Method and system for emptying wetlines of a tanker truck

Abstract

In a system and method for emptying wetlines on a tanker truck, a pipe is secured to the tanker truck and extends from the wetlines to the top of the housing tank of the tanker truck. A pump is mounted in the pipe or a housing connected to the pipe. The pump is preferably driven by air flow from a compressor.

Description

FIELD OF THE INVENTION

[0002] The invention relates to emptying wetlines of tanker trucks prior to the trucks embarking on a journey to deliver fuel to gas stations.

BACKGROUND OF THE INVENTION

[0003] The filling and emptying of tanker trucks is achieved through a system of pipes known as wetlines. Tanker trucks typically have one or more housing tanks for housing different grade fuels. In the past gasoline was filled into these housing tanks by pouring the liquid in from the top. However, due to the hazard of having someone climb on top of the truck to supervise the filling, as well as the substantial vapor emissions that took place in such a system, regulations subsequently required the filling from below.

[0004] While this solved some of the problems, it introduced a new hazard. The wetlines which provided the interconnecting pipe sections between the housing tanks and the supply hoses, remained full of liquid once the filling process was complete. At about a gallon per foot of pipe, a tanker truck with 3 sets of wetlines for its three housing tanks could end up carrying 20 to 45 gallons of fuel in its wet lines. As illustrated in FIG. 1, these wetlines are positioned below the tanker truck where they are vulnerable to breach during a motor vehicle accident. Cars colliding with the tanker truck often end up breaking the wetlines and coming to rest under the tanker truck. The fuel in the wetlines typically spills onto the colliding car and ignites, resulting in severe human injuries and even death.

[0005] Various approaches have been proposed to address this problem. One solution is to drain the fluid from the wetlines after filling. The problem with this approach is one of weights and measures. Since the tanker truck is effectively considered as having received the 20-30 gallons in the wetlines, draining this fuel back into the supply tank produces accounting headaches and requires that the fuel that is siphoned off be measured and credit given accordingly. This is both a complex and costly undertaking.

[0006] Another approach is to provide a protective cage around the wetlines. This, however is economically unattractive since it adds significant weight to the tanker truck, which translates into lower fuel carrying capacity.

[0007] Yet another approach is to force a gas into the wetlines, thereby forcing the liquid remaining in the wetlines after the filling process, into the housing tank of the tanker truck. This, however, requires tremendous pressure to be generated in order to force the fuel up against the downward force of the fuel in the housing tank. As a result, powerful pumps or other mechanisms have to be made available, greatly adding to the cost of filling tanker trucks and conveying fuel. Also, it requires the use of an inert gas or other gas that does not cause an explosion hazard.

SUMMARY OF THE INVENTION

[0008] The present invention discloses a method and system for emptying the wetlines of tanker trucks, so as to avoid the problems in the prior art solutions. The invention involves the use of a separate pipe for conveying fuel from the wetlines to the top of the housing tank of the tanker truck. It further involves the use of a pump that is driven by fluid flow. Preferably the pump is a suction pump such as a diaphragm pump which is preferably driven by compressed air flow from a conventional compressed air source.

[0009] The present invention also discloses a system and method generally for propelling liquid in a pipe, making use of a pump driven by regular compressed air, wherein the compressed air does not have direct contact with the liquid.

[0010] According to the invention, there is provided a method of emptying wetlines associated with a housing tank of a tanker truck, comprising, pumping liquid in the wetlines into the housing tank, through a separated pipe extending from the wetlines to a location at or near the top of the housing tank. Typically, separate pipe extends from the wetlines to a location above or near the highest surface of the liquid in the housing tank. Preferably, the separate pipe extends along an inner surface of the housing tank, but it can also extend along an outer surface of the housing tank. Typically, the liquid is pumped using a suction pump such as a diaphragm pump mounted in the pipe or in a housing connected in fluid flow communication with the pipe.

