WO1989006350A1 - Differential pressure meter - Google Patents
Differential pressure meter Download PDFInfo
- Publication number
- WO1989006350A1 WO1989006350A1 PCT/FI1989/000005 FI8900005W WO8906350A1 WO 1989006350 A1 WO1989006350 A1 WO 1989006350A1 FI 8900005 W FI8900005 W FI 8900005W WO 8906350 A1 WO8906350 A1 WO 8906350A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- tubes
- differential pressure
- connecting member
- pressure meter
- tube
- 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.)
- Ceased
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L11/00—Measuring steady or quasi-steady pressure of a fluid or a fluent solid material by means not provided for in group G01L7/00 or G01L9/00
- G01L11/004—Measuring steady or quasi-steady pressure of a fluid or a fluent solid material by means not provided for in group G01L7/00 or G01L9/00 by the use of counterbalancing forces
- G01L11/006—Measuring steady or quasi-steady pressure of a fluid or a fluent solid material by means not provided for in group G01L7/00 or G01L9/00 by the use of counterbalancing forces hydraulic or pneumatic counterbalancing forces
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L13/00—Devices or apparatus for measuring differences of two or more fluid pressure values
- G01L13/04—Devices or apparatus for measuring differences of two or more fluid pressure values using floats or liquids as sensing elements
Definitions
- the present invention concerns a differential pressure meter for measuring differential pressure between two different points, to be used for instance in water mains systems or in equivalent systems where differential pressures occur .
- differential pressures in water mains systems arise from natural flow resistance , various leakages in the pipe system and blockages which may occur therein .
- these differential pressures are normally relatively small in comparison with the pressure prevailing in the pipe system , and therefore their accurate measuring and inferences to be drawn on the basis of th e measurements tend to present difficulties .
- differential pressures are mainly measured with separate meters located at different points , with the consequence that continuous changes of flow and pressure surges of various magnitudes occurring rather frequently in the flow will interfere with the measurement to such extent that comparison of pressure values recorded at individual measuring points yield virtually no relevant differential pressure information whatsoever .
- a device illustrating the state of art is disclosed in the patent application DE 585 548.
- the object of the present invention is to eliminate the above drawbacks .
- the aim of the invention is to introduce a novel differential pressure meter , with the aid of which the differential pressures between two different points in water mains or equivalent networks located at a distance from each other can be measured accurately and reliably.
- the differential pressure meter of the invention comprises two vertical, substantially transparent tubes , the lower end of one tube being connected to one pressure measuring point and the lower end of the other tube being connected to the other pressure measuring point, by means of suitable pipes , tubing or equivalent, and a connecting member connecting the pipes at their upper parts so that they form a pressure-sealed space.
- the connecting member furthermore comprises a duct through which gas can be introduced in said pressure-sealed space in order to raise the pressure in said space to desired level .
- a graduation is provided adjacent to the transparent vertical portion of the tubes , either on the tubes themselves or close to them, from which the differential pressures can be read.
- the tubes and the connecting member consist of a unitary inverted U-tube, with said duct connected to the curved upper part of the tube.
- the duct is connected to a pump , and said duct furthermore includes a venting valve and a shut-off valve.
- the ends of both tubes also advantageously include on either side of the duct, shut-off valves on equal level so that the tubes can be closed off and separated tightly against pressure.
- the lower ends of the tubes which have a height greater than 1 m, e. g. 1.5 to 3 m, advantageously about 2 m, are provided with appropriate valves for accomplishing various functions .
- Such valves may be e . g. draining valves , shut-off valves , nozzle valves and venting valves .
- a draining valve may then be used to empty the water from the instrument , a shut-off valve to shut off the flow in the tube , a nozzle valve to damp out abrupt pressure fluctuations and pressure surges , and a venting valve can be used to remove from the system any extra air that may interfere with the measurement .
- two vertical, substantially transparent tubes are used , the lower end of one of them being connected to one pressure measuring point and the lower end of the other being connected to the other pressure measuring point .
- the tubes are interconnected at their upper parts by means of a connecting member .
- a connecting member in the volume defined by the upper ends of the tubes and the connectin g member is produced a counter-pressure acting against the pressures being measured , whereby the differential pressure can be measured by the surface heights in the tubes .
- An advantage of the invention over prior art is that it is possible with the means to measure accurately differential pressures e . g. between hydrants located sev eral hundred meters apart without incurring interference from changes of flow or pressure surges occurring in the pipe systems . Reliable information on the pipe system that is being measured is thus gained , and the condition of the pipe system can be efficiently monitored on the basis of this information .
