U.S. patent application number 10/099443 was filed with the patent office on 2003-07-10 for device for closing a pot-like digestion vessel.
This patent application is currently assigned to MILESTONE S.R.L.. Invention is credited to Lautenschlager, Werner.
Application Number | 20030127311 10/099443 |
Document ID | / |
Family ID | 7965439 |
Filed Date | 2003-07-10 |
United States Patent
Application |
20030127311 |
Kind Code |
A1 |
Lautenschlager, Werner |
July 10, 2003 |
Device for closing a pot-like digestion vessel
Abstract
A device 5 for closing pot-like digestion vessel 1 whose opening
is covered by a cover 3, has a pressure-applying plunger 6, a
screwing part 7 arranged co-axially with the pressure applying
plunger 6 and a resilient pressure-generating means 8 arranged
between the pressure-applying plunger 6 and the screwing part. The
screwing part and the pressure-applying plunger 6 fit round one
another in a socketed arrangement.
Inventors: |
Lautenschlager, Werner;
(Leutkirch, DE) |
Correspondence
Address: |
FITZPATRICK CELLA HARPER & SCINTO
30 ROCKEFELLER PLAZA
NEW YORK
NY
10112
US
|
Assignee: |
MILESTONE S.R.L.
SORISOLE
IT
|
Family ID: |
7965439 |
Appl. No.: |
10/099443 |
Filed: |
March 15, 2002 |
Current U.S.
Class: |
202/96 |
Current CPC
Class: |
G01N 1/44 20130101; B01J
2219/1215 20130101; B01J 3/03 20130101; B01J 2219/1209
20130101 |
Class at
Publication: |
202/96 |
International
Class: |
C10B 051/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 20, 2001 |
DE |
201 20 649.8 |
Claims
1. Device for closing a pot-like digestion vessel whose opening is
covered by a cover, said device comprising: a pressure-applying
plunger; a screwing part arranged co-axially with the
pressure-applying plunger; and a resilient pressure-generating
means arranged between the pressure-applying plunger and the
screwing part, one of the screwing part and the pressure-applying
plunger being fitted around the other in a socketed
arrangement.
2. Device according to claim 1, wherein an annular wall extends
from the screwing part and fits around the pressure-applying
plunger.
3. Device according to claim 2, further including a ring seal
arranged between the annular wall and the pressure applying
plunger.
4. Device according to claim 3, wherein the ring seal is formed by
a sealing ring made of resilient material, said ring seal being
mounted in at least one of an annular groove in the circumferential
surface of the annular wall and the outer circumferential surface
of the pressure applying plunger.
5. Device according to claim 1, wherein the screwing part has an
outside thread.
6. Device according to claim 5, wherein the screwing part is
screwed into a fixed abutment which is located above the screwing
part and the pressure-applying plunger.
7. Device for closing a pot-like digestion vessel whose opening is
covered by a cover, said device comprising: a pressure-applying
plunger; a screwing part which fits around the pressure-applying
plunger, said screwing part having a screw thread in a bottom edge
region thereof; and an abutment which surrounds the digestion
vessel, said abutment being formed by a supporting ring which is
fixed to a circumferential region of the digestion vessel.
8. Device according to claim 2, wherein the supporting ring is
fastenable to an outer circumferential surface of, fits under a
flange of, or is formed on a flange of a digestion vessel.
9. Device according to claim 7 or 8, wherein the pressure-applying
plunger is guided to slide move axially along a hollow cylindrical
slide face on the screwing part.
10. Device according to claim 9, wherein axially spaced annular
grooves are arranged in the cylindrical slide face of the
pressure-applying plunger.
11. Device according to claim 7, wherein the pressure-applying
plunger is U-shaped in cross-section, and wherein a resilient
pressure-generating means is arranged in a recess created by the
U-shaped cross-section of the pressure-applying plunger.
12. Device according to claim 11, wherein the resilient
pressure-generating means is formed by disc or coil spring
means.
13. Device according to claim 7, wherein a co-axial hole is formed
in the pressure-applying plunger.
14. Device according to claim 7, wherein the screwing part has a
guiding section in its top region for guiding an extension which
extends from the pressure-applying plunger.
15. Device according to claim 7, wherein the screwing apart is
provided at its top with a formation for receiving a rotational
force.
