US2670873A - Safety equipment for fuel tanks - Google Patents

Description

March 2, 1954 D, wHiDDEN 2,670,873

SAFETY EQUIPMENT FOR FUEL TANKS Filed Nov. 2. 1949 2 Sheets-Sheet 1 INVENTOR.

ATTOEWB March 2, 1954 T. D. WHIDDEN 2,670,873

SAFETY EQUIPMENT FOR FUEL TANKS Filed Nov. 2, 1949 2 Sheets-Sheet 2 I 57 W a? g m 3 L i L v "I I fl- I 43 I i j 40 d 4/ INVENTOR. IQ W///00A/ BY Patented Mar. 2, 1954 UN 1 TE!) STATES PATENT OFFICE SAFETY EQUIPMENT FOR FUEL TANKS Theron :D. Whidden, Jacksonville, Fla. Application November 2, 1949, *Serial No. 125,139

:7 Glsims. (Cl.--220--88) This invention relates to safety devices and more specifically to apparatus for protecting a tank containing an inflammable liquid or gas from fire or explosion. This application is a con tinuation-in-part of application Serial No. 646,921 filedFebruary 11, 1946,1037 T. D. Whidden, now Patent No. 2,552,472, issued May -8, 1951.

It is an important object of this invention to improve the safety of tanks containing inflammable gas or liquid, particularly the tanks of bulk fuel delivery trucks and the like.

The conventional bulk fuel delivery truck tank has many fire and explosion hazards. These tanks are customarily filled to a designated or predetermined level or mark, leaving a portion of the upper section of the tank to be filled by expansion of the fuel. It is obvious that any overflow or leakage of the inflammable fuel constitutes a serious fire hazard. Moreover, these tanks, through negligence, are often filled beyond or above the designated mark, thereby taking up "all or a portion of that space intended as a safety factor and as a means for saving fuel.

Furthermore, these conventional bulk fuel delivery truck tanks have another disadvantage in that they have restricted vacuum relief when unloading fuel, causing the operator to open the fill cap to relieve the restricted condition and this action increases the danger of ignition of inflammable vapors which may cause an explosion.

Another common fault of conventional bulk delivery tanks is the constant danger from sparks or fiame near their vents. No known existing truck tank arrangement provides posi tive flame arrestor action through the vents at all times.

Still another fault or fire hazard of such conventional truck tanks isthe extreme danger of refilling them due to the fact that when the tank has been unloaded the space formerly occupied by the fuel has been replaced by air and under certain conditions a mixture of fuel vapor and air is very explosive needing only a spark of any type (such as a static spark or one caused by human negligence) to ignite it. The danger of static spark is recognized to the extent that a chain is usually required by law to attempt to ground the static electricity. While it has been suggested that the fuel be replaced by carbon dioxide or other non-oxidizinggas, this is rarely done in practice due to the complexity or high cost of existing arrangements or to their unreliable action or to the necessity for their maintenance.

It is another object of this invention to reduce or eliminate the above-mentioned disadvantages of fuel tanks for trucks.

The "above and related obie'cts are 'attained'in accordance with the invention by providing various safety systems for protecting a tank containing an inflammable liquid or gas from fire or explosion. These systems are particularly adaptable for bulk fuel delivery truck tanks but may be used with other types of tanks as well. A feature of all of the systems disclosed herein is the provision of an expansion chamber of predetermined or calibrated size partially within the fuel tank. This reduces the height required for the installation.

In one exemplary embodiment of the invention, the expansion chamber partially within the fuel tank has its inlet at a higher level than the fuel tank inlet (so that no fuel can enter the expansion chamber while the tank is being filled) and has its outlet (at the top of the expansion chamber) connected to an auxiliary expansion'chamber at the side of the fuel tank. The auxiliary expansion chamber is positioned and connected between two flame guard chambers partially filled with a non-inflammable liquid. One of the flame guard chambers is connected to the exhaust pipe of the truck engine while the other is connected to the atmosphere. Each flame guard chamber is provided with a bell chamber having a multiplicity of small holes therein to reduce the size of the bubbles in the liquid.

