CA1051223A - Fluid flow measuring device - Google Patents
Fluid flow measuring deviceInfo
- Publication number
- CA1051223A CA1051223A CA239,445A CA239445A CA1051223A CA 1051223 A CA1051223 A CA 1051223A CA 239445 A CA239445 A CA 239445A CA 1051223 A CA1051223 A CA 1051223A
- Authority
- CA
- Canada
- Prior art keywords
- diaphragm
- fluid flow
- fluid
- upstream
- holes
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
- G01P5/00—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft
- G01P5/14—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft by measuring differences of pressure in the fluid
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
- G01F1/05—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects
- G01F1/34—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects by measuring pressure or differential pressure
- G01F1/36—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects by measuring pressure or differential pressure the pressure or differential pressure being created by the use of flow constriction
- G01F1/40—Details of construction of the flow constriction devices
- G01F1/42—Orifices or nozzles
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Aviation & Aerospace Engineering (AREA)
- Fluid Mechanics (AREA)
- Measuring Volume Flow (AREA)
Abstract
A B S T A C T
A device for measuring the flow of a fluid is a pipe by creating an easily measurable pressure differential which is related to flow comprises a diaphragm transversely contained in the pipe or an associated branch pipe. The diaphragm has a multiplicity of closely spaced fluid flow holes which are so shaped as to increase fluid flow velocity through the diaphragm, and means are provided for sending fluid pressure at or adjacent the upstream and downstream faces of the diaphragm said means being intended to be connected to a differential pressure indicating or recording instrument from which a fluid flow measurement can be derived.
A device for measuring the flow of a fluid is a pipe by creating an easily measurable pressure differential which is related to flow comprises a diaphragm transversely contained in the pipe or an associated branch pipe. The diaphragm has a multiplicity of closely spaced fluid flow holes which are so shaped as to increase fluid flow velocity through the diaphragm, and means are provided for sending fluid pressure at or adjacent the upstream and downstream faces of the diaphragm said means being intended to be connected to a differential pressure indicating or recording instrument from which a fluid flow measurement can be derived.
Description
10512~3 This invention relates to a device for measuring the flow of a fluid such as for instance air or other gas in a pipe or bore and has been devised with the object of providing a simple means for creating an easily measurable pressure different-ial,, related to flow, with a low resistance to flow and readily adaptable to suit various cross-sectional shapes and areas of pipe or bore.
In the following description the term "air" should be read to mean air or any other gas or fluid.
In accordance with the present invention there is provided a fluid flow measuring device comprising a pipe or bore, which transversely contains a diaphragm having a multiplicity of closely spaced fluid flow holes which are so shaped as to increase fluid flow velocity through the diaphragm and means for sensing fluid pressure at or adjacent the upstream and downstream faces of the diaphragm said means being intended to be connected to a differential pressure indicating or recording instrument from which a fluid flow measurement can be derived.
The internal profile of the holes is preferably such that the change in velocity takes place smoothly with negligible loss of total energy. One typical and preferred form of hole is of nozzle form having a bell mouthed entrance leading to a parallel cylindrical section.
The holes in the diaphragm may be of circular or other cross-section and are disposed in any convenient pattern which may take the form of a "honeycomb" or similar arrangement, so that when the air emerges from the diaphragm at increased velocity it is in the form of a multiplicity of closely spaced jets which rapidly coalesce as they proceed downstream to form a reasonably uniform flowing mass in the pipe or bore. This results in a relatively high conversion of velocity energy back to static pressure. It has thus been found, by use of temporary pressure ~J~
~051;~23 sensors, that the overall pressure drop of the device as measured between points of reasonably uniform flow on the upstream and downstream sides is substantially less than the pressure differe-; ntial measured as now proposed by means of a hole or series ofholes preferably facing the flow on the upstream face of the diaphragm and a hole or series of holes at right angles to the flGw or facing partially or wholly downstream or otherwise arranged for static pressure measurement on the downstream face of the diaphragm.
Thus, it was discovered in accordance with the present invention, that if sensing tubes are placed immediately on the upstream and downstream faces of a specially constructed dia-phragm, in accordance with the invention, a pressure differential is obtained between the upstream and downstream measuring points.
When a differential pressure indicating or recording instrument such as a manometer is connected by any suitable ¦ arrangement of tubes to the sensing means on the upstream and ¦ downstream faces of the diaphragm its reading may be converted J to one of velocity or mass flow by the use of a factor relating to the characteristics of the diaphragm device and the fluid flowing and if the fluid density and viscosi~y are substantially ¦ constant the scale of the instrument may be arranged to read directly in velocity or mass flow units.
One other purpose of a diaphragm having a multiplicity of closely spaced and shaped holes as already mentioned is to act j as a flow straightening or smoothing device thus reducing turbulence and, in some applications, pressure loss. For instance when placed in a branch pipe of an air system at or near the point where air enters it from a main air flow duct it can control the flow so as to reduce, substantially, the turbulence and ¦ maldistribution which would otherwise occur downstream of the ~ junction. Furthermore, if placed slightly upstream from a grille lOSlZZ3 or diffuser it can be so arranged as to ensure satisfactory entry conditions to the grille or diffuser and therefore satisfactory ; dischar~e conditions from the grille or diffuser.
