Abstract:
A tanker vehicle for distributing liquid on a surface includes a chassis that supports a tank for holding the liquid. A fluid pump discharges the liquid from the tank and is driven by a hydraulic motor. A hydraulic system delivers hydraulic fluid to the motor through a supply line and returns the fluid to a tank through a return line. A bypass circuit is disposed between the supply line and the return line, bypassing the motor. The bypass circuit includes a system for providing a combination soft start and soft stop of the hydraulic motor that is configured to enable hydraulic fluid to flow from the supply line through the bypass circuit to the return line at a start of the hydraulic system and to flow from the return line through the bypass circuit to the supply line at a shutdown of the hydraulic system.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This patent application is a continuation of U.S. patent application Ser. No. 12/814,061, filed Jun. 11, 2012, which is a divisional of U.S. patent application Ser. No. 10/411,827, filed Apr. 11, 2003, which is a continuation-in-part of U.S. patent application Ser. No. 09/873,032 filed Jun. 1, 2001. This patent application also claims the benefit of U.S. Provisional Patent Application 60/371,778, filed Apr. 11, 2002 and U.S. Provisional Patent Application 60/391,556 filed Jun. 25, 2002. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention pertains to tanks for storing and dispensing fluids, and in particular, to such tanks which are mobile and mounted on vehicles. 
       BACKGROUND OF THE INVENTION 
       [0003]    Dust control can be a particular problem on construction sites, building demolition sites, excavation sites and mine sites. For example, in a mining operation, the mine haul roads essentially consist of dirt and gravel. Dust control is necessary on the haul roads so that the operators of mining vehicles can readily see the other mining vehicles using the roads. Thus, dust control on mine haul roads is a safety issue. Moreover, dust clouds caused by vehicles operating on the haul roads can adversely impact air quality potentially creating environmental issues particularly where the dust clouds drift beyond the mine site. 
         [0004]    Typically, mines have water tanker trucks, which are used to water down the haul roads in order to control dust. Such water tanker trucks generally have a plurality of spray nozzles positioned on either the forward or rearward sections of the vehicles to dispense a fluid spray or mist onto the ground. The water tanker truck can also have hoses or a water monitor/cannon for washing down other mining equipment and, in some cases, fire control. 
         [0005]    Because of the service demands on such water tanker trucks, they are typically capable of carrying very large quantities of water. For example, water tanker trucks used in mining operations can have fluid capacities of over 50,000 gallons. Of course, vehicle stability is a critical issue when transporting large volumes of water that, in the case of a 50,000 gallon tank, can carry a water load of over 200 tons. Specifically, surging and wave motion of the fluid, particularly transverse surging resulting from centrifugal forces experienced during turning of the truck can cause a tanker truck to become unstable or even turn over on its side. To prevent such surging of the fluid, the tank is provided with internal baffles. 
         [0006]    To ensure a long-life, the interior of the tanks must undergo periodic maintenance. For example, to protect against corrosion, the interior surfaces of the tank may need to be periodically cleaned and re-coated with a rust protection coating such as an epoxy. This work is complicated by the fact that tanks only have points of entry on the top of the tank and often just a single point of entry, and thus the work is subject to confined space safety regulations. Accordingly, workers performing tasks inside the tank must be provided with secondary air sources from outside the tank. This can greatly complicate the maintenance operations. Moreover, it can be difficult for the workers to maneuver around the internal tank baffles particularly since the interior of the tank is very dark. Accordingly, maintaining the interior of these tanks can be a difficult and time-consuming process. 
         [0007]    Another problem with these types of mobile tanks is that at larger sizes they can be difficult to ship to the location at which they are to be used, typically on off-highway trucks. For instance, the largest tanks can be over twenty feet wide. As can be appreciated, transporting a tank of this size can be a difficult and expensive operation. 
       OBJECTS OF THE INVENTION 
       [0008]    Accordingly, in view of the foregoing, a general object of the present invention is to provide an improved baffled tank for a tanker truck such as is used for dust control in mining operations, construction sites and the like. 
         [0009]    A more specific object of one embodiment of the present invention is to provide a tank for such a tanker truck which has an improved baffling system. 
         [0010]    Another object of one embodiment of the present invention is to provide a baffled tank for such a tanker truck which is configured so that work can much more easily be performed inside the tank. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a side elevation view of an illustrative tank constructed in accordance with the present invention mounted on the chassis of an off-highway truck. 
           [0012]      FIG. 2  is an end elevation view of the tank of  FIG. 1  mounted on the chassis of an off-highway truck. 
           [0013]      FIG. 3  is a cut away perspective view of the tank of  FIG. 1  showing the assembled internal baffle system. 
           [0014]      FIG. 4  is a cut away side elevation view of the tank of  FIG. 1  showing the assembled internal baffle system. 
           [0015]      FIG. 5  is a cut away top plan view of the assembled internal baffle system of the tank of  FIG. 1 . 
           [0016]      FIG. 6  is a cut away rear elevation view of the assembled internal baffle system of the tank of  FIG. 1 . 
           [0017]      FIG. 7  is a side elevation view of the center section of the tank of  FIG. 1 . 
           [0018]      FIG. 8  is a sectional view of the center section of the tank of  FIG. 1  taken in the plane of line  8 - 8  in  FIG. 7 . 
           [0019]      FIG. 9  is a top plan view of the center section of the tank of  FIG. 1 . 
           [0020]      FIG. 10  is a front elevation view of the center section of the tank of  FIG. 1 . 
           [0021]      FIG. 11  is a perspective view of the inside of the left side section of the tank of  FIG. 1 . 
           [0022]      FIG. 12  is a top plan view of the left side section of the tank of  FIG. 1 . 
           [0023]      FIG. 13  is a side elevation view of the left side section of the tank of  FIG. 1  looking from the inside of the center section of the tank. 
           [0024]      FIG. 14  is a sectional view taken in the plane of line  14 - 14  in  FIG. 13  of the left side section of the tank of  FIG. 1 . 
           [0025]      FIG. 15  is a perspective view of the right side section of the tank of  FIG. 1 . 
           [0026]      FIG. 16  is a top plan view of the right side section of the tank of  FIG. 1 . 
           [0027]      FIG. 17  is a side elevation view of the right side section of the tank of  FIG. 1  looking from the inside of the center section of the tank. 
