US2280657A - Breather roof - Google Patents

Description

April 21, 19425 B. B. MccANDLlss BREATHER ROOF Filed Sept. 14, 1939 3 Sheets-Sheet l INVENTOR. Y zzafdE/Y MW April 21, 1942. B. B. MccANDLlss BREATHER ROOF Filed Sept. 14, 1959 3 Sheets-Sheet 2 Nw T ym f@ 10M A i vm@ wm Q@ QQ ,mnd

April 21, 1942. B. B. MccANDLlss BREATHER ROOF Filed Sept 14, 1939 3 Sheets-Sheet 3 wk u@ QQ INVENTOR.

mw uw@ Patented Apr. 2l, 1942 nEA'rnEn noor Bernard B. McCandliss, Chicago, Ill., assignor to Graver Tank & Mfg. Co., Inc., Catasauqua, Pa., \a corporation of Delaware Application septembern, 1939, serial 10.294307 4 Claims.

The invention relates to storage tanks and has reference more particularly to a breather roof for storage or collection tanks for volatile petroleum fractions such as gasoline or kerosene or distillates containing such volatile substances.

Tanks of the type above described are fairly large in diameter and therefore the surface area of liquid subjected to variations in temperature is substantial. Since a large surface area is subjected to the heat of the suns rays during the day, for example, the vapors produced are considerable and the pressure within the tank is materially increased. However, if these vapors are conserved they can be reclaimed during the night as a result. of the cooling temperature which condenses the vapors. The production of vapors during the day followed by a subsequent cooling and condensing of the vapors during the night is known as breathing" and in large tanks, particularly if only partly filled, such breathing will be substantial. Also when the oil is pumped into such tanks the agitation increases the generation of vapors. However, the lling of the tank with oil decreases the vapor space and here also the vapor pressure within the tank may become dangerously high.

pressure within the tanks. Thus, as a matter of economy. it is necessary to conserve said vapors so that they can be eventually condensed without any loss of the valuable fractions.

The invention has for its primary object to provide a breather roof for oilstorage tanks which as a result of its movement will provide ample vapor space to take care of breathing of the tank under any and all conditions.

Another and more specic object is to provide a gas holder type of breather roof which will have considerable movement in a vertical direction to vary the vapor space within the tank so that it will not be necessary to discharge any vapors to the atmosphere even under most severe breathing conditions. e A further object of the invention is to provide improved means for controlling the movement of a gas holder type of breather roof so that the same will rise and fall in a true vertical direction.

Another object is to provide an improved arrangement of iiexible guide cables for controlling the vertical movement of a breather roof and for constraining the same to prevent tipping from a horizontal plane.

Another object of the invention is to provide flexible guide cables for the purposes described which will be located entirely within the roof of the tank so as to protect the same from climatic conditions such as would tend to rust and corrode yin. the Speciflcation, drawings and claims appended hereto.

In the drawings which illustrate `an embodiment of the invention and wherein like reference characters are used to designate like parts- Figure 1 is a vertical sectional view taken sub-- stantially through the center of a tank showing the same equipped with a breather roof embodyfv ing the principles of the invention; u f Y Figure 2 is a fragmentary sectional view show-y ing the manner of rotatably supporting?"the sheaves for the flexible cables from the tank side walls;

Figure 31s a sectional view taken substantially along line M of Figure 2;

Figure 4 is an elevational view, parts being shown in section, of an oil lstorage tank having a modied form of breather roof coming within the present invention;

Figure 5 is a fragmentary sectional view illustrating the modified arrangement employed in Figure 4 for rotatably supporting certain sheaves from the side wall of the tank;

Figure 6 is a fragmentary sectional view similar to Figure 5 but showing the manner of rotatably supporting other sheaves for the flexible cables; and

Figure 'I is a fragmentary plan view showing both forms of sheaves in their associated relation when xed to the side walls of the tank.

