US2152422A - Safety device for volatile liquid storage tanks - Google Patents

Description

March 28, 1939. J. J. TOKHEIM SAFETY DEVICE FOR VOLATILE LIQUID STORAGE TANKS Filed Jan. 25, 1957 EE mw lllllll III/ 129.1

Patented Mar. 28, 1939 SAFTY lDEV-ICE FOR VOL'ATILE .LIQUID STORAGE .TANKS John J. Tokheim, Cedar Rapids,"lowa 'Application January 25, 1937, Serial No. 122,278

6I Claims.

This invention -relates Vto a -safety Vdevice for volatile liquid storage tanks.

YStorage tank-s l'for gasoline andthe like must -be 'provided with adequate venting means ynot only to take careof the expansion of air or vapor above A`the yfluid level therein, but-also `to permit the ingressof air V/When the liquid vfuel is lwithdrawn `from the ltank to prevent V'the formation of a vacuum which would `tend tolcollapse the tank. IMoreover, such vents must be so constructed as -to provide adequate protection against VAre, dust, sand, rainfsnow and ice.

Accordingly, lthe present invention has primarily in a -viewcombined pressure and vacuum -valve device and a iflre protecting cage therefor. I-n that connection, the *invention contemplates a structure including la single pressure or blow --oi valve -surrounded by a vmultiplicity of vacuum valves, all of -said valves-'being housed within a novel -cage 4'which permits of vfree access tofthe atmosphere so that the valves may reliably'function vunder normalconditions of use, and, on the other hand, will be amply protected in thel case of fire-to prevent failure'of the valves and also to prevent ignition of the contents of the tank.

A further object of the invention is lto provide a novel weather-shield which yin normal use adequately protects the valves from water, or snow and ice, and which, in case of re, will drop out of position to compel flame propagation on the outside of the cage.

With the above and other-objects in view which will more readily appear asv-thenature of the inventioniishbetter understood, the same consists in the novel construction, combination and arrangements `of parts hereinaftermore fully described, illustrated and claimed.

A preferred and practical embodiment of the invention is shown in the accompanying drawing, in which:

Figure l is a vertical sectional View illustrating the invention.

Figure 2 is atop plan view, partly in section of the construction shown in Figure l.

Figure 3 is a detail perspective view of a portion of the Weather shield and cover showing the fusible link connecting the same.

Figure 4 is a detail perspective View of one of the flame arresting plates.

Similar references designate corresponding parts throughout the several gures o-f the drawing.

According to the embodiment of the invention shownv in the drawing, .the same includes inits (Cl. 22o-44) vorganization :a vapor condensation ycompelling andpressure relief or fblow off `valve Asurrounded by an annular series .of vacuum valves B, -all yhoused withinfa .valvecage designated generally Aas .'Cand surrounded by a weather-shield D. f5

The cage C comprises a base I having a cen l-tral Ainternally threaded .nipple 2 for mounting the entire :device on a vent pipe vP connected with the storage tang in the usual manner. The

:base I is provided at its outerperiphery with a tro plurality of1postsJ3 which may besecurecl thereto by suitable 'fastenings 4. `These posts are vchannelecl or groovedat oppositesides 'to form guide- `ways forreceiving -the opposite :ends of the metal flame arresting plates 6. YThese plates are provided with integr-al offset spacing projections so `that whenthey are arranged in stacked formation in the opposed channels 5 of adjacent posts, they provide intervening air passages `for establishing communication between the valves A and'B and 20 the atmosphere. The plates in each stack may be conveniently'held together by the lfastenings il. The top of the posts 3 support a cover plate 9 which is preferably secured 'to the posts by the "fastenings I having vwinged heads to facilitateI sioned by a coil spring contained withina hous- 'l .ing