           [0028]      FIG. 18  is a sectional view taken in the plane of line  18 - 18  in  FIG. 17  of the right side section of the tank of  FIG. 1 . 
           [0029]      FIG. 19  is a rear elevation view of one of the hinged baffles of the tank of  FIG. 1 . 
           [0030]      FIG. 20  is an enlarged rear elevation view of one of the hinges of the hinged baffle of  FIG. 19 . 
           [0031]      FIG. 21  is a sectional view taken in the plane of line  21 - 21  in  FIG. 19  showing an exemplary cover plate installed over the access opening in the hinged baffle door. 
           [0032]      FIG. 22  is an exploded perspective view of the tank of  FIG. 1 . 
           [0033]      FIG. 23  is a perspective view of the baffle system of the tank of  FIG. 1  showing an alternative pivotal baffle door configuration with the pivotal baffle doors in the closed position. 
           [0034]      FIG. 24  is a perspective view of the tank baffle system and alternative pivotal baffle door configuration of  FIG. 23  with the pivotal baffle doors in the open position. 
           [0035]      FIG. 25  is a perspective view of one of the pivotal baffle doors of  FIG. 23  installed in a baffle. 
           [0036]      FIG. 26  is a perspective view of one of the pivotal baffle doors of  FIG. 23 . 
           [0037]      FIG. 27  is a schematic drawing showing three baffles. The first baffle has an access opening therein, but does not have a baffle door. The second baffle has an alternative baffle door in the open position. The third baffle has the alternative baffle door in the closed position. 
           [0038]      FIG. 28  is a plan view of three baffles showing the first step in a process for creating the access openings and baffle doors of the embodiment illustrated in  FIG. 23 . 
           [0039]      FIG. 29  is a plan view of three baffles and three baffle doors showing the second step in a process for creating the access openings and baffle doors of the embodiment illustrated in  FIG. 23 . 
           [0040]      FIG. 30  is a plan view of three baffles with assembled baffle doors showing the final step in a process for creating the access openings and baffle doors of the embodiment illustrated in  FIG. 23 . 
           [0041]      FIG. 31  is a perspective view of the center section of an alternative internal baffle system for a tank according to the present invention. 
           [0042]      FIG. 32  is a top plan view of the alternative internal baffle system of  FIG. 31 . 
           [0043]      FIG. 33  is an end view of the alternative internal baffle system of  FIG. 31 . 
           [0044]      FIG. 34  is a side elevation view of the alternative internal baffle system of  FIG. 31 . 
           [0045]      FIG. 35  is a perspective view of another alternative internal baffle system for a tank according to the present invention. 
           [0046]      FIG. 36  is a top plan view of the alternative tank internal baffle system of  FIG. 35 . 
           [0047]      FIG. 37  is an end view of the alternative tank internal baffle system of  FIG. 35 . 
           [0048]      FIG. 38  is a schematic drawing of a hydraulic circuit associated with the hydraulic drive motor for the fluid pump of the tank according to one embodiment of the present invention. 
           [0049]      FIG. 38A  is a schematic drawing of an alternative hydraulic circuit associated with the hydraulic drive motor for the fluid pump of the tank. 
           [0050]      FIG. 39  is a schematic drawing of the hydraulic circuit of  FIG. 38  operating when the hydraulic drive motor for the fluid pump is first started. 
           [0051]      FIG. 40  is a schematic drawing of the hydraulic circuit of  FIG. 38  operating when the hydraulic drive motor and fluid pump have reached their normal operating revolutions per minute (RPM). 
           [0052]      FIG. 41  is a schematic drawing of the hydraulic circuit of  FIG. 38  indicating that hydraulic flow to the hydraulic drive motor has stopped and the hydraulic drive motor and fluid pump are coasting to a stop. 
           [0053]      FIG. 42  is a partial perspective view of a baffled tank equipped with a fluid agitation system. 
           [0054]      FIG. 43  is a top plan view of the fluid agitation system of  FIG. 42 . 
           [0055]      FIG. 44  is an enlarged perspective view of the fluid agitation system of  FIG. 42 . 
           [0056]      FIG. 45  is a simplified perspective view of the components of the fluid agitation system of  FIG. 42 . 
           [0057]      FIG. 46  is a side elevation view of an illustrative tank equipped with a variable volume system mounted on the chassis of an off highway truck. 
           [0058]      FIG. 47  is a side elevation view of an illustrative tank equipped with an alternative variable volume system mounted on the chassis of an off highway truck. 
           [0059]      FIG. 48  is a side elevation view of an illustrative tank equipped with another alternative variable volume system mounted on the chassis of an off highway truck. 
           [0060]      FIG. 49  is an enlarged view of the end of the air releasing control mechanism of  FIG. 48 . 
           [0061]      FIG. 50  is a side elevation view of an illustrative tank equipped with another alternative variable volume system mounted on the chassis of an off highway truck. 
           [0062]      FIG. 51  is a perspective view of an exemplary tank equipped with a plurality of unique lifting eyes. 
           [0063]      FIG. 52  is a partially cut away, perspective view of one of the lifting eyes of  FIG. 51 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0064]    Referring now more particularly to  FIGS. 1 and 2  of the drawings, there is shown an exemplary tanker truck  10  having a tank  12  constructed in accordance with the present invention. The tanker truck  10  includes a chassis  14  which is supported on a plurality of tires  16  and on which the tank  12  is mounted. While the tank  12  of the present invention is described in the context of an off-highway tanker truck, those skilled in the art will appreciate that the teachings of the present invention are equally applicable to relatively large tanks mounted on other types of vehicles such as, for example, on-highway trucks, trailers, off-highway earth-moving scrapers and airplanes. 
         [0065]    Optionally, as in the illustrated embodiment, the tank  12  can be attached to the chassis  14  for pivotal movement into a raised position so as to allow access to components on the tanker truck  10  such as the drive train, transmission, or gear differential. The tank  12  can be moved between the raised and lowered positions by actuation of a hoist cylinder  18  carried on the chassis  14  of the tanker truck  10 . As will be appreciated, the tank  12  can also be rigidly mounted on the chassis  14 . 
