US2388395A - Combined flame arrester and vent valve - Google Patents

Description

Nov. .6, 1945. J DUGGAN 2,388,395

COMBINED FLAME ARRESTER AND VENT VALVE Fiied NOV. 20, 1942 3 Sheets-Sheet 1 55 /a' 2&9. 1. 36 I0 9 37 r 4/ 19 z Z; 1 v 29 27 A 3; 2;

INVENTOR. James J. Duyyan ATTORNEY.

Nov. 6, "1945. J. J, DUGGAN 2,388,395

COMBINED FLAME ARRESTER AND VENT VALVE Filed Nov. 20; 1942 5 Sheets-Sheet s 9 Hll- 62 I fink 1/ w.

INVENTOR;

James J. Buy an.

ATTbRNEYs.

Patented Nov. 6, 1945 UNITED STATES PATENT OFFICE cor/rema FLAME ARRESTER AND VENT VALVE James J. Duggan, Charleston, W. Va.

Application November '20, 1942, Serial No. 466,377

11 Claims.

This invention relates to a combined flame arrester and vent valve for venting pressure vessels or systems containing ignitable fluids. In vessels containing gases and vaporizable fluids, undesirable pressures are apt to develop therein. Consequently such vessels are provided with valve controlled breather or vent devices to. relieve pressures in excess of a predetermined maximum. Such devices operate satisfactorily when the vessel contains a non-combustible fluid; but when thefluids are ignitable it is the practice to provide the vent or breather opening with a fire stop to prevent the contents of the vessel from igniting by external flame sources, for example when a fire occurs exteriorly of the vessel. Such fire stops or arresters are usually composed of a screen bank which forms a multiplicityof small openings through which a flame must find ingress into the vessel so that the flame contacts the screen in such a manner that the heat of com bustion is radiated with sufficient rapidity that the vapors on the inner side of the screen cannot reach ignition temperature. Thesebanks afford relief of ordinary working pressures, but upon sudden rise in pressure they restrict the vents to such an extent that it is impossible to relieve the pressure in time to avoid injury of the vessel orexplosion thereof.

It is, therefore, a principal object of themesent. invention to provide a flame arrester-and vent valve wherein the flame arrester bank is loosely mounted in cooperating relation with the valving element and which is movable from its seat to effect rapid release of excessive pressureswhen those pressures cannot be relieved through the bank with suflicient rapidity to avoid injury of the vessel.

Itis also a further object of the invention to provide a structure wherein the flame arrester bank is completely removable by excessive pressure to give full flow capacity of the vent or breather opening in which the bank is mounted.

Other objects of the invention are to provide a combined flame arrester and vent valve particularly adapted for venting low pressures; to

provide a combined flame arrester and vent valve of simple, inexpensive construction; and .to provide a combinedflame arrester which, in the larger sizes, may be utilized as a manhole when the cover and fire stop unit are removed therefrom.

A sudden vacuum created in a vessel may not be relieved with .sufficient rapidity through the flame arrester since the many small passes necessary to form an efficient fire stop may resist flow of exterior pressure into the vessel in time to avoid injury to the vessel. It is, therefore, a further object of the invention to provide a combined flame arrester and vent valve with primary and secondary vacuum relief valves, the primary valve functioning at slight vacuum condition, to relieve the vessel through the flame arrester, and the secondary valve functioning to relieve the vessel independently of the flame arrester.

Inaccomplishing these and other objects of the invention, I have provided improved structure, the preferred form of which is illustrated in the accompanying drawings, wherein:

Fig. 1 is a vertical section through a combined flame arrester and vent valve embodying the features of the present invention.

Fig. 2 is a plan view of the combined flame arrester and vent valve showing the cover or valving element and other parts partially broken away to better illustrate the construction.

Fig- 3 is an elevational view of the flame arrester and vent valve.

Fig. 4 is a vertical section similar to Fig. 1 but showing the valving element and flame arrester bank in positions for venting excessively high pressures.