The oil storage tank shown in Figure 1 includes an open top tank having outer side walls I0 strengthened at the upper end by the angle member il and a. base I2 adapted to rest upon the earth or other suitable support. To form a seal for the breather roof the tank is provided with an inner cylindrical wall i4 which forms 4a trough I5 with the outer wall' of the tank. 'Ihe trough is adapted to contain a liquid 'such as oil or the like, whereby the tank is sealed with respect to the breather roof, although the same may have movement to vary the vapor space above the liquid within the tank.

The root for the open top tank I is in the form of a holder bell designated by numeral I6 and which has telescoping relation with 'respect to the outer wall I0 of the tank and the inner cylindrical partition I4. The holder bell essentially consists of a cambered roof Il of sufficient strength to withstand the maximum pressure of the vapors within the tank. The skirt i8 depends from the roof I1, being suitably secured around the periphery thereof, and which securement includes the angle member I9. The skirt has location within trough I5. When the trough contains water or oil the said depending skirt seals the holder bell with respect to the tank. p

A feature of the invention resides in flexible cables for controlling the vertical movement of the holder bell and in the improved manner of supporting the sheaves for the cables from the cylindrical wall of the tank. The cables constrain thek roof so as to prevent tipping from a horizontal plane as the roof moves up and down to vary the vapor space within the tank. A plurality of pairs of said ilexible cables are located within the holder bell and it will be understood that one end of each cable is secured to the cambered roof Il, whereas, the other end has securement at a point on the opposite side of the roof to the lower end of the depending skirt I8. Therefore, the ilexible'cables and the sheaves with which they engage are located entirely within the tank and are thus protected from the elements. Also as a result of the oil in the trough I5, which forms the sealing medium for the roof, the flexible cables and the sheaves are at all times well lubricated to facilitate the rise and fall of the holder bell which thus functions as a breather roof.

For purposes of illustration Figure 1 shows a pair of flexible cables and sheaves for the same which, in accordance with the invention, are supported from the inner wall I4 of the tank. For a part of its length each cable includes a rod,

namely, 20 and 2l, respectively, having a turnbuckle 22 and connecting by means of hooks 23 with chains which engage the sheaves. At the right hand end of rod 20 the chain 24 is iixed to the roof of the holder bell and said chain passes under a sheave-26 suitably journalled by support 21. At the other end of rod 2B the chain 24 passes over sheave 28 and extends to near the bottom of the depending skirt I8, where said chain is iixed by the hook 30. In a similar manner chain 25 for the rod 2I is xed to the roof as at 8|, Figure 2, and passes under a sheave 2li,A whereas, the chain at its other end will pass' over a sheave 28 and depend theproper length into the trough I5 for securement by the hook 30 to the lower end of skirt I8.

For operation of the breather roof of Figure 1 it will be understood that the trough I5 is adapted to contain oil or water as a sealing` medium for the depending skirt I8. The space within the cylindrical wall I4 may also contain oil if the tank is being used for a storage tank, or the entire space within the tank may be used for storing gas. In both cases when the pressure exceeds the weight of the holder bell the same will tend to rise and it is this movement of the holder bell that is controlled by the ilexible cables. Also the holder bell is constrained tomove in a true vertical plane and therefore tipping of the breather roof is effectively prevented.

Figures 2 and 3 show the .iournalling means for the sheaves and the manner of supporting the same from the cylindrical wall of the tank.

Each support, indicated in its entirety by numeral 2l, includes a pair of spaced upright members 32 united at their top and bottom by plates 83 and 34, respectively, the bottom plate beiner secured as by welding or the like to a circular angle member 35, which reinforces the upper end of the wall I4 of the tank. The partition 3B divides the supporting structure into two compartments Within each of which is located a sheave adapted to engage either the chains 24 or 25. The sheave 2B, positioned in the right l hand compartment, Figure 3, has contact with chain 25, while the sheave 28, located in the left hand compartment, has contact with chain 24. The stud shaft 29 provides journalling means for both sheaves.

In the form of the invention shown in Figure 4 the open top tank includes a cylindrical side wall 40, a base 4I, which rests on the earth'or other suitable support, and supporting structure comprising rafters 42 and vertical supports 43 adapted to sustain the breather roof of the tank when in deilated position and to transmit the weight of the roof directly to the side wall and base of the tank. In this form or the invention the trough 44 for the sealing liquid is formed by an outer cylindrical wall 45 concentric with the wall 40 of the tank and having location at the upper end of the tank. The trough is completed by the angle member 46 forming the bottom of the trough.