         [0066]    The tank  12  consists of a pair of opposing sidewalls  20 , a rear wall  22 , a front wall  24 , a top wall  25  and a floor  26 . In this case, the floor  26  includes the components for mounting the tank to the chassis including the tank/chassis pivots  28  and the mounts  30  for the hoist cylinder  18  (see, e.g.,  FIGS. 1 and 7 ). The floor support structure includes the longitudinally extending tank frame rails  31  and a plurality of laterally extending cross supports  33 . This floor support structure adds to the structural integrity of the tank  12 . Moreover, because the floor  26  of the tank  12  follows the top of the truck frame, the tank is mounted lower on the truck chassis improving the stability of the tank and, in turn, the tanker truck. In the illustrated embodiment, as shown in  FIG. 1 , the floor  26  angles downward as it extends from the rear wall  22  to the front wall  24 . Additionally, the front wall  24  includes a portion which is angled away from the rear wall  22  of the tank  12 . It will be appreciated that the walls of the tank  12  can have any shape including curved. 
         [0067]    For discharging fluid, the tank  12  includes, in this case, a plurality of spray nozzles which are supplied by a spray bar assembly  32  arranged on the exterior of the rear wall  22  of the tank  12  and in communication with a fluid pump mounted on the rear of the tank  12 . As shown in  FIG. 2 , the illustrated embodiment includes four lower spray nozzles  34  spaced across the width of the tank  12  for producing a horizontal flat spray to the rear of the tanker truck  10 . The tank  12  also includes two upper spray nozzles  36  which are arranged to provide a vertical spray to the sides of the tanker truck  10 . Of course, the spray nozzles can be arranged in various other locations on the tank  12  including on the sides and the front. Additionally, as desired, the tank  12  can be provided with one or more hose reels  39  and manually or remote-controlled monitors or cannons  41  for distributing fluid onto other equipment, material piles and other hard to reach areas as shown in  FIG. 1 . The hose reels  39  and monitors  41  could also be used for fire fighting. A pump can be provided to disburse the fluid into the spray bar assembly  32  and thereby into the various spray nozzles. It will be appreciated that the tank  12  of the present invention is not limited to any particular method or arrangement for discharging the fluid. 
         [0068]    In a conventional manner, the top wall  25  of the tank  12  includes a fill hole  38 , as shown  FIG. 2 , through which the tank can be filled. Additionally, a ventilation tube  40  is provided through the top wall  25  of the tank  12  to facilitate the filling process. The tank  12  can also be provided with a water level gauge such as for example a sight gauge. To permit an operator to have access to what is typically the active work area on the top of the tank  12 , for example to assist in the filling operation, the tank  12  can optionally include a ladder  42  and a guard rail  44  which goes around the outer edges of the top wall  25  of the tank  12  such as shown in  FIG. 1 . 
         [0069]    In accordance with an important aspect of one embodiment of the present invention, the tank  12  includes a novel baffle system in which the structural components of the tank also serve as baffles. Moreover, as described in detail below, the baffle system can also be configured to make the interior of the tank  12  much more accessible to workers than baffled tanks that are presently available. The baffle system is best described by separating the tank into a center section  46  best shown in  FIGS. 7-10  and left and right side sections  48 ,  50  best shown in  FIGS. 11-14  and  15 - 18 , respectively, that are symmetrical with each other. Though, as can be appreciated, relatively smaller tanks could be produced in a single section. The entire baffle system is shown assembled together in  FIGS. 3-6 . Left and right are used herein with reference to looking forward from the rear of tanker truck  10  of  FIG. 1  towards the front. 
         [0070]    In order to allow the tank  12  to be shipped more easily to a location where it is assembled to an off-highway truck, the center, left and right side sections  46 ,  48 ,  50  can comprise separate components that are assembled together. In particular, as shown in the exploded view of  FIG. 22 , the left and right side sections  48 ,  50  can be connected to their respective side of the center section  46  via welding or any other appropriate method to form the tank  12 . The three-piece construction allows the tank  12  to be broken into relatively smaller components for shipment. Of course, other aspects of the present invention, such as the baffle arrangement described below, are not limited to tanks having a three-piece construction, rather they can be incorporated into single-piece tanks or tanks consisting of any number of components. 
         [0071]    To suppress wave motion and surging of the fluid in the lateral or side-to-side direction, the center section  46  has longitudinal baffles that generally form an X-shaped baffle arrangement  52  (see  FIGS. 3 ,  6 ,  8  and  10 ). Advantageously, this X-shaped baffle arrangement  52  also provides the structural supports for the top wall  25  and floor  26  of the tank. As shown in  FIGS. 3 ,  6 , and  10 , the X-shaped baffle arrangement  52  extends vertically between the top wall  25  and floor  26  of the tank  12  and has a rectangular shaped chamber  54  arranged in its center. In particular, as best shown in  FIG. 8 , upper legs  56  of the X-shaped baffle arrangement  52  extend between an upper surface  60  of the chamber  54  and the top wall  25  of the tank  12  and lower legs  58  of the X-shaped baffle arrangement  52  extend between a lower surface  62  of the chamber  54  and the floor  26  of the tank. The rectangular chamber  54  and the upper and lower legs  56 ,  58  of the X-shaped baffle arrangement  52  extend longitudinally through the center section  46  between the front  24  and rear  22  walls of the tank  12  as shown in  FIGS. 7 and 9 . The rectangular chamber  54 , in this case, gets gradually larger as it extends from the rear end of the center section  46  towards the front end because the lower surface  62  of the chamber  54  angles downward parallel in relation to the chassis  14  and the tank floor  26  as shown in  FIG. 7 . 
         [0072]    A plurality of holes  64  are provided in the upper and lower surfaces  60 ,  62  (best shown in  FIGS. 4 ,  6  and  8 ) of the rectangular chamber  54  to allow fluid to work its way downward in the tank  12  during filling or emptying of the tank. Similarly, holes  66  are provided along the upper edges of the upper legs  56  and the lower edges of the lower legs  58 , as shown in  FIG. 7 , to assist fluid in migrating through the entire tank  12 . 
         [0073]    To assist fluid migration and also provide access for workers performing maintenance operations, openings  68  are provided, in this instance, in the middle of upper and lower legs  56 ,  58  of the longitudinal X-shaped baffle arrangement  52  as shown in  FIGS. 3-5  and  7 . During normal operations of the tank  12 , some or all of these openings  68  can be closed with loose fitting hatch plates to prevent the lateral surging of the fluid in the tank. In this case, the hatch plates are received in slots which are arranged on either side of the openings  68  as shown, for example, in  FIGS. 5 and 7 . When work is being performed on the interior of the tank  12 , the loose hatch plates can be removed to provide access to the interior of the upper and lower portions of the longitudinal X-shaped baffle arrangement  52 . 
