GB2131958A - Fluid flow measurement - Google Patents

Abstract

To allow a flowmeter to be inserted into a pipeline (12), (14) or for the flowmeter to be easily removed a manifold (10) is arranged in the pipeline. This is suitable for a flowmeter or a filter. The meter extends at right angles to the pipeline in a cansister (18). The meter comprises a spring loaded piston (24) on a tapering sleeve and pin assembly (28, 30), within a cylindrical sleeve (22). Both the sleeve (22) and the canister (18) are transparent to permit the displacement of the piston to be seen. A scale allows the displacement to be read off as flow, by suitable calibration. <IMAGE>

Description

SPECIFICATION Improvements in and relating to flow measurement The invention relates to fluid flow meters for indicating the rate of flow of a fluid along a pipeline.

Background of the invention Conventionally fluid flow meters are inserted into a pipeline to indicate fluid flow rate. Historically a section of pipeline is removed and replaced by a tubular member having pipefittings at opposite ends to which the pipeline is connected and containing with in it a displaceable piston co-orporating with a tapering pin which passes through an aperture in the piston and forms therewith an annular orifice. As the piston moves axially so the area of the annular orifice increases or decreases depending on the direction of movement and by incorporating spring means so as to urge the piston towards the larger diameter end of the tapering pin, so the flow control orifice is normally reduced to a minimum.Flow along the pipeline and into the measuring tube causes displacement of the piston away from the maximum diameter end of the pin until the pressure drop across the orifice is just balanced by the restoring force exerted by a spring acting on the piston.

A calibrated scale associated with the tube allows an indication of the displacement of the piston from its rest position and thereby the flow through the tube.

There are problems associated with such arrangements in that once the tubular member has been fitted into the pipeline, it is not easy to remove it from the pipeline and in view of the nature of the device, any dirt or sediment which may be in suspension in the fluid flowing through the pipeline may cause the interior of the flow indicator to become clogged or at worsed dirty so that the piston can no longer be seen clearly.

Routine servicing may therefor be required as may replacement in practice.

Another problem is that many fluid pipeline systems are formed without incorporating any flow indicator in the pipework. Incorporating a flow meter for testing the pipeline subsequently is a major plumbing activity if the pipeline has to be broken and a meter inserted albeit temporarily, since after insertion and testing, the pipeline must be made good again.

To obviate this, and related problems, it is an object of the present invention to provide inter alia a flow control device which will allow flow along a pipeline to be monitored by using an offline flow measuring unit which can be connected to the line as required and in some circumstances in place of filters and other devices normally connected as offline components to the line.According to one aspect of the present invention a fluid flow meter comprises: 1- a first housing at least part of which is transparent, 2- a second inner housing mountable within the first housing also at least in part transparent so that the interior of the second housing can be seen from outside of the first housing, 3- a piston slideable as a close slipping fit in the inner housing and visible through the two housings, 4- a manifold which with the first and second housings forms a fluid tight container which is divided into two regions by the piston, 5- a pin having a tapering cross-section which extends axially through the said inner housing 6- an aperture in the piston whereby the latter can slide along the pin, the diameter of the aperture being such that it forms with the pin an annular flow control orifice which increases in area as the piston is moved along the pin in a direction away from the region of greatest diameter of the pin, 7-spring means acting on one face of the piston to urge it in the direction of increasing taper diameter thereby to reduce the flow control orifice to a minimum in the absence of any external influence on the piston, and 8- inlet and outlet means in the manifold for connection into a fluid pipeline, the outlet communicating with the region in the fluidtight container which communicates with the said one face of the piston and the inlet communicating with the other region in the said fluid tight-container which is in communication with other said face of the piston.

According to another aspect of the invention a fluid flow meter comprises: 1- an outer tubular housing having one closed end, 2- an inner tubular housing having both ends open and containing within it a flow indicator, and mounted within the outer tubular housing so that one of its open ends extends through the other said end of the other tubular housing, 3- an end closure member which closes-off the annular space between the inner and outer housings at the said other end of the outer housing, 4- a first fluid connection in the end closure member communicating with the annular space between the inner and outer tubular housings, and 5- a second fluid connection communicating with the said one end of the inner tubular housing which extends through the end closure member, one fluid connection forming an inlet and the other forming an outlet for connection into a pipeline, the flow along which is to be indicated. In either case, the pin may include a central region of maximum diameter and end regions which taper from the central region towards the opposite ends, and 2- spring means is provided urging the piston into the central position so that flow through the device can be monitored in either direction.

According to another aspect of the invention a a fluid flow meter for connection into a pipeline for indicating the flow of a fluid through the pipeline comprises: 1- a tubular member at least part of which is transparent so as to allow the interior thereof to be seen, 2- a piston located within and slidabie along the tubular member, 3- a pin extending axially through the tubular member and passing through an aperture in the piston, the cross-section of the pin tapering from a central region of maximum diameter towards each end, 4- the diameter of the aperture in the piston being commensurate with the maximum diameter of the pin so that when the piston is in the central position along the pin, the annular flow control orifice defined between the piston and the pin is at a minimum or is zero, but is increased if the piston is moved either to one side or the other along the pin, and 5- spring means urging the piston into the central position in the absence of any other influence on the piston.