Yet another purpose of a diaphragm containing a multiplicity of shaped holes as already described above is to act as a sound attenuator if constructed of suitable materials.
Alternatively, the device may be used in conjunction with another device, having a matching series of holes, designed for sound attenuation.
The accompanying drawings illustrate alternative fluid flow measuring devices according to the invention and their mode of use. In these drawings:
Figure 1 is a diagrammatic cross-section of an air flow pipe 1 equipped with a diaphragm 2 having a multiplicity of holes 3;
Figure 2 is an enlarged fragmentary elevation of the diaphragm;
Figure 3 is a transverse section corresponding to Figure 2 showing a tapping point 4 on the upstream side of the diaphragm facing the direction of fluid flow and a tapping point 4_ on the downstream side of the diaphragm lateral to the fluid flow. Each tapping point has a connection 7 to a manometer, the arrow F indicating the direction of intended air flow through the diaphragm 2;
Figure 4 is a similar transverse section through another form of a diaphragm 5 showing an alternative scheme of tapping points 6 and 6_ with connections 8 to a manometer;
Figures 5 and 6 show two alternative modes of instal-lation of a diaphragm device 9 including pressure sensing tubes in a branch pipe from the side wall of a main air flow pipe 10.
In each instance there is an associated diffuser 11 downstream of the diaphragm. It should be noted that in the Figure 6 instal-iO51223 lation the diaphraqm device is recessed in the side branch 11which has a chamfered upstream corner or shoe 12.
; It should be understood that the diaphragm may be formed by moulding or by casting or be otherwise fabricated and that the holes neea not necessarily have a circular cross-section or be of the same size. The perforations could, for instance, be of elongated form or of hexagonal or other polygonal form.
Alternatively, the diaphragm could be constructed in any com-bination of solid or hollow members arranged in "egg box", j 10 parallel or other form to provide the necessary velocity increase and to provide convenient means for connecting single or multiple pressure tappings to a manometer or other differential pressure j indicating or recording instrument.
3 It may be convenient in some circumstances to arrange the fixing of the pressure tapping points for both upstream and downstream pressure connections in one or more plugs which are ¦ inserted into the formed holes in the diaphragm, as shown in ¦ Fig- 3-2a
In the following description the term "air" should be read to mean air or any other gas or fluid.
In accordance with the present invention there is provided a fluid flow measuring device comprising a pipe or bore, which transversely contains a diaphragm having a multiplicity of closely spaced fluid flow holes which are so shaped as to increase fluid flow velocity through the diaphragm and means for sensing fluid pressure at or adjacent the upstream and downstream faces of the diaphragm said means being intended to be connected to a differential pressure indicating or recording instrument from which a fluid flow measurement can be derived.
The internal profile of the holes is preferably such that the change in velocity takes place smoothly with negligible loss of total energy. One typical and preferred form of hole is of nozzle form having a bell mouthed entrance leading to a parallel cylindrical section.
The holes in the diaphragm may be of circular or other cross-section and are disposed in any convenient pattern which may take the form of a "honeycomb" or similar arrangement, so that when the air emerges from the diaphragm at increased velocity it is in the form of a multiplicity of closely spaced jets which rapidly coalesce as they proceed downstream to form a reasonably uniform flowing mass in the pipe or bore. This results in a relatively high conversion of velocity energy back to static pressure. It has thus been found, by use of temporary pressure ~J~
~051;~23 sensors, that the overall pressure drop of the device as measured between points of reasonably uniform flow on the upstream and downstream sides is substantially less than the pressure differe-; ntial measured as now proposed by means of a hole or series ofholes preferably facing the flow on the upstream face of the diaphragm and a hole or series of holes at right angles to the flGw or facing partially or wholly downstream or otherwise arranged for static pressure measurement on the downstream face of the diaphragm.
Thus, it was discovered in accordance with the present invention, that if sensing tubes are placed immediately on the upstream and downstream faces of a specially constructed dia-phragm, in accordance with the invention, a pressure differential is obtained between the upstream and downstream measuring points.
When a differential pressure indicating or recording instrument such as a manometer is connected by any suitable ¦ arrangement of tubes to the sensing means on the upstream and ¦ downstream faces of the diaphragm its reading may be converted J to one of velocity or mass flow by the use of a factor relating to the characteristics of the diaphragm device and the fluid flowing and if the fluid density and viscosi~y are substantially ¦ constant the scale of the instrument may be arranged to read directly in velocity or mass flow units.