If desired, the bulk fuel tank can have a divided construction and two or more expansion chambers provided, one for each division of the fuel tank. One of these modifications is provided with mechanical check valves while the other doesnot have such valves.

The invention will be more readily understood by referring to the following description taken in connection with the accompanying drawings, in which:

Fig. 1 is an elevation view, with portions in cross-section, of a bulk delivery fuel tank with an improved safety arrangement in accordance with theinvention;

Fig. 2 is a top view of the arrangement of Fig. 1;

'Fig. 3 is an elevation View, with portions in cross-section, of a modification of the arrangement of Fig. l; and

Fig. *4 is an elevation view, with-portions in cross-section, of a modification of the arrange: ment of Fig. 3.

Referring more specifically to the drawings, Figs. 1 and 2 show, by way of example for purposes of illustration, a bulk fuel delivery tank l0 and safety apparatus therefor, in accordance with the invention, which will .be described below.

The tank T0 is, by way (if-example, of the type used by trucks for the transportation of fuel bulk but it will be appreciated that certain features of novelty of the present invention are applicable to other types of tanks as well. The tank I has a filler cap H and a withdrawal or delivery line l2 having a valve l3 therein.

The safety apparatus for the tank It will now be described. Positioned almost, but not entirely, within the confines of the tanki t is an expansion chamber It, the upper portion 65 of the chamber I4 extending above the filler opening closed by the cap H. A connecting line [5 extends from the top part of the tank It almost to the bottom ll of the chamber 14. From the extreme top of the chamber M a pipe line I8 connects with an auxiliary expansion chamber l9. From the top of chamber I9 a pipe line 20 extends into and nearly to the bottom of side chamber 23 while another pipe line 22 connects from the chamber 28 to the top of side chamber 23. The pipe 24 extends from thelower portion of chamber 23 out through the top of this chamber to the exhaust pipe 25 of the truck. The pipe lines as and 2f! extend below the surfaces of the liquid (such as glycerine) B ll and 31 in the chambers and 2%, respectively, and

are connected, respectively, to the bell chambers 25 and 21 therein. Each bell chamber has a multiplicity of apertures 23 therein. From the top of chamber 21 a line 29 opens tothe atmosphere. The chambers l9, 2i and 23 and the connecting lines thereto and therefor are all external of the tank H3. The use of I 'ycerine is particularly valuable due to its ant reeae qualities and since it is mixable with water but not with gasoline. Its weight and viscosity also make it suitable for the purpose.

The expansion chamber is is calibrated for a predetermined rate of fuel expansion, such as 3 percent for example. Since the line it extends above the filler opening closed by the cap H,

even if the tank It! is filled completely full and 4- the filler cap is screwed on tight, no fuel can reach the expansion chamber Hi during the filling operation even if the operator is careless enough to overflow the tank. For this reason, this predetermined margin of safety for expansion is absolutely available even if the operator is careless or negligent in filling the tank.

As the temperature rises and the fuel in the tank Ii) increases in volume, the excess flows through pipe it into the expansion chamber 84. This displaces the air in the chamber is, causing an increased pressure of air in line it and also in lines 28 and 22. Thus, pressure applied to the surface of the liquid in chamber 23 raises the level of the liquid in line 25 equal to the distance that an equivalent pressure forces the liquid down in line Eli inside of chamber As the pressure forces the liquid down further in line 29 into bell chamber 2?, air escapes through the openings 28, bubbling up through the liquid 31 and the line at to the atmosphere. The purpose of the bell chamber 2? is to allow a large area for many small holes 23 thus causing smaller bubbles and less agitation or splash of liquid seal.

Consideration will now be given to the reverse operation, that is to contraction of the fuel in the main tank iii or to the opening of the delivery valve l3 (either of which will cause a partial vacuum in the main tank). This partial vacuum draws or lifts any excess fuel in chamber is back into the main tank it through line it. The same partial vacuum is applied to line (3, chamber l9, lines 22 and 2i) and lifts the liquid up in line 28 the same distance that it pulls the liquid level down in line 24 into bell chamber 25, thus opening the holes 28 and allowing the engine exhaust gases from the pipe 25 to enter. Any carbon or dust particles are trapped in the liquid in chamber 23 and settle on the bottom of this charm her where they cannot interfere with passage of gases. The chamber [9 acts as a trap for any splash of liquid seal from either chamber 25 or 23 to prevent it from entering the expansion chamber M. It also has the function of trapping any overflow (caused by excessive expansion of fuel) from the chamber l i. Any fuel entering chamber l9 will not return to the main tank l9 and examination of the amount of fuel therein will provide a reading, if desired, which can be used to ascertain whether the tank id is large enough for the installation. The chamber i9 can be drained by means of the opening 32.

