Closure member for pressure vessel

A closure member for a pressure vessel, the closure member including a flange member secured with the pressure vessel, a pressure vessel door supported by the pressure vessel, a ring assembly mounted with the flange member for engaging the pressure vessel door as a result of selective rotational movement of the ring assembly from an unlocked position to a locked position by the radially contracting cooperative movement of engaging members into engagement with the pressure vessel door as a result of such rotational movement.

FIELD OF THE INVENTION 
The present invention relates to closure members utilized in selectively 
sealing vessels capable of withstanding elevated pressures. 
BACKGROUND OF THE INVENTION 
Locking mechanisms for door assemblies have long been used on a wide 
variety of doors to a chamber and/or room that is desired to be isolated. 
Examples of various types of locking structures are shown in U.S. Pat. 
Nos. 1,269,572; 2,664,611; 4,114,933; and 4,342,207. 
However, if the chamber and/or room that is to be secured requires an 
ability to maintain an greater pressure from within the chamber than 
exists outside the chamber, additional pressure-related considerations 
must be taken into account. Such pressure vessel closure assemblies have 
long been known and include a wide variety of structures as shown in U.S. 
Pat. Nos. 2,010,200 and 3,258,151. Of the types of pressure closure 
assemblies for pressure vessels utilizing some type of annular or radially 
expanding element, some examples are shown in U.S. Pat. Nos. 2,196,895; 
4,102,474; 4,315,577; and 4,489,850. However, so far as known, all of the 
aforementioned pressure vessel closure members require a locking structure 
mechanism that is in part contained within the door assembly itself. In 
some cases, as for example with U.S. Pat. No. 4,102,474, a central portion 
of a closure member is required to be maintained at a pressure in order to 
properly actuate particular elements thereof in order to accomplish the 
locking operation. In like fashion, U.S. Pat. No. 4,315,577 discloses a 
centrally mounted operator rotating in such a fashion that the locking 
elements are individually and independently moved outwardly based upon 
movement of a pin in a spiraling track. Likewise, in U.S. Pat. No. 
4,489,850, the door mechanism contains a plurality of locking pawls 
contained with the door assembly which move radially outwardly into an 
engaging position with the pressure vessel to effectuate sealable 
engagement therewith, with the locking pawls having elongate slots formed 
therein. 
Thus, so far as known, no pressure vessel closure member is available for 
securement of the pressure vessel door by the radial contraction of the 
retaining elements about a pressure vessel door which has no sealably 
movable parts therewith. 
SUMMARY OF THE INVENTION 
The present invention relates to a new and improved closure member for a 
pressure vessel having a pressure vessel door and a ring assembly with 
engaging members that are radially movable between an unlocked position 
and locked position, wherein the engaging means is in a radially expanded 
position when in the unlocked position and is movable to a locked position 
wherein the engaging means is in a radially contracted position for 
engaging the pressure vessel door for securing same with the pressure 
vessel.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The closure member of the present invention is designated generally with 
the letter C. The closure member C is adapted to be used with a pressure 
vessel V. The closure member C includes generally a flange member F 
mounted with the pressure vessel V by mounting means M. A pressure vessel 
door D is supported by the mounting means M for movement with respect to 
the pressure vessel V. The closure member C further includes a ring 
assembly A that is mounted with the flange member F for selective 
rotational movement between a locked position wherein the pressure vessel 
door D is lockably engaged and an unlocked position wherein the pressure 
vessel door D is not lockably engaged. The ring assembly A further 
includes engaging means E which is movably mounted therewith for radially 
contracting into engagement with the pressure vessel door D upon 
rotational movement of the ring assembly A from the unlocked position to a 
locked position, as detailed more specifically hereinbelow. 
The closure member C of the present invention is adapted to be used with 
the pressure vessel V. As shown in FIG. 1, the pressure vessel V may 
include a hyperbaric chamber 10, or any other type of chamber 14 
(cylindrical or otherwise) designed to contain elevated pressures therein. 
