Abstract:
An apparatus and method for dislodging a solidified plug formed in the delivery line of hot asphalt blocking the delivery of the flowable asphalt to a site close to or remote from the site of application to a surface to be fixed or coated with the flowable hot asphalt.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     This invention generally relates to asphalt distribution and more particularly for a procedure for unblocking drain lines on asphalt distributors.  
         [0003]     2. Description of the Related Art  
         [0004]     It is well known in the industry that asphalt in the liquid phase used on road surfaces and roof tops adhere to these surfaces and form a coating layer when it solidifies. It is also known that asphalt adheres to surfaces of the equipment used to handle and transport it, and under certain conditions, can build up in the pipes/hoses rendering the delivery to the sites of application unsuitable for coating purposes.  
         [0005]     Asphalt handling equipment conventionally includes a tank, a pump, a spray bar and a plumbing system for delivering asphalt from the tank to the spray bar which then spreads the asphalt on the surfaces desired to be coated. The tank, pump and spray bar along with the plumbing system are conventionally supported directly by a vehicle, such as a truck, or supported by a detachable trailer behind the vehicle. The plumbing system&#39;s main function is to circulate the asphalt in the tank during initial asphalt, heating, spraying the asphalt and circulating the asphalt through the spray bar while not spraying to prevent freezing of the asphalt therein.  
         [0006]     Keeping the asphalt in a flowable state has been a serious issue and problem in the industry both during transportation and its application to the site of delivery. The prior art has provided various solutions to the problem which include the following.  
         [0007]     U.S. Pat. No. 4,620,645 is directed to an asphalt melting and dispensing apparatus wherein a jacketed flexible hose having a controlled circulating system for circulating an oil heating medium is used for heating the asphalt in a kettle to maintain the asphalt within the flexible hose in a fluid state during periods of non-use.  
         [0008]     U.S. Pat. No. 4,695,186 discloses an asphalt handling apparatus which includes a gas burner to keep the asphalt in a flowable state.  
         [0009]     U.S. Pat. No. 4,944,632 relates to a device for dispensing asphalt repair materials comprising a hopper compartment for transporting and dispensing asphalt mix materials. A separate tack oil tank is provided with an internal circulation system for maintaining liquid tack oils in an emulsified state.  
         [0010]     U.S. Pat. No. 5,366,308 discloses a hot asphalt transfer and application device to transfer hot asphalt to roof surfaces via a hose wherein said hose can be 500 feet long. The device comprises:  
         [0011]     heating elements disposed within a storage tank and heating wires wrapped around the inner tube members of the hoses which keep the asphalt material in a liquid form during operation of the device.  
         [0012]     U.S. Pat. No. 5,607,254 is directed to a method and apparatus for automatically controlling the temperature of an asphalt paver wherein:  
         [0013]     the control senses the screed temperature and compares the screed temperature to a lower set point, the control causes the fuel to dispense into a combination chamber and subsequently causes the fuel to ignite in order to heat the screed.  
         [0014]     U.S. Pat. No. 5,974,227 relates to a hot melt applicator with electrically heated hose. The hot melt applicator comprises:  
         [0015]     a source of solid materials/asphalt,  
         [0016]     a heater, in thermal relation with the source for heating the solid materials for the same to become flowable;  
         [0017]     a movable, elongate conduit in fluid flow communication with the source;  
         [0018]     a pump to move the flow of melted material into the elongated conduit;  
         [0019]     an electric heating element in the conduit for heating the flowable heating material that is disposed in the conduit.  
         [0020]     The use of the heater in the source and in the elongate conduit in the form of electric current are said to maintain flowability of the source material/asphalt so that the source material/asphalt remains spreadable during its application to a site.  
         [0021]     U.S. Pat. No. 6,126,757 is directed to a method of releasing asphalt from equipment using surfactant solutions. The method comprises: diluting a concentrate with about 4-50 parts water to one part of concentrate and haulting, such as spraying, rolling, or brushing the diluted concentrate on the equipment, and coating the equipment prior to its coming into contact with the asphalt. The concentrate comprises a fatty acid amide, a fatty acid neutralizer with an alkyl- or alkanol- or mixed-type amine or ammonia.  
