is formed with a central circular through hole 7, and a plurality of peripheral through holes 8 located at the outer periphery of the central circular through hole 7. The surrounding through holes 8 are divided into two groups. The distance between the center of the through hole 8 around the inner group and the center of the orifice plate is I ₂ , and the distance between the center of the through hole around the outer group and the center of the orifice plate is ϋ _ω .

Similarly, the through holes in the orifice plate 4 are designed to satisfy the equal Reynolds number flowing through each of the through holes. Different from the embodiment shown in Fig. 2, the center of the surrounding through hole 8 is located at two radii respectively! ^ mouth

I ₂ on both circumferences.

Fig. 4 shows a plan view of an orifice plate 4 having a central circular through hole 7 and a peripheral through hole 8 around the central circular through hole 7, in accordance with another embodiment of the present invention. Different from the embodiment shown in Figs. 2 and 3, in the embodiment shown in Fig. 4, the peripheral through hole 8 is in the form of an arcuate groove, and the longitudinal center line of the arcuate groove is at a distance I from the center of the orifice plate.

Fig. 5 shows an orifice plate 4 according to another embodiment of the present invention. The surrounding through holes in the orifice plate 4 are divided into two groups, and the centers of the surrounding through holes are located at Rc _hl and R, respectively. _On the circumference of _h2 , this point is the same as the embodiment shown in FIG. Different from the embodiment shown in Figs. 2-4, the orifice plate 4 shown in Fig. 5 does not form a central circular through hole 7.

Fig. 6 is a plan view showing another embodiment of the orifice plate 4 according to the present invention, and the orifice plate 4 shown in Fig. 6 has a rectangular cross section for use in a pipe having a rectangular cross section. The through hole forming pattern of the orifice plate 4 shown in Fig. 6 coincides with the orifice plate 4 shown in Fig. 2.

The orifice plate according to an embodiment of the present invention has been described above with reference to the accompanying drawings. It should be noted that, in the embodiments shown in FIGS. 2-3 and 5-6, the surrounding through holes 8 are formed as four circular holes; in the embodiment shown in FIG. 4, the surrounding through holes are formed into four arcs. Groove; around in Figures 3 and 5 The holes are divided into two groups, and the centers of the through holes around the two groups are respectively located at a radius R. _Hl and R. _On the circumference of _h2 , however, the present invention is not limited thereto, and the surrounding through holes of the orifice plate 4 may be formed in any suitable number, for example, six or eight, and the centers of the surrounding through holes may be respectively located on the circumferences of the plurality of radii The form of the surrounding through holes on the orifice plate 4 may be inconsistent. For example, one set of through holes may be circular holes, and the other group may be curved grooves or the like. Further, the shape of the orifice plate 4 is not limited to a rectangular shape and a circular shape, and the shape of the orifice plate 4 may be any suitable geometric shape depending on the cross-sectional shape of the pipe used.

As shown in Fig. 13, the peripheral through holes are formed at an oblique angle 8A at each surface 4A of the orifice plate 4. Of course, the present invention is not limited thereto, and the oblique angle 8A may be a right angle.

FIG 14 shows a partial cross-sectional view of the orifice plate in the pipe 4 at which the fluid flow rate through the central circular through-hole 7 is V _el, the flow rate of the fluid flowing around the through hole 8 is Vc _h, and around each The longitudinal axis of the through hole 8 is parallel to the longitudinal axis of the pipe.

Therefore, according to the present invention, as long as the design of the through holes on the orifice plate satisfies that the Reynolds number of the fluid flowing therethrough is substantially equal, for example, the formulas 1 - 2 and 4 - 6 in the above embodiment are satisfied.

Based on the principle that the Reynolds number is roughly equal, the aperture and position of the via hole of the orifice plate can also be obtained by an approximate calculation formula. For example, referring to Figure 7-12, the formula given below:

A _R = a / (X _R V^ ) ( 7 ) where _& is from the center of the central circle region 7A to the equilibrium flow region 4C, and the center is at the radius

The sum of the areas of the holes on the Rch;

X _R is the flow coefficient on the circumference of radius Rch, which is equal to (p K) _R , where _& is the density of the fluid flowing through the pipe 10 at the radius Rch, ^^ is the flow through the pipe at the radius Rch

a fluid flow correction factor of 10, which is related to one of fluid dynamics, kinetic energy, energy density, volumetric flow, flow, and the like;

V _R is the velocity of the fluid flowing through the conduit at radius Rch, wherein as in the prior art, the flow rate follows a known distribution function based on factors including specific fluid outflow, pipe size/shape, etc. b is used to make at least one (with The fluid-dependent process variable flowing through the pipe is equal or "equalized" at each radius Rch, where b is an arbitrary value, but is typically between -5 and +5 (eg b is 1 when the flow is equalized) When the power or speed head (speed difference) is equalized, Although different flow correction coefficients K can be used for each example, b is generally 2, etc., and a is a constant equal to (X _R A _R V _R ^b ) at each radius Rch.