         [0074]    For limiting longitudinal wave action and surging of fluid such as during braking or acceleration of the tanker truck  10 , vertically extending baffles are arranged between the legs of the X-shaped baffle arrangement  52 . As shown in  FIGS. 6-8  and  10 , an upper lateral baffle  72  is provided between the upper legs  56  and a lower lateral baffle  74  between the lower legs  58  at spaced intervals along the length of the X-shaped baffle arrangement  52 . Additionally, side lateral baffles  76  are provided to either side of the X-shaped baffle arrangement  52  at spaced intervals along the length thereof. Again, because, in this case, the tank  12  gets deeper as it extends from its rear wall  22  to its front wall  24 , these side lateral baffles  76  to the sides of the X-shaped baffle arrangement  52  get larger towards the front of the tank  12 . This can be seen via broken lines in the rear end views of  FIGS. 6 and 10 . Access openings  78  are provided in each of the upper and lower lateral baffles  72 ,  74  to provide access into the compartments formed in the upper and lower portions of the X-shaped baffle arrangement  52  by the lateral baffles  72 ,  74 . Similar to the access openings  68  in the legs  56 ,  58  of the X-shaped baffle arrangement  52 , the access openings  78  in the upper and lower lateral baffles  72 ,  74  can be closed by loose fitting hatch plates that are received in slots to either side of each opening  78  (see, e.g.,  FIG. 8  in which exemplary slots are shown for the upper access opening  78 ). Moreover, at least one of the access openings  68  in the legs  56 ,  58  of the X-shaped baffle arrangement  52  is arranged between each pair of upper and lower lateral baffles  72 ,  74  and side lateral baffles  76  to allow access into each compartment created by the upper and lower lateral baffles and side lateral baffles  76 . 
         [0075]    Additional lateral baffling can also be provided to either side of the center section  46  in the left and right side sections  48 ,  50 . As shown in  FIGS. 11-14  (left section  48 ) and  FIGS. 15-18  (right section  50 ), with the exception of certain accessory type components such as the fill hole  38  and the ventilation tube  40 , the left and right sections  48 ,  50  are mirror images of each other. Each side section  48 ,  50  includes a plurality of longitudinally spaced C-shaped ribs  82  as best shown in  FIGS. 11 ,  13 ,  15  and  17 . These C-shaped ribs  82  extend around the interior surface of each side section  48 ,  50  (see, e.g.,  FIGS. 14 and 18 ) to support the sidewalls  20  of the tank  12  as well as the portions of the floor  26  and top wall  25  of the tank defined by the side sections. Additional support for the sidewalls  20  of the tank  12  is provided, in this case, by reinforcing plates  84  which extend longitudinally between the C-shaped ribs  82  on the side of each side section  48 ,  50 . In the illustrated embodiment, each side section  48 ,  50  includes parallel upper and lower sets of reinforcing plates  84  as shown in  FIGS. 11 ,  13 ,  15  and  17 . These reinforcing plates  84  disrupt side-to-side liquid surging, particularly up the sidewalls  20  of the tank  12  thereby also acting as sidewall baffles or surge suppressor plates  84 . As shown in  FIGS. 14 and 18 , each of the sidewall baffles or surge suppressor plates  84  include, in this case, a first leg that extends inward at a downward angle from the sidewall of the tank  12  and a second leg extending downward from the end of the first leg. Side-to-side liquid surging is further disrupted by the generally squared-off, sharp transitional bends between the floor  26  and sidewalls  20  of the tank  12 . 
         [0076]    Lateral baffle doors  88  are provided in each side section  48 ,  50  that extend between the C-shaped ribs  82  and the center X-shaped baffle arrangement  52  as shown, for example, in  FIGS. 3 and 5 . In order to provide workers with substantially unobstructed access to the interior of the side sections  48 ,  50  of the tank  12 , these lateral baffle doors  88  are pivotally supported or hinged such that they can swing into an open position in which they extend longitudinally with respect to the tank  12 . When the pivotal or hinged baffle doors  88  are in this open position, the side sections  48 ,  50  are substantially open from end-to-end. Again, in the illustrated embodiment, an access opening  90  is provided in each of the hinged baffle doors  88  which can be closed by a loose fitting hatch plate  91  (see, e.g.,  FIGS. 19 and 21 ). As will be appreciated, a hatch plate such as shown in  FIGS. 19 and 21  could also be used to close any of the other access openings provided in the other baffles. 
         [0077]    For supporting the hinged baffle doors  88 , a plurality of longitudinally spaced upright support members  92  that extend between the floor  26  and top wall  25  of the tank  12  are provided on either side of the center section  46  as shown in  FIGS. 5 and 7 . Hinges  94  are provided on each the upright support members  92  (see  FIGS. 19 and 20 ) for pivotally supporting one edge of a respective hinged baffle door  88 . In the illustrated embodiment, the other end of each hinged baffle door  88  can be secured in a closed, deployed position by a pair of chains  96  that are captured in corresponding keyways  98  in the C-shaped ribs  82  as shown in  FIG. 19 . In the closed, deployed position, the hinged baffle doors  88  are substantially aligned with the lateral baffles  72 ,  74 ,  76  that extend between the legs  56 ,  58  of the center X-shaped baffle arrangement  52  as shown in  FIGS. 3 ,  5  and  6 . 
         [0078]    The hinged baffle doors  88  allow the side sections  48 ,  50  to be constructed in a manner similar to the hull of a ship with the C-shaped ribs  82  supporting the walls of the tank  12 . However, the C-shaped ribs  82  also form part of the lateral baffling in the tank  12  when the hinged baffle doors  88  are closed. Thus, the illustrated baffling configuration also allows the structural components of the side sections of the tank  12  to also serve as baffles. Alternatively, the C-shaped ribs  82  could be arranged on the exterior surface of the tank  12  with the hinged baffle doors  88  being latched directly to the inside surface of the sidewalls  20 . Attaching the hinged baffle doors  88  to the center section  46  can also permit the left and right side sections  48 ,  50  to be interlocked for shipment on a single truck. The center section  46  then can be shipped separately with the hinged baffle doors  88  swung into the longitudinally extending open position against the outside of the X-shaped baffle arrangement  52 . 