16. Device according to claim 7, wherein the pressure-applying
plunger forms a digestion vessel cover.
17. Device according to claim 7, wherein, a position-indicating
marking is arranged between the screwing part and the abutment.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The invention relates to a device for closing a pot-like
digestion vessel for the analysis of heated materials.
[0003] To perform an analysis of materials, it is known for one or
more materials, e.g. a solid or liquid sample material, to be
heated in a digestion vessel, as a result of which a pressure above
atmospheric is generated in the digestion vessel and this in turn
promotes the digestion of the sample material.
[0004] A device of this kind is described in EP 0 830 891 A1. In
this generic design a resilient pressure-generating means which
acts between a screwing part and a pressure-applying plunger is
formed by a stack of metal disc springs arranged one above the
other, the pressure-applying plunger taking the form of a U-shaped
component in which is arranged a dome-like cage part which is of
metal and forms a Faraday cage for the disc springs. This device
has a large number of parts and is structurally large and in
particular tall, which means that it too has the advantages
described above.
[0005] A device for closing a pot-like digestion vessel is also
described in GB 2 184 040 A. In this known device, the
pressure-applying plunger, the screwing part, and the resilient
pressure-generating means arranged between them, are held in a
hat-like screwed cover of a pot-like supporting vessel, into which
is fitted a holding vessel against whose cover the
pressure-applying plunger acts. The screwing part is mounted to be
vertically displaceable on a pressure-applying piece in a vertical
guide hole in the screwed cover and is in the form of a nut which
is screwed onto a pressure-applying piece, which latter extends
co-axially upwards from the pressure-applying plunger and is on a
threaded stem which passes through a guide hole. In the annular
wall of the hat-like screwed cover there is arranged, at the same
height as the top edge of the supporting vessel in the screwed-on
state, an internal annular groove from which a venting passage
extends radially outwards through the annular wall. This known
design has a large number of parts, is structurally large, is
complicated and costly to manufacture and is time-consuming to
manipulate. There is also the risk that the pressure-applying piece
and the nut will move away from one another, due to fouling for
example, as a result of which different pressure ranges will arise
when the cover of the holding vessel is closed and opened.
SUMMARY OF THE INVENTION
[0006] The object of the invention is to simplify a device of the
kind detailed at the beginning and to design it in such a way that
a small or low construction is obtained. Furthermore, the device is
to be improved in respect of its operation. An attempt is also made
to reduce the number of separate parts in the device and the amount
of material it consumes.
[0007] In a device according to the invention, a pressure-applying
plunger and a screwing part fit around one another in a socketed
arrangement.
[0008] In more specific aspects, at least one annular wall, which
may be part of the pressure-applying plunger and which extends
upwards therefrom preferably as an integral part thereof, fits
around the screwing part like a socket. Also, the annular wall may
be part of the screwing part and may extend downwardly therefrom,
preferably as an integral part thereof and may fit around the
pressure-applying plunger like a socket.
[0009] In other specific aspects, two circumferential walls are
provided of which extends upwardly from the pressure-applying
plunger and the other extends downwardly from the screwing part
wherein one of the annular walls fits around the other in a
socketed arrangement. Not only does this allow guidance and/or
radial support to be obtained for the pressure-applying plunger but
the interior space between the pressure-applying plunger and the
screwing part which holds the resilient pressure-generating means
is closed off by at least one annular wall, which means that it is
possible neither for contaminants from the holding space in the
holding vessel to make their way out into the interior space for
the resilient pressure-generating means if there is a reaction
which produces an excess pressure and lifts the cover of the
holding vessel, nor for other contaminants to do so from the
surroundings of the device. The interior space is also protected
against aggressive treating or digesting chemicals in this way, as
a result of which the movement mechanism of the device is protected
and a long life is obtained. If mounting is on a thread, this gives
positive guidance in both axial directions of movement, and in the
event of an adjustment this means that the screwing part will still
be safely and securely adjusted when there is some tightness in the
mounting.
[0010] According to a further aspect, the seal between the
pressure-applying plunger and the screwing part can be improved by
arranging between the guide faces which co-operate in a socketed
arrangement a seal, and preferably a ring seal, which may for
example be an O-ring, which can be inserted in an external annular
groove in the part which is fitted round or in an internal annular
groove in the part which fits round.