The pressure vessel V may include a base member 12 having a chamber 
support 12a for supporting a the chamber 14. The chamber 14 may include a 
cylindrical window 14a, a central band 14b and an end plate 14c. 
Preferably, the closure member C is mounted with the chamber 14 at the end 
portion 14g, which opposes end portion 14h where end plate 14c is mounted. 
As detailed more fully hereinbelow, the closure member C is secured with 
the chamber 14 by tie rods 16. An interior chamber 18 that is adapted to 
be sealably closed by the closure member C is formed by the inner annular 
surface 14d of the chamber 14 (FIG. 3) and the interior end surface 14e of 
the end plate 14c of the chamber 14 of the pressure vessel V. 
The closure member C of the present invention includes a flange member F. 
The flange member F includes flange member 20 having an inner annular 
surface 20a, an outer annular surface 20b, an inner radial surface 20c and 
an outer radial surface 20d (FIGS. 5,6). An annular flat 20e and an 
adjacent radial surface 20f are formed proximate to the juncture of the 
outer annular surface 20b and outer radial surface 20d. 
The closure member C of the present invention further includes a ring 
assembly A that is adapted to be mounted about the flange member F for 
rotational movement. The ring assembly A includes a ring member R and 
engaging means E. The ring member R includes a ring member 30 having an 
exterior annular surface 30a, an interior annular surface 30b, an interior 
radial surface 30c adjacent to the interior annular surface 30b, and an 
exterior radial surface 30d. Preferably, the exterior annular surface 30a 
and interior annular surface 30b are concentric with one another, while 
interior and exterior radial surfaces 30c, 30d are preferably parallel 
with one another. Preferably, an annular surface 30e is formed adjacent to 
the interior radial surface 30c proximate to the exterior annular surface 
30a. Radial surface 30f is formed between annular surface 30e and exterior 
annular surface 30a. A bearing detent 30g is formed in the interior 
annular surface 30b of the ring member 30 by radial surfaces 30h, 30i and 
annular surface 30j (FIG. 5). Radial surface 30k is formed substantially 
parallel and proximate to the exterior radial surface 30d adjacent inner 
annular surface 301 which is formed between radial surface 30k and 
exterior radial surface 30d. Preferably, all radial surfaces 30f, 30c, 
30i, 30h, 30k and 30d are parallel with one another with all annular 
surfaces 30a, 30e, 30b, 30j, and 30l being concentric with respect to one 
another. 
A plurality of elongate slots 32, 33 are preferably formed on the interior 
radial surface 30c of the ring member 30 of the ring member R. As best 
seen in FIG. 9, each of the elongate slots 32, 33 has a slot center line 
32a, 33a with the slot center lines 32a, 33a extending between radially 
innermost portions 32b, 33b and radially outermost portions 32c, 33c. 
Arcuate surfaces 32d, 32e, 33d, 33e are preferably formed adjacent 
portions 32b, 32c, 33b, 33c respectively. The elongate slots 32,33 further 
include slot top surfaces 32f, 33f and slot bottom surfaces 32g, 33g, all 
of which are joined by arcuate surfaces 32d, 32e, 33d, 33e, respectively 
in forming the overall perimeter of the elongate slots 32, 33. A radial 
slot surface 33h (FIG. 6) is formed between the slot top surface 33f and 
slot bottom surface 33g. As best seen in FIGS. 2 and 4, preferably, there 
are a total of 16 elongate slots 32, 33 that are formed in the interior 
radial surface 30c of the ring member 30 of the ring member R for the 
purposes discussed more fully hereinbelow. 
In addition to the ring member R, the ring assembly A further includes 
engaging means E, which includes a plurality of retaining plates 40. The 
retaining plates 40 are formed each having an inner annular plate surface 
40a, an outer annular plate surface 40b, an inner radial plate surface 
40c, an outer radial plate surface 40d and end engaging surfaces 40e, 40f. 
As best seen in FIGS. 2 and 4, preferably the closure member C of the 
present invention includes eight retaining plates 40 that are adapted to 
be mounted with the ring member 30 for radial movement as described more 
fully hereinbelow. 