The breather roof for the open top tank 4I! comprises the holder bell designated by numeral 41 and which has telescoping relation with respect to the cylindrical wall of the tank. The said bell includes a cambered roof 48 having a depending skirt 50 for location within the trough 44 and also having a depending outer flange 5I which forms a cover for shielding the trough and its associated equipment from the weather. The flange 5I is concentric with the depending skirt 50 and the same is suitably secured to the periphery of roof 48 by the angle member 52. In de flated position the roof will rest on the supporting structure within the tank, including the rafters 42, and it will be noted that in this deated position of the roof the depending skirt 50 termir ates just short of the base 46 of the trough.

The flexible cables for constraining the holder bell, so as to prevent tipping from a horizontal plane as the same moves up and down to vary the vapor space within the tank, includes rods having fixed to their ends chains which pass over sheaves in a manner similar in all respects to that described in Figure 1. A plurality of pairs of flexible cables are employed for the roof such as shown in Figure 4, although only one pair has been shown for purposes of illustration. The rod 53 at its right hand end is connected to the chain 54 which passes under a sheave 55 and then upwardly for securement to the roof 48 as at 56. The other end of rod 53 includes a turnbuckle 5'I to which is secured a chain 54, which, however, passes over a sheave 58 and depends into trough 44, being eventually secured by hook to the lower end of the skirt 50. It will be understood that a pair of sheaves 55 and 58 are located opposite each other and that each pair of sheaves will be suitably supported from the cylindrical wall 40 of the tank. Thus the rod 6I at its right hand end also connects with a chain, namely, 62, which will pass over a sheave 58 and depend into the trough for attachment to the lower end of the skirt 50. The chain 62 at the other' end of rod 6| will pass under a sheave 55 and then upwardly for securement to the roof of the holder bell.

In the operation of the tank equipped witl,` the breather roof, as disclosed in Figure 4, the trough 44 is filled with a sealing liquid such as oil by the supply line 53 connecting with the trough through the base member 46. An over-flow line 64 maintains the liquid within the trough at the proper level. The space within the tank lwill also contain oil such as gasoline or kerosene or other volatile petroleum fractions. When the vapors given off by the stored liquid are such as to build up a pressure exceeding the weight of the breather roof 41 of the tank, the same will rise to thereby increase the vapor space and relieve the dangerously high pressure. A roof of the kind described may have considerable movement and accordingly the vapor space thatmay be provided will be ample to take care of the breathing of the tank under the most severe conditions. The cables control the vertical movement of the roof so that the same will move in a true vertical plane.

Figures 5, 6 and 7 illustrate the modified arrangement employed in Figure 4 for supporting the sheaves from the side wall of the tank.` The tank wall at its upper end is strengthened and reinforced by an annular angle member 65 to which is secured another angle member B6 so that the reinforcing structure essentially comprises a channel. The support for each sheave rests on the member 65 which is directly secured to the side wall of the tank. For accommodating the sheaves 58 the sidewall of the tank is cut away to provide a slot 61 which opens into the trough 44. The sheave is rotatably mounted by side plates B8 so as to extend through the slot, whereupon the chain which passes over this sheave may depend vertically downward into the trough for securement to hook 60. plate 10 and an angle member form guiding means for this depending portion of the'chain. The side plates 68 are joined by an arcuate member l2 which seals the trough 44 with respect to the interior of the tank.

The sheave 55 is rotatably mounted by stud shaft 13 in a support comprising spaced side members 14. The chains having engagement with this sheave pass under the same and are secured to the roof 48, as previously described. Referring to Figure 7, it will be noted that the stud shaft 69, journalling the sheave 58, is out of alignment with respect to shaft 13 for the sheave 55. This comes about by reason of the fact that the sheave 58 extends through the slot 61 in the cylindrical wall of the tank so as to allow the chain passing over this sheave to depend vertically downward in the trough 44.