Preferably the meter includes a graduated scale associated with the tubular member to indicate the displacement of the piston relative to its rest position and calibrated to indicate flow through the tube.

According to a preferred feature of any of the aspects of the invention the outer housing may be removable from a manifold independently of the inner housing and the latter may itself be removably secured to the manifold.

The manifold may be permanently fitted into a pipeline with a cavity into which either the inner or outer or both housings of the flow meter can be secured, as by a screwthread connection.

According to a further aspect of the invention a fluid flow meter for filtering to a pipeline in place of a filter or other off-line component having a male connector for fitting in a socket in the pipeline and located within a canister which is normally attached to the pipeline but is removable to permit removal of the filter or other off-line component from its socket, comprises: 1- a tubular housing at least part of which is transparent to allow the interior to be viewed, 2- a centrally apertured piston located as a close slipping fit within the housing, 3- a tapering pin secured within the housing with the pin passing through the aperture of the piston and cooporating therewith to form a variable annular flow control orifice, 4- one end of the tubular housing being adapted to be secured into the said socket located in the pipeline in place of the filter or other off-line component normally fitted therein, thereby to allow the fluid flow along the pipeline to be measured during servicing or checking. As before mentioned the pin may taper in both directions and there may be provided spring means to urge the piston into the central maximum diameter region of the pin so that the flow control device is bidirectional.

The invention will now be described by way of example with reference to and illustrated in the accompanying drawings, in which: Figure 7 is a cross-section through a flow measuring device constructed as one embodiment of the invention, Figure 2 illustrates an alternative fluid flow measuring insert.

In the drawing a manifold 10 secured in a pipeline 12, 1 4 provides a socket 1 6 into which a dome-shaped canister 1 8 can be screwed. The direction of fluid flow along the pipeline is denoted by arrow 20 and the interior of the canister communicates with the section 1 2 from which the flow is coming.

The manifold provides a fluid tight connection for a cylindrical sleeve 22 having a displacable piston 24 which has a central cylindrical passage 26 surrounding a tapering sleeve 28 which itself is located on a central pin 30. This latter extends from an integral end cap 32 which forms on end of the sleeve 22, and the pin 30 is formed with a screw head 34 at the lowe end as shown, to retain the end cap 32 and is formed with a screw thread at its upper end 36 as shown, for screwing into a threaded recess 38 in a pillar 40 at the upper internal end of the manifold 10.A hexagonal nut 42 is also screwed onto the threaded section 36 and secures the end cap 32 within the sleeve 22 and in turn holds the latter in an annular recess 44 in a circular end plate 46 which is rebated around its periphary to fit snugly within the lower open end of an upper cylindrical support 48 the interior 49 of which communicates with the down stream section 14 of the pipeline.

The interior of the sleeve 22 is effectively divided into two parts by the piston 24. The lower part 50 communicates with the interior of the canister 1 8 via apertures 52, 54 in the end cap 32 whilst the upper par 56 communicates with the interior 49 of the upper support 48 (and thence the down-stream pipeline 14) via apsr.ures 58, 60.

The piston 24 is urged in a downward direction by a spring 62 so that in the absence of any positive pressure differential across the piston 24, the latter is maintained at the large diameter end of the sleeve 28 so as to shut-off the flow.

If the pressure on the upstream side increases (as is the case if there would be flow along arrow 20), the piston 24 is displaced (in known manner) away from the position down, towards the smaller diameter of the sleeve 28, thereby increasing the area of the annular gap between piston 24 and sleeve 28 to permit flow to occur.

In known manner, equilibrium is established when the pressure drop across the piston 24 is just equal to the restoring force exerted by the spring.

A scale, not shown but typically on the wall of the sleeve 22, and visible through the canister 1 8 (at least part of which is therefore transparent to permit said viewing), allows the pressure differential to be measured and therefore the flow rate indicated, by appropriate calibration of the scale.

0 ring seals are provided at 64, 66 and 70 to prevent escape of fluid from one region of the assembly to another, and may if required be employed in the pipe connectors to the manifold 10.

The canister 1 8 may normally house a filter element (not shown), similar to the sleeve 22 assembly and secured in place by a central threaded pin such as 30. The filter may be replaced by the fluid flow measuring device by first shutting off the pipeline from the manifold using gate-valves (not shown) or the like - which may form part of the manifold 10, and then removing the canister 1 8 and unscrewing the pin holding the filter in place and romoving same.

Thereafter the flow measuring assembly of sleeve 22 and piston 24 may be postioned and screwed into place by screwing in the pin 30 after which the canister 1 8 can be replaced (if necessary by a transparent one to permit the sleeve to be seen). The fluid flow can then be resetablished by opening the valves (not shown).

Replacement of the fluid flow measuring device with the filter may be effected by eversing the above described procedure.

Fig. 2 shows another sleeve and piston assembly whicn will allow flow measurement in either directin of flow and which may be employed off-line such as shown in Fig. 1 or in an in-line device (not shown) in which the sleeve corresponds to a continuation of the wall of the pipeline.

