AU599983B2 - Flame-proof luminaire - Google Patents

Description

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COMMO1NWEALTH OF~ AUSTRALIA PATENTflS ACT 19.5:Z-L)6Z CO0M P L ZTE P EC I F rtA T (Original) FOR OFFiTCE USE~ C las s ft, Gl ass Application Nu.mber: Lodged: zcetd Complete Specification Lodged: Published: 30 May 1986 Priority: L his dcocurnint contains the anit~nddicnts rnade tund-i Section -11) and ii corrtct foi Related Art: Namne of Applicant: PAUL CHRISTOPHER BURCHELL Address of Applicant: 36 Morns Crescent, Selection Park, Springs, Transvaal, SOUTH AFRICA Actual Inventor@s): PAUL CHRISTOPHER BURCHELL Address for Servicet F,B. RICE CO, 28A Montague Street, Balmain, NEW SOUTH WALES, 2041, AUSTRALIA Complete Specification for the invention entitled! "FLAME-PROOF LUMINAIRE" The following statement is a full description of this invention, including the best method of performing it known to %e/us: _Ili- 1-~-I BACKGROUND TO THE INVENTION THIS invention relates to a flame-proof luminaire which is suitable for use in hazardous areas such as underground mines.

Of the known flame-proof luninaires, two types are relevant. The first has a safety wellglass within which is housed an incandescent globe and which is surrounded by a protective wire mesh. The wellglass is attached to a metal housing by a complicated system of screws. The use of screws means that maintenance of the lamp, for example the insertion of a new globe, is a time consuming operation. In *to underground mines, such as collieries, where the luminaires find particular application, working conditions are not ideal, and frequent maintenance can be a time-consuming and finicky operation. Also, the globes which are used, being incandescent, draw considerable power.

oo Another kind of pendant luminaire is described in SuL[. AF. :,.patent This luminaire uses a fluorescent tube and includes lamp, control gear .and power supply housings. There are various screw-threaded connections between these housings which are less than ideal from a maintenance point of view.

0 The present invention seeks to provide an alternative flame- proof O luminaire.

SUMMARY OF THE INVENTION According to the invention a flame-proof luminaire comprises a tubular housing for a ballast and any associated switchgear, the housing including connecting means to an electrical supply and an open mouth at one end thereof, a tubular, translucent cover for a fluorescent tube, which is connectable electrically to the ballast and switchgear, the cover being closed at one end and including an outwardly extending flange at the opposite, open end thereof and the flange being a tight fit in the open mouth of the housing, and releasable locking means adapted to engage the housing and the flange to prevent detachment of Sthe cover from the housing.

S- tINIT -3- The term "tight fit" refers, essentially, to a clearance fit with a small fit tolerance which, of course, will be determined by the degree of fire-proofing required for the luminaire the higher the degree of fire-proofing required, the smaller the fit tolerance will be.

The releasable locking means may be constituted by a groove extending circumferentially about the inner wall of the housing adjacent the open mouth thereof and an element, such as an internally releasable circlip, which is engagable in the groove. Similar locking means may be used to close the end of the housing opposite to the open mouth.

I In a preferred form of the invention, the flange is a separate component which is engaged about the end of the cover. Typically, the cover will be of clear polycarbonate material and the flange of steel.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows an exploded view of a luminaire according to the invention; Figure 2 shows a longitudinal cross-sectional view through the assembled luminaire; Figure 3 shows an optional locating member; and Figure 4 shows a detail of part of a modified luminaire according 0 to the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS The illustrated luminaire has a cylindrical, mild steel housing which has a closed end 12 and an open mouth 14. The housing has an

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inlet 16 and an outlet 18 each of which receives a conventional flame-proof wiring gland 20,22 of the kind manufactured by Pratley Manufacturing and Engineering Company (Proprietary) Limited. The glands 20 and 22 convey electrical wiring (not shown) into and out of the housing The housing 10 accommodates a ballast 24 and associated switchgear -4which is supported by spaced, plastic discs 26 which are a friction fit in the housing. The assembly of ballast and discs is held together by a strap 28 having a long tail portion 30 arranged loosely within the housing Adjacent its open mouth 14, the housing 10 is formed with an internal annular groove 32. Inwardly of the groove 32 is a shoulder 34.