[0011] Within the scope of the invention there are many possible
ways for the screwing part to be supported against an abutment. An
abutment of this kind may for example be formed by a supported disc
which fits round a location for the digestion vessel in a space to
which microwaves can be applied. If a disc of this kind is open in
all directions it can also be used to cover a plurality of
circumferentially distributed locations for digestion vessels
having the device. In this case the disc may, in a known manner, be
a turntable which is mounted to be rotatable in the microwaving
space together with the locations.
[0012] The abutment may also be formed by the top wall of a
pressure-supporting body which defines the two sides, the top and
the bottom of a location for a digestion vessel. In this embodiment
the digestion vessel may be placed in the location and removed from
it again from one side, with the device if required.
[0013] It is also possible in accordance with another aspect of the
invention for the abutment to be formed on or supported against the
circumferential surface of the digestion vessel. For this purpose
the screwing part may be formed by the top wall of a cap whose
annular wall can be connected, in the free area of its edge for
example, to the digestion vessel, by screws for example. It is
particularly advantageous in this case if an externally-threaded
screwed ring is fitted onto the circumferential surface of the
digestion vessel and is supported against the vessel, preferably
against the underside of a flange in the edge region of the
digestion vessel, so that the flange will provide the reaction
forces from the device and will ensure the screwed ring is located
by contact. This embodiment is notable for its small structure,
which takes up little space, is handy, consumes little material and
is also low in weight.
[0014] It is possible and advantageous in all the embodiments for a
marking or scale to be so arranged between the screwing part or
parts added thereto and the abutment that, in respect of the
resilient closing force from the pressure-generating means, the
screwing part can be preset in steps or steplessly in such a way
that a given opening pressure is obtained at which, if it is
exceeded in the interior space in the digestion vessel, the cover
of the vessel automatically lifts and thus opens. This allows the
operator to preset desired maximum internal pressures in the
holding space in the holding vessel in the light of the material or
materials to be treated.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] Advantageous embodiments of the invention will be explained
in detail below by reference to a plurality of embodiments and
drawings. In the drawings
[0016] FIG. 1 is a vertical section through a vessel arrangement
having a device according to the invention for closing a digestion
vessel;
[0017] FIG. 2 is an enlarged view of the detail marked X in FIG. 1;
and
[0018] FIG. 3 is a vertical section through a modified vessel
arrangement having a device for sealing a digestion vessel which is
also modified.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0019] A pot-like digestion vessel 1, having a circumferential wall
1a which is in the form of a hollow cylinder and is for example
relatively thin, and a flat bottom wall 1b, is surrounded, and
supported in the radially outward direction, by a supporting shell
2 in the form of a hollow cylinder which may extend up to a flange
1c at the top edge of the circumferential wall 1a, thus allowing
the flange 1c to rest on the top front face of the supporting shell
2.
[0020] The opening at the top of the digestion vessel 1 has to be
opened and closed with a cover 3 which is for example flat and in
the form of a stepped cylinder and of which, in the embodiment
shown, a bottom cylindrical extension 3a fits into the digestion
vessel 1 with little play and is sealed, preferably by a ring seal
4. The latter may be formed by an O-ring 4a which is mounted in an
annular groove in the circumferential surface of the cover
extension 3a. The cover 3 thus rests on the flange 1c by face 3b of
its shoulder.
[0021] The device for closing the digestion vessel 1 even when
there is a pressure above atmospheric in the digestion space 1d
within the vessel, which device is referred to as a whole by
reference numeral 5, comprises three main parts, namely a
pressure-applying plunger 6, a screwing part 7 at least part of
which is arranged over the latter, and a resilient
pressure-generating means 8 which is arranged between an upwardly
directed supporting face 6a on the pressure-applying plunger 6 and
a downwardly directed supporting face 7a on the screwing part 7 and
which in functional operation is preloaded with a given compressive
force. In the embodiment shown the pressure-generating means 8
comprises a plurality of disc springs stacked on top of one another
in opposite directions. At least in its upper region the screwing
part 7 has an outside thread 7b by which it is screwed into a
threaded bore 9a in an abutment 9 as a screwing part. To allow the
screwing part 7 to be turned, there is arranged in its top face an
element 11 for applying rotation intended for a tool for rotation
which can be positively engaged therewith in rotation. In the
embodiment shown the element 11 for applying rotation is formed by
a non-circular recess for insertion.
