GB2292197A - Installing measuring or control devices by self-sealing couplings - Google Patents

Abstract

Use of self-sealing couplings 9, 6 and 10, 7 in place of conventional isolation valves facilitates installation and removal of inline devices such as fluid control valves or flow meters 11, and optionally provides for prevention of reverse flow. The diagram shows how two such couplings 9, 6 and 10, 7 may be combined in a single concentric meter receptacle, which is provided with means of clamping it to a service line which crimp-seal the line between tee connectors 4, 5, so that a water meter 11 may be retrofitted without difficulty to an existing underground service line 2 within the restricted access offered by a narrow meter pit. When coupling parts 9, 6 couple a valve is displaced to allow fluid connection between line 2 and meter or control device. Fluid then flows out (downstream of meter or control device) through a second coupling 10, 7 by forcibly displacing the valve in the second coupling. <IMAGE>

Description

METER INSTALLATION This relates to means of installing measuring or control devices of a type which is in operation required to form part of a closed conduit conveying a fluent medium, and in particular to reans of connecting such devices to the other parts of such a conduit whereby the mediu is automatically retained in the other p arts during device installation and removal.

Control valves and certain types of measuring instruments are installed in pipelines with the fluid flow passing through the body of the valve or instrument, and consequently they are commonly known as "inline" devices. From time to time such devices need to be removed from their pipelines for servicing or replacement and so it is usual to provide them with flanged or screwed and/or union pipe connections to facilitate this; it is also common practice to provide upstream and downstream "block" valves which may be closed to minimise escape of fluid fre the pipeline during such operations.Block vaives, which in some @ases give rise to significant additional fluid frictior, usually add significantly to the cot of an installation and are themselves often prone to problems such as leakage and corrosion or seizure cf their spindles.

According to a first aspect of the invention there is provided @ means of installing inline devices whereby pipeline @@nnettions to the devices are provided with automati@ sealing mechanisms which act to prevent escape of material from within the pipelines whilst the connections are in the disconnected state, and methods by which this may be accomplished.

According to another aspect of the invention there is provided a means as described above whereby at least one of the automatic sealing mechanisms in a given installation may be used additionally to prevent reverse low occurring whilst the inline device is operational.

These metheds are now described for example as if an inline device were a measuring instrument such as a water c@@surption meter. In each case the meter is provided with pipeling @@nne@ti@@s e@@@ of which comprises two ser@r@@le parts. and those p@@t@ of such connections which remein attached @@@ the pipeline when the mater is dies@@nne@ted are equipped internally with self-closing valve mechanisms like these well known in typ@@ of sheck valve.The @@rresponding parts of the connections, which remain attached to the meter are each equipped with a projection which enters the part containing the valve mechanism when the parts are brought together and engages with the valve mechanism so as to hold it in the open position, except in such cases of downstream meter connections where it is desil@ble that the valve @echanism act to prevent @everse flow at all times and not merely during disconnection. (This is sometimes highly desirable in the case of water supply meters, where backflow occurring during unusually low mains pressure could lead to contamination of the public potable water supply).

The valve mechanism may be a swinging plate as in a swing check valve, but the use of a spring-loaded poppet mechanism as in concentri@ spring-loaded check valves is preferred in order to ensure positive shutoff even at very low pressure differentials The use of resilient valve seating materials is also preferred in order to ensure tight shutoff, and examples of this include the incorporation of synthetic rubber seating surfaces in metal valve trim components and the use of polyamide peppets in same spring-loaded types.

The pipeline ends of the separable connections may be secured to the pipeline by any conventional means (including screwed joints and compression joints. that is to say joints in which a form of nut is used to squash a deformable annular sealing component into a permanent tight fit around the pipe), but the joints between the mating parts of the separable connections should be union joints or preferably a form of joint relying on at least one reailient member such as an o-ring to achieve its fluid seal and on other mechanical means to prevent the joint springing apart.The o-ring type is preferred because not only is it proved to be highly reliable in use, but minimal force is @equi@ed for its joining and separation (which may be parti@ulerly impertant in restricted spaces such as meter pits) and @@@porents such as o-rings may be replaced quite easily (and much more easily than compression joint clives).