Preferably, each of the retaining plates 40 has a first dowel member 42 and 
a second dowel member 44 mounted therewith adjacent the corners formed by 
the outer annular plate surface 40b and end engaging surfaces 40e, 40f, 
respectively. Each of the dowel members 42, 44 includes a bearing member 
42a, 44a that is preferably affixed with the dowel members 42, 44 by means 
of suitable pins or fasteners 42b, 44b, respectively. The dowel members 
42, 44 are adapted to be received in compatibly formed elongate slots 32, 
33, respectively, so that aligned radial movement of the retaining plate 
40 may be accomplished as the dowel members 42, 44 correspondingly move in 
their respective elongate slots 32, 33. As shown in FIGS. 1 and 9, when 
the dowel members 42, 44 as affixed to each of the retaining plates 40 are 
positioned adjacent the radially innermost portion 32b, 33b of the 
elongate slots 32, 33, the retaining plate 40 is positioned in its most 
radially contracted position, that is, the retaining plates 40 are 
positioned in their most radially inwardly extended position. On the other 
hand, when the dowel members 42, 44 of the retaining plates 40 are 
positioned adjacent the radially outermost portions 32c, 33c of the 
elongate slots 32, 33, the retaining plates 40 are positioned such that 
their respective inner annular plate surfaces 40a are of a maximum inside 
diameter (as best seen in FIG. 4). Each of the retaining plates 40 as a 
result of their respective coaction with elongate slots 32, 33 formed with 
the ring member 30 via dowel members 42, 44 are mounted for radial 
movement with respect to the ring member 30 and flange member 20 upon 
arcuate rotation of the ring member R. As such, the retaining plates 40 
move radially inwardly or outwardly via an arcuate path defined by the 
rotation of the ring member R and the interaction of the dowel members 42, 
44 with the elongate slots 32, 33. 
A plurality of retaining plates spacer guides 46 are positioned between 
adjacent retaining plates 40 such that each of the retaining plate spacer 
guides 46 preferably engage the end engaging surface 40e of one retaining 
plate 40 and the end engaging surface 40f of the adjacent retaining plate 
40 (FIGS. 2, 4, 6). While the retaining plates spacer guides 46 may be of 
any suitable configuration capable of properly engaging the end engaging 
surfaces 40e, 40f of adjacent retaining plates 40 [for example, such as a 
truncated pie shape (not shown)], it is preferred that such spacer guides 
46 be of a circular configuration (as viewed in FIGS. 2,4) and include an 
annular bearing member 46a mounted about a suitable spacer ring 46b (FIG. 
6), with the outer annular surface 46c of the annular bearing member 46a 
contacting end engaging surfaces 40e, 40f of adjacent retaining plates 40. 
The spacer guides 46, as positioned between adjacent retaining plates 40, 
ensure the equidistant, circumferential disposition of the retaining 
plates 40 about the ring member 30 of the ring member R (as viewed in 
FIGS. 2 and 4). Each of the retaining plates 40 are maintained in a spaced 
relationship to each other by the spacer guides 46 and are movable between 
a radially expanded position wherein the inner annular plate surface 40a 
of the retaining plates 40 are of a maximum inside diameter, corresponding 
to an unlocked position and a radially contracted position which 
corresponds with a locked position, as detailed more fully below. As such, 
each of the retaining plate spacer guides 46 help position and guide the 
retaining plates 40 for proper movement thereof during rotational movement 
of the ring assembly A between the unlocked position (FIG. 4) and the 
locked position (FIG. 2). 
The closure member C of the present invention further includes an annular 
transition flange 50 and flange fastening means designated generally as 
54. The transition flange 50 is adapted to be mounted adjacent the flange 
member F and includes transition flange inner surfaces 50a, 50b, 50c, 50d, 
50e, a radial surface 50f formed adjacent to inner surface 50e, with a 
stepped radial surface 50g formed adjacent to radial surface 50f. Radial 
surface 50h is formed between inner surface 50a and transition flange 
outer surface 50i. As best seen in FIGS. 2, 4 and 6, preferably a 
plurality of openings 50j are formed in the radial surface 50h of the 
transition flange 50, with openings 50k formed adjacent to openings 50j. 
