AU699564B2 - Coupling for a demountable conduit system - Google Patents

Description

Regulation 3.2

AUSTRALIA

Patents Act 1952 COMPLETE SPECIFICATION FOR A STANDARD PATENT

(ORIGINAL)

S.

0 4 5 0 S. Name of Applicant: HYGENELEC PTY. LTD.

Actual Inventor(s): John Todd ANDERSON Address for Service: DAVIES COLLISON CAVE, Pater.- Attorneys, 1 Little Collins Street, Melbourne, 3000.

Invention Title: "Coupling for a Demountable Conduit System" Details of Associated Provisional Application(s): No(s): S" PM 6151/94 filed 9 June 1994 SThe following statement is a full description of this invention, including the b method of performing it known to me/us: Bi -1- 'est if I j i 1 -r f

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i Q:tOPERlGCF 216;4.C- 21/10/98 t -2- COUPLING FOR A DEMOUNTABLE CONDUIT SYSTEM a. a a a a *r a 9* a a, *r a a aSk This invention relates to a coupling for a demountable conduit system.

More particularly, the invention relates to a coupling for a demountable conduit system for electric cables or pneumatic or hydraulic lines or the like.

In many environme'its such as in the food handling or processing industries, it is necessary for electric power cables, control cables and pneumatic or hydraulic lines to be enclosed in watertight and dust proof conduits. Typically the conduits comprise stainless steel tubes and usually the watertight joints, couplings and terminations and the like are formed by welding the stainless steel components together. Usually the welding is gas purged which is time consuming and expensive. Further, once the conduit has been installed it is a very difficult and costly process to make modifications to the conduit system.

Accordingly, it is an object of the invention to provide a coupling and conduit system which has the necessary waterproof and dust proof ratings but which is demountable. This gives much greater flexibility to make modifications to the cabling or pneumatic or hydraulic lines within the conduit system. Further, the components which are used to form couplings 20 and terminations can be moulded from plastics material selected to have the necessary fire ratings and colour coding standards (AS3000) thereby reducing installation costs by avoiding sophisticated welding techniques which are normally required for stainless steel conduits.

According to the present invention there is provided a coupling for a demountable conduit system, said coupling including: a nut provided with internal threads and an internal shoulder; a bush provided with a tapering surface which terminates at an end face of the bush I and threads which are located on the exterior of the bush and extend to or substantially to said end face and can mesh with said internal threads; yt ii 30 a sleeve including an external shoulder which is engagable with said internal shoulder, g said 'leeve including a tapering surface which terminates at an end face thereof; and 9 (i ;-1

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Np Q:\OP ER\GCP\21624.C 21110198 -3a pair of substantially identical sealing elements each having a bore therethrough and a frustoconical outer surface which is complementary to both the tapering surface of the nut and the tapering surface of the bush whereby in use the sealing elements can be located with their frustoconical surfaces adjacent to respective tapering surfaces and said threads tightened to thereby cause the sealing elements to seal against a conduit or conduits passing through the bores and wherein the nut, bush and sleeve are formed from flame retardant plastics material whereby the coupling can be used in food handling or processing industries and for electric cables.

It is possible to use some of the components referred to above to form a termination which comprises a nut and the second member comprises a hollow body, the arrangement being such that tightening of the nut on the hollow body causes the end piece to engage the end of the conduit and the sealing element to seal against the outer periphery of the conduit I wo near the end thereof.

0 S:Where the system is to form a connection to a junction box or the like, components of the coupling may be used in conjunction with an adaptor which includes a shoulder ard a second threaded part the arrangement being such that a second nut can be threaded onto the second threaded part to thereby clamp a wall of a junction box or is clamped between the shoulder and the second nut and wherein one of tb e sealing members is sealed against and end zone of the conduit.

te It is further preferred that the colour of the plastic components is selected in accordance with the usage of the conduit. More particularly, it is preferred that where electric cables (power and/or control) are to be used, the components are moulded from orange materials. Where the conduit is to be used for pneumatic lines the components are moulded from blue material.

The invention also includes a demountable conduit system comprising conduits and couplings as defined above demountabl i Lunted thereon..

-4- The invention will now be further described with reference to the accompanying S drawings, in which: Figure 1 schematically illustrates a coupling for a conduit system prior to assembly; Figure 2 is a longitudinal section through the unassembled coupling; Figure 3 is a longitudinal section through the assembled coupling; Figure 4 shows the use of an adaptor for connection to a junction box; and Figure 5 is a cross-section through a conduit end.

