CA1087489A - Pressure relief valve - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

Disclosed is a safety vent for a covered hopper car which has a hopper and a pneumatic discharge mechanism adapted to be connected to a fluid pressure system for material unloading.
The vent includes a tubular member having a tubular wall, one portion of the wall being connected to and communicating with the interior of the hopper car and a second portion of the wall communicating with the atmosphere. A seating surface is on one of the portions and a valve member is solely seated upon the surface and is rupturable at a predetermined design pressure outside the car. The valve member is adapted to seat fluid tight against the surface solely by reduction of pressure in the car, and the valve member includes a stretchable diaphragm stretched transversely across the tubular wall in tensioned condition where, upon rupture of the same, the diaphragm is substantially destroyed to permit flow of fluid through the tubular member.

Description

~0~7~L~9 PRESSURE RELI EI~ VALVE

This application is a division of Canadian patent application Serial No. 266,130 filed November 19, 1976.
, sackground of the Invention 1. Field of the Invention --T.he present invention relates to safety vents or valves useful with pressurized tanks which includes ruptura~le valve members designed to relieve pressure occurring within a tank or hopper at a predetermined PSI in order to protect the -structural integrity of the unit to which it is connected.

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2. Description of the Prior Art .

The prior art is disclosed in U.S. patents

3,145,874, August 25, 1964 to Webb; 3,294,277, December 27, 1966 ~ ~.
to Wood; 3,526,336, September 1, 1970 to Wood; 3,685,686, : ~ August 22,~ 1972 to Raidle; 3,797,511, March 19, 1974 to Selby;
: 3,834,581, September 10, 1974 to Solter et al; and 3,845,878, November 5, 1974 to Carlson.

The present invention is an improvement over~the ~;
above patented structures.

' Summary of the Invention .
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- The invention disclosed is particularly adapted -to closed or covered hopper cars which are provided with ~ ' ' , '`'~'' :

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7~89 pneumatic gate arrangements for unloading the car. In unloading this type of car the gate is attached to a fluid pressure system causing a subatmospheric pressure within the car whereupon the material is discharged from the pneumatic gate usually to a pres~urized conduit leading to a suitable storage bin or reservoir. The safety vent in one embodiment of the disclosed system includes a tubular housing which is connected to a pipe extending vertically within the hopper car adjacent the roof thereof for allowing the entrance of air through a filter arrangement with which the safety vent is associated. The safety vent may in one aspect include a rupturabLe valve or diaphragm which at a predetermined subatmospheric pressure within the car ruptuxes to alleviate the situation and protects the structural lntegrity of the tank or hopper. The diaphragm or valve comprises a rubber-like material which is stretched or ~ tensioned across the tubular wall of the housing in association ; with the tubular ring, which, when it ruptures, is destroyed with the remains of the diaphragm receding or withdrawing , .

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substantially close to the inner wall oE the housing thereby occupying a minimum of space area so that the flow of fluid through the housing is not impeded in any way.

The invention to which this divisional application is directed comprehends a safety vent for a covered hopper car which has a hopper and a pneumatic discharge mechanism ada~pted to be connected to a fluid pressure system for material unloading. The vent includes a tubular member having a tubular wall providing a passage therein, one portion of the wall being connected to andcommunicating with the interior of the hopper car and a second portion of the wall communicating with the atmosphere. A valve member is rupturable at a predetermined design pressure supported on the tubular member between the tubular portions to block 1uid flow through the tubular member. The valve member is a balloon-like element expanded within the member and includes a stretchable diaphragm stretched transversely across the tubular wall which, upon rupture of the member, torn portions of the diaphragm recede in a radially outward direction toward the tubular wall so as not to impede the fluid flow therethrou~h.

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- -: Brief Description of the Drawings FIG. 1 is a side elevational view of a hopper car having portlons of the same broken away to illustrate an improved filterlng end vent system;

FIG. 2 is a cross-sec tional view taken substan~lally along the line 2-2 of FIG. l;

FIG. 3 is a cross-sectional view taken subs~antially along the line 3-3 of FIG, 2;
.' FIG . 4 is a view s imilar to FIG. 2 dis-closing the condition of a rupture valve or diaphragm, : appearing with Figs. 1 and 2; and ` - , FIG. 5 is a cross-sectiollal vl~w slmi-- - lar to FIG. 2 disclosing a modified diaphragm struc-: ture.
., Description of the Pre~erred ~mbodiment -- ' , ~
; ~ - Fig. 1 dlscloses a closed hopper car 10 having conventlonal stub center sllls 11 at oppo-site ends ~hereof wh~ch.are supported on conventional~
whe~l ~rucks 12. The car 10 includes a car body 13 having ver~ical car sides 14 and sLopin~ end ~alls .