Preferably, the openings 50j, 50k are compatibly formed to receive flange 
fastening means 54. The flange fastening means 54 includes a fastener 54a 
which is adapted to be compatibly received within openings 50j, 50k. 
Preferably, corresponding openings 20g are formed in the flange member 20, 
originating adjacent inner radial surface 20c and extending towards the 
outer annular surface 20b of flange member 20. It is preferred that the 
fastener 54a be adapted to be disposed within the openings 50j, 50k, 
therethrough spacer ring 46b and thereunto aligned opening 20g formed in 
flange member 20. Upon the fastener 54a of the flange fastening means 54 
being secured with the transition flange 50 and flange member 20 of the 
flange member F, the spacer ring 46b of the spacer guide 46 permits a 
tight, secure makeup of the transition flange 50 with the flange member 
20, while permitting suitable rotation of the annular bearing member 46a 
as such is required. 
The closure member C of the present invention further includes seal means 
designated generally as 56 for sealably engaging the pressure vessel door 
D when the pressure vessel door D is in a closed position. The inner 
surfaces 50b, 50c, 50d of the transition flange 50 form an inner annular 
surface seal detent 50l wherein the seal means 56 is mountable therewith. 
Preferably, the seal means 56 includes a mounting body portion 56a which 
is received in the seal detent 50l, with the seal means 56 also including 
a depending tab 56b formed with the mounting body portion 56a. Preferably, 
the seal means 56 is formed of a suitably resilient material, such as 
neoprene or the like. 
The closure member C of the present invention further includes a pressure 
vessel door D including door 60. The door 60 includes an outer door 
surface 60a, an inner door surface 60b, an annular surface 60c formed 
adjacent to outer door surface 60a, a generally radial surface 60d formed 
adjacent to annular surface 60c and a ring surface 60e preferably of a 
tapered configuration that is formed between the radial surface 60d and 
inner door surface 60b. Thus, the overall axial thickness of the door 60 
is determined by the dimension between door surfaces 60a and 60b. The door 
60 may include central cutouts (not shown) or windows to provide a door 
view port if such is desired. As best seen in FIGS. 5 and 6, preferably 
the maximum radial extent of the door 60 is defined by the ring surface 
60e, which is of a lesser diameter than that of the inner annular surface 
20a of flange member 20 or annular surface 50e of transition flange 50. 
The closure member C of the present invention further includes mounting 
means M for mounting the flange member F with the pressure vessel V. The 
pressure vessel door D is also preferably supported by the mounting means 
M for movement of the pressure vessel door D between an open position 
(FIG. 4) permitting access to the interior chamber 18 of the pressure 
vessel V and a closed position (FIG. 2) wherein the pressure vessel door D 
is proximate the inner annular surface 20a of the flange member 20, where 
access to the interior chamber 18 of the pressure vessel V is not 
permitted. Movement of the pressure vessel door D from the fully opened 
position as shown in FIG. 4 towards a closed position is shown via the 
phantom line 62 (FIG. 3) and possible directional relative movement is 
depicted by arrow 64. Preferably, a suitable handle 66 is mounted with the 
outer door surface 60a of the door 60. The handle 66 is configured so as 
to permit opening and closing of the pressure vessel door D as desired. 
The handle 66 is formed having a standoff portion 66a that is secured with 
the pressure vessel door D by suitable handle fasteners 66b. Extending 
radially outwardly from the standoff portion 66a is handle offset portion 
66c which may be formed having provisions for a handle grip 66d. 
The closure member C of the present invention further includes mouting 
means M with the flange member F for mounting the flange member F with the 
pressure vessel V. The mounting means M includes a hinge member 68 having 
a first hinge portion 68a mountable with the pressure vessel door D and a 
second hinge portion 68b for mounting with the pressure vessel V. 