I5. The eye I4 receives a .fusible link or loop I6 which engages `theiastening Il on ilange I-I. 'I'his arrangement locates the fusible link I6 atlthe hole .or yslot l2, and the spring ten- ,40 sioned eyebolt I4 .holds the Weather-shield D firmly in place. In the event of ire, any flame propagatedat the outer .side -of the plates 6 will pass through the openings vrI2 and quickly melt the links I6 thereby .permitting Athe shield to 45 drop. Ordinarily, however, the shield remains in the position shown in Figurel to prevent water rentering the valve cage,.or togprevent the formation of ice on the plates which 'would obstruct .the free passage of fair. :Thercover is provided 50v with a central :boss "I8 Ywhich is interiorally threaded .to receive a tubular valve .stem guide I9. 4'I'he'upper end of .thetubular guide is vtted .with Yaremovable xcap `20. As will be observed :fromthe drawing, theaguide .I-9.:receives . thesstem 75,5

of the pressure relief valve A to guide it in its movement.

The pressure relief valve A is of substantially the same diameter as the pipe l? so as to permit of full efficiency under service conditions. The body of the valve AV fits within the collar 2l]a of the valve supporting casting which is common to both the pressure valve A and vacuum valves B as will presently appear. The body of the valve is provided with an annular flange which overlies the upper edge of the collar Ztla so that the valve will tightly seat on the collar.

The valve casting which supports the pressure valve A and vacuum` valves B, and which also includes the collar 2l)EL previously referred to is designated generally as 22. This casting is provided With the base flange 23 which is vsecured to the base I about the opening `formed by the threaded nipple 2 and is also provided with an intermediate horizontal wall 24 provided with ports or openings surrounded by the seats 2411L for the vacuum valves B. This wall 24 is connected by a vertical web 25 with another or top horizontal wall 26 which is provided with openings for receiving the vacuum valve guide members 21.

The Wall 26 carries the collar 20a previously referred to, and the portion of the casting below the collar 20B is provided with a series of openings 28 for establishing communication between the pipe P and the vacuum valves B which rest on the seats 24a formed in the wall 24. The ports about which seats 2lla are formed communicate with the atmosphere through the space between the plates 6. The vacuum valve guiding members 21 are threaded into the top horizontal wall 26 of ythe valve casting, and by receiving the stems of the valves B serve to guide, them in their opening and closing movements.

From the foregoing it will be apparent thatY the present construction provides a safety device performing the essential functions of (l) permitting air or vapor pressure in the tank to escape when the pressure exceeds the Weight or load on the valve while on the other hand normally holding the vapors in the tank so that they may be condensed, thus preventing ordinary vapor losses; (2) when liquid is withdrawn from the tank the vacuum vvalves Will function to admit air to displace the fluid withdrawn and prevent warping-of the tank; (3) provide a flame arrestor screen which normally functions to prevent dust, soot, sand, etc., from entering the valve chambers and obstructing the proper closure of the pressure and vacuum valves. Further, in case escaping vapors through pressure valve and flame arrester cage' ignite, the flame arrester stops 'the flame from entering the valve chamber, preventing consequent damage to valves or finally igniting the gases within the tank, causing tank explosion;` (4) provides a weather shield with fusible link fasteners, normally functions to protect flame arrester and valves against rain, snow and sleet, and in case of fire at flame arrester to automatically drop down to protect the tank roof from becoming too hot, by permitting flame to spread outwardly instead of downward.

In breather vents it is important that all valve seats are provided with complete or perfect drainage, otherwise the escaping vapors when coming in contact with the atmosphere condense and form moisture in the valve chambers. Unless the valves are provided with complete drainage this moisture in cold weather freezes the valves fast to the valve seats. In warm weather the moisture dries and leaves a gummy substance on the valves and seats, glueing the valves to the seats. In either case prevents the valve from properly functioning. It will be noted from drawing Figs. 1 and 2 that the pressure valve seat 2l, in casting 22 provides complete drainage both inside and out. The vacuum valves are provided with complete drainage on the outside between base casting I, and valve seat bottom 24, and on the inside through vapor p0rt 28, which opening is below valve seat 24a and drains directly into pipe P.