         [0079]    According to a further aspect of the present invention, to relieve concerns regarding working in a confined space and thereby eliminate the necessity for an external secondary air supply, the tank  12  can include entry hatches  100  in the sides and/or ends of the tank. In this instance, an entry hatch  100  is provided in both the front wall  24  and rear wall  22  of the tank  12  for each of the tank sections  46 ,  48 ,  50 . In particular, as best shown in  FIGS. 9 and 10 , an entry hatch  100  is provided at either end of the center section  46 . Similarly, as shown in  FIGS. 11 and 15 , entry hatches  100  are provided in either end of both side sections  48 ,  50 . These entry hatches  100  can be closed by corresponding hatch plates  102  such as shown in  FIG. 2 . 
         [0080]    When work must be performed inside the tank, the hatches  100  can be opened to provide light and air into the interior of the tank. By swinging the hinged baffle doors  88  into their open positions and removing the loose fitting hatch plates  91  on the access openings in the various baffles, all of the compartments inside the tank  12  can be easily accessed thereby minimizing confined space concerns. Moreover, with the hinged baffle doors  88  in the open position, workers can see and walk from one end of the tank  12  to the other substantially unobstructed. If sized appropriately, the entry hatches  100  can also allow the hinged baffle doors  88  or other internal baffling structures to be inserted into or removed from the interior of the tank  12  after the components are assembled together. 
         [0081]    To facilitate installation and removal of the tank from a tanker truck chassis, a plurality of uniquely configured lifting eyes  804  can be disposed on the upper surface of the tank. Such lifting eyes  804  are shown with respect to an exemplary tank  802  in  FIG. 51 . As shown in  FIG. 52 , each lifting eye  804  includes a body  806  and a reinforcing plate  808 . The body  806  includes a keyed lower portion  810  and an upper portion  812  having the eye formed therein. The reinforcing plate  808  includes an opening through which the upper portion  812  of the body  806  can extend. The opening in the reinforcing plate  808  is configured such that when the body  806  is inserted through the opening, the keyed lower portion  810  of the body  806 , which is larger than the opening in the reinforcing plate  808 , abuts against the lower surface  814  of the reinforcing plate  808 . The reinforcing plate  808 , in turn, extends generally transverse to the upper portion  812  of the body  806  that contains the eye. When the body  806  and reinforcing plate  808  are installed in the top wall  815  of the tank  802 , the upper portion  812  of the body  806  extends through an opening in the top wall  815  of the tank  802  such that the eye is positioned above the upper surface  816  of the tank top wall  815 . The reinforcing plate  808 , in turn, extends parallel to the top wall  815  of the tank  802 . The reinforcing plate  808  is larger than the opening in the tank top wall  815  through which the upper portion  812  of the body  806  extends so that the upper surface  818  of the reinforcing plate  808  abuts against the lower surface  820  of the tank top wall  815 . Thus, the reinforcing plate  808  helps to distribute the load applied to the top wall  815  of the tank when the tank  802  is lifted using the lifting eyes. 
         [0082]    In an alternative embodiment illustrated in  FIGS. 23 and 24 , each of the hatch plates associated with the access openings in the baffles is in the form of a pivotal baffle door  202  that is movable between open and closed positions. In the illustrated embodiment, each pivotal baffle door  202  is supported for pivotal movement on the corresponding baffle (a generic baffle section  204  is shown in  FIG. 25 ) by hinges. As shown, the hinges can comprise tabs/hooks  206  that extend at an angle from an edge of the pivotal baffle door  202  (see  FIG. 26 ) and are received in corresponding slots  208  provided in the baffle  204  adjacent the access opening  210  (see  FIG. 25 ). In contrast to conventional hinges, the tabs/hooks  206  will not fail as a result of rust despite being submerged in water thereby helping to ensure reliable operation of the pivotal baffle doors  202 . The pivotal baffle doors  202  can be secured in the closed position by any suitable means such as bolts or chains. To provide added strength, the pivotal baffle doors  202  can be bent as shown in  FIG. 27 . As will be appreciated by those skilled in the art, the pivotal baffle doors  202  or hatch plates  91  used to provide access through the various baffles can have any suitable configuration that allows the door or plate to be moved between open and closed positions. 
         [0083]    Advantageously, with the illustrated embodiment, the pivotal baffle doors  202  also can be formed from the pieces that are cut out of the baffles  204  to create the access openings  210 . Specifically, for a particular pivotal baffle door  202 , the door skeleton is first cut out of ( FIG. 28 ) and separated from ( FIG. 29 ) one of the baffle pieces  212 . As shown in  FIG. 29 , the door skeleton includes the main body of the pivotal baffle door  202  as well as the tabs/hooks  206 . In addition, the slots  208  for the tabs/hooks  206  are also cut out of the baffle piece  212 . The tabs/hooks  206  are then bent and the pivotal baffle door  202  is flipped over and the pivotal baffle door  202  hung by inserting the tabs/hooks  206  into the slots  208  as shown in  FIG. 30 . 
         [0084]    In the embodiment illustrated in  FIGS. 23-24 , side baffles  214  (shown individually in  FIG. 27 ) having central pivotal baffle doors  202  are provided to either side of the center X-shaped baffle arrangement  252 . In particular, the side baffles  214  extend from the center X-shaped baffle arrangement  252  to the inside surface of the sidewall of the tank. Like the lateral baffle doors  88  of the embodiment illustrated in  FIGS. 1-22 , the pivotal baffle doors  202  in the side baffles  214  pivot between a closed position wherein the pivotal baffle door  202  extends laterally ( FIG. 23 ) and an open position wherein the pivotal baffle door  202  extends more longitudinally ( FIG. 24 ). However, the pivotal baffle doors  202  are relatively smaller than the lateral baffle doors  88  used in the embodiment illustrated in  FIGS. 1-22  and, thus, are easier to move between the open and closed positions. 