Preferably, the first and second hinge portions 68a, 68b are pivotally 
affixed together by hinge pin 68c to permit pivotal movement of the 
pressure vessel door D about the hinge pin 68c. Preferably suitable 
fasteners 68d are utilized in securing the first hinge portion 68a with 
the pressure vessel door D. As best seen in FIG. 3, preferably the first 
hinge portion 68a of the hinge member 68 is formed having a standoff 
portion 68e which permits clearance of the hinge member 68 with respect to 
the ring assembly A and flange member F when the pressure vessel door is 
in a closed position so that the hinge member 68 does not interfere with 
the ring assembly A or flange member F. The first hinge portion 68a also 
includes a suitable offset portion 68f and pin portion 68g formed 
therewith. A pin portion 68g of the first hinge portion 68a cooperatively 
engages with a compatibly formed pin portion 68h formed in the second 
hinge portion 68b. 
The mounting means M of the present invention further includes an annular 
window flange 70 for mounting with the transition flange 50. The window 
flange 70, as best seen in FIG. 8, has a first radial surface 70a and a 
second radial surface 70b, with the axial thickness of the window flange 
70 being determined by the distance between the radial surfaces 70a, 70b. 
The window flange 70 further includes an outer annular surface 70c and an 
inner annular surface 70d (FIGS. 5,6). Preferably the inner annular 
surface 70d is of the same bore as that of inner surface 50a of transition 
flange 50, with the outer annular surface 70c of the window flange 70 
being of the same diameter as that of the outer annular surface 50i of 
transition flange 50. Preferably, the first radial surface 70a is formed 
having a seal detent 70e of any suitable configuration and adapted to 
receive a suitable sealing member 72 therein for establishing a sealable 
relationship between the first radial surface 70a of the window flange 70 
and the radial surface 50h of transition flange 50. Also, the second hinge 
portion 68b of the hinge member 68 further includes a mounting portion 68i 
for securing the hinge member 68 with the second radial surface 70b of the 
window flange 70. 
The window flange 70 further includes an annular detent 70f formed in the 
second radial surface 70b for sealably receiving the cylindrical window 
14a of the cylindrical chamber 14 of the pressure vessel V. More 
specifically, the annular detent 70f includes an annular detent surface 
70g and a radial detent surface 70h, with the radial detent surface 70h 
being of sufficient dimension to accommodate the thickness of the 
cylindrical window 14a of the cylindrical chamber 14, while the radial 
dimension of the annular detent surface 70g is slightly greater than the 
outside diameter of the cylindrical window 14a (FIG. 8). Preferably, end 
surface 14f of the cylindrical chamber 14 (FIG. 8) abuts a window sealing 
member 74 which is disposed between the end surface 14f and radial detent 
surface 70g of the annular detent 70g of the window flange 70. In 
addition, the window flange 70 is formed having a plurality of fastener 
openings 70i which are adapted to be formed so as to be axially aligned 
with a similarly sized fastener openings 50m formed in transition flange 
50. The transition flange 50 further includes an axially aligned fastener 
head recess 50n formed adjacent to the fastener opening 50m (FIG. 8). The 
window flange 70 is further formed having a tie rod recess 70j formed in 
second radial surface 70b, with recess 70j being in axial alignment with 
the fastener opening 70I and being of suitable dimension to receive tie 
rod end 16a within the tie rod recess 70j. 
A pressure vessel fastener 76, preferably including a head portion 76a, a 
shank portion 76b and a threaded portion 76c is adapted to be disposed 
within the aligned openings 50n, 50m and 70i such that the head portion 
76a is disposed within opening 50n, the shank portion 76b is disposed 
within opening 50m and a portion of opening 70i with the threaded portion 
76c extending from opening 70i of the window flange 70 for threaded 
engagement into a compatibly threaded opening 16b in tie rod 16 of the 
pressure vessel V of the present invention. A suitable locking washer 76d 
may be disposed between the head portion 76a and shank portion 76b to 
resist any unfastening forces that may be encountered by the pressure 
vessel fastener 76. Preferably, the head portion 76a is formed having a 
suitable tool receiving receptacle 76e for receiving a suitable tool (not 
shown) used in the threading and unthreading of the pressure vessel 
fastener 76 with the pressure vessel V. Further, the second hinge portion 
68b of hinge member 68 is preferably mounted with the pressure vessel V by 
suitable fasteners (not shown) which permit the mounting portion 68 to 
abut radial surface 70b of window hinge 70. 