         [0022]     U.S. Pat. No. 6,161,775 discloses a feed line assembly and asphalt circulation system for an asphalt distributor which comprises a coaxial feed line assembly that serves as heat exchanger to transfer heat from the delivery conduit to the return conduit and thereby prevents freezing the static asphalt in the return conduit during spraying mode.  
         [0023]     As illustrated above, the prior art has made substantial improvements in the delivery of asphalt to the site of application in terms of maintaining the asphalt in flowable condition and preventing freezing of the asphalt prior to and during delivery. However, freezing the asphalt prior to and during delivery, the prior art does not provide a method of unplugging of the delivery exit from plugging the system. The present invention is to provide a solution when such system fails and the results in blockage which may cause serious operating problems and associated injury to operators.  
       SUMMARY OF THE INVENTION  
       [0024]     Once the blockage/freezing occurs in the delivery/tube exit, it must be resolved by removing the exit plug from the asphalt material safely and inexpensively so that the delivery of asphalt to the site could continue. The present invention is directed to a method and apparatus to achieve that goal.  
         [0025]     The apparatus according to the present invention comprises:  
         [0026]     a truck or attached vehicle containing hot asphalt or a heating means associated with hot asphalt to maintain the hot asphalt in a flowable state;  
         [0027]     an exit or delivery port in direct or indirect communication with the hot asphalt contained in the truck;  
         [0028]     a pressure device tank containing nitrogen or other inert, non-flammable materials, such as argon, connected to said exit port of the hot asphalt tank, when the exit delivery port is partially or substantially clogs said exit port thereby failing continuous delivery of said asphalt;  
         [0029]     said pressure device being capable of unblocking/unfreezing said partially or substantially clogged exit delivery port.  
         [0030]     In a method aspect the invention comprises dislodging a plug solidified in the exit port or extension hose emanating from the truck or trailer of an asphalt-containing truck or trailer, comprises:  
         [0031]     closing the valve on the asphalt-containing truck or trailer;  
         [0032]     opening the lid of the asphalt-containing tank or trailer;  
         [0033]     attaching the pressure device coupling onto the drain line or hose of the pressure device;  
         [0034]     setting the pressure device to zero psi;  
         [0035]     closing the vent valve on the pressure device;  
         [0036]     opening the truck valve or trailer asphalt valve;  
         [0037]     starting and increasing the pressure of the inert, non-inflammatory gas up to 90 psi;  
         [0038]     closing the vent valve on the inert, non-flammable source of gas;  
         [0039]     opening the vent valve when removal of the solidified asphalt plug is achieved; and  
         [0040]     removing the pressure device from the truck valve or trailer to allow the flow of said asphalt to the site of application  
     
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0041]      FIG. 1  is a schematic representation of an asphalt truck attached to which is a nitrogen tank with associated hoses, valves, regulators and gauges.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0042]     The present invention is directed to unclogging drain lines in asphalt distributor trucks and trailers. Referring to the drawing, the asphalt distributor truck or trailer  10  comprises a tank  12  containing flowable asphalt or similar material  14  which are to be dispensed on road surfaces and roof tops which flowable asphalt or similar materials then solidify or freeze on the surfaces creating a protective seal against precipitation, such as rain or snow, from penetrating into the underlying surfaces. The tank is made of steel, or an alloy containing steel, to withstand the high temperatures of the asphalt or similar materials being in a flowable state. The tank  12  is conventionally equipped with a drain line or hose  16  to deliver the flowable material away from the tank for distribution to said surfaces. Accordingly, the drain line or hose may be short, such as a few inches, or it may be several feet up to 100 and 150 feet depending on the distance of the surface to be coated. At the end of the drain line or hose there is a valve  18  for opening and closing the flow of the flowable material emanating from the tank  12 .  
         [0043]     The exit port for the hot asphalt may have an extension hose  16 ′ attached thereto to transfer the hot asphalt from the asphalt-containing tank to a more remote site, such as a roof on the top of a building. In this case the pressure device is attached onto the remote end of the extension hose.  