There in now @iven as an example a method of installing a water meter in an existing underground domestic supply pipe with the aid of the means above mentioned. With reference to Fig. 1, an excavation is made below the ground surface 1 to expose the service pip 2 an? to receive a prefabricated meter enclosure 3.The service pipe is cleaned to receive the tees 4 and 5 which are of a spe@ial type which clamps around the pipe and contains a tubular cutter in the end of the perpendicular part which is driven th@@@g@ the pipe wall by sere@ing in the p@@perdi@@ler part The @@es @re connected befere instellation @@ identi@@l asse@@@lies @@@ and 7 b@th of which @ontain self@@@sing valve @echanisme as provi@vsly desoribed and which w@@@ @@@@@@@@@@@@ j@i@ed @@@@ @@@@@ @@esp@@tive @@rresp@@ding part@ @@ and !0 form separable connections in the @ondu@ts to and f@@@ the @@@@@ 11 T@@ @@@@ is eques@e@ @@ @@@@@ed at the point 8 to prevant any future flow of water through the ripe at this point and then the speciel tee@ are installed being positioned carefully with the aid of a jig or template in order to ensune accurate subsequent mating of the separable connections. No water escapes through 6 or 7 because their salve asse@llies are in the cl@eed position. Fig. 7 illustrates diagrammatically how 9 and 6, here shown in part se@tion fit toqethet @@@ @@@ a proj@@@j@@ pa@@ @@ within @ causes the valve disc within E to be forced clear of its seat against the action of its spring 13 when the two parts of the connection are pushed together. 14 is an o-ring seal.When the meter with 9 and 10 attached is connected to 6 and 7 water enters it via 9 and leaves via 10. It will be seen that flow in this direction would in any case cause the valve mechanism in 7 to open; no projecting part corresponding to 12 is therefore necessary in 7 and the omission or removal of such part enables 7 to act additionally to prevent backflow in the event of supply Y pressure failure.Sone way is needed to prevent the separable connections being pushed apart by the water pressure inside them and for the purpose of this example this is accomplished by tightening a ligature round the supply pipe and che meter then securing it with the water supplier's seal so that the meter cannot be removed b the consumer without temp@ring being evident.To disconnect the water supply from the consumer's premises it is merely necessary for the supplier to withdraw the meter assembly and if desired to secure in its place a dummy assembly preventing any bypassing of point . If the meter enclosure allows sufficent access the separable connections may be provided with integral reans of holding the parte together such as a union nut, preferably ?.inged as shown in Fig. 3, engaging a thread on the one part and a radially projecting part 15 on the other.Alternatively there may be used for this purpcse a quick-release collar or sleeve assembly ongaging a hayonet fitting, or constraining an elastic assembly into a detent slot or reverse taper in the connection WANT, or any suitable means of preventing unintended disconnection, but in any such case the use of resilient members such as o-rings (not shown in Fig. 3) to ensure good sealing remains recommended.

Parts of the separable connections not @onteing value me@hanisms may be made integral with the body of the inline device. Detachable filter screens may be incorporated in the separable connections. There are available water meters wherein the inlet and outlet passages are comhined in a single concentris connection @ppesite the meter fa@e, and it is possible to rombine the inlet and outlet seper@ble @@nnections, or those parts of them containing the automatic valve mechanisms, in a single unit and to provide concentric fluid pathe at a separable interface.A combined unit may also contain trep@nning tees like these shown as ceperate items in Fig. 1. and pay @lse i@@orp@rete means of squsshing the pipeline so as to seal it permanently between the tees. @@se of such a combined unit makes for a very quick, compact and economical installation.