Preferably, four tie rods 16 are used in securing the main component parts 
of the pressure vessel V together. The pressure vessel fasteners 76 
cooperate with the tie rods 16 to secure the closure member C with the 
pressure vessel V while the tie rods 16 attachment adjacent the other end 
of the pressure vessel V with the end plate 14c of the chamber 14 permits 
proper assembly thereof. In this regard, it should be noted that the 
flange member 20 is formed having a suitable tool relief area 20h (FIG. 8) 
adapted to be positioned adjacent to each of the pressure vessel fasteners 
76 so that a suitable tool (not shown) may be properly positioned for 
tightening and untightening the pressure vessel fastener 76 in the proper 
makeup or disassembly of the closure member C of the present invention. 
The closure member C of the present invention further includes axial 
bearing means designated generally as 80, which preferably includes roller 
bearing 80a which is secured with the flange member 20 by threaded bearing 
fastener 80b. Preferably, the axial bearing means 80 is disposed between 
the outer annular surface 20b of the flange 20 within bearing detent 30g 
formed in the inner annular surface 30b of ring member 30 (FIG. 8). As 
such, the axial bearing means 80 ensures aligned axial movement between 
the flange member 20 and ring member 30 when the ring assembly A is moved 
between the locked and unlocked positions. 
The ring member 30 of ring member R of the ring assembly A further includes 
at least one rotation tab 30m mounted with the exterior annular surface 
30a of the ring member 30 to enhance ease of rotation thereof for 
selective movement of the ring assembly A between locked and unlocked 
positions (FIG. 8). Preferably, the rotation tab 30m is formed having a 
suitable fastener detent 30n for receiving tab fastener 30o. The tab 
fastener 30o has a fastener head 30p, a fastener shank 30q and a fastener 
threaded portion 30r. When the tab fastener 30o is in proper position for 
securing the rotation tab 30m with the ring member 30, the threaded 
portion 30r of the tab fastener 30o extends into a threaded bore 82a of a 
sleeve member 82. The sleeve member 82 preferably is formed having a 
threaded exterior surface 82b which is adapted to be threadedly received 
within a compatibly formed threaded opening 30s formed in ring member 30. 
Upon proper aligned rotation of the ring member 30 and the tab fastener 
30o with sleeve member 82, all are axially aligned with the axial bearing 
means 80 such that upon removal of the tab fastener 30o and rotation tab 
30m, the sleeve member 82 may be threadedly removed from opening 30s to 
allow access to axial bearing means 80 for removal or installation of such 
bearing means from its attachment with the flange member 20. The tab 
fastener 30o and sleeve member 82 comprise the tab fastening means 84 of 
the present invention. As such, the axial bearing means 80 may be accessed 
by removal of the tab fastening means 84. 
Concentric bearing means designated generally as 86 including roller 
bearing 86a and threaded bearing fastener 86b is disposed between the 
flange member F and ring member R for ensuring concentrically aligned 
movement of the ring member R with respect to the flange member F. As best 
seen in FIG. 7, the concentric bearing means 86 is mounted with the flange 
member 20 such that the roller bearing 86a engages interior annular 
surface 30b of ring member 30, with the threaded bearing fastener 86b 
being compatibly received in a suitably formed threaded opening 20i formed 
in radial surface 20f. 
As best seen in FIG. 5, the closure member C of the present invention 
further includes safety means designated generally as 90 for preventing 
inadvertent movement of the ring assembly A from the locked position to an 
unlocked position. The safety means 90 includes a safety pin 90a that is 
mounted with the radial surface 60d of door 60 adjacent the outer 
perimeter thereof at safety pin mount portion 60f. The safety pin 90a of 
the safety means 90 is adapted to be received in safety pin detent 40g 
formed in inner radial plate surface 40c of retaining plate 40 adjacent 
inner annular plate surface 40a of retaining plate 40. 