- a differential pressure meter according to the inven tion, depicted in the drawing, comprises two transparent, vertical tubes 1 and 2, interconnected at their upper ends by means of a curved, tubular connecting member 3 , in other words, the tubes together with the connecting member constituting an inverted U-tube 6.
- the connecting member 3 comprises a duct 4 , which is through a shut-off valve 7 connected with an air pump 15 , and this duct furthermore comprises a venting valve 16.
- both tubes are provided with tube connectors 13 , to which tubing or equivalent 14 can be connected , with which the measuring instrument is connected with the desired measuring points .
- the lower ends of both tubes are provided with four separate valves: a draining valve 9 , a shut-off valve 10, a nozzle valve 11 and a venting valve 12.
- the differential pressure meter of the invention operates as follows .
- the pressures in pipe systems of this kind usually amount to several bar, while the differential pressures are only on the order of a few percent thereof.
- the basic idea of the invention is that a counter-pressure is established to the pressures which are being measured and only the differential pressures between the points of measurement are studied, paying no heed to the absolute pressure heights . Therefore , when there is sufficient flow at the points being measured so that a differential pressure is established, water flows through the tubing 14 into the tube ⁇ 1 and 2. While the shut-off valves 8 are open .
- the volume defined by the tubes 1 and 2 is confluent and equal pressure prevails in both, and this pressure is augmented with a pump 15 , or alternatively the pressure is lowered by means of the venting valve 16 , so that the surfaces of the water columns in the tubes become visible in the vertical parts of the tubes , opposite to the graduation 5.
- the true differential pressure h between the two points of measurement is then directly readable on the centimetre graduation .
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Measuring Fluid Pressure (AREA)
Abstract
The present invention concerns a differential pressure meter for measuring differential pressure between two different points. As taught by the invention, the meter comprises two vertical, substantially transparent tubes (1, 2), said tubes being connected at the lower ends with the pressure measuring points, and a connecting member (3) connecting the tubes at their upper ends, said connecting member being provided with a duct (4) for introducing pressurized gas in the volume defined by the upper ends of the tubes and the connecting member.
Description
DIFFERENTIAL PRESSURE METER
The present invention concerns a differential pressure meter for measuring differential pressure between two different points, to be used for instance in water mains systems or in equivalent systems where differential pressures occur .
Differential pressures in water mains systems arise from natural flow resistance , various leakages in the pipe system and blockages which may occur therein . However, these differential pressures are normally relatively small in comparison with the pressure prevailing in the pipe system , and therefore their accurate measuring and inferences to be drawn on the basis of th e measurements tend to present difficulties . Nowadays , differential pressures are mainly measured with separate meters located at different points , with the consequence that continuous changes of flow and pressure surges of various magnitudes occurring rather frequently in the flow will interfere with the measurement to such extent that comparison of pressure values recorded at individual measuring points yield virtually no relevant differential pressure information whatsoever . A device illustrating the state of art is disclosed in the patent application DE 585 548.
The object of the present invention is to eliminate the above drawbacks . In particular, the aim of the invention is to introduce a novel differential pressure meter , with the aid of which the differential pressures between two different points in water mains or equivalent networks located at a distance from each other can be measured accurately and reliably.
Regarding the characteristic features of the invention , reference is made to the claims section .
The differential pressure meter of the invention comprises two vertical, substantially transparent tubes , the lower end of one tube being connected to one pressure measuring point and the lower end of the other tube being connected to the other pressure measuring point, by means of suitable pipes , tubing or equivalent, and a connecting member connecting the pipes at their upper parts so that they form a pressure-sealed space. As taught by the invention, the connecting member furthermore comprises a duct through which gas can be introduced in said pressure-sealed space in order to raise the pressure in said space to desired level .
Advantageously, a graduation is provided adjacent to the transparent vertical portion of the tubes , either on the tubes themselves or close to them, from which the differential pressures can be read.
In an advantageous embodiment of the invention , the tubes and the connecting member consist of a unitary inverted U-tube, with said duct connected to the curved upper part of the tube.
Advantageously, the duct is connected to a pump , and said duct furthermore includes a venting valve and a shut-off valve. The ends of both tubes also advantageously include on either side of the duct, shut-off valves on equal level so that the tubes can be closed off and separated tightly against pressure.