[0022] To cover the space 12 occupied by the pressure-generating
means and thus to protect it from fouling, there is provided an
annular wall 7c which surrounds the space 12 and which fits at
least partly round the pressure-applying plunger 6 and/or the
screwing part 7 in a socketed arrangement. In the embodiment shown
the annular wall 7c, which is preferably in the form of a hollow
cylinder, extends downwards from the screwing part 7 as an integral
part thereof, in which case it at least partly fits over the
preferably cylindrical circumferential surface of the
pressure-applying plunger 6 with clearance for movement, thus
making space 12 inaccessible from the sides.
[0023] The amount of vertical overlap a may be sufficiently large
to allow a guidance function to be performed between the
pressure-applying plunger 6 and the screwing part 7 and/or a ring
seal 13 when the device 5 telescopes in a manner which has yet to
be described. Arranged in the gap at the overlap there is
preferably a sealing ring 13a, e.g. an O-ring, which is mounted in
an annular groove in the circumferential surface of the
pressure-applying plunger 6 and which is covered by the inner
surface of the annular wall 7c in any telescoped position. The
maximum amount of telescoping movement b in the vertical direction
is determined in the present embodiment by the distance between the
annular wall 7c and the cover 3. If the pressure-applying plunger 6
is formed to have a flange 6b as indicated in ghost lines, then the
maximum amount of telescoping movement b will be determined by the
distance from flange 6a. Flange 6b allows the area over which the
pressure-applying plunger 6 acts against the cover 3 to be enlarged
and the pressure per unit area which comes into play in operation
to be reduced.
[0024] The pressure-generating means 8 or rather the spring discs
may be located by the inner circumferential surface of the annular
wall 7c. However, to reduce the frictional wear which occurs
between the two during telescoping, the pressure-generating means
8, which is preferably annular, is located on the inside with a
small amount of clearance for movement by a locating spigot 6c
which in the embodiment shown extends upward from the
pressure-applying plunger 6 as an integral part thereof and may
then engage in, or terminate shortly before, a guide hole 7d
present between supporting face 7a and the element 11 for applying
rotation, thus providing additional guidance, which is not
absolutely essential however, for the pressure-applying plunger
6.
[0025] Arranged in the pressure-applying plunger 6, preferably
co-axially therewith, is a full-length hole 14 which may for
example be lined with an annular wall 15 which may have at the
bottom end a flange which allows it to be inset into a recess in
the pressure-applying face. To allow it to be secured axially in
the pressure-applying plunger 6, the annular wall 15 may be a
press-fit in the plunger.
[0026] The hole 14 may be used to hold functional members, e.g.
sensor members, which pass through the screwing part 7 and which
are functionally connected above it to associated control or
regulating devices. A temperature sensor for example may be
provided, which is inserted in hole 14. A pressure measuring
element may also be inserted in hole 14, whose vertical position,
or rather whose change in position, when the cover 3 lifts serves
as an indication of the level of the internal pressure prevailing
in the digestion space 1d in operation.
[0027] In the embodiment shown in FIG. 1, the abutment 9 is formed
by the top wall 16a of a supporting housing 16 which may be of
box-like configuration with a curved wall 16b and two side walls
16c and which forms a holding space 17 for the digestion vessel 1
which is open at the front or extends right through horizontally
and in which the vessel can be set up from the appropriate side and
from which it can be removed again. In the set-up state, the
digestion vessel 1 stands with its bottom wall 1b, which is flat in
the embodiment shown, on the bottom wall 16b of the supporting
housing 16, by which means the first bottom wall 1b is supported
against the internal pressure. An intermediate layer 18, which is
preferably made of a thermally insulating material, e.g. plastics
material, is arranged between bottom walls 1b and 16b to reduce the
heat withdrawn from digestion vessel 1.
[0028] Due to the relatively great length which is possible for it,
the annular wall 7c which extends downwards from screwing part 7
allows the screwing part 7 to have a relatively large range of
adjustment and thus to be adapted to digestion vessels 1 of
different heights, if the outside thread 7b extends at least to the
bottom end region of the annular wall 7c or for example for its
entire vertical length.