The arrangement shown in Fig. 1 can also be used to force fuel from the main fuel tank HI by providing the out off valve 33 in the line 25. Since lines 24, 22, l3, I6, 29 and 29 are of equal size piping, which is also the same as that used for the gas pipe 25, it is perfectly safe to apply the pressure of the engine exhaust to the tank ll). By closing or partially closing valve 33 in exhaust pipe 25, the pressure of exhaust gas is routed through line 213, the liquid 3%, and line 22 to chamber l9. Pressure is built up to a point sufiicient to force glycerine down in line 25 into bell chamber 21, before escaping to the atmosphere through the glycerine 3i and line 29. The pressure that was exerted in line 29 is also applied to line it and, of course, to the tank ii] and its contents. If the drain valve I3 is open and the gases are insumcient in volume to replace the liquid being drawn oil, the weight of the glycerine will close line 28. Speeding up the motor of the truck is not dangerous since this will again open line 26. Line 21), chamber 23, glycerine 3| and line 29 form a low pressure relief or check valve. Line 24, chamber 23, glycerine 35 and line 22 form a low stage vacuum relief or check valve. This feature of utilizing the compression of the exhaust engine gases to force fuel from the tank ii; is very valuable. It also prevents any possibility of explosion of the tank ME by flame, spark or static electricity. Since this arrangement will unload the bulk fuel more quickly when the fill cap H is closed, the driver will have no reason to leave the cap off. Moreover, since the arrangement of Fig. 1 can (by the pressure of the exhaust gas) lift the fuel to a delivery point higher than the level in the tank, in many cases it takes the place of a delivery pump. It also has positive flame arresting on inhaling and exhaling openings and no mechanical check valves are necessary since the liquid in the flame guard chambers 2i and 23 serves as liquid check valves. This liquid quenches any sparks which may be present if conventional pumps are used to force or transmit stack, flue or engine exhaust to the fuel tank.

Figs. 3 and 4 show modifications suitable for divided tanks but it will be obvious that some features are applicable to single chamber fuel tanks as well. In Fig. 3, the tank 10 comprises two divisions til and ll. Partially-within each of the divisions is an expansion chamber 42 (or iii). Each of these two chambers has an inlet pipe 44 (or 45) opening into the top of the fuel tank Iii and a drain pipe 36 (or 47) having a check valve M3 (or 49) therein. A drain 50 is provided for the tank l8 and the expansion charm bers 42 and 43 have their upper portions connected to the pipe 5| which is a vent line to.a flame guard chamber or to an auxiliary expansion chamber such as the chamber 19 in Fig. 1 or is opened directly to the atmosphere or to a source of carbon dioxide such as the pipe 24 in Fig. 1. Caps 52 and 53 are provided to fill the divisions 40 and 4|. The expanded fuel flows into the chambers 42 and 13 and when the fuel contracts it flows back into the tank Ill through the check valves 43 and 49. In the arrangement of Fig. 4, no mechanical check valves are required as the pipes 6E: and 65 from the main tank In to the expansion chambers 42 and 43 are carried almost to the bottoms of the chambers 42 and 43. In this arrangement, the expanded fuel reenters the tank 19 through pipes 39 and BI in a manner similar to that described above in connection with pipe iii of Fig. 1. Otherwise the operation is the same as that of the arrangement of Fig. 3.

Various other modifications are possible without departing from the spirit of the invention, the scope of which is indicated in the claims. In the claims, the term gas is intended to cover a mixture of gases, such as air.