Advantageously, the lower ends of the tubes , which have a height greater than 1 m, e. g. 1.5 to 3 m, advantageously about 2 m, are provided with appropriate valves for accomplishing various functions . Such valves may be e . g. draining valves , shut-off valves , nozzle valves and venting valves . A draining valve may then be used to empty the water from the instrument , a shut-off
valve to shut off the flow in the tube , a nozzle valve to damp out abrupt pressure fluctuations and pressure surges , and a venting valve can be used to remove from the system any extra air that may interfere with the measurement .
In the differential pressure measuring system of the invention two vertical, substantially transparent tubes are used , the lower end of one of them being connected to one pressure measuring point and the lower end of the other being connected to the other pressure measuring point . In addition , the tubes are interconnected at their upper parts by means of a connecting member . As taught by the invention , in the volume defined by the upper ends of the tubes and the connectin g member is produced a counter-pressure acting against the pressures being measured , whereby the differential pressure can be measured by the surface heights in the tubes .
An advantage of the invention over prior art is that it is possible with the means to measure accurately differential pressures e . g. between hydrants located sev eral hundred meters apart without incurring interference from changes of flow or pressure surges occurring in the pipe systems . Reliable information on the pipe system that is being measured is thus gained , and the condition of the pipe system can be efficiently monitored on the basis of this information .
The invention is described in detail in the following , reference being made to the drawing attached , in which a differential pressure meter conforming to the invention is described in exemplary manner , without in any way restricting the invention .
A differential pressure meter according to the inven
tion, depicted in the drawing, comprises two transparent, vertical tubes 1 and 2, interconnected at their upper ends by means of a curved, tubular connecting member 3 , in other words, the tubes together with the connecting member constituting an inverted U-tube 6.
Between the tubes 1 and 2 is provided a graduation 5 , extending substantially over their entire length, and at the upper end of the tubes on equal levels and before the connecting member are provided shut-off valves 8 , with which the tubes can be shut off and isolated from each other with pressure-tight sealing. The connecting member 3 comprises a duct 4 , which is through a shut-off valve 7 connected with an air pump 15 , and this duct furthermore comprises a venting valve 16.
The lower ends of both tubes are provided with tube connectors 13 , to which tubing or equivalent 14 can be connected , with which the measuring instrument is connected with the desired measuring points . In addition , in the present embodiment the lower ends of both tubes are provided with four separate valves: a draining valve 9 , a shut-off valve 10, a nozzle valve 11 and a venting valve 12.
The differential pressure meter of the invention operates as follows . The pressures in pipe systems of this kind usually amount to several bar, while the differential pressures are only on the order of a few percent thereof. Thus , the basic idea of the invention is that a counter-pressure is established to the pressures which are being measured and only the differential pressures between the points of measurement are studied, paying no heed to the absolute pressure heights . Therefore , when there is sufficient flow at the points being measured so that a differential pressure is established, water flows through the tubing 14 into the tubeε 1 and 2. While the shut-off valves 8 are open .
the volume defined by the tubes 1 and 2 is confluent and equal pressure prevails in both, and this pressure is augmented with a pump 15 , or alternatively the pressure is lowered by means of the venting valve 16 , so that the surfaces of the water columns in the tubes become visible in the vertical parts of the tubes , opposite to the graduation 5. The true differential pressure h between the two points of measurement is then directly readable on the centimetre graduation .
If, however , the differential pressure is of such height that the length of the tubes 1 and 2 does not suffice for displaying this differential pressure , a more approximative measurement can be accomplished by setting with the aid of the valves the water level in both tubes to be at the same , relatively low level and closing the shut-off valves 8. When thereafter pressure is admitted into the tubes 1 and 2 through their lowerends , the water levels will ascend towards the shut-off valves 8 , and the pressures can be calculated with fairly good accuracy , using the formula p * V = Const .
Claims
1. A differential pressure meter, e. g. in a watermains system, for measuring differential pressure between two different points , said meter comprising two vertical, substantially transparent tubes ( 1 , 2) , the lower end of one tube (1) being connected with one pressure measuring point and the lower end of the other tube (2) being connected with the other measuring point, and a connecting member (3 ) which connects the tubes with each other at their upper ends , characterized in that the connecting member (3) comprises a duct (4) for introducing pressurized gas in the space defined by the upper ends of the tubes and the connecting member.
2. Differential pressure meter according to claim 1 , characterized in that adjacent to the transparent part of the tubes (1 , 2) is provided a graduation (5 ) for reading the differential pressure.
3. Differential pressure meter according to claim 1 or 2, characterized in that the tubes (1 , 2) and the connecting member (3 ) constitute a unitary inverted U-tube (6) .