[0029] To prevent the pressure-applying plunger 6 from dropping out
of the position where the screwing part 7 fits round it when there
is no digestion vessel 1 under the device 5, a limiting arrangement
21 is provided between the pressure-applying plunger 6 and the
screwing part 7, or rather the annular wall 7c, to restrict the
maximum extension movement of the pressure-applying plunger 6 and
in the present embodiment this is formed by a stop arrangement
having a stop member 22 in the region of the bottom end of annular
wall 7c. The opposing stop member is preferably formed by the
sealing ring 13a, which projects slightly from the circumferential
surface of pressure-applying plunger 6 in the radial direction and
can thus form the opposing stop member 22 without the need for any
special opposing stop member. As a result, sealing ring 31a
performs a sealing and stopping function. Stop member 21 is formed
by an internal annular bead on the inner circumferential surface of
annular wall 7c. To allow a small clearance for movement or
sliding, the diameter of the annular bead is made larger than the
diameter of pressure-applying plunger 6, thus enabling the latter
to move in the annular bead. The inside diameter d2 of the annular
bead is made somewhat larger than the inside diameter d1 of the
rest of the annular wall 7c, thus enabling the annular bead to be
formed. At the same time, the inside diameter d2 is made only
sufficiently large for sealing ring 13a still to form a resilient
seal against the inner circumferential surface 7e of annular wall
7c. In the present embodiment, the outer flank of the stop member
22 or annular bead is formed by an oblique or rounded lead-in face
23. The inner flank 24 is the face of a step which preferably
extends approximately at right angles to the axis of the
pressure-applying plunger 6. In the present embodiment the internal
annular bead is pointed in cross-section, thus giving a pointed
annular edge. This will cause the sealing ring 13a to be sliced off
if the pressure-applying plunger 6 is forcibly extracted from its
socketed connection and protection is provided against dismantling
in view of the damage that would be done to the sealing ring
13a.
[0030] In the embodiment shown in FIG. 3, where the same or
comparable parts have been given the same reference numerals, the
screwing part 7 and its annular wall 7c have been made so large
that it fits round the digestion vessel 1 like a cap, at least in
the region of the vessel's upper edge, and is screwed to the vessel
so that the circumferential wall 1a or the flange 1c or a
supporting shell 2 which is present if required, to any of which
the annular wall 7c may be screwed, forms the abutment 9. In the
present embodiment a supporting ring 25 is fitted onto the
digestion vessel 1, preferably in the top region of the digestion
vessel 1, and in particular is arranged to rest against flange 1c
and to be connected to the outer circumferential surface of the
digestion vessel 1, e.g. by pressing on or bonding. A connection of
this kind ensures that the forces applied to the abutment are
transmitted to the digestion vessel 1. If the supporting ring 25
rests against flange 1c, there is no need for a connection to the
outer circumferential surface as the flange 1c supports the forces
from the abutment. However, in this case too it is advantageous for
the supporting ring 25 to be retained on the digestion vessel 1 in
such a way that it cannot be lost, e.g. by pressing on or
bonding.
[0031] The screwed connection between the screwing part 7 and the
supporting ring 25 preferably comprises an inside thread 7f in the
region of the end of annular wall 7c and a matching outside thread
on the supporting ring 25.
[0032] In the two embodiments described above, the
pressure-applying plunger 6 can form the cover 3, as shown in FIG.
3. In the embodiment shown in FIG. 1 the cross-sections of the
pressure-applying plunger 6 and the screwing part 7 would have to
be enlarged as appropriate to allow the pressure-applying plunger 6
to form the cover 3. The hole 14 would also have to end at a
distance from that end of the pressure-applying plunger 6 which is
adjacent the digestion vessel 1.
[0033] In all the embodiments it is also possible for the
pressure-applying plunger 6 to be made U-shaped in cross-section as
shown in FIG. 3 and for it thus to be provided with a
circumferential wall 6d which, due to its axial length, ensures
that the pressure-applying plunger 6 is guided in such a way as to
be secure against tilting and which can also ensure that there is a
sufficiently good seal. It is also advantageous for one or more
grooves 6e spaced at an axial distance from one another to be
arranged in the circumferential surface of the circumferential wall
6d, these grooves both improving the seal and, in view of the
differing thermal expansions, preventing any harmful stresses from
arising in the fit, particularly when the material of the
pressure-applying plunger is soft or yielding particularly at
fairly high digestion temperatures.
