Abstract:
A baffling system for vehicle-mounted tanks is disclosed that reduces the concentration of vehicle destabilizing inertial forces of contained liquids caused by vehicle movements during transportation. The baffling system includes circular dish-shaped head baffles antipodally positioned with respect to each other, which attenuate forward and rearward directed liquid surges, and a plurality of longitudinal baffles that attenuate side-to-side liquid surges. The circular-shaped head baffles include removable cutouts for access to the tank compartments.

Description:
TECHNICAL FIELD  
       [0001]     This invention relates to a baffling system installed in truck-mounted tanks of emergency vehicles. More particularly, this invention relates to the installation of tank baffles designed to attenuate the inertial forces of liquids contained in such tanks produced by the abrupt movements of the vehicles on which such tanks are mounted. Specifically, this invention relates to a baffling system utilizing longitudinal baffles and transverse baffles wherein the transverse baffles incorporate a removable cutout portion allowing improved access for work in the tank when removed, and allowing reduced water flow through the passageway of the baffle when the cutout is installed. The combination of the restricted flow through the transverse baffles and the directed slosh protection of the longitudinal baffles substantially restricts water movement during high speed movement of the tanker, allowing better control of the vehicle.  
       BACKGROUND OF THE INVENTION  
       [0002]     Tank trucks are widely used as emergency vehicles for transporting water to remote locations to battle a fire where local access to water may not be adequate or available. Fire tanker trucks used for carrying water commonly do so by drawing a supply of water from a local lake, river, or other body of water into the tank by vacuum, and then rushing to the scene of the fire where the water is unloaded into a temporary structure, the truck thereafter returning for additional water. In such service, the truck is operated at high speeds, frequently over uneven terrain, with partial loads, and with frequent sudden braking and turning. Since the tanks carried by such trucks are normally not completely filled, sudden surges of the water held therein are common.  
         [0003]     Water has a liquid density of about 8.3 pounds per gallon, and a load weight of about 6 tons is typical for emergency tankers. The momentum of such loads, i.e., the product of the load&#39;s mass times its velocity, can be extremely high. As time is of the essence for emergency vehicles, the vehicles must travel quickly to their destination, often making quick starts, stops and abrupt turns. For example, in an abrupt stop of the emergency vehicle, the inertial forces created by the sudden shifting of the load can have a serious destabilizing effect on the vehicle. Such forces, including others generated by violent movements of the vehicle encountered in high speed operation, particularly over uneven surfaces, make it difficult to exercise control over the vehicle, with attendant risks of damage to the vehicle and its load, as well as injury to the driver and others who may be involved in the incident.  
         [0004]     To avoid such destabilization, the tank can be filled to capacity; however, it is not always possible or desirable to carry full loads. An alternative expedient involves the installation of baffles in the interior of the tank positioned at right angles to the anticipated movement of the vehicle carrying it. Such baffles, in effect, form compartments within the tank, limiting the distance that the tank&#39;s cargo can shift, thus minimizing the build-up of liquid velocities, and thereby ameliorating the destabilizing effects that would otherwise occur. An example of such baffles is presented in co-owned U.S. Pat. No. 4,789,170, herein incorporated by reference.  
         [0005]     While relatively successful, the baffles have several limitations. During turns, the transverse baffling has limited effect on the side-to-side movement of the water commonly referred to as sloshing. Sloshing also can result in destabilization of the vehicle. Another problem is related to the servicing of the tanks. It is often required that the interior of the tanks be inspected, cleaned, and/or treated with a protective coating to prevent corrosive effects of the water. In order to allow access, the baffling must have a cutout large enough for a person to pass to the compartments of the tank formed by the baffles. The cutouts allow flow of the water between compartments during operation of the tanker. The larger the cutout, the less effect the baffles will have in preventing destabilization of the vehicle.  
         [0006]     The foregoing illustrates limitations known to exist in present baffle systems for tank trucks, especially for emergency vehicles. Thus, it is apparent that it would be advantageous to provide an alternative directed to overcoming one or more of the limitations set forth above. Accordingly, a suitable alternative is provided including features more fully disclosed hereinafter.  