[0011] Further, according to the invention, there is provided a means for emptying wetlines associated with a holding tank on a tanker truck, comprising, a pipe extending from the wetlines to a location at or near the top of the housing tank, and a pump for pumping the liquid along the pipe into the housing tank. Preferably the pump is a diaphragm pump mounted in the pipe or in a housing connected in fluid flow communication with the pipe. The pump is preferably operated by fluid flow such as the flow of air, water, or oil, for example. Preferably air flow is used, making use of a conventional compressed air source.

[0012] Still further, according to the invention, there is provided a means for propelling liquid through a pipe, comprising a diaphragm pump which is operated by the flow or regular air from a conventional compressed air source.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] FIG. 1 is a side view of a tanker truck showing a set of wet lines;

[0014] FIG. 2 is a sectional end view of the tanker truck of FIG. 1;

[0015] FIG. 3 is a sectional end view of one embodiment of a wetline emptying system of the invention, and

[0016] FIG. 4 is a sectional end view of another embodiment of a wetline emptying system of the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0017] A typical tanker truck is shown in FIGS. 1 and 2. Tanker trucks 100 typically include one or more housing tanks 102, each housing tank supporting a particular grade fuel, and having its own set of wetlines 104. The wet lines 104 each include a filling pipe 106 and a draining pipe 108. Fuel is supplied to a filling pipe 106 at a supply station by means of a supply hose 110 connected between a supply tank and a dry connector 112 on the filling pipe 106. The dry connector 112 provides a liquid tight connection for the supply hose 110 and includes a valve that is automatically pushed open by a pin (not shown) mounted in the mating portion 114 on the supply hose 110.

[0018] A second valve 120 is located between the housing tank 102 and the wet lines 104. This valve 120 is a one way valve that is pressure operated and automatically opens as fuel flows into the filling pipe 106.

[0019] Emptying of a housing tank 102 is achieved by draining the fuel, under gravity, from the draining pipe 108. As with the filling pipe 106, the draining pipe 108 is terminated by a dry connector 122.

[0020] Once fuel has been supplied to a housing tank 102 via the filling pipe 106, the supply hose 110 is disconnected, thereby, automatically closing the valve 120 and the valve of the dry connector 112. It will be appreciated that fuel remains trapped in the wet line 104. Since each of the housing tanks 102 has its own set of wetlines 104, and each retains several gallons of fuel, the combined volume of fuel in the wetlines 104 of a typical tanker 100, presents a significant danger.

[0021] In accordance with the present invention, the fuel in the wetlines 104 is pumped out of the wetlines 104 and into the housing tanks 102. As shown in FIG. 3, each of the wetlines 104 is provided with a pipe 130 that extends from the lowest point in the wetline 104 to a location near the top of the housing tank. In a preferred embodiment, the pipe 130 runs along a surface (in this case, the outer surface) of the wetlines 104, passes through the wall 132 of the housing tank 102 at a location 134 adjacent to the valve 120, and runs up the inner surface of the housing tank 102 to a location near the top of the housing tank. Thus fuel is fed from the wetlines 104 into the housing tank 102, thereby emptying the wetline 104. By having the pipe 130 empty out near the top of the housing tank 102, in this embodiment, above the highest surface of the fuel in the housing tank, there is no need to force the fuel up into the tank against the weight of the fuel in the tank, as in the prior art system. It will be appreciated that the outlet of the pipe 130 could also be located below the surface of the fuel in the housing tank 102, however, the outlet should ideally not be located too far below the upper surface of the fuel in the housing tank, to minimize the pressure at the outlet. It will also be appreciated that the pipe 130 could, instead, be mounted on an outer surface of the housing tank 102. In tanker trucks having a double walled housing, the pipe 130 could run between the two walls. While the term pipe has been used to depict the fuel path 130, this could be either a rigid pipe or a flexible hose.