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or sheets 15 connected to the car sides 14. The slope sheets or end walls 15 with intermediate slope sheets or walls 16, comprise and form a total of four separate hoppers 17 which are adapted to contaln bulk material such as plastic pelle~s etc. The hopper car 10 is of the closed type and includes conventional pneumatic discharge gates 18 attached to each of the hoppers 17 at their lower ends thereof ~he same in-cluding capped discharge tubes 19 which during un-102ding are uncapped and connected to a suitablefluid pressurized system for unloading and conveylng materials from the car.

The car-10 comprises a roof structure 20 including a plurality of longitudinally spaced hatch covers 21 whlch are removable for ov~rhend loadltl~ pur-poses. The vent systcm or arrangement 22 comprises a filter 23 cons~sting of a tubular body or housing :' member 24 connected-to a vent pipe 25 which ~xtends upwardly withln the car through one o~-the hopper ~alls ~:
terminating at its upper end in an opening 26 adjacent the roof structure. Tle tubular body and housing member `'~

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24 and p$pe 25 are suitably supported on a central part~tion wall 27 and hopper wall 16~ sub~tantlally centrally on the body and below ~hereof thus providing ready access to the operator for servlcing the unit.
The car also ~ncludes two other partition walls 27 thus dividing the car into the four hopper uni~s a~ described.
The present invention relates to ~ safety valve or vcnt system 28 which is positioned at the upper end of the tubular`body or housing member 24. Referring particularly to FIGS. 2, 3 and 49 the vent 2B is provided at the upper end of the tubular body or housing member 24 which ~ncludes a vertical inner tubul~r wall 29. The wall 29 is ~ro.vided at its upper end w~th a 1ange 30.
which is connected by means of nuts and bolts 339 to a - collar 31 having a flange 32. The collar 31 also ln-- cludes an inner tubular wall 34 in registry with the wall 29. The upper end of ~he c~llar 31 is provided w~th an annular undercut seat 35. The outer.circum-ferential surface of the collar 31 includes circumfereno , 20 tially spaced lugs 36 having outwardly directed arcuate . ~ indentations 37. The safety valve system 28 includes a cap 38 which m~y be hingedly remosred to an opened position for service reasons that will be presently described.
The collar 31 includes outstanding ears 39 and a hlnge br~cket 40 on the cap 38 is hingedly connec ted thereto ' ~ . 6 .~ .
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by ~.eans of a hinge pin 41. A latch bolt 42 is pivotally connected to hinge ears 43 supported on the collar 31 and is adapted to enga~e in locked relation split latch lu~s 44 held in this position by means of a nut 45.
FIGS. 2, 3 and 4 disclose a valve assembly 46 comprising a ri~d ring 47 havin~ a di~phragm 48 connected thereto.
The diaphra~m 48 comprises a rubber-like material which is stretched across the rin~ and ;s securely fastened thexeon by me~ns of a wrapped and glued connection portion 49 enclosin~ the rin~ 47. ~hile a rubber material is disclosed~ any ma,teria,l which has a high resiliency and wh.~ch when ruptured will recede or diminIsh sub- ' :.
sta,ntially in length~ can be utilized. The ring 47 a5 disclosed i,n FIGS. 2, 3 and 4, is removably seated upon the annular undercut seat 35. As best shown in .' : FIG~, 2 a~d 5, ~ conventional knife or p~ercing element s 50 i$ d;~sposed immediately below the valve 46. As can be seen in Fi~ure 2~ the valve assembly includin~ ring -'':
47 and diaphragm 48 is solely seated upon the surface of .,20 a,n~ula,~ undercut seat 35~ The vertical space between the vertical surface of the ring and diaphragm (~7,48~ and the opposin~ vertical wall member.31 allows the ring and ~ .
diaphragm to be displaced from the seatin~ surface such as ~ ~, i~ there ~ere a sudden increase in pressure in the car.
FIG~ 4 discloses the condition of the diaphragm 48 ', afte~ it has ruptured whereiin the stretched or pretensioned condLtion of the diaphragm results in the shredded or destroyed remainin~ pieces 51 havin~ receded or withdrawn outw~xdly against the wall 34 thus permittin~ the uninterrupt~
, 3Q ed or unimpeded ~low of air therethrough.
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In the m~dification of ~IG. 5, the ring 47 supports a diaphragm 52 which comprises a circumfer-en~i~l vertical wall 53 integral wlth p~rallel spaced walls 54 one of wllich is provided wi~h an inflating closure 55. The diaphragm 52 here again i5 of a rubber-like material and is held ~nan inflated cor~dition against the ring 47 and which when ruptured it i~ substant~ally destroyed with ~he pre-stre~ched conditlon of the dia-phragm c~using only fragm2n~s to re ~ in after destruction 10 so that agaih the air can frcely travel through the tubular wall`29 to the hopper.