       SUMMARY OF THE INVENTION  
       [0007]     At least one disadvantage identified in the prior art is overcome by providing a fire tanker truck comprising: a generally cylindrical tank mounted on the truck, wherein a longitudinal axis of the tank is parallel to the truck&#39;s direction of locomotion; a plurality of circularly shaped head baffles mounted at right angles to, and spaced along the longitudinal axis of the tank; an access cutout formed in each head baffle; a door being removably fastened to each head baffle and at least partially covering the access cutout; and a vacuum pump connected to the tank for charging and discharging water. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]     The invention will be better understood when reference is made to the following drawings, in which like numbers refer to like parts, and wherein:  
         [0009]      FIG. 1  is a side view of a vacuum type fire tanker truck.  
         [0010]      FIG. 2  is a rear end view of the fire tanker truck of  FIG. 1 .  
         [0011]      FIG. 3  is a cross-section of a tanker invention along its longitudinal axis, showing installed transverse and longitudinal baffles of the present invention.  
         [0012]      FIG. 4  is a cross-sectional view of  FIG. 3 , along line  4 - 4 .  
         [0013]      FIG. 5  is an exploded perspective view of a transverse baffle and access door of the present invention.  
         [0014]      FIG. 6  is a front view of a removable access door from a transverse baffle of the present invention.  
         [0015]      FIG. 7  is a partial cross-sectional view of  FIG. 4 .  
         [0016]      FIG. 8  is a cross-sectional view of  FIG. 6 , along line  7 - 7 .  
         [0017]      FIG. 9  is a partial cross-sectional view of  FIG. 4 , illustrating a longitudinal baffle having an arcuate cross section.  
         [0018]      FIG. 10  is a cross-section of a tanker invention along its longitudinal axis, showing multiple rows of longitudinal baffles. 
     
    
     DETAILED DESCRIPTION  
       [0019]      FIG. 1  is a side view of a fire tanker truck, indicated generally by the numeral  10 , comprising a water tank  12 , equipped with a clean-out hatch  13 . Tank  12  may be loaded, for example, by attaching a hose, one end of which is immersed in a convenient water source, for example, a pond, to fill valve  20 . A vacuum is then drawn on the tank  12  with a vacuum pump, housed in an enclosure  19 , attached to the tank through vacuum line  18 . Water is prevented from being drawn into, and damaging the vacuum pump by means of safety check valves  14   a  and  14   b , respectively.  
         [0020]      FIG. 2  shows a rear end view of a fire tanker truck of  FIG. 1  showing details of the truck  10 , including tank  12 , which may be emptied through discharge valve  22 . Safety check valves  14   a  and  14   b  are also shown.  
         [0021]      FIG. 3  shows a cross-section through tank  12  along its longitudinal axis, illustrating the baffles of the invention. In the Figure, tank  12  is shown with a clean-out hatch  13  and fitted with an external port  29 , which is in communication with discharge valve  22 . Tank  12  is fitted with a plurality of transverse baffles  24  commonly referred to as head baffles  24  and a plurality of longitudinal baffles  40 . The head baffles  24  are circular, parabolic or dish-shaped members mounted at right angles to, and spaced along the longitudinal centerline axis A of the tank  12 . The ratio of the depth  23  of the dished center of the head baffles  24  to their diameter is in a range from about 1 to 6 to about 1 to 10. The longitudinal baffles  40  are mounted on the interior sidewalls of the tank in a radial position generally below a horizontal plane through centerline axis B as shown in  FIG. 4 . The shape of the head baffles of the invention may vary considerably. For example, they may be conical, pyramidal, substantially parabolic, etc.; however, the use of dish-shaped internal baffles is especially efficient in attenuating the forward surge described here.  
         [0022]     Referring now to  FIGS. 4 and 5 , the head baffles  24  include a removable access door  32 , at least partially covering an access cutout  34  such that when access door  32  is removed, a person can pass through the access cutout  34  to maintain or inspect the tank. In one embodiment, access door  32  includes a handle  38  and one or more tabs  36 , through which bolts, screws, or other removable fasteners affix the access door  32  to the head baffle  24 . When fastened, the access door  32  is rigidly and securely affixed to the head baffle  24  through tabs  36 . The door  32 , when rigidly and securely fastened to the head baffle  24 , operates as a functional part of the baffle to withstand the strong forces of the liquid moving within the tank  12 . Access door  32  is sized to cover all or a portion of access cutout  34  when access door  32  is installed on the head baffle  24 . In  FIG. 6 , it is shown that the door  32  conforms to the dished shape of the head baffle  24 .  