Fig. 5 is a vertical section through a modified form of the invention to afford primary and secondary vacuum relief.

Fig. 6 is a partial horizontal section on the line 6-6, Fig. 5.

Referring more in detail to the drawings:

l designates a combined flame arrester and vent valve embodying the features of the present invention and which includes a body 2 having an upper cylindrical wall portion 3 and a lower cone portion 4 terminating in a flange 5 that is suitably attached to the wall of a closed vessel 6, through a suitable fitting 6, by fastening devices such as cap-screws l. The upper part of the wall portion 3 terminates in an outwardly and upwardly flaring flange 8 which provides an internal annular beveled shoulder or seat 9 and an encircling lip forming a valve seat Ill.

The wall-portion 3 forms a compartment ll of a size to contain a fire stop, such as a flame arrester bank l2, having a sufficient number of openings l3 so that the combined flow capacity thereof may be equal to or in excess of the normal flow capacity of the inlet opening M of the body 2 that registers with an opening [5 of the vessel 6. The compartment II is also of a size relative to the flame arrester bank so as to provide an annular by-pass I6 between the circumferential wall I! of the bank and the inner face of the wall 3 for a purpose later described.

The upper portion of the body 2 is ordinarily closed by a cover or vent valve element l8 to retain a predetermined maximum working pressure in the vessel 6 but which is movable from covering relation to allow release of pressure in excess of the predetermined maximum. The cover l8 preferably includes a cap-like body having a top l8 of larger diameter than the lip ll] so that an annular depending flange H3 at the marginal edge of the top I8 is spaced a suflicientdistance from the lip ill to provide an annular outlet passageway 20 and to accommodate a flex ible valving ring member or annulus 2|.

In the illustrated instance the cover ispivotally connected at one side thereof with the body 2 by a hinge 22 comprising outwardly extendingears 23 and 24 on the portion 3 of the body 2 and ears Z and 26 depending from the flange Is and" which are connected with the ears 23 and.

24 .bya hinge rod 21 passing through suitable openings'in the respective ears. The opposite side? of the cover is'supported in proper relation with the lip It: by means. of an outwardly extending: lug. 28 which carries. a resilient button 2I9':s'eating-!the cover, as best shown in Fig. l.

The flexible valvingringi'll has its outer margina l'edge 3 0. clamped between a ring 3| fixed to the inner face of the flange l9 and a.removabIe-I'ring-GZ that is-securedr to the fixed ring by fastening devices, suchas screws 33, extending through rsuitable openings in the removable ring, through registeringopenings in the flexible ring, and: into threaded openingsinsthe fixed ring, as shownin Fig;v 2. The. inner: marginal edge of the flexible ringrests upon the seat or lip I0 and thus cooperateswiththe cover to close the passageway 2D1from-the inner flow passageway formed by thei-compartmentrl'l and the'lower portion of the bodya'2 so asfitos retain normal working pressures withinithe vessel 6*. The valving. ring is yieldingly retained on the seat IDJ by a ring-shaped weight 34' adapted to seat upon-the ring in'outwardlyspacedrelation with the seat I 0', as shown in Fig.1, the weight being retained in guided relation with the cover I8 by an outwardly spaced guidering 35*that is connected with the weight ring by arms 3B whicl1' engage guide ribs 31 projecting inwardly from the flange I9. In order to:support the flexible valving ring circumferentially of the seat H], the clampingring 32 maybe providediwithiinwardly extending arms 38 -carrying aasupportingring 39I spaced slightly from the-flange 3U".

Theflre stop or flame arrester bank previously mentionedimay be of any standard construction and i suspendedly supported within the compartment I if by. means of an annular, bell-shapedflange 40 of suflicient. diameter to extend across the passageway. l6 with itsrim 4| engaging the seat 9 st) as-to-normally close the outlet end of the annular passageway l6.