[0022] The invention contemplates any pump system connected to the pipe 130. In one embodiment a centrifugal pump is used, and in another embodiment a suction pump such as a diaphragm pump is used. In the example illustrated in FIG. 3, the pump 200 is a suction pump, and is mounted in a housing 202 which is in fluid communication with the pipe 130. In one embodiment, the pump 200 was made of a non-ferrous metal, in this case brass, and having a housing 202 with a male screw connector receivable in a complementary female screw connector welded to the wetline 104. In the embodiment of FIG. 3, the pump 200 is connected directly to the wetlines 104. A separate pump is provided for each set of wetlines 104. The pipes 130 extend from the pumps 200 to the tops of the housing tanks 102.

[0023] It will, however, be appreciated that in another embodiment, as shown in FIG. 4, a suction pump 240 could be fluidly connected with the wetlines 242 by means of a pipe. Thus the pipe 130 comprises a section 250 extending from the wetlines 242 to the pump 240, and a second section 252 extending from the pump 240 to a housing tank 254. Furthermore, in this embodiment, a single pump (in this case suction pump 240) is provided to pump fuel sequentially for each of the sets of wetlines on the tanker truck. In such an arrangement each of the pipes 130 would be in two sections with one section (section 250) extending from a set of wetlines to the pump and a second portion (section 252) extending from the pump to a housing tank.

[0024] In the illustrated embodiments, the pumps 200, 240 are driven by the flow of regular air from a conventional compressed air source. As shown in FIG. 3, air source 210 is connected through a hose 212 to the pump 200. The compressed air source 210 can be any conventional compressor as is commonly used to inflate tires or power tools. The invention preferably envisages the use of conventional air compressors which are readily available and thus allow quick and cheap implementation of the invention. By keeping the air supply driving the pump, separate from the fuel, and avoiding contact between the air supply and the fuel, this invention realizes the benefit of using a cheap, readily available propulsion source for the pump, while avoiding the need for inert gases or other gases that reduce the risk of explosions. As mentioned above, other pumps could be used instead of suction pumps. In order to still be able to use regular compressed air or other fluid flow as the source for driving other types of pumps, a turbine driven by compressed air or other fluid flow, may be necessary to drive the pump.

[0025] It will be appreciated that the pumps 200, 240 could, instead, be driven by a motor such as an electric motor connected, however, such an arrangement is less desirable when flammable fluids are to be pumped, due to the danger of sparks and the possibility of a fire or explosion. It will be appreciated that, if the pipe 130 is wide enough to accommodate the pump, the pump could be mounted directly in the pipe 130. It will also be appreciated that the wetlines 104, 242 will have to be provided with a way of replacing the fuel pumped from the wetlines with air or other gas. In the embodiment of FIG. 4, a vent tube 260 extends from each of the wetlines into the corresponding housing tank to allow fuel rich gas to enter the wetlines as the gas and fuel is sucked out of the wetlines 242. The vent tube 260 is provided with a check valve to allow the gas to enter the vent tube 260 but avoid fuel being pumped into the vent tube 260. By sucking fuel rich gas from the housing tank, the explosion hazard is reduced by avoiding highly oxygenated air from entering the wetlines. It will be appreciated that the tube 260 could, instead be supplied by an inert gas from a separate source. Insofar as such a source is under pressure, the check valve becomes unnecessary. In fact the tube 260 can be avoided altogether by connecting a canister of compressed inert gas such as helium, directly to the wetline.

[0026] Furthermore, in order to ensure that substantially all of the fuel in the wetlines 104 is removed, the housing 202 in the FIG. 3 embodiment is preferably mounted to be in fluid communication with the lowest point on the wetlines. This may require the shape or attitude of the wetlines to be adjusted. In the embodiment of FIG. 3, the housing 202 is mounted at an elbow 222 of the wetlines 104, wherein the wetlines 104 are shaped to define the elbow 222 as the lowest point on the wetlines 104.