         [0023]     In one embodiment, access cutout  34  has a rounded shape at the top. Rounded cutout shapes reduce stress in the head baffle, whereas square cutouts may result in areas of increased stress in the head baffle. The size of access cutout  34  may be varied to accommodate the passage of different sized persons. In one embodiment, access cutout  34  through the head baffle  24  is large enough to allow an average-sized person to comfortably pass through when access door  32  is removed. In this embodiment, access cutout  34  has an area of approximately 415 square inches. Smaller cutouts that accommodate small or skinny persons may also be used, however, larger cutout areas make passage easier and faster. Easier passage through the access cutout  34  reduces accidents and injury when workers are inside the tank for maintenance or inspection, and speeds emergency response if there is an accident inside the tank.  
         [0024]     Although some form of bracket arrangement can be employed to fasten head baffles  24  to tank  12 , in view of the considerable forces involved, it has been found desirable to secure the head baffles of the invention to the tanks in which they are mounted by means of welding.  
         [0025]     Referring again to  FIGS. 3 and 4 , the head baffles  24  are fitted with equalizer ports  26  for the purpose of equalizing pressure in the tank on both sides of the baffles, and water transfer ports  28  that allow liquids to be moved from area-to-area within the tank. The water transfer port  28  allows water to flow from one side of the head baffle  24  to the other. The most efficient location for the water transfer port  28  is along the lowest edge of the head baffle such that the baffle does not trap water. In one embodiment, the water transfer port  28  is an aperture through the head baffle, separate and away from the access cutout  34  (not shown). In another embodiment, the access door  32  comprises an aperture functioning as the water transfer port  28  when access door  32  is installed on the head baffle  24  (not shown). In yet another embodiment, the water transfer port  28  is a gap between a lower edge of the access door  32  and the wall of the tank  12  when access door  32  is installed on the head baffle  24 , as is shown in  FIG. 4 .  
         [0026]     While the dimensions of the water transfer port  28  and equalizer port  26  are not critical, it is important in the case of a fire engine, for example, that the tank be capable of rapid loading or unloading. As water filling the tank passes through the water transfer port  28 , the dimensions selected should permit liquids to flow past the head baffles  24  quickly and easily. In this regard, the size of the water transfer port  28  may be larger than the cross-sectional area of the intake and discharge piping. In one embodiment, the water intake and discharge pipes are 6 inch diameter pipes, which have a cross-sectional area of approximately 28.3 square inches. In this embodiment, the water transfer port  28  is larger than 28.3 square inches to allow liquid to pass through the water transfer ports  28  as quickly as it is pumped in or out of the tank. This ability to limit the size of the water transfer port is a significant advantage over the prior art where the water transfer port had to be large enough for a person to pass through. When the water transfer port is large enough for a person to pass through, the head baffle loses effectiveness because liquid sloshes through the large water transfer port instead of being attenuated against the head baffle.  
         [0027]     An equalizer port  26  having a diameter of from about 4 inches to 8 inches, usually about 6 inches, is adequate for pressure equalization purposes. The shapes of the water transfer port  28  and equalizer ports  26  may be circular or may be any other shape.  
         [0028]     The longitudinal baffles  40  are best shown in  FIGS. 7 and 8 . Longitudinal baffles  40  comprise end portions  42  that are mounted to the interior wall of the tanks by brackets  44 . The longitudinal baffles  40  are configured to stop the advancing water and redirect it back toward its source such that the inertial movement of the water is attenuated. In the embodiment shown, the longitudinal baffle  40  comprises a longitudinal first plate portion  47  between two angled plate portions  48 ,  49 . The longitudinal baffle  40  is mounted such that side slosh hits the first plate portion  47  at a generally perpendicular angle. The water is then redirected by the angled plate portions  48 ,  49 , back upon itself as best shown by arrows C and D in  FIG. 4 . The angle shown between the first plate portion  47  and the angled plate portions  48 ,  49  is 135 degrees, however, the invention is not limited to a particular angle. It is also contemplated that the longitudinal baffle  40 ′ could be configured with a cross-section in the form of a full or partial radius as illustrated in  FIG. 9 . For example, the first plate portion could be a longitudinal flat plate between two arcuate portions. The present invention is not intended to be limited to a particular cross-sectional form for the baffles. The longitudinal baffles  40 ,  40 ′ can be any shape that effectively attenuates the side slosh.  
