US1714209A

US1714209A - Liquid-seal expansion roof

Info

Publication number: US1714209A
Application number: US251195A
Authority: US
Inventors: Charles F H Bohnhardt
Original assignee: Individual
Current assignee: Individual
Priority date: 1928-02-01
Filing date: 1928-02-01
Publication date: 1929-05-21
Anticipated expiration: 1946-05-21

Description

' y 21,1929- a. F. H. BOHNHARDT 1,714,209

.LIQUID SEAL EXPANSION ROOF I Filed Feb. 1, 1928 can 7 Patented May -21, 1929.

- the tank shell. the trough is shown at 4.

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Application filed February 1, 192 8. Scriai No. 251,195.

, My invention relates to the art 5 Oil Stop age with especial reference to a tank'roof. An objectiof my invention is to prevent the loss of vapor through the daily breathing of such tanks caused by variations in temperature between night and; day. As the temperature increases the. vapor in the tank expands and escapes through a relief valve;

'converscly as the tank cools at night, air 10 is drawn into the tank through a vacuum relief valve. Such breathing causes large evaporation losses. By providing a tank "with suflicient"expansibility to accommodate this volumechange, breathing and evaporation losses are stopped.

Other objects and advantages. will be apparent from the following description of a preferred embodiment of my present invention,- reference being made to the accompanying drawing, in which:

Figure 1 is a section through a tank showing one manner of applying myliquid seal expansion roof. 7

Figure 2 is a section through a tank show ing a second manner of applying the same. FigureB is a dctailof the liquid seal. Figure 4 is a detail of a. liquid seal relief valve. I

In the application of my invention I provide around the top. of the. tankshell a continuous trough designated by numeral 1. This trough is made. in sections, each section a single piece of steel bent to the shape shown and welded to the tank shell 2 as at 3. It is desirable to have the outer peripheral wall 5 of this trough about as high as the top of Suitable bracing to support The tank foot 6 extendsbeyond the tank shell to reach about the center of the trough. A downward extending skirt 7 is non-leakably secured to the edge of the roof and dips into the trough. The trough is filled with water and, as skirt 7 extends below the water level a gas tight joint is made between the tank shell and the roof. The roof floats on the vapor in the tank. The depth of the trough is determined by the expansibility required. The pressure necessary to float a roof of usual weight is only a few inches of water.

Where a tank is large it is economical to use the arrangement shown in Figure 2. The trough is secured in the roof and the center part of the roof is equipped with a skirt extending into the trough as before. By providing a deeper trough and a longer skirtthe same degree of expansibility can be obtained as is obtained in the first arrangement, the moving parts being smaller. 1

It is necessary to prevent the roof from rotating. I accomplish this b providing two or more closed tubes 9 noneakably secured to the tank roof, into each of which a pipe column 10 extends. braced within the tank and prevent the roof from rotating, yet allow it to move vertically.

When the roof is at its lowest position it rests on the columns 11 which are braced within the tank.

It is to be noted that the pressures in the tank are very nearly constant. A pressure relief valve operated by change'in pressure would not function here, but by providing a valve as in Figure 4 which depends on the position of the roof to operate it this difficulty is eliminated. This valve consists of a cup 12 secured to the tank roof, open end down and extending into a second cup 13 secured to vapor recovery system or simp y to the outside of the tank. In this manner the roof is preventedfrom over-traveling and the vapor is got permitted to blow through the roof sea The means above described for sealing the vapor outlet is desirable for several reasons; it is reliable, free from working parts and is absolutely gas tight. However, there are conditions in which such a valve would not be entirely satisfactory. Where any liquid in the vapor lines except the condensate of the vapor itself is undesirable such a liquid sealed valve would not do. For such installations I contem late the use of other valves. Any valve whic can be operated by the movement of the roof is suitable, such valves as the ordinary stockcock and others answer this requirement.

My present invention canbe very economically applied to old tanks. B cutting the old roof free from the tank shell and providing the trough 1 and the skirt 7 the old roof can be used as an expansion roof. Other omy is efiectedby using the old roof.

These columns are.-

By weighing my expansion roof with suitable ballast, pressures greater than atmos cured thereto, said tube extending upward pheric can be maintained on the vapor in the tank. In storing liquids with high vapor pressure this would materially reduce the volume of vapor formed.

The principle of my liquid seal expansion roof can be utilized on all manner of storage tanks and reservoirs for storage of other liquids than oil, and I do not limit myself to the specific embodiments herein described except as defined in the following claims. v

I claim as my invention:

'1. In vapor disposal means for an oil storage tank equipped with a vapor sustained roof, a relief valve comprising: a first cup stationarily secured within said tank, open end up, said end being higher than the surface of said oil; a second cup secured to the roof of said tank, open end down, and adapt ed to enter said first cup; and a tube passing through the bottom of said first cup and sewithin said cups to substantially the level of thetop of said firstcup the. opposite end ofsaid tube communicating'with said-va or disposal means; said first cup being fille with a, I

liquid into which said second cup dips to 'form a gas tight seal between said tube and cups; the larger of said cups stationarily secured within said tank, open end up, said end being above the surface of said oil and -filled with a liquid; the smaller of said cups secured tosaid roof, open end down and.

adaptedto enter said lower cup;and means :Eor'conveying tank vapors from within said smaller cup when said roof has lifted said smaller cupfrom the liquid in said lower cup. 1

In witness thatI claim the foregoin I have hereunto subscribed my name this 2 th day of January, 1928. v

CHARLES BOHNHARDT.