In the use or operation of the closure member C of the present invention, 
it is readily seen that the retaining plates 40 move between a position 
wherein the inner annular plate surface 40a is of a maximum inside 
diameter permitting in an unlocked position, and a radially contracted 
position wherein the inner annular plate surface 40a of the retaining 
plate 40 is moved radially inwardly into contact with the outer annular 
surface 60c of the door 60 of the pressure vessel door D, which 
corresponds to a locked position. As noted above, the pressure vessel door 
D is movable from an opened position (FIG. 4) to a closed position (FIGS. 
1,2). After the pressure vessel door D is in a closed position the ring 
member 30 of ring member R of ring assembly A may be appropriately rotated 
such that the engaging means E, which includes retaining plates 40, may 
move from their radially expanded position corresponding to the unlocked 
position to that of a radially contracted position corresponded to the 
locked position. 
As best seen in FIGS. 2 and 4, preferably there are eight retaining plates 
40 that are circumferentially disposed in equidistant relationship about 
the ring assembly A of the closure member C of the present invention. As 
each of the eight retaining plates 40 has their own respective first and 
second dowel members 42, 44, to the extent that any one of the eight 
retaining plates 40 is incapable of movement from an unlocked to a locked 
position, then no rotation of the ring member 30 may take place as all 
retaining plates 40 must move simultaneously or none will move at all. 
This is principally accomplished because of the cooperation of the dowel 
members 42, 44 with their respective elongate slots 32, 33 and the 
cooperative engagement between adjoining retaining plates 40 by the 
careful placement of the retaining plate spacer guides 46. Thus, when the 
inner annular plate surface 40a of each of the retaining plates 40 is 
radially contracted so as to engage the annular surface 60c of the door 
60, a locking arrangement is established so that the pressure vessel door 
D may not be opened. On the other hand, when the inner annular plate 
surface 40a of the retaining plate 40 is in a radially expanded position 
so as to be of a greater diameter than that of the ring surface 60e, then 
the door 60 is in an unlocked position (even though it may be closed), and 
may thereafter be moved from the closed position to an opened position for 
access to the interior chamber 18 of the pressure vessel V. 
When the pressure vessel door D is moved from its opened position to the 
closed position, the inner door surface 60b of the door 60 first engages 
the depending tab 56b of the seal means 56 in the position shown in 
phantom at 92 (FIG. 6), thereby flexing the depending tab 56b into a more 
sealable engagement with the inner door surface 60b. Because of the 
resiliency of the seal means 56, the depending tab 56b flexes from the 
position shown in phantom at 92 to that as shown in FIG. 6. When in this 
closed position, the ring member R may be rotated so that the retaining 
plates 64 radially contract inwardly towards engagement with the annular 
surface 60c of the door 60. The extent that the retaining plate 40 
contacts the safety pin 90a of the safety means 90 (FIG. 5), a further 
slight pressure against the pressure vessel door D permits further closing 
movement of the pressure vessel door D so that safety pin 90a clears the 
inner annular plate surface 40a of the retaining plate, permitting further 
final rotation of the ring member R such that the inner annular plate 
surface 40a of the retaining plate 40 engages the annular surface 60c of 
the door 60, with the safety pin 90a being received within safety pin 
detent 40g. Compression of the resilient seal means 56 permits the 
pressure vessel door D to be closed sufficiently to permit proper safety 
pin 90a clearance for its subsequent reception in safety pin detent 40g. 