[0027] Instead, as shown in the FIG. 4 embodiment, the section 250 of the pipe 130 could feed into the wetlines 104 and extend to a low point of the wetlines 104. This allows the pump 240 to be mounted anywhere on the truck, with the various sections 250 extending to the pump 240, and the sections 252 extending from the pump to the tops of the housing tanks 254. It will be appreciated that in this embodiment, valves are included in the pipe sections 250 to ensure that the pump 240 pumps from one set of wetlines 242 only at any one time. The valves can be manually controlled or by an electronic controller that sequentially opens and closes the valves in the sections 250 to sequentially drain the wetlines 242.

[0028] The embodiments of FIGS. 3 and 4 use compressed air as a propulsion source for the pumps 200, 240 since compressed air is readily available. However, other fluid flow could, instead, be used to drive the pumps, such as water or oil flowing through the pumps.

[0029] While the invention was described specifically for propelling fuel from wetlines of a tanker truck into the housing tank of the truck. However the use of an air driven pump which is driven by regular air from a conventional compressed air source, where the air is kept separate from the liquid being pumped, has other applications. The invention can be used for conveying liquid along a pipe generally, in a cost effective manner without resorting to an unconventional compressed air sources such as compressed inert gas, and without causing a safety hazard.

[0030] Thus, while the invention was described in detail with respect to a specific implementation, it has much broader scope, as defined by the claims to this application.

Claims

1. A method of emptying wetlines associated with a housing tank of a tanker truck, comprising, pumping liquid in the wetlines into the housing tank, through a separate pipe extending from the wetlines to a location at or near the top of the housing tank.

2. A method of claim 1, wherein the separate pipe extends from the wetlines to a location above or near the highest surface of the liquid in the housing tank.

3. A method of claim 1, wherein the separate pipe extends along an inner surface of the housing tank.

4. A method of claim 1, wherein the separate pipe extends along an outer surface of the housing tank.

5. A method of claim 1, wherein the liquid is pumped using a suction pump.

6. A method of claim 5, wherein the pump is driven by fluid flow.

7. A method of claim 6, wherein the fluid flow is air flow from a conventional compressed air source of regular air.

8. Means for emptying wetlines associated with a holding tank on a tanker truck, comprising a pipe extending from the wetlines to a location at or near the top of the housing tank, and a pump for pumping the liquid along the pipe into the housing tank.

9. Means according to claim 8, wherein the pump is a suction pump mounted in the pipe or in a housing connected in fluid flow communication with the pipe.

10. Means according to claim 8, wherein the pump is a suction pump driven by fluid flow.

11. Means according to claim 10, wherein the fluid flow is regular air flow from a conventional compressed air source.

12. Means according to claim 10, wherein the fluid is air, water, or oil.

13. Means according to claim 8, wherein the pipe extends from the wetlines to a location above or near the highest surface of the liquid in the housing tank.

14. Means according to claim 8, wherein the pipe extends along an inner surface of the housing tank.

15. Means according to claim 8, wherein the separate pipe extends along an outer surface of the housing tank.

16. Means for pumping liquid from a liquid container, comprising a suction pump mounted in the container or in a housing connected in fluid flow communication with the container, wherein the pump is operated by air flow from a conventional compressed air source.

17. A method of claim 5, wherein a vent is provided for supplying gas from the housing tank to the wetlines as gas or liquid is pumped from the wetlines.

18. Means according to claim 8, further comprising a vent tube extending from the housing tank to the wetlines.

19. Means according to claim 16, further comprising a vent for supplying gas to the container as gas or liquid is pumped from the container.

20. Means of claim 19, wherein the gas does not react with the liquid.

21. A method of claim 1, wherein the liquid is pumped using a pump that is driven by a gas driven turbine.

22. Means according to claim 8, wherein the pump is driven by a gas driven turbine.

23. Means for pumping liquid from a liquid container, comprising a pump mounted in the container or in a housing connected in fluid flow communication with the container, wherein the pump is driven by a turbine which is driven by air flow from a conventional compressed air source.