         [0085]    An alternative baffle system incorporating an X-shaped longitudinal baffle arrangement  352  that is particularly suited for relatively smaller tanks is shown in FIGS.  31 - 34 . The X-shaped longitudinal baffle arrangement  352  illustrated in  FIGS. 31-34  is generally similar to the X-shaped baffle arrangement  52  of the embodiment illustrated in  FIG. 3  except that it does not include a longitudinally extending center chamber. Specifically, the X-shaped longitudinal baffle arrangement  352  includes a horizontal center baffle  354 , upper baffle legs  356  and lower baffle legs  358 . As best shown in  FIG. 33 , the upper baffle legs  356  extend between the horizontal center baffle  354  and the top wall  325  of the tank and the lower baffle legs  358  extend between the horizontal center baffle  354  and the floor  326  of the tank. The horizontal center baffle  354  and upper and lower baffle legs  356 ,  358  extend longitudinally through the tank between the front and rear walls of the tank as shown in  FIGS. 31 ,  33  and  34 . To provide access through the upper  356  and lower baffle legs  358 , access openings  368  are provided therein at spaced intervals along the length thereof. 
         [0086]    To limit longitudinal wave action and surging of fluid, vertically extending lateral baffles  372 ,  374  and  376  are arranged between the upper  356  and lower baffle legs  358  of the X-shaped longitudinal baffle arrangement  352 . Specifically, an upper lateral baffle  372  is provided between the upper baffle legs  356  and a lower lateral baffle  374  is provided between the lower baffle legs  358  at spaced intervals along the length of the X-shaped longitudinal baffle arrangement  352 . Moreover, side lateral baffles  376  are provided to either side of the X-shaped longitudinal baffle arrangement  352  at spaced intervals along the length thereof. To provide access into the compartments formed in the upper and lower portions of the X-shaped longitudinal baffle arrangement by the lateral baffles  372 ,  374  and  376 , access openings  378  are provided in each of the upper  372  and lower lateral baffles  374 . At least one of the access openings  368  in the upper  356  and lower baffle legs  358  is also arranged between each pair of upper  372  and lower lateral baffles  374  and side lateral baffles  376  to ensure that there is adequate access into each of the compartments defined by the baffles. Each of these access openings  368 ,  378  is configured to receive an associated pivotal baffle door like the baffle doors  202  illustrated in  FIGS. 25-30 . As with the embodiment illustrated in  FIGS. 1-22 , when selected ones of the baffle doors associated with the access openings in the various baffles are open, it is possible for workers to traverse from the entry hatch in the rear wall of the tank to the entry hatch in the front wall of the tank. 
         [0087]    Another baffle system particularly suited for relatively small tanks is shown in  FIGS. 35-37 . Unlike the embodiments illustrated in  FIGS. 1-22  and  FIGS. 31-34 , the baffle system illustrated in  FIGS. 35-37  does not include an X-shaped center baffle arrangement. Instead, as best shown in  FIGS. 35 and 36 , the baffle system includes a plurality of longitudinally extending baffles  402  which extend between the front and rear walls  424 ,  422  of the tank and a plurality of lateral baffles  404  that extend between the sidewalls  420  of the tank. The tank further includes sidewall baffles/surge suppressors  410  on the sidewalls  420  of the tank as shown in  FIG. 37 . Each of the lateral baffles  404  is provided with a central access opening  406  and each longitudinal extending baffle  402  includes a plurality of longitudinally spaced access openings  408  so as to provide a means for accessing each of the compartments in the tank defined by the baffles. Again, each of these access openings  406 ,  408  is configured to receive a pivotal baffle door like that illustrated in  FIGS. 25-30  and when selected ones of the doors are open it is possible for a person to traverse between the entry hatch in the front wall  424  of the tank and the entry hatch in the rear wall  422  of the tank. 
         [0088]    To drive the fluid pump associated with the tank, a hydraulic motor can be provided which is, in turn, powered by the hydraulic system of the tanker truck. Specifically, tanks that are to be used in off-highway applications are often mounted to off-highway dump or scraper trucks that have been converted by removal of the dump body or scraper bowl. Such trucks typically are equipped with a hydraulic fluid system that can be used to drive a hydraulic motor and fluid pump associated with the tank. Because the hydraulic systems on these trucks are typically used for dumping loads, they can produce relatively high flow rates and pressures. For example, depending on the vehicle size, the hydraulic systems on these trucks may produce a flow rate of 100-200 gallons per minute at a pressure of up to 2500-3000 psi at normal truck engine operating speeds. Such flow rates and pressures do not pose problems for the hydraulic cylinders that are typically used to dump loads. However, these flow rates and pressures can cause problems when the truck hydraulic system is tied into a hydraulic motor such as is used to power the fluid pump for a tank. 
         [0089]    In particular, starting the hydraulic motor at the full fluid flow and pressure that the truck&#39;s hydraulic system produces at normal engine operating speeds can subject the hydraulic motor and the fluid pump associated with the tank to a significant shock load. For example, the hydraulic motor associated with a tank may be designed to turn at approximately 2000 RPM at full hydraulic flow. Thus, in such a case, at start-up, the hydraulic motor essentially would have to accelerate instantaneously to 2000 RPM in order to alleviate the shock of the hydraulic fluid supplied by the truck hydraulic system. Obviously, the hydraulic motor is not capable of such rapid acceleration. Moreover, since the hydraulic motor is connected through a coupling to the fluid pump, the inertia caused by the fluid pump impeller and any fluid in the pump also has to be overcome at start-up. Thus, unless the hydraulic motor is engaged at a fairly low hydraulic flow, i.e. idle RPM of the transport vehicle, the hydraulic motor and the fluid pump will be subjected to substantial shock loads at start-up. These shock loads could over time result in damage to the coupling between the hydraulic motor and the fluid pump as well as damage to the hydraulic motor itself. 
         [0090]    To help protect the hydraulic motor and fluid pump during start-up, a soft start/stop system can be provided. With reference to  FIGS. 38-41 , to provide such a soft-start/stop system, a hydraulic valve  502  is provided in a bypass line  506  that extends parallel to the hydraulic motor  504  supply line that powers the tank fluid pump (not shown in  FIGS. 38-41 ). This hydraulic valve  502  permits hydraulic fluid supplied through a supply line  510  from the truck hydraulic system, particularly at high truck engine RPMs, to bypass the hydraulic motor  504  through the parallel bypass line  506  and return to the truck hydraulic fluid tank  508  (via tank line  512 ) until the hydraulic motor  504 , coupling and fluid pump come up to normal operating RPM.  FIG. 39  is a schematic diagram of the soft start/stop system operating in the fluid pump start-up mode with the hydraulic valve  502  open so as to allow the flow of hydraulic fluid through the parallel bypass line  506  (arrows show the flow of hydraulic fluid through the system). According to one embodiment of the present invention, the hydraulic valve  502  comprises a standard pressure relief valve that preferably opens relatively quickly (e.g., 10-50 milliseconds) after pressure is sensed at both the inlet port of the hydraulic motor  504  and the hydraulic valve  502 . The pressure relief valve can be either direct or pilot-operated. 