~ration In the uncapped posit~on of the pneu~tic clischarge gates 18 a fluid pressure sys~em is connected - thereto and the m~terial is withdrawn fro~ the hoppers ~ :
by suction to unload the same. Alr enters through the filter 23 through the tubular body 24 and is discharged into ~he upper ends of the hoppers so that the ~terial ~ is discharged and flows freely through the pneumatic . gates. The maximum sub-atmospheric pressure within the car durLng pneumatiC unloadlng is one-half PSI and any sub-a~mospheric pressure below this figure causes the diaphragm 48 to be dra~n b~ suction against the knife edge 50 ~hereby rupturing the diaphragm and permitting `~; the entrance of air through the housing and pipe lnto .: the carO Thus, the safety vent guarantees that any ~ ~ 8 , . ~,, . ~ .

4~g malfunction of the filter or air co~ing therethrough which if impeded in any way will permit air to enter into the car when the diaphragm is ruptured thus assuring that the walls of the car cannot be inadvertently collapsed because of the lowering of the sub-atmospheric pressure below one-half PSI.
It will also be noted that by virtue of the fact that the ring and diaphragm are solely seated upon the seating surface 35, they are displaceable upwardly from the seating surface such as if there were a sudden increase in pressure in the car as might occur when lading shifts or ,... .
temperature changes. However, when the pressure in the car is reduced during unloading, the valve assembly of the ring 47 and diaphragm 48 will be positioned against the seat 35 and held there solely by the reduction in pressure in the car.
In the prior art ahove described, and generally in the field of safety vents, many different types of rupturable diaphragms or discs have been provided. These generally ~20 have consisted of material such as paper, aluminum, plastic, etc. and will function well particularly in tank cars wherein high pressures are encountered and where the ruptured material is subjected to said high pressures so that the flow of fluid through the tubular housing is not generally impeded.
However in the utilization of hopper cars which are placed under a sub-atmospheric pressure of at least one-hal~ PSI, difficulties with the diaphragms of the prior art have been encountered. The paper or plastic disc in sub-atmospheric pressure utilization would par-tially rupture when encountering the knife edge 50.However the blade would provide a center support ~or the disc to prevent the disc from completely rupturing at the maximum pressure permitted in the car. As a result, _ g _ ~ ' .
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at the low pressure, the disc would remain supported in position across the tubular wall substantially impeding the flow of air through the housing to relieve the pre~sure withln the hopper car. In the present invention, the seretched rubber having stored up energy due to the stretching, comple~ely ruptures wlth the destroyed condition of the diaphragm being dls-closed in FIG.4~ wherein the fragments 51 have receded exposing substantially the entire throat opening of the collar 31 and providing for the free flow of air through the housing walls 29. .Thus for the type of operation of a hopper which is pneumatlcally unloaded the s ~ruc ture of the present invention provides A
diaphragm which will functlon to ensure adequate safety protection.
. In FIG. S a modified valve 46 includes ; a balloon-like diaphragm 52 which is inflated and ; which is tightly held aga~nst the inner clrcum~erence of the r~ng 47. Upon rupture the balloon will collapse bec~use of the pre-stretched, or tensioned rubber material, and the fragmentary elements remaining will not substantially prevent the inflow of air tbrough the collar 31 and tubular member 24. The inflated balloon diaphragm may be suitably attached to the inner clrcumferential wall of the rlng 47 so that the fragments remain with the rin~ after rup~ure or if desired the .

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lnflation of the dlaphragm 52 is sufficient to m~in~ain its position ~ightly against the inner surface of the ring 47 and when ruptured i~ will dlsintegrate into shreds which are removed through the tubular member 29 and are discharged with the material.

., The cap 38 of course can be easlly re-moved for replacing any ruptured diaphragm and is eas~ly placed ~n posit~on on the annular lugs 36 of the collar 31~

The foregoing descr~ption and drawings - merely explain and illustrate the lnvention and the invention is not limited thereto, except lnsofar as the appended claims are so lim~ted, as those skilled in t~e art who have the disclosure before them will be able to make modifications and variations therein without d~parting from the scope of the invention.
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Claims (5)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A safety vent for a covered hopper car having a hopper and a pneumatic discharge mechanism adapted to be connected to a fluid pressure system for material unloading, comprising:
a tubular member having a tubular wall providing a passage therein, one portion thereof connected to and communicating with the interior of said hopper car, said tubular wall having a second portion communicating with the atmosphere, a valve member rupturable at a predetermined design pressure supported on said tubular member between said tubular portions to block fluid flow through said tubular member, said valve member being a balloon-like element expanded within said member and including a stretchable diaphragm stretched transversely across said tubular wall which upon rupture of the said member torn portions of said diaphragm recede in a radially outward direction toward said tubular wall so as not to impede the fluid flow therethrough.

2. The invention in accordance with claim 1, said diaphragm being of cylindrical shape having a circumferential wall and-spaced parallel walls connected thereto, the same being inflated in balloon-like condition to maintain said stretched condition.

3. The invention in accordance with claim 2, said valve including a containment ring supporting said diaphragm in said stretched condition on said one tubular portion.

4. The invention in accordance with claim 3, said tubular member having an annular shoulder and said ring being supported on said shoulder.

5. The invention in accordance with claim 4, including a piercing member on said tubular member supported on one side of said diaphragm.