The luminaire also has a clear, cylindrical polycarbonate cover 36 which is closed off at one end by means of a cap 38 fixed to the cover by a suitable adhesive. Secured to the cover 36 near to its open end I is a flange or an enlarged collar 40 of mild steel. Located inside the cover 36 is a U-shaped fluorescent tube 42 manufactured by Wotan Dulux of Lest Germany. In this case, the tube is an 11W tube. The o holder 44 at the end of the tube fits frictionally inside the open Smouth of the cover 36 as shown, with its electrical leads 46 being connectable in the normal way with the terminals of the ballast 24 and S the electrical wiring entering the housing through the inlet 16 so as S to place the ballast in series with the tube 42.

The flange or collar 40 locates in the open mouth of the housing with a tight, frictional fit, with the leading end of the collar S abutting the shoulder 34. A spring steel circlip 41 is engaged in the o groove 32 behind the collar to prevent accidental removal thereof.

It is a simple matter to take the luminaire apart when maintenance, o for instance replacement of the fluorescent tube or ballast, is required. All that is needed is a conventional tool for releasing the circlip from the groove. Once the circlip has been removed, the collar an be pulled out of the housing, and such maintenance as is required o° can be carried out. The ballast can be withdrawn by pulling on the tail portion 30 of the strap.

The closed end 12 of the housing 10 carries a holed boss 50 which permits the attachment of a hook which in turn enables the housing to be suspended from a cable or the like which is used to suspend a series of luminaires in spaced apart relationship. This is conventional practice in mine tunnels and the like. The luminaire can therefore be used as a pendant luminaire.

The closed end of the housing may be constituted by a steel disc located within the housing in the same manner as the flange or collar that is by means of a shoulder formed within the upper end of the housing 10, which is open and into which a disc of steel or the like is a tight fit. A circumferentially extending groove can then be formed within the now open end of the housing 10 to accommodate an internally releasable circlip by means of which the disc may be retained in place. This arrangement is more convenient with larger fittings which require a commensurately large housing 10. By allowing opening of the housing 10 in this manner, the connection and servicing of the ballast and associated switchgear is facilitated.

In the embodiment illustrated in Figures 1 and 2, the collar 40 is secured to the end of the cover by a friction fit or by means of a suitable adhesive. Figure 4 illustrates an alternative arrangement in which mating grooves 52 are formed in the collar and in the outer surface of the cover. The mating grooves are filled with a suitable cement to bond the collar and cover to one another.

In yet another embodiment, the collar is of polycarbonate and is formed integrally with the cover 36 during manufacture of the tube.

Figure 3 illustrates an optional locating member 54 of flexible plastics material which has a cut-out 56 shaped as shown. This member is dimensioned to fit transversely and reasonably tightly in the cover 36 with the legs 58 of the tube located in the round portions of the cut-out 56. The member 54 prevents undue movement of the tube within the cover.

The embodiments described above satisfy the regulations regarding flame-proofing, the various fits and tolerance being varied to 3O accommodate the requirements in respect of flame propagation, gas permeation and the like.

Claims (2)

1. 3. A flame-proof luminaire according to claim 2 in which the retaining element is an internally releasable circlip, which is engageable in the groove. A flame-proof luminaire according to any one of the preceding claims in which the |i flange is a separate component which is engaged about the end of the cover. 1 A flame-proof luminaire according to any one of the preceding claims in which the end of the housing opposite the open mouth is closed by means of a closure element which is a tight fit in the end of the housing, releasable locking means being provided which is adapted to engage the housing and the closure element to prevent detachment thereof from the housing. AA1 'NT -7-
2. 6. A flame-proof lumninaire substantially as described in the specification with reference to the accompanying drawings. DATED this 14 day of may 1990 PAUL CHRISTOPHER BURCHELL Patent Attorneys for the Applicant: F.B. RICE CO. 0 00 00 0 0000 O 0~O 0 0 0 O 004 CO 00 00 0 a 00 0 0; 4'A LWi7 C-)