Patent GB-874758-A (GB)
Title: Improvements in or relating to pressure vessels
Inventor: LORD ROBIN KIRKBY
IPC: F16J13/24
Filed: 1957-07-18
Abstract: 874,758. Doors for resisting fluid pressure. LORD & SONS Ltd., R. July 18, 1958 [July 18, 1957], No. 22735/57. Class 123(1) [Also in Group XXV] A pressure vessel having a rack and pinion operated door lock is characterized by the provision of a pressure-operated latch bar 24 capable of being located in an inoperative position when the vessel is not pressurized, the bar being operatively associated with the stem of a piston 18 adapted to be operated responsive to pressure increase within the vessel to move the bar into an operative position normally to prevent operation of the lock and opening of the door, a warning device for example, a whistle 32, being provided in association with a valve, the device being adapted to give a warning if the latch bar is displaced from its operative position when the vessel is pressurized. In the construction shown the pressure vessel is provided at each end with a circular door 10 and each door has around its periphery a plurality of radially disposed lugs 11 and the ends of the body of the vessel are provided with similar lugs 12 the doors being locked by rotation so that the lugs 11 engage behind the lugs 12. Each door is provided with a rack 13 and cooperating with this is a pinion (not shown) which is removably mounted on a pivot bar 14 on the body. The pinion is attached to a lever and the arrangement is such that the lever must be pivoted through an arc several times, the pinion being disengaged from the rack between each movement before the door can be locked or unlocked. Secured to the body is a bracket 16 carrying a valve housing 17; inside the housing is the piston 18 which is attached to one end of a push rod 19 the other end of which mounts the latch bar 24. The push rod 19 also passes through a cross-bar 20 which is held in position by a shaft 21 which passes through the bracket 16 and which is loaded by a spring 23. The spring tends to keep the piston clear of a seat 18a. The latch bar 24 adjacent its outer end has a cut-out 25 which is a clearance fit over a reduced diameter portion 15 of the pivot bar 14; the cut-out 25 extends into a circular hole 26 which is a sliding fit over the larger diameter portion of the pivot bar 14. A stop 27 secured to the end wall of the pressure vessel is provided with a stepped end 28 which can engage a notch 29 in the latch bar. When the door has been fastened by the pinion, steam from the pressure vessel enters the valve housing 17 through a pipe 30 and this moves the piston against the pressure of the spring 23. The initial movement of the piston disengages the notch 29 from the stop 27 and the latch bar then rotates under the influence of gravity until the cut-out 25 engages the reduced diameter portion 15 of the pivot bar 14. Further movement of the piston then causes the circular hole 26 to engage the larger diameter portion of the pivot bar 14 and hence the latch bar cannot then be pivoted out of engagement with the pivot bar 14; this prevents the pinion being replaced on the pivot bar if it has been removed or alternatively if it has been left on the pivot bar it cannot be removed and hence the door cannot be opened since the arc through which the pinion can then be moved is insufficient. The piston is provided with a plurality of holes 35 through which steam passes until the piston becomes seated on the seat 18a the piston and seat comprising the valve; the steam passing through the holes causes the whistle 32 to sound a warning which ceases as soon as the piston is seated since the steam cannot then pass through the holes. If the piston is manually pushed back against a small steam pressure the steam sounds the whistle to give a warning.