GB2135784A - Fluid flow indicating device - Google Patents

Abstract

A flow meter, especially for use in compressed air systems, comprises a body member (1), having opposed lateral inlet and outlet ports (8, 9), for mounting in a compressed air line and sealingly engaging a transparent enclosure (2) containing a flow-rate measuring device (23) through which the compressed air passes in use. The device (23) is supported by the body member (1) and comprises a transparent, graduated tube (24) housing an axially movable index member (25) which assumes a visible position along the length of the tube (24) in dependence upon the flow rate of the compressed air. The flow meter may readily be incorporated into a compressed air system on either a temporary or a permanent basis, as desired. <IMAGE>

Description

SPECIFICATION Fluid flow indicating device This invention relates to devices for indicating the rate of flow of a fluid in a system, and is especially, but not exclusively, concerned with devices for indicating the rate of flow of compressed air in a compressed air system.

In compressed air systems, it is usual to control the air pressure using a pressure regulator, the regulator often being mounted in juxtaposition with a filter unit for filtering out water, oil and solid impurities and optionally, when desired, with a lubricator for introducing controlled amounts of lubricant into the air.

The combination of such a filter, regulator and lubricator is commonly referred to in the art as an "FRL" and one example thereof is disclosed and claimed in British Patent Specification No 1 387 344.

In certain cases, it is desirable, in use, to have an indication of the absolute air flow rate and this can be achieved by incorporating a conventional flow meter at a convenient location in a pipe-line of the system. However, compressed air systems are often intended to operate at relatively high pressures, for example between 8 bar and 1 6 bar or higher, which means that the flow meter casing has to be particularly strong in order to withstand the high pressure. This, in turn, means that they are relatively expensive items. Further, a given flow meter is usually capable of operating over only a relatively small range of'flow rates which means that, in cases where the desired flow rate is outside the working range of the particular meter jnstalled, it would be necessary to replace the meter with another capable of working within the appropriate range.The replacement operation, in the case of conventional flow meters, is somewhat inconvenient.

It is an object of the present invention to provide an improved fluid flow rate indicating device that is especially suitable for use in compressed air systems and that, in its preferred forms, may, when installed, readily be adapted and/or replaced, inter alia, to cope with different ranges of air flow rates.

According to the present invention there is provided a flow meter for use in compressed gas, for example compressed air, systems characterised in that it comprises a body member having in gas tight engagement therewith an elongate enclosure capable of withstanding relatively high pressures and the interior of which communicates with a first passageway formed in said body member, and, supported by the body member and extending longitudinally within the enclosure, an elongate tubular member whose bore contains an index-member that, in use, moves within the bore in dependence upon the rate of flow of gas therethrough, the bore, at the end of the tubular member remote from the body member, communicating with the interior of said enclosure and, at its other end, communicating with a second passageway formed in said body member, said body member defining a pair of opposed lateral ports communicating respectively with said first and second passageways, whereby the body member may be connected into a compressed gas pipe-line with the longitudinal axis of the enclosure extending normally to the run of said pipe-iine and whereby the compressed gas will flow between said ports via the bore of said tubular member and said first and second passageways, and the wall(s) of said enclosure being at least partially transparent so that, in use, the absolute or relative flow rate indicated by the index member can be observed.

Preferably, the index member is movable axially within the tubular member and, in use, assumes a position along the length thereof in dependence upon the prevailing flow rate, the tubular member being graduated in an appropriate manner (for example so as to give an indication of the absolute flow rate) and being at least in part transparent so that the position of the index member relative to the graduations can be observed. Alternatively, for example, the use of a rotating index member is possible.In a flow meter of the present invention, because both the outer and inner surfaces of the tubular member will be subjected to substantially the same gas pressure, there will be only a very small pressure differential across its wall(s) and so commercially available index-type flow-rate measuring devices that are normally intended to measure the flow rate of gases or liquids at lower pressures may be used.