It is thus obvious that normal working pressures must pass through the openings of the flame arrester bank so that: theyact upon the inner face'of the covertop l8. When the working pressur'e'rises above'a predetermined maximum,

as governed by the weight" of the cover; the coveris raisedthereby toefiect' lifting of the inner marginaledge of the flexible ring fromsealing contact withthe lip" seas-to allow'd'ischarge of the=excessive pressure toatmosphere through the annular passageway -20.- When the pressures" increase-so rapidly thatthey-cannot be adequately relieved through the openings of the flame arrester bank, the increased pressure, acting on the under side of the flange 40 and the bottom of the bank, bodily lifts the flame arrester so that the pressure is passed between the flange 40 and its seat.

Attention is directed to the fact that the inner marginal edge of the flexible sealing ring preferably overlies the marginal edge of the flange 40 so that upward movement of the flame arrester bank, responsive to sudden rise in pressure, causes the flange to engage the projecting portion of the ring and effect positive unseating thereof.

In order that the flame arrester bank may be unseated'ata predetermined pressure relative to or independently of the cover, the flame arrester bank is contacted by an arm 42 projecting inwardly of the portion 4 of the body 2, and which has a curvedend43bearing against a button 44 on the bottom of the bank. The arm 42 is fixed on a shaft '45 which is rotatably mounted in suitable bearingsiin an outward: extension 46 of the body 2: One end. of: the; shaft projectsthrough a-.stuffin'g boxi4 7 on-the:=extension 46 and carries an; arms4'8rwhich. projects from the shaft in an opposite direction toithe arm 42 and carries a weightflfi movablethereomwhereby the effective leverage acting onthearrester bank may be adjuste'dzby slidingrtheweight along. the arm 48 in themanner of apoiseon a scale beam.

vIn'lorder toguide theiflame'arrester bank during movementthereof, the. wall of the compartment It. may be provided with a series of inwardly-extendingguide ribs-50 which loosely engage the wall l'l of the flame arrester bank, as bestishown inlFigs; 1 and-2.

Assumingthatthecombined flame arrester and ventvalve constructed and assembled as described is'mountedon a vessel fiand that normal workingspressures are-carried in the vessel, such pressuresaar'e 'not sufficient to'efiect unseating of the cover or-"flexible valvingring. However, should the working pressures exceed the predetermined amount, -they' act through'the openings of the flame arrester: upon the cover- 18 and-effect lift-- ing-ithereof' sol-that the flexible valving ringis ralsedi from the seat/'10 to'allow release of the excess-pressure.

The vent valve also *functionsin case the'pres sures .in the tank should drop below a predetermined-minimum,- for example-when emptying the contents of the'ves'sel. 'Ih'isis'eifected by atmosplieric pressure-acting on the under 'sideof" the flexible ringtolift the ring from' contact with the seat l0 and i allow exterior air to enter the vessel the sma-lhpassages increase the velocity'ofvapors passing therethroug'h to apoint abovethe rate offlame propagation.- other words, velocity of vapor passing through" the multiplicity'of small. openings orthrough theb'y-pass, when the arrester bank-islifted due'tcr increased pressure, ,is

increased to the point where the velocity of the escaping vapor is faster than a flame can' DIODE? gate in the-directlonof'thetank; Therefore the,

amear'rester-protectsthetank fromfireihazard under ordinary operation or the valving' elements.

of the flame arrester, and:

such conditions.

Shouldpressure in thevessel rise above the point atwhich adequate relief cannot be effected through openings inthe fiame arrester bank, the pressure acting thereon and againsttheunder side of the supporting; flange: 4D lifts the bank-so, that thepressure is by-passed. therearound. vIf the: pressure; should continue to rise, the flame arrester bank, being completely removable, may

be blown by the pressure from the compartment,

lifting the cover, and thereby completely opening the outletthroughthebody 2.