The assembly of Fig. 2 comprises a cylindrical sleeve 72 within which is slideable a piston 74 apertured at 76 and movable along a double tapered sleeve 78 held in place by a central pin 80 corresponding to the pin 30 of Fig. 1.

The ends of the sleeve are formed by cupshaped caps 82-84 similar to the cap 32 of Fig. 1 and two springs 86 and 88 normally centre the pistion 74 in the cylinder.

Pressure to one side (or the other) of the pistion due to flow, will cause the spring on the opposite side of the piston 1 5 to compress until equilibrium is reached (i.e. when the net restoring forces acting on the piston are balanced by the pressure differential across the piston) and a scale (not shown) suitably calibrated, allows the displacement of the piston 74 to be "seen" as a fluid flow measurement (since for normal flow pressure is proportional to flow).

Apertures (not shown) in the end caps 82, 84 allow fluid to pass into and out of the sleeve.

The end 86 of the pin 80 is threaded for securing the latter into the pillar 40 of Fig. 1, if so required.

A nut 90 secures the end caps to the pin 80 and into the sleeve 72, which as shown is rebated to provide annular seating for the caps.

Claims (9)

1. A fluid flow measuring device comprising: (1) a first housing at least part of which is transparent, (2) a second inner housing mountable within the first housing also at least in part transparent so that the interior of the second housing can be seen from outside of the first housing, (3) a piston movable within the inner housing and visible through the two housings, (4) a manifold which with the first and second housings removably connect to form a fluid tight container which is divided into two regions by the piston, (5) inlet and outlet means in the manifold for connection into a fluid pipeline, the outlet communicating with the region in the fluidtight container which communicates with one face of the piston and the inlet communicating with the other region in the said fluid-tight container which is in communication with the other face of the piston.

2. A fluid flow measuring device comprising: (1) a first housing at least part of which is transparent, (2) a second inner housing mountable within the first housing also at least in part transparent so that the interior of the second housing can be seen from outside of the first housing, (3) a piston slideable as a close slipping fit in the inner housing and visible through the two housings, (4) a manifold which with the first and second housings forms a fluid tight container which is divided into two regions by the piston, (5) an elogate member (hereinafter referred to as a pin) having a tapering cross-section which extends axially through the said inner housing (6) an aperture in the piston whereby the latter can slide along the pin, the diameter of the aperture being such that it forms with the pin an annular flow control orifice which increases in area as the piston is moved along the pin in a direction away from the region of greatest diameter of the pin, (7) means acting on one face of the piston to urge it in the direction of increasing taper diameter thereby to reduce the flow control orifice to a minimum in the absence of any external influence on the piston, and (8) inlet and outlet means in the manifold for connection into a fluid pipeline, the outlet communicating with the region in the fluidtight container which communicates with the said one face of the piston and the inlet communicating with the other region in the said fluid tight-container which is in communication with other said face of the piston.

3. A fluid flow measuring device comprising: (1) an outer tubular housing having one closed end, (2) an inner tubular housing having both ends open and containing within it or comprising the outer casing of a flow indicator, and mounted within the outer tubular housing so that one of its open ends extends through the other said end of the outer tubular housing, (3) an end closure member which closes-off the annular space between the inner and outer housings at the said other end of the outer housing, (4) a first fluid connection in the end closure member communicating with the annular space between the inner and outer tubular housings, and (5) a second fluid connection communicating with the said one end of the inner tubular housing which extends through the end closure member, one fluid connection forming an inlet and the other forming an outlet for connection into a pipeline, the flow along which is to be indicated.

4. A fluid flow measuring device as claimed in any of the preceding claims in which the outer housing is removable from a manifold independently of the inner housing and the latter is itself removably secured to the manifold.

5. A fluid flow meter as claimed in claim 4 in which the manifold is permanently fitted into a pipeline and has a cavity into which either the inner or outer or both housings of the flow meter can be secured as by a screwthread connection.

6. A fluid flow measuring device for fitting to a pipeline in place of a filter or other offline component having a male connector for fitting in a socket in pipeline and located within a canister which is normally attached to the pipeline but is removable to permit removal of the filter or other off-line component from its socket, comprising:: (1) a tubular housing at least part of which is transparent to allow the interior to be viewed, (2) a centrally apertured piston located as a close slipping fit within the housing, (3) an elogate member having a tapering cross section and hereinafter referred to as a pin secured within the housing with the pin passing through the aperture of the piston and co-oporating therewith to form a variable annular flow control orifice, (4) one end of the tubular housing being adapted to be secured into the said socket located in the pipeline in place of the filter or other off-line component normally fitted therein, thereby to allow the fluid flow along the pipeline to be measured during servicing or checking.

7. A fluid flow measuring device as claimed in any one of the preceeding claims in which the elongate member is in two parts, an inner pin and an outer sleeve and it is the latter which tapers in cross section.

8. A fluid flow measuring device as claimed in any one of the preceeding claims in which the means acting on the piston is one or more springs.

9. A fluid flow measuring device constructed and arranged and adapted to operate substantially as herein described with reference to and as illustrated in the accompanying drawings.