The body member constitutes a member for mounting the flow meter in a fluid flow passageway such as a compressed air passageway. The flow meter may be mounted in any suitable manner. For example, it may be supported simply by fluid flow pipework but the body member is preferably substantially as described in British Patent Specification No 1 387 344 referred to above, the disclosure of which is incorporated herein by way of reference. In that case, the body member, with its lateral inlet and outlet ports, simply plugs into an apertured support frame and is thereby automatically brought into fluid flow communication with the compressed air system.

This gives rise to a number of advantages, as follows: a) The flow meter may be left permanently in situ or it may temporarily take the place of another unit such as a filter or lubricator having a like mounting portion thereby en abling a spot check on the flow rate to be readily carried out.

b) Even if the flow meter is intended to be left permanently in situ for the purposes of continual checking of the flow rate, it can still be easily removed for servicing or re calibrating.

c) A given flow meter can be easily re moved and replaced by another with a different flow calibration, that is to say one capable of indicating a flow rate over a different range. Alternatively, this may be achieved in the manner described below.

Any of the above operations can be readily carried out without disturbing the system pipework which would not, of course, be possible in the case of a conventional flow meter located in a pipe-line.

However, alternative forms of body member and support means may be utilized. For example, adjacent pairs of devices selected, for example, from a filter, regulator or lubricator and a flow meter of the invention may be connected together by separate connecting members from which any device may be individually disengaged for, for example, servicing purposes, and the body member would have the appropriate configuration. In any event, the body member and the support means are preferably brought into operative engagement with one another by means of a "wedge" action, and are maintained in such engagement by locking means, for example a locking ring as described in the above-mentioned specification.

In preferred embodiments, the whole of the fluid-tight enclosure is substantially transparent and is preferably made of a strong plastics material such as a polyearbonate, which is the material commonly used in the art for the enclosures ("bowls") of filter and lubricator units. Indeed, it can be seen that a preferred form of flow meter of the invention may include certain parts, eg the body member and the enclosure, that are identical to corresponding parts of a filter or lubricator unit, which has obvious advantages.

The present invention also provides a compressed air system including a flow meter of the invention, optionally in juxtaposition with one or more fluid flow devices, for example a filter, regulator and lubricator.

A preferred form of flow meter of the invention will now be described by way of example only with reference to the accompanying drawing which is a side elevation, partly in section, of the flow meter shown mounted in a frame-like support means connected in a compressed air line.

The flow meter comprises an upper body member 1 from which depends a transparent bowl 2 screw-threadedly engaged at 3 with a skirt 4 of the body member 1. A sealing ring 5 ensures a good fluid seal between the body member 1 and the bowl 2.

The body member 1 defines internally thereof an inlet passageway 6 and an outlet passageway 7 in the form of a chamber. A lateral inlet port 8 and a lateral outlet port 9 communicate respectively with the passageways 6 and 7, each of which ports terminates, at its other end, at an inclined sealing surface 10, 11 having an annular recess 12, 1 3 containing an elastomeric O-ring seal 14, 15.

The flow meter is shown mounted in a support means 1 6 which is in the form of a frame having an aperture 1 7 for receiving the body member 1 of the flow meter. The aperture walls are formed with opposed, tapered sealing surfaces which surround the respective ends of passageways 1 8 and 1 9 formed in the frame. The flow meter is retained in the frame by means of a threaded ring 20 which, when tightened, brings the sealing surfaces of the body member 1 and those in part defining the aperture 1 7 into fluid-tight engagement, the O-rings 14 and 1 5 being sandwiched therebetween and the ports 8 and 9 being in communication with the passageways 1 8 and 1 9 respectively.The passageway 1 9 is shown as being in communication with the delivery pipeline 21 of a compressed air system via a connector 22.