         [0044]     The pressure device  20  preferably attached to the asphalt containing tank  12 , or to the extension hose  16 ′ when blockage/freezing occurs in the exit port.  
         [0045]     The pressure device  20  is carried on a handcart carrying a cylinder having 50 to 80 cubic feet of nitrogen or other inert gas. The pressure device is provided with a coupling chain which attaches to the exit port and safely holds the pressure device to the exit port.  
         [0046]     The pressure device  20  contains a nitrogen or other non-flammable gas in a tank  22 . The tank is equipped with a valve  24  and regulator gauge  26  to controllably release one of said gases when unblocking of the asphalt-containing drain line or hose  16  is required.  
         [0047]     The pressure device  20  further comprises a hose  28  extending from the regulator gauge  26  towards the truck valve. The end of the hose is equipped with a Camlock coupling  28  releasably attached to the truck valve  18 .  
         [0048]     The pressure device is further equipped with a gauge  30  to measure the pressure originating from the tank  22 ; a relief valve  32  to relieve the pressure in the pressure device; and a vent valve  34  which serves as a safety exit for overpressure.  
         [0049]     The details of source materials in connection with the present invention are as follows.  
         [0050]     Relief valve  32  supplied by Advanced Specialty Gas Equipment by Allied/Kunkle Valve Industries (S/N A0335549-1-1K) having a pressure/temperature limit of 3 to 400 psig/−60° F. to 300° F.;  
         [0051]     Valve and Regulator Gauge  24  and  26  manufactured by Wika having 0-160 psig, operating temperature −40° F. to 140° F.;  
         [0052]     Camplock Coupling  28  manufactured by Dixon, made of aluminum, maximum pressure 125 psig;  
         [0053]     Drain line or hose  16  manufactured by Parker/Dayco under the tradename Dayco Hose;  
         [0054]     Compressed nitrogen in cylinder  22  is widely available from suppliers, such as Chapman Gas, Erie, Pa. A having 40 ft. 3  capacity.  
         [0055]     The pressure device  20  is conveniently carried on a handcart equipped with chains to securely hold the nitrogen cylinder and associated items to attach the pressure device to the asphalt distributor tank or trailer.  
         [0056]     The method of use of the pressure device  20  to dislodge a plug of asphalt from the drain line or hose  16  of the asphalt truck or trailer  10  comprises the steps of:  
         [0057]     closing the valve  18  on the asphalt tank or trailer  10 ;  
         [0058]     opening the lid on the asphalt tank or trailer;  
         [0059]     attaching hose  16 ′ on pressure device  20  using the camlock coupling  28  onto drain line or hose  16  of the asphalt truck or trailer;  
         [0060]     setting regulator gauge  26  on pressure device to zero pressure;  
         [0061]     closing the vent valve  34  on hose  16 ′ of the pressure device;  
         [0062]     opening the truck or trailer asphalt valve;  
         [0063]     opening nitrogen supply valve  24 ;  
         [0064]     starting nitrogen pressure using regulator gauge  26 ;  
         [0065]     increasing nitrogen pressure up to 90 psi or until blockage is dislodged;  
         [0066]     closing truck valve  18 ;  
         [0067]     closing valve  24  on nitrogen tank;  
         [0068]     opening vent valve  34  to bleed of pressure; and  
         [0069]     removing pressure device  20  from truck valve or trailer  18 .  
         [0070]     The above description is intended in an illustrative rather than a restrictive sense. Variations may be apparent to persons skilled in the art without departing from the spirit and scope of the invention as defined by the claims set for the below.  
                                             PARTS LIST                                    Distributor truck or trailer   10           Tank of truck or trailer   12           Asphalt or similar material   14           Drain line or hose on asphalt truck or trailer   16           Hose on pressure device 20       16′           Valve for opening and closing the flow of asphalt   18           Pressure device   20           Tank of pressure device   22           Valve on nitrogen tank   24           Regulator gauge on pressure device   26           Camlock coupling   28           Gauge to measure pressure in system   30           Release valve in system   32           Vent valve in pressure device to release pressure in system   34