Based on the fluid flow rate, the flow coefficient X _R can be varied as a constant or due to the orifice surface. In particular, the & coefficient is variable when the change in the product of X _R (i.e., (p K) _R ) is greater than the specified upper limit of the different regions of the orifice plate.

In the case where there is only one process variable to consider, the constant b is chosen to equalize or equalize the process variable on the circumference of each orifice radius. If more than one process variable needs to be taken care of, the value of b is chosen so that the equalization or equalization of the process variables (those that need to be considered) across the orifice equalization flow region is optimal. In order to optimize all process variables that need to be considered, the absolute equalization of a single process variable needs to be compromised. As a result, equalizing a plurality of process variables in accordance with the present invention will achieve a degree of process variable that approximately equalizes each of the equalized flow regions across the orifice.

The total hole area A _R is defined differently depending on the arrangement of the holes, and the arrangement is usually divided into two different categories. The center of the first type of finger-shaped structure (for example, a circular hole, a circular arc-shaped groove) is located on the radius Rch, and the holes are discretely distributed in the equalization flow region 4C. The second type of hole-shaped structure refers to the area of all the holes only on the radius Rch, wherein each hole extends from the circumference of the central circular through hole 7 to the circumference 4D

Regardless of the distribution structure of the pores, the total flow area A _{T of the} orifice plate 4 is provided. The ratio of _tal to the flow area A of the pipe can be calculated by the following well-known formula.

Q = 2G _cP Ap(C ₀ YA _pipe /M)

Where G. Newton conversion constant

P is the fluid density, Δρ is the different measured pressure of the orifice plate,

C. For the orifice coefficient,

Υ is the coefficient of expansion, usually used for compressible fluids, and

Μ is the mass flow.

Equations (8) and (9) are derived directly from McCabe et al., Unit Operations in Chemical Engineering, 5th Edition, McGraw-Hil, Inc., NY, 1983, p. 222, the contents of which are incorporated by reference.

Use the total area of the pore flow A _T . _Td , the total area of the orifice equalization flow region 4C is

^ TOTAL _ A _RO = A _R1 + A _R2 + ... + A _Rn ( 10 ) where A _RQ (i) is 0 when there is no hole in the center circle area 7A, (ii) is a single center tact when the radius is Rcl When the hole is located in the central circular area 7A, it is 2 R _c l, (iii) the total area of the plurality of holes in the central circular area 7A. The radius of a single central circular through hole in the central circular area 7A may be at most (including) Rcl.

Figures 7-9 show an embodiment in which the first type of apertured structure is distributed within the central circular area 7A. These examples do not represent special cases, but illustrate the arrangement of holes that are generally based on the radius-radius approach. Each example is based on the use of surrounding through holes 8. The diameter of the surrounding through holes on a particular radius is the same, but the diameters defined by equation (7) do not need to be the same. Usually satisfying equation (7), the holes can be of any shape. The diameter of the uniform discrete circular hole of the center at a given radius Rch can be calculated by the following equation

Dch = 2(A _Rch / N π ) ^{1 2} ( 11 ) where A _Reh is the area of all the holes centered on the radius Rch,

N is the preferred number of holes centered on the radius Rch.

In Fig. 7, the center of the surrounding through hole on each radius Rch is aligned with the center of the through hole around the hole at other radii. The center of the peripheral through hole 8 on each radius Rch in Fig. 8 is misaligned with the center of the surrounding through hole on the adjacent radius. In Figures 7 and 8, there are no surrounding vias whose centers are located on adjacent radii. But in Figure 9, some centers are located around the radius. The through holes overlap each other.