The inlet passageway 6 communicates at its lower end with the interior of the bowl 2, in which is vertically supported a flow-rate measuring device 23. The device comprises a graduated, transparent tube 24 which houses a spring loaded index member in the form of an annular piston 25 which, with clearance, surrounds a tapered cone 26. In use, the piston 25 assumes any one of a number of visible positions along the length of tube 24 according to the flow rate of gas passing through it, the absolute or relative flow rate, as the case may be, being indicated by the position of a piston ring 27 relative to the graduations (not shown). Examples of suitable devices 23 are those supplied by International Controls Corporation Limited under trade mark FLOWLINE. The lower end 28 of the tube 24 is open to the interior of the bowl 2.The upper end of the tube 24 is partially closed by a generally circular plate 29 provided with apertures 30. The device 23 and the plate 29 are held in position by a bolt 31 which screwthreadedly engages a thread formed in a boss 32 forming an integral part of the body member 1. As can be seen, the plate 29 also serves to prevent direct communication between the chamber 7 and the interior of the bowl 2. However, the plate 29 may have one or more peripheral by-pass apertures formed in it to allow a degree of such direct communication. This expedient may be employed if the flow rate would otherwise exceed the working range of the device 23. Alternatively, such an eventuality could be dealt with by substituting a like device 23, or the flow meter as a whole, with one capable per se of working within the range in question.

In use, comressed air enters the flow meter through inlet port 8 and flows into enclosure 2 via the passageway 6. It then enters the tube 24 through its lower end 28 and causes the piston 25 to assume a position along the tube 24 according to the flow rate of the compressed air. The air, after flowing through the clearance between the piston 25 and the cone 26, flows through the apertures 30 into the chamber 7 and then into pipe-line 21 via the outlet port 9. The air flow path and direction is indicated by arrows. If desired, the gas flow through the flow meter may be arranged to be in the opposite direction (port 9 thus being the inlet and port 8 the outlet), the flow-rate measuring device 23 being orientated and adapted accordingly.

As already indicated, the device 23 may be adapted to give an absolute indication of the flow rate, although in any case corrections for temperature and/or pressure deviations from standard values will usually be necesary. However, the device 23 may be adapted to indicate a relative flow rate in which case the actual flow rate may be calculated by using a predetermined conversion factor appropriate to the device 23 being used.

The flow meter may, after closing off the compressed air flow using a valve, readily be demounted from the frame 1 6 simply by unscrewing the ring 20 and withdrawing the device in a downwards direction.

Claims (7)

1. A flow meter for use in compressed gas, for example compressed air, systems characterised in that it comprises a body member having in gas tight engagement therewith an elongate enclosure capable of withstanding relatively high pressures and the interior of which communicates with a first passageway formed in said body member, and, supported by the body member and extending longitudinally within the enclosure, an elongate tubular member whose bore contains an index-member that, in use, moves within the bore in dependence upon the rate of flow of gas therethrough, the bore, at the end of the tubular member remote from the body member, communicating with the interior of said enclosure and, at its other end, communicating with a second passageway formed in said body member, said body member defining a pair of opposed lateral ports communicating respectively with said first and second passageways, whereby the body member may be connected into a compressed gas pipe-line with the longitudinal axis of the enclosure extending normally to the run of said pipe-line and whereby the compressed gas will flow between said ports via the bore of said tubular member and said first and second passageways, and the wall(s) of said enclosure being at least partially transparent so that, in the absolute or relative flow rate indicated by the index member can be observed.

2. A flow meter according to Claim 1 characterised in that said body member is adapted for engagement, in use, with support means therefor, the said support means having opposed lateral supply and delivery fluid flow passageways formed therein such that when the body member is brought fully into engagement with said support means, the opposed lateral ports of the body member are brought into sealed communication with the supply and delivery passageways, respectively, formed in the support means.

3. A flow meter according to Claim 2 characterised in that said ports are surrounded by respective sealing surfaces that are inclined to the axes of said ports and that are adapted to engage, in the nature of a wedge action, with correspondingly inclined sealing surfaces of the support means.

4. A flow meter according to any one of Claims 1 to 3 characterised in that said enclosure comprises a wholly substantially transparent bowl.

5. A flow meter according to any one of Claims 1 to 4 characterised in that said enclosure is detachably engaged with the body member.

6. A flow meter substantially as described herein with reference to, and as illustrated in, the accompanying drawing.

7. A compressed air, or other compressed gas, system incorporating a flow meter as claimed in any preceding claim.