THIS INVENTION relates to coupling devices and particularly a coupling
for connecting a vacuum line to a body such as an autoclave having an internal
chamber to be evacuated.
A coupling of this kind conventionally comprises a cylindrical body
which is threadedly engaged upon the wall of the autoclave about an aperture therein,
using PTFE tape or the like to provide a seal and to prevent leakage past the thread.
Such a coupling requires frequent replacement in view of the high temperatures
experienced in the operation of such equipment. This is carried out by unscrewing
the coupling from the autoclave wall and replacing it with renewed tape or other
Notwithstanding frequent replacement, there is a continuous risk of
leakage past the thread.
It is an object of the present invention to provide a coupling of
this kind for such an application, where the risk of leakage is at least substantially
avoided and where replacement of any part of the coupling is required much less
According to the present invention there is provided a coupling for
connecting a vacuum line to a body having an internal chamber to be evacuated,
the coupling comprising a first part adapted to be sealingly engaged upon the wall
of a body about an aperture therein and having an internal bore which thus communicates
with the internal chamber of the body, and a second part also having an internal
bore for communication with the bore of the first part, the second part being removably
and slidably engaged with the first part, sealing means cooperating with the first
and second parts to prevent fluid leakage there between, and means for readily
enabling separation of the two parts.
The first or second part may have an internal valve adapted to seal
a passage through the coupling except when connected to a vacuum line.
The valve may be removably retained within the coupling by a circlip.
The sealing means which cooperates with the first and second parts
may comprise a first seal ring adapted to seal in an axial direction of the coupling
between two cooperating radial faces respectively of the two parts, and at lest
one further seal ring forming a seal between cooperating axial faces of the two
The means for readily enabling separation of the two parts may comprise
a circlip cooperating between an annular face of one part and a cylindrical wall
of the other of said parts and readily accessible externally of the coupling thus
to enable removal of the second part from the first part.
The second part may be removably and slidably engagable within a
cylindrical recess in the first part and the sealing means may comprise a plurality
of O-rings mounted on the second part and cooperating with internal faces of the
The first part may include a spigot adapted to be received within
the aperture in the wall of the body and to be fixed therein by welding.
Both parts of the coupling may be predominantly of stainless steel.
An embodiment of the invention will now be described, by way of example
only, with reference to the accompanying drawings in which:-
- Fig. 1 is a cross-sectional view of a conventional coupling for connecting
a vacuum line to a body having an internal chamber to be evacuated;
- Fig. 2 is a similar view but of a coupling made in accordance with the invention;
- Fig. 3 is a view similar to Fig. 2 illustrating, within the coupling, a closure
- Fig. 4 is an exploded view of the parts of which the coupling is comprised.
Referring now to Fig. 1, in a conventional arrangement the coupling
comprises a cylindrical body 10 having in one end region an internal thread 11
adapted to be engaged upon an externally threaded spigot welded or otherwise attached
sealingly to a body such as an autoclave having an internal chamber to be evacuated.
A valve mechanism (not shown) is provided within the bore 12 of the
body 10 such that the central passage through the coupling shall be closed except
when connected to a vacuum line having an actuator to open the valve.
The body 10 comprises a spigot 13 to which a vacuum line is conventionally
The threaded connection between the body 10 and the spigot on the
autoclave provides an inadequate seal without the use of PTFE tape or the like
which thus requires frequent replacement. Between replacements there remains the
risk of leakage across the thread and so such an arrangement is unreliable in some
Referring now to Fig. 2, a coupling made in accordance with the invention
comprises two parts the first being a cylindrical body 20 having a central axial
passage 21 and at one end a spigot 22 which may be plain faced or grooved as required
but is adapted to be inserted into an aperture in an autoclave wall, to be in communication
through the passage 21 with an internal chamber to be evacuated, the spigot 22
being preferably welded into the aperture thus to be permanently attached and sealed
The cylindrical body 20 defines an internal cylindrical recess 23
into which passes a cartridge generally indicated at 24. The cartridge comprises
a cylindrical body 25 and a spigot 26 to which a vacuum line may be connected.
A central passage 27 within the body 25 is tapered at 28 to provide a valve seat
as will be described and communicates with a narrower bore 29 extending centrally
and axially within the spigot 26.
O-rings 30 are situated around the body 25 within annular grooves
therein and serve as a seal between the opposed cylindrical walls of the recess
23 and the body 25, while a further O-ring 31 is located in an outwardly open annular
groove on an inner end face 32 of the body 25 and therefore bears against an end
face 33 of the body 20.
Thus, the second part or cartridge 24 of the coupling is slidably
and removably engaged within the recess 23 of the first part 20. A circlip 34 removably
fixes the two parts together, an annular groove 35 being provided in an outer end
wall of the part 24 to enable access with circlip pliers for removal of the circlip
Referring now to Figs. 3 and 4 it can be seen that within the second
part 24 of the coupling there may be located a valve pin 36 carrying a valve member
37 with an O-ring 38 to seal against the tapering wall 28 of the bore 27, and a
coil spring 39 normally urges the valve member 37 into the closed condition to
seal the passage. The spring 39 engages a member 40 having a central bore 42 through
which passes an extension 43 of pin 36. The member 40 is maintained within the
bore 27 of the second part of the coupling by means of a circlip 41.
In use therefore with the first part 20 permanently attached to an
autoclave wall the cartridge or second part of the coupling may be readily removed
by first removing the circlip 34. Any parts of the valve mechanism to be replaced
are then easily withdrawn from the second part of the coupling after removal of
the circlip 41.
For connection of the coupling to a vacuum line the valve is opened
by engagement and movement of the pin 36 to lift the valve member 37 from the tapered
wall portion 28 against the action of spring 39. A conventional connector (not
shown) for attachment of the coupling to the vacuum line containing an actuator
which depresses the pin 36 when the connector is attached to the spigot 26.
It will be appreciated that the coupling includes no threaded parts
through which leakage may occur, and the vacuum created within the autoclave chamber
serves only to draw the cartridge inwardly thus enhancing the seal between the
O-ring 31 and the face 33 of the first part of the coupling.
The two parts of the coupling are preferably made from stainless steel
but may be of any material suitable to the application and the ambient conditions
It is not intended to limit the invention to the arrangement described
and illustrated herein. For example, the two parts could be reversed in function
i.e the second part could be permanently fixed to the autoclave wall with the first
part being removably and slidably engaged therewith. The essence of the invention
is the avoidance of a threaded interface between the coupling and the body to be
evacuated, and that ready removal and dismantling of the coupling can be effected
for replacement of the valve parts if and when necessary.