Figure 1 diagrammatically illustrates a conduit system 2 comprising two stainless steel conduits 4 and 6 having abutting ends 8 d 10. The coupling between the conduits 4 and 6 is formed by means of a coupling assembly 12 which comprises a nut 14, sleve 16, first and second sealing elements 18 and 20 and a bush member 22. The nut 14, sleeve 16 and bush member 22 are preferably injection moulded from a medium impact flame retardant grade of ABS plastics material. Suitable materials are ASTALAC 943 or AUSTRAN ABS 943 which is supplied by Chemflex Australia Limited. These materials are also resistant to attack from caustic cleaning materials.

i :These components conform to AS3000 and/or AS1345. Where the conduit system is to be used to protect electric cables, the components are preferably moulded from orange material. Where the conduit is to protect pneumatic or hydraulic lines, the components are preferably moulded from blue material. The sealing members 18 and 20 are preferably moulded from resilient material which is also fire resistant. One suitable material comprises a thermoplastic rubber known as SANTOPRENE.

9 0 Figure 2 shows in more detail the structure of the components of coupling 12.

More particularly, it will be seen that the sealing elements 18 and 20 have an internal i bore which is the same as or slightly smaller than the outer diameter of the conduits 4 and 6. The elements thus snugly engage the conduits 4 and 6. Each of the elements includes a conical surface 23 which tapers away from an end face 24. In the final assembly, the end faces 24 of the sealing elements 18 and 20 abut one another, as seen I in Figure 3. The sleeve 16 includes a conical camming surface 26 whichhas the same taper as the surface 23 of the sealing elements. The outer surface of the sleeve 16 1 1 1 rtr PMAI; SI1 A 4_ I 1 1 1 1 1 k 1 1 it^ osvy>n-i^i Ttr <pi~iirod A includes a cylindrical portion 28 which defines an annular shoulder 29. The nut 14 includes a main body portion 30 provided with grooves 32 to facilitate gripping and rotation of the nut. The nut 14 is internally threaded with threads 34 which are a metric thread consistent with those used in the processing industry. The inner end wall of the nut 14 includes an annular shoulder 36 which is engageable with the shoulder 29 of the sleeve 16 in the assembled coupling.

The bush 22 includes external threads 35 which mesh with the threads 34 of the nut 14. The bush 22 includes a conical camming surface 38 which is complementary to the conical surfaces 23 of the elements 18 and 20. j A coupling is formed on the conduits 4 and 6 by placing the nut 14 and sleeve 16 over the end of the conduit 4. The sealing element 18 is then fitted to the end with the end face 24 substantially coplanar with the end 8 of the conduit. On the end of the other conduit, the bush 22 is first mounted and then the sealing element 20 is fitted on the end of the conduit with its end face 24 flush with the end 10 of the conduit. The components 14, 16 and 22 are then moved towards one another so that the threads 34 and 35 engage. The nut 14 is tightened on the bush 22 which causes the camming I *surfaces 26 and 38 to engage and clamp against the conical surfaces 23 of the sealing elements so that they press firmly against the outer surfaces of the conduits 4 and 6 and their end faces 24 abut one another. This forms a substantially watertight and dust proof coupling. The assembled coupling is shown in Figure 3. It will be appreciated of course that the coupling can be readily uncoupled by simply unscrewing the nut 14 from *lo the bush 22.

The couplings 12 can be used to connect straight lengths of the conduit 4 and 6 together or by connecting conduits to a T-piece (not shown) of the conduit. Prior to assembly of the coupling 12 the control cables, pneumatic lines or the like can be pulled through the conduits in the usual way.

SFigure 4 illustrates the way in which an end of the conduit is coupled to a j junction box 40 or the like. This is accomplished by utilising an adaptor 42 of the L 950W,pAcpepP.M6151.94,5 -6invention. In this arrangement, the adaptor 42 basically replaces the sealing element and the bush 22. The nut 14, sleeve 16 and sealing element 18 perform the same function as is illustrated in Figures 1, 2 and 3. The adaptor 42 includes external threads 43 which mesh with the threads 34 of the nut. The adaptor has an annular end face 44 against which the end faces 8 and 24 of the conduit and sealing element bear, as shown in Figure 4. Preferably part of the internal bore 45 of the adaptor 42 is the same internal diameter as the conduit 4 and the other part of the bore is smaller. Alternatively a bore 45 of constant diameter may be provided in the adaptor according to requirements. The adaptor 42 includes a threaded spigot 46, the threads of which comprise metric threads which conform to usual size for electric conduits. Thus the adaptor 42 constitutes the link between processing industry thread standards on the one hand and electric industry standard threads on the other. The adaptor 42 also includes a shoulder 48 and a resilient washer 50 interposed between the shoulder 48 and a side wall of the junction box 40. A clamping ring 54 is threaded onto the spigot 46 so as to clamp against the inner side of the side wall 52. This causes a watertight seal to be formed between the junction box 40 and the adaptor 42. After the cables or pneumatic lines have been pulled through the conduit 4 and the internal bore of the adaptor 42 into the junction box 40, the coupling is completed by tightening the nut 14 on the adaptor 42 so that again the sealing element 18 is firmly sealed against the outer surface of the conduit 4. The adaptor 42 is preferably moulded from the same material as the nut 14 and bush 22. Alternatively, the adaptor could be machined from nylon, ERTALON 6 PLA or ERTALON 6 XAU.