P@r example Fig. 4 shows diagrammatically in section an arra@@@ement in which p@@@eding @@th@d@ @@@ @@@@@@@@ Her@@@ @@@@@ With @@@@@@@@@@ @@@@@@tions of which the @@@@@@l tube @@ is the outlet and where fluid enters via the annular space between this tube and the meter body 17, itself forms that part of the combined @ep@rable c@uplings which does not remain @@@@@@@@ @@@@@@@ pip@@@@@@@ @@@@@@ the @@t@@ is @@@@@@@@ @@@@ @@@@ meter body is attached to this lower part 19 with the union nut 18 the inlet valve is automatically opened as the cylindrical projecting part 27 pushes down the valve stem against the action of the valve spring.The outlet valve is opened by fluid flow in the forward direction, but is closed by its spring when forward flow ceases thus preventing reverse flow. 20 is an optional appular filter screen. The lower part is previcusly secured to the pipeline p1 by the clamp 23 which as it is tightened squashes and seals the pipeline between the outlet nozzle 22 and the inlet noz@le numbered 30 in Fig. 5 (which is a partial se@tion in a plane parall@l to that of Fig. 4).Initially both the inner assembly 25 and the nezzle screw 29 are in raised positions with threads just @ngegad. When 25 is screwed home with the aid of a tool made to angege with its upper end the sharpened end of 22 cuts through the pipeline wall and the elastic packing 24 is compressed making a tight seal whilst permitting precise rotational alignment of 25 so that 29 may be driven home to make the inlet connection to the pipeline in a similar manner. 32 is part of the flange of 25 which contains the valve mechanisms, that is to say chamber 31 is continuous with that into which the inlet valve poppet descends, so the fluid path@ are complet@d as the meter body is attach@d @@ is a part fitted for engagement of the union nut in the manner of @ piston ring. 2 is a tightening lug with provision for the attachment of an anti-tamper @igature. @esilient fluid seals es previcusly mentioned are i@@orporated where appr@priate (hut not shown in Fig. 4), and when pipeli@@s are of resilient material such as polyethylene the use of @lamp s@rews with ratchet locking or other appr@priate anti-tamper provisions mey be derirable to prevent any illicit slac@oning The use of the clamping arrangements such as that shown where a hemicylindrical nut engages behind a yoke in the end -f a hinged clamp so that an assembly with no bits which can drop off may be presented to the pipeline is preferred for awkward locations with restricted access, such as narrow meter pits.

Manual operation of the automatic valve mechanisms is possible, for instance wherever it is desired to bleed pipelines, when the inline devi@e is not connect@d.

M@ny n@@ele@tri@@l @@@@t@@l @alves and @easuring i@@truments rely on fluid transmissio@ by pip@ling of @@gnal@ and op@@@@ting pow@@ @nd it is @@@@@ag@d that it @@@@ install ti@@s signal @@@ r@@er @@@@e@t@@@@ @@y, i@ addition to @@y cop@@@ti@@@ for @@@@@@@@@@ @@ @@@t@@lled @@@@@@@ to pass th@@@g@ the b@dies of such devices. he accomplished @@@ the @@ys des@@ibod with -- -, 9 -9. -- ... - 4 9'-, - - -. - -- - - - - -- -,- - -- 4 -- - - 4 - - 4 particular advantage in @@@@@@@@@ @@@ as tyese partining i@ subsee cil production fecilitie@ where r@@@t @ppli@@@@@ @ust be used for meinterance work

Claims (12)

1. CLAIMS 1 A way of installing fluid measurement or control devices whereby self-sealing couplings are used instead of isolation valves.
2. 2 A way according to Claim 1 whereby trepanning tee connectors are used.
3. 3 A way according Claim 1 or Claim 2 whereby a pipeline is crimp-sealed between two tee connections.
4. 4 A way according to any preceding claim whereby the said couplings are of a quick-release type.
5. 5 A way according to any preceding claim whereby the said couplings may when disconnected be used for pipeline bleeding.
6. 6 A way according to any preceding claim whereby a selfsealing coupling downstream of a device optionally may serve additionally to prevent reverse flow.
7. 7 A way according to any preceding claim whereby a plurality of fluid paths pass through a single self-sealing coupling assembly.
8. 8 A way according to any preceding claim whereby provision is made against the possibility of tampering.
9. 9 A way according to any preceding claim whereby power and'or signal fluid connections are made via one or more self-sealing couplings.
10. 10 A way according to any preceding claim whereby elastic members are used to prevent fluid leakage.
11. 11 A way according to any preceding claim whereby a coupling assembly contains all parts, including pipe sealing and connecting parts, necessary to retrofit a device into an existing pipeline within restricted access such as in a narrow meter pit.
12. 12 A vay of installing fluid measurement or control devices substantially as described herein with reference to Figures 1 - 5 of the accompanying drawing.