[0034] In the embodiment shown in FIG. 3, the resilient
pressure-generating means 8 is formed by a coil spring which is
supported against the top wall of the screwing part 7 and engages
against the pressure-applying plunger 6, in the bottom of a recess
in the present case.
[0035] In the embodiment shown in FIG. 3 too, there may be provided
a locating spigot 6c which is once again preferably circular in
cross-section and can be guided longitudinally or rather vertically
in the top wall of the cap-like screwing part 7 with clearance for
movement. At its bottom end the locating spigot 6c preferably has a
flange to reduce the pressure per unit area, against which the
pressure-generating means 8 can bear.
[0036] In all the embodiments it is advantageous for there to be
made, between the screwing part 7 and a part positioned on the
digestion vessel 1 or the cover 3 or the pressure-applying plunger
6, a marking which shows the axial position of the screwing part 7
in relation to the part which is positioned and which preferably
allows the screwing part 7 to be preset in a defined manner. The
marking may for example be formed by a scale and a pointer which
are situated on respective ones of the two parts to be compared. In
the embodiment shown in FIG. 1 the marking 27 may be arranged for
example on the top faces of the screwing part 7 and the abutment 9,
preferably close to or at the threaded joint in the screwed
assembly, e.g. in the form of an annular scale on the top wall 16a
and a pointer on the screwing part, 7.
[0037] In the embodiment shown in FIG. 3 the marking 27 may for
example be formed by the front end of the locating spigot 6c and
the top or bottom edge of the guide hole 7d. It is also possible
for the markings or scale divisions to be made on the surface of
the inner wall of the guide hole at axial distances from one
another which, against the free end of the locating spigot 6c,
allow the position of the locating spigot 6c, and hence the opened
or closed position of the pressure-applying plunger 6 and if
required of the cover too, to be seen or read off.
[0038] In the embodiment shown in FIG. 1 the digestion vessel 1 is
made of a corrosion-resistant material and in particular of
plastics material and preferably PTFE. The other parts of the
digestion vessel 1 including the supporting housing 16 are
preferably made of material which is permeable to microwaves and
preferably plastics material. This may also be true of the device
5. In the embodiment shown, the spring or the resilient members
forming the pressure-generating means 8 are made of metal and in
particular of spring steel or stainless steel. The screwing part 7
too may be made of metal, e.g. stainless steel, in which case it
acts as a Faraday cage for the spring. Operation is improved if the
cage has a polished surface and its edges are rounded. It is also
advantageous for the dimensions of the cage, i.e. its diameter and
axial length, preferably to be sized at between a quarter and one
complete wavelength of the microwave radiation used. In addition,
the surface of the metal cage may be coated with a material, such
as PTFE for example, which is resistant to corrosive chemicals, to
prevent the surface of the metal from being attacked by such
chemicals.
[0039] For a digestion process, a sample material is placed in the
digestion vessel 1 and the digestion vessel 1 is closed with device
5. In the course of this the screwing part 7 is screwed in (FIG. 1)
or on (FIG. 3) sufficiently far for the resilient
pressure-generating means 8 to exert a closing force which
corresponds to a given internal pressure. If the internal pressure
rises in operation to more than a given value or rather the set
value, the cover 3, i.e. the pressure-applying plunger 6,
automatically opens, in which case the pressure-generating means 8
yields and the internal pressure can escape. This being the case,
the device 5 acts as a pressure-release valve with the opening
pressure being settable by screwing in the screwing part 7.
[0040] The embodiment shown in FIG. 3, where the same or comparable
parts have been given the same reference numerals, differs from the
embodiment described above in respect of a plurality of
arrangements.
[0041] Firstly, the abutment 9 is not part of a supporting housing
16 which holds the entire digestion vessel 1 but of a small
cap-like supporting housing 22 which, although it similarly
transmits the reaction forces to the digestion vessel 1, only fits
round the top region of the digestion vessel 1 and is supported
directly or indirectly against this top region and thus transmits
the reaction forces to this region of the digestion vessel 1. The
direct or indirect connection to the top region of the digestion
vessel 1 is made by a screwed connection. Provided in the annular
wall 7c above the flange 1c or the supporting ring 25 is a radial
venting opening 7e. The bottom wall 1b of the preferably
cylindrical holding vessel 1 is preferably hemispherical in shape,
thus enabling the wall to be evenly stressed.
* * * * *