         [0091]    Once the hydraulic pressure relief valve  502  opens, the hydraulic fluid flow that the hydraulic motor  504  is unable to accept as it accelerates to full operating speed is allowed to bypass the hydraulic motor  504  through the parallel bypass line  506  and return to the truck hydraulic fluid tank  508 . As the hydraulic motor  504  begins to come up to normal operating RPM, it is able to accept more of the hydraulic fluid thereby reducing the pressure at the inlet to the hydraulic pressure relief valve  502 . As a result, the hydraulic pressure relief valve  502  gradually closes so that more of the hydraulic fluid flow from supply line  510  goes through the hydraulic motor  504 . Once the hydraulic motor  504  nears or reaches its normal operating RPM, the hydraulic pressure relief valve  502  closes completely and all the hydraulic fluid from the truck hydraulic supply line  510  flows through the hydraulic motor  504  allowing the fluid pump to operate at full capacity.  FIG. 40  is a schematic diagram of the soft start/stop system operating in a fluid pump running mode with the hydraulic pressure relief valve  502  closed (arrows show the flow of hydraulic fluid through the system). 
         [0092]    Alternatively, instead of a standard pressure relief valve, a so-called “soft start pressure relief valve” could be used (see  FIG. 38A ). A soft start pressure relief valve differs from a standard pressure relief valve in that in its normal non-operative state, the soft-start valve is open. Thus, instead of allowing hydraulic fluid to bypass around the hydraulic motor  504  only after the pressure has built to a certain value, during start-up of the hydraulic motor, the soft-start valve initially permits all of the hydraulic fluid to bypass the hydraulic motor  504  and return to the truck hydraulic fluid tank  508 . Then, over a prescribed time interval (e.g., 250 milliseconds), the soft-start valve gradually closes thereby allowing the pressure at the hydraulic motor  504  to gradually build. Thus, the soft-start pressure relief valve limits the rate at which the pressure at the hydraulic motor  504  rises. Once closed, the soft-start valve functions as a normal pressure relief valve limiting the maximum system pressure. An example of a soft-start pilot operated relief valve that could be used in the soft start/stop system of the present invention is the RPGT valve available from Sun Hydraulics. Of course, it will be appreciated that other soft-start valves could also be used. 
         [0093]    To permit the hydraulic motor  504  to softly coast to a stop, a one-way check valve  514  can be installed in the bypass line  506  parallel to the hydraulic pressure relief valve  502  that would allow hydraulic fluid to circulate from the outlet port of the hydraulic motor  504  through the bypass line  506  and back to the fluid supply line  510  and the inlet port of the hydraulic motor  504 . The check valve  514  is configured to block flow in the direction from supply line  510  ensuring that the hydraulic pressure relief valve  502  controls the flow of hydraulic fluid from supply line  510  through the bypass line  506  towards the truck hydraulic fluid tank  508 . This arrangement creates a closed loop that allows the momentum of the turning hydraulic motor and pump to gradually dissipate when the supply of hydraulic fluid from the truck hydraulic system is shut-off.  FIG. 41  is a schematic diagram of the soft start/stop system operating in the pump shut down mode with hydraulic fluid flowing through the one-way check valve  514  (arrows show the flow of hydraulic fluid through the system). 
         [0094]    Tanker trucks used in environments like construction sites, building demolition sites, excavation sites and mine sites are often filled with polluted water. In particular, these sites may have run-off collection ponds from which polluted non-potable water is pumped for use in tanker trucks. This polluted water may have a high degree of suspended solids. Since this water is used for various non-drinking purposes, these pollutants/suspended solids in no way inhibit the operation or effectiveness of these tanks. However, these suspended solids may settle to the tank floor or onto other internal tank surfaces (e.g., baffles) as sediment if a tanker truck is allowed to sit for any period of time. This sediment, depending on its chemical makeup, may cause accelerated corroding of the floor, baffles or other surfaces in the tank even if stainless steel is used. 
         [0095]    To help keep such sediment from settling on the tank floor, the tank of the present invention can include a tank agitation system. In particular, the tank can include a closed loop fluid circuit which draws fluid from the tank through the tank fluid pump and pumps it back into the tank at a high flow rate and pressure in order to agitate the contents of the tank. This agitation system could be operated, either automatically or manually, when fluid is not being dispersed from the tank such that the tank fluid pump runs semi-continuously. 
         [0096]    An illustrative embodiment of a fluid agitation system constructed in accordance with the present invention is shown in  FIGS. 42-45  in an exemplary baffled tank  600 . As shown in  FIG. 42 , the agitation system includes an agitation tube  602  that extends in the lengthwise direction of the baffled tank  600  near the tank floor  604 . The agitation tube  602  is supported on the tank floor  604  by a plurality of tube supports  606  that are longitudinally spaced from one another along the length of the agitation tube  602 . 
         [0097]    To provide agitation of the fluid in the baffled tank  600 , a plurality of short cross tubes  608  as well as a plurality of apertures  610  are provided in the surface of the agitation tube  602 . Each of the short cross tubes  608  consists of a tube which branches off from the agitation tube  602  at an angle from perpendicular. As can be seen from the top view of  FIG. 43 , the short cross tubes  608  are spaced along the length of the agitation tube  602  such that at least one short cross tube  608  is provided in each compartment of the baffled tank  600  defined by the internal baffle structures. Each of the apertures  610  consists of a simple hole in the outer wall of the agitation tube  602  (see, e.g.,  FIGS. 43 and 44 ). Like the shorter cross tubes  608 , the apertures  610  are spaced along the length of the agitation tube  602  such that sufficient agitation is provided in each of the compartments of the baffled tank  600 . In the illustrated embodiment, the apertures  610  are placed in the tube at angles of 45 degrees to either side of vertical. 