The breather roof of the invention can be very easily adapted to old tanks and of course may be employed with new tanks. The movement of the roof may vary considerably, depending on the size of the tank to which the same is applied and the nature of the liquid stored therein. In any event, the roof can have movement such as will provide ample space to take care of breathing of the tank under most severe conditions. It is of prime importance that the roof move up and down in a true vertical plane and this is the function of the exible cables. It will be noted that each cable is secured at its respective ends to the holder bell and has connection with A backingv the\tank only by reason of its engagement with the sheaves which are in turn supported by the tank.v A feature/of the invention resides in the provision of brackets whereby the sheaves are supported from the cylindrical wall of the tank and are therefore independent of any supporting structure which'may be provided for supporting the roof in deflated position. The cables not only restrain the roof to prevent tipping from a horizontal plane but said cables additionally function to prevent undesirable rotation of the roof.

The invention is not to be limited to or'by details of construction of the particular embodiment thereof illustrated by the drawings, as various other forms of the device will of course be apparent to those skilled in the art without departing from the spirit of the invention or the scope of the claims.

What is claimed is:

1. In a storage container for petroleum products and the like, in combination, an open top tank yarranged to provide a body of sealing liquid,

a movable roof for said open top tank including a holder bell having its depending member located within the sealing liquid so as to confine vapors within the tank, flexible cables secured at their respective ends to substantially diametrically spaced points 'on the holder bell and movable with respect to said tank for guiding and controlling theholder bell in its up and down movement, sheaves adapted to engage the cables'respectively at points intermediate their connectionwith the holder bell, supporting brackets for the sheaves, and an annular reinforcing member xed to the cylindrical wall of the tank at the upper end thereof and extending inwardly of the tank, said annular member supporting the brackets for the sheaves and having the same fixed thereto.

2. In a storage container for petroleum products and the like, in combination, an open top tank arranged to provide a'body of sealing liquid, a movable roof for said open top tank including a holder bell having its depending member located within the sealing liquid so as to confine vapors within the tank, at least one pair of ilexible cables each being secured at their respective ends to substantially diametrically spaced points on the holder bell, sheaves adapted to engage each cable at points intermediate its connection with the holder bell, the cables of said pair being fixed at the end opposite each other to the roof and being secured at their other end to the def pending skirt of the holder bell, and an annular strengthening and reinforcing member fixed to the cylindrical wall of the tank at the upper end, said member providing a support for the sheaves.

3. In a storage container for petroleum prod- Y ucts and the like, in combination, an open top tank having a launder at the upper end thereof containing sealing liquid, a movable roof for the tank including a holder bell having its depending member located within the sealing liquid so as.

to confine vapors within the tank, flexible cables for maintaining the holder bell substantially horizontal during vertical movement thereof, each cable at its respective ends being secured to the holder bell at substantially diametrically spaced points, sheaves for `engaging the cables at points intermediate their connection with the holder bell, said sheaves being supported from the side walls of the tank and being grouped to form pairs positioned substantially diametrieally opposite ech other, one sheave of each pair being spaced inwardly from the tank side wall and the other sheave of said pair projecting through an opening in the said side wall so as to communicate with the launder, whereby the cable passing over said sheave may depend vertically downward in the launder for connection with the lower end of the depending member of the holder bell.

4. In a storage container for petroleum products and the like, in combination, an open top tank having a launder at the upper end thereof containing sealing liquid, a movable roof for the tank including a holder bell having its4 depending member located within the sealing liquid so as to confine vapors within the tank, v

flexible cables for maintaining the holder bell substantially horizontal during vertical iov ment thereof, said cables being grouped to form pairs and the cables of each pair being xed at the end opposite each other to the roof and being secured at their other lend to the depending member of the holder bell, sheaves supported from the side wall of the tank and adapted to engage the cables, said sheaves also being grouped to form pairs positioned substantially diametrically opposite each other, one sheave of each pair projecting through an opening in the tank side wall and extending within said launder,

whereby the exible cable passing over said sheave may depend vertically downward within the holder bell for connectipn with the depending member of the holder ball.

BERNARD B. MCCANDLISS.

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