         [0029]     It is noted that the longitudinal baffle  40  is shown radially spaced from the side of the tank  12  as represented by radial spacing  50  in  FIG. 8 . This spacing prevents water from being trapped between the tank  12  and the longitudinal baffle  40 . The longitudinal baffle  40  is intended to prevent major surges of water moving laterally in the tank  12 . It is contemplated that the radial spacing  50  can be adjusted to optimize the effectiveness of the longitudinal baffle  40 .  
         [0030]     The angular position of the longitudinal baffle  40  is shown 10 to 12 degrees below the horizontal centerline axis B of the tank  12  in  FIG. 7 . It is contemplated that longitudinal baffles  40  could be located lower on the tank wall to check side slosh at lower tank fill levels. It is also contemplated that the longitudinal baffles  40  could be located higher on the tank wall. In alternate embodiments, more than one row of longitudinal baffles  40  is positioned on the tank wall, one row being positioned lower on the wall than other rows as illustrated in  FIG. 10 . The number of baffles employed will naturally depend upon factors such as the length of the tank, the nature of the liquids to be carried, the vehicular speed anticipated, and similar considerations. The present invention is not limited to a particular number or positioning of the longitudinal baffles  40  or head baffles  24 .  
         [0031]     Dimensions of the tank and the transverse and longitudinal baffles may vary; however, generally such components will have a thickness of about from 3/16 inch to ⅜ inch, about ¼ inch being common. Similarly, the diameter of the tank  12  may be varied widely, depending upon the service to which the tank is to be put and, therefore, the volume required. Generally, in fire tanker trucks, the tank diameter will vary from about 54 inches to 84 inches, with tanks of about 66 inches being common.  
         [0032]     While the head cross-sections of the tanks and, therefore, the head baffles illustrated in the various figures have been shown as round, other shapes may also be employed, for example, elliptically shaped tanks. The use of the baffles of the invention with circular tanks, however, is particularly effective for various reasons including, but not limited to, the fact that force components produced by the parabolic angularity on opposite sides of circular perimeters on the surface of such baffles are substantially balanced.  
         [0033]     The head baffles  24  and longitudinal baffles  40  operate together as a system. When the tanker truck  10  brakes rapidly, the symmetrical, dish-shaped head baffles  24  of the present invention tend to break up and dissipate the forward-moving liquid surges. The longitudinal baffles  40  assist in checking the edges of the forward surge. When the tanker truck  10  turns or changes direction, the longitudinal baffles  40  check the side surges within the tank. The longitudinal baffles  40  are especially important when the tank is carrying less than a half load.  
         [0034]     Another benefit of the baffle system  10  of the present invention is mobility of a worker in the tank for maintenance or inspection. Longitudinal baffles of the prior art configured to check side slosh often include large straight baffles through the center of the tank and running the length of the tank. In these prior art baffle systems, cutouts are placed through the baffles for workers to crawl through; however, these cutouts are difficult to maneuver, and the presence of the large cutouts naturally reduces the effectiveness of the head baffle. The baffle system of the present invention, conversely, allows worker mobility through the center of the tank, increasing worker safety, while improving side slosh reduction in operation.  
         [0035]     The baffling system of the type described greatly minimizes control problems caused by surges of the liquids being transported, and the baffling system may be used not only for fire tank trucks carrying water, but also those used for transportation of any type of liquid substances ranging, for example, from milk to gasoline. The baffles of the invention have been found to be particularly useful, however, in controlling liquid surges in fire trucks because of the difficult service conditions experienced by such vehicles, including partial loads, high speeds, roughened road surfaces, and the like. Normally fire tanker trucks involve tanks having volumes of from about 1,500 to 4,500 gallons; however, the baffles described are not limited to such capacities.  
         [0036]     While this invention has been described with reference to preferred embodiments thereof, it shall be understood that such description is by way of illustration and not by way of limitation. Accordingly, the scope and content of the present invention are to be defined only by the terms of the appended claims.