Attention is directed'to the fact that the larger of the devices may serve the purpose of a manholer forthe vessels on which they may be, installed. Upon opening of the cover and removal of the fire stop unit the passageway therethrough is sufiiciently clear of obstruction to afford access into the interior of the vessel. r

. Under some conditions a dangerously high vacuum may be caused to occur in a vessel for the reason that air cannotpass through the fire stop unit {with sufficient :velocity to; prevent high vacuurns. This is obvious since with the structure illustrated, the fire stop unit retains its seat under Therefore the modified structure is equipped with a secondary. ,vacuumrelief which becomeseffective when theprimaryrelief, or-that effected by way of the valve 2| andpassages I3, is not adequate to protect the vessel; In this form, the body member 155 is of slightly different shape between the cylindrical wall portion 56 andthe base portion 51 that attaches to the tank or vessel to be protected than the portion 4, of the body member 2 of the first described form so as to provide a substantiallyhorizontal ,ofiset 58 circumferentially of: the portion 51 and below the'fiame arrester bank or fire stop unit 59.. Provided in this offset is a substantially annular port. 66 which connectsthe interior-of the vesselgwith atmosphere and through which airmay enter, the vessel independently of the fire stop unit 59 when adequate' relief cannotbe effected therethrough by way of the primary inlet port 6|,under control of the primary valve 62. The valve 62, weight 63 therefor, and cover, 64 are of identically the same construction and function in accordance with the corresponding parts of the first described form of invention. In order that the port 60 may be substantially continuous, the upper portion of the body is connected to the lower portion by webs 65. The secondary port i normally closed by an annular valving ring 66 also preferably formed of flexible material and having its inner and outer edges 61 and 68 supported on annular seats 69 and 10. The valving ring is supported in valving position by a metal ring H which is carried by spring arms 12, the'spring arms having outer ends anchored to lugs 13 on the inner wall of the body member by screws 14 and the inner ends are secured to the rings 66 and H by fastening devices such as bolts 15. The arms 12 are designed to retain the valving ring seated under pressure differentials which may be adequately relieved by the primary valve 62 through the fire stop unit 59 but when the vacuum increases the arms 12 yield to unseat the valving ring 66 and provide secondary relief independently of the passages through the fire stop unit, thereby assuring safety of the tank when excessively high vacuums tend to occur.

From the foregoing it is obvious that I have provided a flame arrester and vent valve which protects a vessel or pressure system from excessive internal and external pressure differentials, and

What I claim and desire to secure by Letters Patent is:

, 1., A combined flame arrester andvent valve including, a body member having a flow passageway, a pressure vent valve cooperating :with the body member to close said passageway and unseatable under a'predeterminedpressure to relieve pressure through the passageway, a fire stop unit loosely mounted in said passageway, a bypass connected with the passageway and extending around thefire stop unit, and means on the fire stop unit normally closing said by-pass, said unit being shiftable responsive to pressure greater than said predetermined pressure to discharge the greater pressure through said by-pass upon opening of therelief valve.

2. A combined flame arrester and vent valve including, a body member having a flow passageway and a seat encircling said passageway, a pressure vent valve cooperating with the body member to close said passageway and adapted to open under a predetermined pressure to relieve pressure through the passageway, a fire stop unit in said passageway and spaced from the body member to form a passageway therearound, and a flange encircling the fire stop unit and engaging said seat ,to close the by-pass, said unit being shiftable by pressure in excess of the predetermined pressure to move said flange fromseating position to by-pass said'excess pressure when the vent; valve is open.

- 3. A combined flame arrester and vent valve including, a body member having a flow passageway, seats encircling said passageway, a pressure vent valve cooperating with the body member. and engaging one of said seats to closev said passageway and adapted to open under a predetermined pressure to relieve pressure through the passagewas. a. fire stop unit in said passageway and spaced from the body member to form a passageway therearound; and a flange encircling the fire stop unit and engaging said other seat to close the by-pass, said unit being shiftable by pressure to move said flange from seating position for bypassing said excess pressure when the vent valve is open.