Figure 5 illustrates the use of some of the components of the system of the invention to form an end termination 53. The end termination 53 can be provided for future expansion of the conduit system or to enable cables or fluid lines to pass therethrough for coupling to equipment, as described below. The end tr-mination 53 utilises the nut 14,bush 22 and sealing element 20, the bush 22 and sealing element being mounted on the end of the conduit 6 as before. An end termination disc 55 is placed inside the nut 14 so that its end face 57 engages the annular shoulder 36 of the nut 14. The end disc 55 includes an inner annular face 56 which abuts the end of the conduit 6 and the end face 24 of the sealing element 20. The termination is completed 95OO9pouj9,16lI.4, -7by threading the nut 14 on the threads 35 of the bush. This causes the sealing element to be firmly sealed against the outer surface of the conduit 6 and the annular face 56 of the disc 55. The central portion 58 of the disc 55 preferably has a relatively thin wall thickness so that it can be drilled so as to enable easy mounting of glands (not shown) or grommets (not shown) through which cables or fluid lines can pass. The termination 53 is preferably moulded from the same material as the nut 14, bush 22 or adaptor 42.

Alternatively it could be machined from nylon.

It will be appreciated by those skilled in the art that couplings between the ends of conduits, terminations, or couplings to junction boxes in accordance with the invention can be readily made and demounted. This gives to the user the ability to readily make changes to a conduit system in a processing plant.

The conduit system of the invention can be used to protect power cables, 15 instrument cables, pneumatic lines, hydraulic lines, vacuum lines, steam lines or other .lines which require waterproof protection.

The components of the invention can be nade in a variety of sizes to r accommodate different diameter tubes. For instance, the components can be made to cooperate with stainless steel conduit which is readily available in the following outer 960 diameters: 31.8, 38.1, 50.8, 63.5, 76.2 and 101.6. The pitch of the threads 34 is 3mm Sfor the smaller diameter tubes up to and including 50.8mm and 4mm in pitch for the i o63.5mm a diameter and above.

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Claims (6)

1. A coupling for a demountable conduit system, said coupling including: a nut provided with internal threads and an internal shoulder; a bush provided with a tapering surface which terminates at an end face of the bush and threads which are located on the exterior of the bush and extend to or substantially to said end face and can mesh with said internal threads; a sleeve including an external shoulder which is engagable with said internal shoulder, said sleeve including a tapering surface which terminates at an end face thereof; and a pair of substantially identical sealing elements each having a bore therethrough and a frustoconical outer surface which is complementary to both the tapering surface of the nut and the tapering surface of the bush whereby in use the sealing elements can be located with their frustoconical surfaces adjacent to respective tapering surfaces and said threads tightened to thereby cause the sealing elements to seal against a conduit or conduits passing through the 15 bores and wherein the nut, bush and sleeve are formed from flame retardant plastics material whereby the coupling can be used in food handling or processing industries and for electric cables.

2. A coupling as claimed in claim 1, wherein the nut, bush and sleeve are injection 20 moulded from plastics material.

3. A coupling as claimed in claim 1 or 2, wherein said threads comprise a metric thread i: conforming to standards in the processing industry.

4. A coupling as claimed in claim 1, 2 or 3, wherein said plastics material conforms to AS3000. A coupling as claimed in claim 4 wherein the plastics material comprises a medium impact flame retardant rade of ABS plastics material.

V v Q:\OI'ER\GCP\21624.C 21/10198 -9-

6. A demountable conduit system substantially as hereinbefore described with reference to the accompanying drawings. DATED this 21st day of October, 1.998 HYGENELEC PTY. LTD. By its Patent Attorneys DAVIES COLLISON CAVE a 9* a. a a.. a a a. a aq a a a a, a~ a. a a a a. a 4. ABSTRACT A coupling for demountable conduit systems which can be used for forming substantially waterproof couplings and/,r terminations in conduits for cables, fluid lines or the like, the coupling comprising first and second members which can be threaded together, at least one sealing element which, on tightening the first and second members, seals against an end of a conduit. c t IlL I' L CI *C C Si, 0 :e 1n