One other purpose of a diaphragm having a multiplicity of closely spaced and shaped holes as already mentioned is to act j as a flow straightening or smoothing device thus reducing turbulence and, in some applications, pressure loss. For instance when placed in a branch pipe of an air system at or near the point where air enters it from a main air flow duct it can control the flow so as to reduce, substantially, the turbulence and ¦ maldistribution which would otherwise occur downstream of the ~ junction. Furthermore, if placed slightly upstream from a grille lOSlZZ3 or diffuser it can be so arranged as to ensure satisfactory entry conditions to the grille or diffuser and therefore satisfactory ; dischar~e conditions from the grille or diffuser.
Yet another purpose of a diaphragm containing a multiplicity of shaped holes as already described above is to act as a sound attenuator if constructed of suitable materials.
Alternatively, the device may be used in conjunction with another device, having a matching series of holes, designed for sound attenuation.
The accompanying drawings illustrate alternative fluid flow measuring devices according to the invention and their mode of use. In these drawings:
Figure 1 is a diagrammatic cross-section of an air flow pipe 1 equipped with a diaphragm 2 having a multiplicity of holes 3;
Figure 2 is an enlarged fragmentary elevation of the diaphragm;
Figure 3 is a transverse section corresponding to Figure 2 showing a tapping point 4 on the upstream side of the diaphragm facing the direction of fluid flow and a tapping point 4_ on the downstream side of the diaphragm lateral to the fluid flow. Each tapping point has a connection 7 to a manometer, the arrow F indicating the direction of intended air flow through the diaphragm 2;
Figure 4 is a similar transverse section through another form of a diaphragm 5 showing an alternative scheme of tapping points 6 and 6_ with connections 8 to a manometer;
Figures 5 and 6 show two alternative modes of instal-lation of a diaphragm device 9 including pressure sensing tubes in a branch pipe from the side wall of a main air flow pipe 10.
In each instance there is an associated diffuser 11 downstream of the diaphragm. It should be noted that in the Figure 6 instal-iO51223 lation the diaphraqm device is recessed in the side branch 11which has a chamfered upstream corner or shoe 12.
; It should be understood that the diaphragm may be formed by moulding or by casting or be otherwise fabricated and that the holes neea not necessarily have a circular cross-section or be of the same size. The perforations could, for instance, be of elongated form or of hexagonal or other polygonal form.
Alternatively, the diaphragm could be constructed in any com-bination of solid or hollow members arranged in "egg box", j 10 parallel or other form to provide the necessary velocity increase and to provide convenient means for connecting single or multiple pressure tappings to a manometer or other differential pressure j indicating or recording instrument.
3 It may be convenient in some circumstances to arrange the fixing of the pressure tapping points for both upstream and downstream pressure connections in one or more plugs which are ¦ inserted into the formed holes in the diaphragm, as shown in ¦ Fig- 3-2a
Claims (5)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A fluid-flow measuring device comprising a tubular member, a diaphragm in said tubular member having a multiplicity of closely spaced fluid flow holes, said holes having bell-mouthed entrances merging into parallel cylindrical sections, fluid pressure sensing tubes opening at the upstream and down-stream faces of said diaphragm with the opening of the upstream pressure sensing tube facing the direction of fluid flow, the opening of the downstream pressure sensing tube facing laterally and at least partly downstream relative to the fluid flow, the pressure sensing tubes being connectable to a differential pressure indicating or recording instrument from which a fluid measurement can be derived.
2. A device according to claim 1 and placed in a branch pipe of a fluid flow system at or near the junction of that branch pipe with a main air flow pipe.
3. A device according to claim 1 when placed upstream of a grille or diffuser in a fluid flow system.
4. A device according to claim 1 wherein at least some of said holes are of non-circular cross-section.
5. A device according to claim 2 in which the up-stream corner of said branch pipe is chamfered.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB4881674A GB1476147A (en) | 1974-11-12 | 1974-11-12 | Fluid flow measuring device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1051223A true CA1051223A (en) | 1979-03-27 |
Family
ID=10450012
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA239,445A Expired CA1051223A (en) | 1974-11-12 | 1975-11-12 | Fluid flow measuring device |
Country Status (2)
| Country | Link |
|---|---|
| CA (1) | CA1051223A (en) |
| GB (1) | GB1476147A (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0422317A1 (en) * | 1989-10-13 | 1991-04-17 | Preussag AG Feuerschutz | Apparatus for detecting fluid currents through a conduit |
| NO174015C (en) * | 1991-10-24 | 1994-03-02 | Bjoern Dybdahl | Device for aa could bring a mixing body into and out of a pipeline |
| GB9319025D0 (en) * | 1993-09-14 | 1993-10-27 | Ans Karsto Metering & Technolo | Flow cobditioner |
| CN115267240B (en) * | 2022-07-06 | 2023-04-11 | 山东省地质矿产勘查开发局第五地质大队（山东省第五地质矿产勘查院） | Hydrogeology underground water flow detection device |
-
1974
- 1974-11-12 GB GB4881674A patent/GB1476147A/en not_active Expired
-
1975
- 1975-11-12 CA CA239,445A patent/CA1051223A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| GB1476147A (en) | 1977-06-10 |
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