Figure 10 shows another embodiment of a discrete aperture of a first type of apertured structure with an arcuate slotted aperture centered on a radius Rch. The circular groove-shaped hole 8 has a circular segment head (i.e., a semicircular shape) having a diameter D and a groove width D. Since the center of the circular groove-shaped hole 8 is located at the radius Rch, the groove width D is calculated by the following equation

Dch = (-aRch / 90) + {(32400* A _Rch + a ₂ R _c ² _h ^S) /(8100^S) }/ ^{1 / 2} ( 12 ) where a =360/2S,

S is the number of slots on a given radius Rch, and

A _Rch is the total groove area centered on the radius Rch.

The equidistant or unequal spacing of the slots over a given radius does not depart from the scope of the invention. As with the circular holes described above, the grooves on the adjacent radii can be aligned or misaligned. In addition, as long as the equation is satisfied

(7), the slots can be of different shapes and sizes.

Figures 11 and 12 show an embodiment of an orifice plate distributed in the equalization flow region 4C according to the above-described second type of orifice. In addition, in each of the embodiments, the hole extends from the center circular area 7A to or near the circumference 4D of the equalization flow area 4C. The examples are intended to illustrate the shape and position of the holes in general. In each of the embodiments, the area of the surrounding through hole 8 increases with an increase in the radial distance from the central circular area 7A. The arc angle Sch on the radius Rch is calculated by the following equation

Sch= {ARch /(2Rch + AR) + A _(Rch+1) + AR) }/ 2NAR ( 13 )

Where is the radial length change from Rch to Rch+1

N is a preferred number of surrounding through holes 8 formed in the orifice plate 4.

Other methods can also be used to calculate the arc angle Sch without departing from the scope of the invention. In Fig. 11, the hole 8 is V-shaped, and the hole 8 in Fig. 12 is an expanded geometric shape.

The above formulas (6)-(13) are based on the principle that the Reynolds numbers are roughly equal, divide and calculate the central circular area and the equal flow area area, and use at least one process variable associated with the Reynolds number at each radius Rch. Constant or "equalized" constants to regulate and count One embodiment of the size and distribution of orifice holes.

As described above, the orifice plate of the present invention can be used as it is to simply adjust the flow. In addition, an "instrument measurement" that measures the process variable throughout the orifice can be done with one or more sensors. The radially expanded bore can be formed by drilling a hole in the orifice plate and measuring it with a sensor mounted on the sidewall of the orifice. This way the measurement hardware is not in the flow field at all. Note that traditional measurement methods measured upstream and downstream of the orifice plate can also be used.

The advantages of the present invention are numerous. Fluid-dependent process variables can be easily balanced (covering the equilibrium flow region) by a variety of methods. Advantages of the present invention include improved measurement accuracy, better pressure recovery, and lower noise generation than conventional orifice plates. In addition, the present invention can also reduce permanent pressure loss from one side of the board to the other. Therefore, the fluid passing through the orifice plate of the present invention requires less suction energy than the orifice plate of the prior art. The invention is useful in a wide range of fluid flow applications. While the invention has been described with reference to the embodiments of the embodiments of the present invention, it will be understood that many changes and modifications can be made without departing from the scope of the invention.

Claims

Claim

1. An orifice plate comprising:

A plate adapted to be disposed within the conduit and extending through a cross-section of the conduit, the plate having a plurality of through-holes formed such that the Reynolds number of fluid passing through each of the through-holes is substantially equal.

2. The orifice plate of claim 1 wherein the plurality of through holes comprises:

a central through hole at the center of the plate; and

A plurality of peripheral through holes located around the central circular through hole, the central circular through hole and the plurality of surrounding through holes satisfying the following relationship:

Rcl _c l ⁼ Rch ch

among them:

The radius of the center circular through hole;

The flow rate of the fluid in the pipe at the center of the central circular through hole;

Vc _h is the fluid flow rate of the fluid in the pipe at the center of the surrounding through hole.

3. An orifice plate according to claim 2 wherein each of the peripheral through holes is beveled at each of the faces of the plate.

4. An orifice plate according to claim 2 wherein the longitudinal axis of each of the peripheral through holes is parallel to the longitudinal axis of the conduit.

5. The orifice plate of claim 2, wherein each of the peripheral through holes is a circular hole.

6. The orifice plate of claim 2 wherein each of the peripheral through holes is an arcuate groove.

7. The orifice plate of claim 1 wherein the plate is circular.

8. The orifice plate of claim 1 wherein the plate is rectangular.