4. Differential pressure meter according to any one of claims 1 to 3 , characterized in that the duct (4) of the connecting member (3) comprises a shut-off valve (7) .
5 . Differential pressure meter according to any one of claims 1 to 4 , characterized in that the upper ends of both tubes ( 1 , 2) are provided with shut-off valves ( 8 ) on identical heights .
6. Differential pressure meter according to any one of claims 1 to 5, characterized in that the lower end of at least one tube is provided with a draining valve (9), a shut-off valve (10), a nozzle valve (11) and/or a venting valve (12).
7. Differential pressure meter according to any one of claims 1 to 6, characterized in that the height of the tubes is over 1 m, e.g. 1.5 to 3 m, preferably about 2 m.
8. A procedure for measuring differential pressure between two points, e.g. in a water mains system, in said procedure being used two vertical, substantially transparent tubes (1,2), the lower end of one tube being connected with one pressure measuring point and the lower end of the other with another pressure measuring point, and said tubes being interconnected at their upper ends with a connecting means (3), characterized in that, in the procedure, in the volume defined by the upper ends of the tubes (1,2) and the connecting member (3) is established a counter-pressure, whereby the differential pressure can be measured by the liquid levels in the tubes.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FI880046 | 1988-01-06 | ||
| FI880046A FI78783C (en) | 1988-01-06 | 1988-01-06 | Differential pressure gauges |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO1989006350A1 true WO1989006350A1 (en) | 1989-07-13 |
Family
ID=8525678
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/FI1989/000005 Ceased WO1989006350A1 (en) | 1988-01-06 | 1989-01-06 | Differential pressure meter |
Country Status (2)
| Country | Link |
|---|---|
| FI (1) | FI78783C (en) |
| WO (1) | WO1989006350A1 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100409269B1 (en) * | 2001-11-30 | 2003-12-12 | 현대건설주식회사 | A Manometer Device For Precision Measurement Of Pressure Differnce |
| FR2927995A1 (en) * | 2008-02-21 | 2009-08-28 | Degremont Sa | Device for measuring water pressure in a filter bed, comprises a rigid envelope tube to be pressed in the filter bed to a specified depth, a flexible measuring tube fixed inside the envelope tube, and a beam for the measuring tube |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US949598A (en) * | 1906-12-08 | 1910-02-15 | Bertrand John Price Roberts | Differential-pressure gage. |
| US1499759A (en) * | 1921-03-14 | 1924-07-01 | Bacharach Ind Instr Company | Gauge |
| DE585548C (en) * | 1931-07-29 | 1933-10-05 | Linde Eismasch Ag | Inverted U-tube manometer |
| US2300327A (en) * | 1939-06-12 | 1942-10-27 | William M White | Pressure measuring instrument |
| GB1346432A (en) * | 1972-03-01 | 1974-02-13 | Glasspool M H | 4-tube pressure gauges |
-
1988
- 1988-01-06 FI FI880046A patent/FI78783C/en not_active IP Right Cessation
-
1989
- 1989-01-06 WO PCT/FI1989/000005 patent/WO1989006350A1/en not_active Ceased
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US949598A (en) * | 1906-12-08 | 1910-02-15 | Bertrand John Price Roberts | Differential-pressure gage. |
| US1499759A (en) * | 1921-03-14 | 1924-07-01 | Bacharach Ind Instr Company | Gauge |
| DE585548C (en) * | 1931-07-29 | 1933-10-05 | Linde Eismasch Ag | Inverted U-tube manometer |
| US2300327A (en) * | 1939-06-12 | 1942-10-27 | William M White | Pressure measuring instrument |
| GB1346432A (en) * | 1972-03-01 | 1974-02-13 | Glasspool M H | 4-tube pressure gauges |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100409269B1 (en) * | 2001-11-30 | 2003-12-12 | 현대건설주식회사 | A Manometer Device For Precision Measurement Of Pressure Differnce |
| FR2927995A1 (en) * | 2008-02-21 | 2009-08-28 | Degremont Sa | Device for measuring water pressure in a filter bed, comprises a rigid envelope tube to be pressed in the filter bed to a specified depth, a flexible measuring tube fixed inside the envelope tube, and a beam for the measuring tube |
Also Published As
| Publication number | Publication date |
|---|---|
| FI78783B (en) | 1989-05-31 |
| FI78783C (en) | 1989-09-11 |
| FI880046A0 (en) | 1988-01-06 |
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