The interlocking breather valves, ame and dust arrester and Weather-shield, insure unobstructed function and protection to storage tanks of volatile liquids.

It is further to be noted that the vacuum valves are made comparatively small in diameter. This to enable them to be light in weight and still retain the required strength to withstand the pressure applied by the pressure on the tank without warping and defeating their purpose. The light weight vacuum valves are especially important in storage of volatile liquid blends, as the light ends are drawn to the surface by vacuum, becoming vapors, and thus separating the blend and depreciating the value of the mixture.

The relatively large single pressure relief valve A adequately permits of adapting the device to a tank of a given size. For example, the diameter of the tank in feet, plus one fourth of the diameter is approximately the same as its area of the vent valve in square inches. Thus, if the tank is 40 feet in diameter, this formula snows that the index for computing the area of the valve is 50, that is square inches. Therefore, since the area of an eight inch pipe is 50 square inches this size valve will meet all requirements. The total area of the vacuum valves is substantially equal to the area of the single pressure relief valve so that the valves are fully designed to compensatefor movement of air or gas either in or out of' the tank.

'I'he foraminous valve cage, dust and sand screen flame arrester and its weather shield are essential to the proper functioning of all of the valves and the means which permits the shield to drop; in case of fire affords further protection to the tank as theflame will blaze outwardly and upwardly, in place of being forced down against the tank roof. Since the ame arrester and valve cage preventriire propagation to the valve chamber, but burns entirely on the outside of plate stack 6. The valves function properly under re and when the vapor pressure on the tank becomes less than the valve pressure, the valve closes and automatically the re is extinguished for lack of fuel.

Without further description it is thought that the features and advantages` of the invention will be readily apparent to those skilled in the art, and it will of course be understood that changes in the form, proportion and minor details of construction may be resorted to, without departing from the spirit of the invention and scope of the appended claims.

I claim:

l. A safety device for volatile liquid storage tanks including in combination, a casting having a central valve seat and a plurality of separate valve seats surrounding the central valve seat,

said casting having passages for establishing communication between the last named valve seats and the space beneath the central valve valve seat, and vacuum valves on said separate valve seat.

2. In a safety device for volatile liquid storage tanks, the combination with a supporting vent pipe carried by the tank, of a pressure relief valve of substantially the same area as the pipe, and a plurality cf vacuum valves of substantially the saine total area as the pressure valve spaced radially from the axis of said pressure valve and arranged circumferentially there-about.

3. in a safety device for volatile liquid storage tanks, a casting mounted on the base member and having a central valve seat, and a plurality of separate valve seats in said casting surrounding and below the central valve seat, said casting having ports in the side thereof for establishing communication between the said separate valve seats and the space beneath the central valve seat, a pressure valve mounted on said central valve seat, and vacuum valves on said separate valve seats.

4. In a safety device for volatile liquid storage tanks, valve means comprising a casting having a central valve seat at the top portion thereof and having a laterally offset portion provided with a plurality of valve seats, said casting being provided between said laterally offset portion and the central valve seat with ports for establishing communication between the plurality of valve seats and the space beneath said central valve seat, a pressure responsive valve mounted on said central Valve seat and a plurality of vacuum l valves mounted on said separate valve seats.

5. In a safety device for volatile liquid storage tanks, a base member having an opening, pressure and vacuum valve means carried by said base above the opening therein, said means including a casting having a bottom portion adapted to rest on said base, an inner vertical wall provided with ports, a central valve seat formed above said inner wall, a pressure responsive valve for said valve seat, a laterally extending wall on the casting arranged substantially medially of the height of the latter and having a plurality of vacuum valve seats therein arranged opposite said ports in the vertical Wall of the casting, and vacuum valves for said vacuum valve seats ln the casting.

6. In a safety valve for volatile liquid storage tanks, a base having an opening and adapted to be fitted to the vent pipe of the storage tank; valve means arranged over said opening in the base and including a central pressure responsive valve and a plurality of vacuum valves, arranged circumferentially about the pressure responsive valve.

JOHN J. TOKHEIM.

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