What is claimed is:

1. A safety system for a liquid fuel tank having a filler opening at the to thereof, comprising a closed expansion chamber at least the major portion of which is within the confines of the outer walls of said fuel tank, said expansion chamber being normally free of liquid, a connection from the upper portion of said tank into the top portion of said chamber and extending to a point near the bottom thereof, a portion of said connection being at a higher level than said filler opening to prevent entrance of liquid into said expansion chamber should said tank be filled to overflow said filler opening, and said top portion of the expansion chamber having connections to the atmosphere for both pressure relief and vacuum relief.

2. A safety system for a liquid fuel tank having a filler opening at the top thereof, comprising a closed expansion chamber at least the major portion of which is within the confines of the outer walls of said fuel tank, a connection from the upper portion of said tank to said chamber, a portion of said connection being at a higher level than said filler opening, a flame guard chamber adjacent said tank and containing non-inflammable liquid, means for admitting inert gas to said flame guard chamber, and pipe means for connecting said flame guard chamber to said closed chamber, said gas admitting means including a bell chamber having a plurality of apertures therein submerged Within the liquid of said flame guard chamber.

3. A flame guard chamber comprising a closed tank adapted to contain non-inflammable liquid, an opening in the top of said tank, a second opening in the top of said tank, a pipe adapted to have inert gas applied thereto projecting through said second opening and extending almost to the bottom of said tank, and a bell chamber connected to the lower end of said pipe, said bell chamber having a plurality of small apertures therein.

4. In combination, a tank adapted to contain an inflammable fluid, a hollow container which is normally free of liquid and which is at least partially within said tank, means connecting the upper part of said tank to the upper part of said container in such a way that fluid will not enter the hollow container should the filler opening be caused to overflow and that when fluid in said tank expands or overflows it flows into said container, drain means in the lower part of said container for draining fluid therein into said tank, said drain means having a check valve therein to prevent the entrance of fluid into said hollow container through said drain means, and means for admitting non-inflammable gas into said container when the fluid is being reduced in volume and for directing the flow of said gas from said container when the fluid is being expanded.

5. A safety system for a liquid fuel tank having a filler opening at the top thereof, comprising a closed expansion chamber at least the major portion of which is within the confines of the outer walls of said fuel tank, a connection from the upper portion of said tank to said chamber, an auxiliary expansion chamber at the side of said fuel tank, a pipe connection from the upper part of said first expansion chamber to said auxiliary expansion chamber, a flame guard chamber on each side of said auxiliary expansion chamber, and pipe connections from the flame guard chambers to said auxiliary expansion chamber.

6. A safety system for a liquid fuel tank having a filler opening at the top thereof, comprising a closed expansion chamber at least the major portion of which is within the confines of the outer walls of said fuel tank, a connection from the upper portion of said tank to said chamber, a portion of said connection being at a higher level than said filler opening, a liquid check valve chamber adjacent said tank and containing noninflammable liquid, pipe means for connecting said chamber to top of said closed chamber and pipe means for connecting and transmitting pressure relief to the atmosphere, a second liquid check valve chamber adjacent said tank and containing non-inflammable liquid, pipe means for connecting said chamber to the top of said closed chamber, and pipe means foradmitting inert gases into said second liquid check valve chamber and transmitting vacuum relief to said tank.

7. A safety system for a liquid fuel tank having a filler opening at the top thereof, comprising a closed expansion chamber at least the major portion of which is within the confines of the outer Walls of said fuel tank, said expansion chamber being normally free of liquid, a connection from the upper portion of said tank into the top portion of said chamber and. extending to a point near the bottom thereof, a portion of said connection being at a higher level than said filler opening to prevent entrance of liquid into said expansion chamber should said tank be filled to overflow said filler opening, a second expansion chamber, a connection from the top portion of said first expansion chamber to the top portion of said second expansion chamber, and connections from the top portion of the second expansion chamber to the atmosphere for both pressure relief and vacuum relief.

THERON D. WHIDDEN.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 57,479 Church Aug. 28, 1866 57,866 Church et a1 Sept. 11, 1866 61,213 Knight Jan. 15, 1867 1,974,034 Pelleriti Sept. 18, 1934 FOREIGN PATENTS Number Country Date 381,409 Germany Sept. 20, 1923 398,524 Germany July 15, 1924 467,334 Great Britain June 14, 1937

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