The resiliency of the seal means 56 thereafter urges the pressure vessel 
door D into engagement with the inner radial plate surface 40c of the 
retaining plate (with the safety pin 90a of the safety means 90 properly 
received within the safety pin detent 40g). Thus, with the pressure vessel 
door D closed (but with no elevated pressure within the pressure vessel 
V), inadvertent rotation of the ring member R is prevented unless the 
pressure vessel door D is forced into a further closed position (as 
against the seal means 56) in order that the safety pin 90a be cleared for 
proper radial expansion of the retaining plates 40. Upon the pressure 
vessel V being pressurized from within, the interior pressure acts against 
the inner door surface 60b of the door 60, pressing such outwardly against 
the inner radial plate surface 40c of the retaining plate 40. Furthermore, 
the interior pressure further forces the depending tab 56b and mounting 
body portion 56A of the seal means 56 into sealable engagement with the 
door 60 of the pressure vessel door D. 
When the first and second dowel members 42, 44 are in the positions within 
elongate slots 32, 33, respectively, as shown in FIG. 9, such corresponds 
to the retaining plates 64 being in a radially contracted, locked 
position; conversely, when the first and second dowel members 42, 44 are 
adjacent arcuate surfaces 32e, 33e such corresponds to the retaining plate 
64 being in an unlocked (i.e., fully radially expanded) position. As 
viewed in a slot plane on the interior radial surface 30c of the ring 
member 30 (that is preferably perpendicular to the longitudinal axis of 
the pressure vessel V) it is preferred that the arcuate rotation depicted 
by numbers 94, 96 (FIG. 9) along the slot center lines 32a, 33a between 
arcuate surfaces 32d, 33d to arcuate surfaces 32e, 33e correspond to 
preferably a substantially nine degree arc, which defines the overall 
length of the elongate slots 32, 33 along their respective slot center 
lines 32a, 33a between arcuate surfaces 32d, 33d and 32e, 33e, 
respectively. Preferably, each of the first dowel members 42 are 
positioned substantially thirty degrees from the second dowel member 44 of 
each retaining plate as shown by number 98 in FIGS. 2 and 9. Furthermore, 
preferably, the arcuate distance between the second dowel member 44 of one 
retaining plate 40 to the next first dowel member 42 of the adjacent 
retaining plate 40 is positioned an arcuate distance of preferably 
substantially fifteen degrees which is shown by the arcuate distance shown 
by number 100 in FIG. 2. With these respective relationships, rotation of 
ring member R results in all retaining plates 40 moving uniformly together 
in order for proper movement to occur. Furthermore, the radial movement of 
the retaining plates 40 is accomplished by the arcuate coaction of the 
dowel members 42, 44 in their respective slots 32, 33 during rotation of 
the ring member R while any friction encountered in the rotational 
locking/unlocking movement of the ring assembly A is minimized so as to 
enhance ease of operation by the operator. 
When the pressure vessel V is under pressure, because of the forces on 
inner door surface 60b acting against inner radial plate surface 40c of 
the retaining plate 40, manual rotation of the ring member R is simply a 
physical impossibility because of the substantial engaging forces. In the 
event the pressure vessel V has been substantially relieved of its 
interior pressures but, nonetheless, a slight residual pressure remains, 
the safety means 90 cannot be manually overcome by the operator until all 
residual pressure from within the pressure vessel V has been relieved, as 
even a slight residual pressure acting against the seal means 56 will not 
permit sufficient seal means 56 resiliency for the safety pin 90a to be 
disengaged from the safety pin detent 40g to effectuate an unlocking of 
the retaining plates 40 of the engaging means E. Thus, the closure member 
C of the present invention provides an easily operable mechanism having 
inherent safety features for preventing inadvertent opening of the closure 
member C when the pressure within the pressure vessel V is greater than 
the pressure outside the pressure vessel V. Furthermore, due to the 
configuration of the ring assembly A, along with its ring member R and 
engaging means E, the retaining plates 40 either all fully engage the 
pressure vessel door D or none do, thus eliminating the possibility of a 
partially secured door. 
Thus, the closure member C of the present invention provides a new, 
improved mechanism for releasably securing a pressure vessel door D with a 
pressure vessel V. 
The foregoing disclosure and description of the invention are illustrative 
and explanatory thereof, and various changes in the size, shape and 
materials, as well as in the details of the illustrated construction may 
be made without departing from the spirit of this invention.