         [0098]    The various components of the agitation system are shown in  FIG. 45  including the agitation tube  602 , a suction line tube  612  and the tank fluid pump  614  (although a separate dedicated agitation pump could be used). In operation, when the tank fluid pump  614  is not providing fluid to the spray nozzles, the tank fluid pump  614  can be operated to draw fluid out of the baffled tank  600  through the suction line tube  612  and then circulate the fluid back into the baffled tank  600  through the short cross tubes  608  and apertures  610  in the agitation tube  602 . In this case, an expansion joint  616  is provided adjacent the upstream end of the agitation tube  602  (i.e., the end nearest the tank fluid pump  614 ). It will be appreciated that the agitation system can be configured other than as specifically shown in  FIGS. 42-45 . 
         [0099]    To simplify tank-filling operations when filling the tank to less than its full capacity, the tank can be equipped with a variable volume system. Such a variable volume system is shown with respect to an exemplary tanker truck  702  in  FIG. 46 . More specifically, occasionally it is desirable to fill the tank of a tanker truck to less than its full capacity such as when training a new operator of a tanker truck or when conditions at the work site are such that less water is required to control dust. The illustrated variable volume system provides a quick and easy way by which the tank can be configured such that it cannot be filled above a predetermined level. To this end, with reference to  FIG. 46 , the variable water system includes a fill tube  704  that extends downwardly into the interior of the tank  706  from the fill hole in the top wall  710  of the tank. When the tank  706  is being filled, the fluid is introduced into the interior of the tank through the fill tube  704 . Once the fluid in the tank reaches the level  712  of the lower or bottom edge  713  of the fill tube  704 , the air in the tank  706  becomes trapped. This prevents the fluid level in the tank  706  from rising above the lower or bottom edge  713  of the fill tube  704 . In particular, after the fluid reaches this level, any excess fluid that is introduced into the tank  706  will simply collect in the fill tube  704  and, if the filling operation is not stopped, the fluid will eventually overflow out of the fill hole  708 . However, the water level in the main body of the tank  706  will remain at the reduced level  712  defined by the lower or bottom edge  713  of the fill tube  704 . 
         [0100]    To permit the tank  706  to be filled to maximum capacity, the variable volume system further includes an air releasing control mechanism. The air releasing control mechanism provides a way by which the air can bleed or vent out of the tank  706  once the fluid level reaches and then rises above the lower or bottom edge  713  of the fill tube  704  during a filling operation. To permit the fluid to rise to the maximum level in the tank  706 , the outlet point of the air releasing control mechanism (i.e., through which air outlets from the tank) should be located as close as possible to the top wall  710  of the tank  706 . In the embodiment illustrated in  FIG. 46 , the air releasing control mechanism comprises a manually operable valve  714  in the top wall  710  of the tank  706 . This manually operable valve  714  allows an operator to quickly change the maximum fill level  712  or line in the tank  706  from the lower or bottom edge  713  of the fill tube  704  to the top wall  710  of the tank  706  or any place in between simply by manually opening and closing the valve  714 . 
         [0101]    To allow the maximum fill level to be set at other levels, the variable volume system could include a plurality of air releasing control mechanisms each of which has an air outlet at a different vertical level in the tank. For example, in the embodiment illustrated in  FIG. 47 , the tank  706  has two air releasing control mechanisms in the form of first and second manually operable valves  716 ,  718 . The first valve  716  is similar to the manual valve  714  in the  FIG. 46  embodiment in that its outlet is positioned adjacent the top wall  710  of the tank  706 . The second manual valve  718  has an air outlet tube  720  that extends downward into the tank  706  so that the outlet to the second valve  718  is at a lower vertical level  722  than the outlet to the first valve  716 . Thus, an operator has the option of setting the maximum fill level to the level  712  of the lower or bottom edge  713  of the fill tube  704  (i.e., by closing both the first and second valves  716 ,  718 ), the level  722  of the lower edge of the air outlet tube  720  of the second valve  718  (i.e., by opening the second valve  718  and closing the first valve  716 ) or adjacent the top wall  710  of the tank  706  (i.e., by opening the first valve  716 ). 
         [0102]    Alternatively, the variable volume system could include an air releasing control mechanism that is configured such that the vertical level at which the pressure relief mechanism outlets air from the interior of the tank can be selectively adjusted. For example, as shown in  FIG. 48 , the air releasing control mechanism could include a tube  724  that is open at either end and extends vertically downward into the interior of the tank  706 . A floatable ball  726  is connected to the lower end  730  of the tube  724  via a guide  728 . When the fluid level reaches the floatable ball  726 , the ball  726  will float (guided by the guide  728 ) into engagement with the open lower end  730  of the tube  724  thereby sealing the lower end of the tube  724  closed. This prevents any additional air from exiting the tank and defines the maximum fill line  734  at the lower end  730  of the tube  724 . In the embodiment of  FIG. 48 , the tube  724  is slidably received in the top wall  710  of the tank  706  such that the vertical position of the lower end  730  of the tube  724  can be selectively adjusted by unfastening a clamp  732 , sliding the tube  724  up or down as desired and refastening the clamp  732 . Thus, the maximum fill line  734 , which is defined by the lower end  730  of the tube  724 , can be selectively adjusted to any desired position. 
         [0103]    An alternative arrangement for the variable volume system is illustrated in  FIG. 50 . In this embodiment, the air releasing control mechanism includes a plurality of openings  735  and  737 , two in this instance, at different vertical levels in the sidewall  736  of the fill tube  704 . Each of these openings  735 ,  737  can be selectively closed with an associated plug to prevent air from venting out of the tank  706  therethrough. When both of the openings  735 ,  737  are plugged or otherwise closed, the maximum fill level is the lower or bottom edge  712  of the fill tube  704 . When the lower opening  735  is open and the upper opening  737  is closed, the maximum fill level is the vertical level  738  of the lower opening  735 . When the upper opening  737  is opened, the maximum fill level is the vertical level of the upper opening  737 , which in this case is adjacent the top wall  710  of the tank  706 . Of course, openings could be provided in the sidewall  736  of the fill tube  704  at any number of different vertical levels in order to provide additional options for setting of the maximum fill level. 
         [0104]    All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein. 
         [0105]    The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention. 
         [0106]    Preferred embodiments of this invention are described herein, including the best mode known to the inventor for carrying out the invention. Of course, variations of those preferred embodiments will become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventor expects skilled artisans to employ such variations as appropriate, and the inventor intends for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.