4. A device of the character described including, a body member having a fire stop compartment, a valve seat encircling the compartment, 2. fire stop seat in said compartment, a fire stop unit in said compartment having a Peripheral portion engaging said fire stop seat, a flexible annulus having its inner marginal edge supported on the valve seat, a cover for said compartment, means for securing the outer marginal edge of said annulus with the cover around the periphery thereof, and means movably mounting the cover on the body member.

5. A device of the character described including, a body member having a fire stop compartment, a valve seat encircling the compartment, a

whichalso protects contents of.-.the: vessel from? ing; a body member: having a fire stopcompartment, a .valve seat: encircling-the compartment} a firestopseat, afire stop unit-lin said compart ment having. axperipheral portion engaging said;

fire stop seat, an annulus having'itsinner mar ginal edge supported onlthe Valve seat {r cover for said compartment, means for securing: the outer marginalaedge of 'said. annulus tothe-oover aroundthe periphery thereof; means movablysupporting theoover on the body member; and meansiin thebody member for exertingalifting leverage on the fire stopmnit.

7.1 Inra combine'dfiame arrester andvent valve, ai-body member having laflow passageway adaptedto be connected-atone endto avessel, a-fire stop unit loosely contained in said passageway to form a by-pass therearound; means onsaid unit and-engaging the body member to normally close the lay-pass, a cover for saidpassageway and cooperating with-the bod member to provide a port therebetween, a-relief valve normallyclosing said port: and yieldable to provideprimarysrelief. of said vessel through the fire stop unit; said/flow passageway having a secondary relief port on the vessel side of said fire stop unit, and asecondary valvecontrolling saidsecondary relief port for relieving the vessel independently A of said 'fire 'stop unit.

8; Inacombinedfiame arrester and ventvalve, a; body member having a-flow passageway adaptedto. be connected at oneendto avessel, a fire stop-unit loosely contained in: said passageway to form a: by-pass therearound; means-onsaid unitva'ndengagingthe bodymember to normally close. the byr-pass, a cover for said passagewayv and cooperating with the body member to providena port therebetween, a relief valve normally olosingi said port and yielda'ble toprovide'primary: relief of said vesselthrough-the. fire stop unit,. said flow passageway having a secondary relief port on.the-vesse1 side of said fire stop unit, and a secondary valve controlling-said secondary reliefport for relieving the vesselindependently or saidfire stop unit, said-primary relief .valve being set to operate atalower pressure differ ential than the secondaryrelief valve.

' is seate in'said'passageway.

assesses 10; In: a combined flame arrester and 'vent valve; abbey member having a fiow'passageway;

a"- pressurevent valve cooperating with the body memberto'close said passageway and unseatable under a predetermined pressure to relieve pressure through said passageway, a fire stop'unit'in said passageway and smaller in diameter than said passagewayto provide a by-pass around said firestop unit; means on the fire stop unit for closing: flow through said by-pass, and means in-s'aid' passageway providing a support for said fire stop unit, said fire stop unit being movable from said supporting means to open said bypass-when the pressure vent valve is opened in excess of said predetermined pressure.

11; In a combined flame arrester and. vent valve, a-body member having aflow passageway through which fiuidis adaptedto flow in either direction in said passageway, a fire stopunitin said passageway, avent valve normally closing flow through'the passageway and located on one side ofthe fire'stop unit, cooperating means on the body member and saidfi're stop uriit'to seat Sfiid'uhi'G-lfi' one new direction throughthe passageway; said firestop unit being movable in the other direction o'f'fioW throughthe passagewayresponsive-to pressure aeting on the fire stop unit in'excess of pressure'req'ui'red to aetuatethe vent valve; and a secondvent'valveon the opposite side of the fire stop unit for relieving flow through the fire stop unit when thefire stop unit JANIES J A DUGGAN;

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