Abstract:
A potable water system capable of being drained in flight. The system provides positive separation between the potable and gray water systems. The design of the system will allow draining of components such as water tanks or interconnect lines that are below the level of the drain point. The systems will allow draining of components such as water tanks or interconnect lines that would not gravity drain due to the routing of their interconnect lines. This invention would apply to aircraft that need the capability to drain their potable water system in flight.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not Applicable. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not Applicable. 
     REFERENCE TO A “MICROFICHE APPENDIX” 
     Not Applicable. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention Art 
     The present invention relates generally to the potable and gray water systems on board commercial and general aviation aircraft and the capability to drain their potable water system in-flight. 
     2. Description of the Related Art 
     More and more airports are imposing stringent rules and regulations regarding the dumping of fluids on the tarmac area whether it is potable water, gray water, or more hazardous materials like hydraulic fluids, or engine oils. Potable water systems need to be drained for a variety of reasons such as general aircraft maintenance, sterilization, and cold weather storage. Typical water systems have provisions to drain potable water on the ground through a skin port. Draining the potable water system in-flight is one way to eliminate the need to dump the potable water on the tarmac. Discharging liquid in-flight presents two problems: first the liquid may freeze at the exit point; second, it may come in contact with the skin of the aircraft and form an ice block which is hazardous to people in the ground. Both of those problems are overcome with the use of a heated drain mast. Heated drain masts are currently used to drain gray water overboard in flight. Federal Food and Drug Administration rules require physical separation between the potable water system and the gray water system to prevent potable water contamination. Dual port heated drain masts currently allow the drainage of both the potable and gray water systems with the required separation. 
     Most business jets and commercial size aircraft are delivered from the original equipment manufacturer with at least one, and commonly two, single port drain masts. Retrofitting the aircraft with a dual port drain mast can be accomplished by replacing the single port drain mast with a dual port drain mast. To retrofit an aircraft that already has two single port drain masts, it is advantageous to replace the aft most drain mast such that drainage from the new dual port drain mast is less likely to form an ice block on the exterior of the aircraft or other exterior components such as antennas and inlet ducts fairings. However, on certain aircraft the aft most drain mast location may be above the lowest level of one or more of the potable water tanks and/or their interconnect lines, which prohibits sufficient gravity draining of the tanks. 
     Draining the potable water system can be accomplished through a single port drain mast dedicated to the potable water system. In some cases this drain mast may need to be installed above the lowest level of the potable water tank and/or portions of the potable water interconnect lines. In those cases, potable water cannot be sufficiently drained using gravity. 
     SUMMARY OF INVENTION 
     One object of this invention is to provide the required separation between potable and gray water systems by installing an additional single port drain mast dedicated to the potable water system, which can be used to sufficiently drain the potable water system despite being above the lowest level of the potable water tank or portions of the potable water interconnect lines. 
     Another object of this invention is to provide the required separation between potable and gray water systems by installing a dual port drain mast, which can be used to sufficiently drain the potable water system despite being above the lowest level of the potable water tank or portions of the potable water interconnect lines. 
     Another object of this invention is to provide a system and method to use either the potable water pressurization system and/or the cabin differential pressure to push water up to the level of a dual port drain mast or a dedicated potable water drain mast that is installed above lowest level of one or more potable water tanks or interconnect lines. This will allow the potable water tanks to be sufficiently drained in flight. 
     Another object of the invention is to facilitate drainage of potable water tanks through potable water lines that are routed in such a way that they would prevent drainage without the use of the potable water pressurization system or cabin differential pressure. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF DRAWINGS 
       The foregoing summary as well as the following detailed description of the preferred embodiment of the invention will be better understood when read in conjunction with the appended drawings. It should be understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown herein. The components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present invention. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. 
       The invention may take physical form in certain parts and arrangement of parts. For a more complete understanding of the present invention, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  depicts an embodiment of the present invention with a single water tank, in which a portion of the tank and a portion of the plumbing lines connecting the tank to a single port drain mast are located below the level of the single drain mast. 
         FIG. 2  depicts an embodiment of the present invention with two potable water tanks, a primary and auxiliary water tank, in which a portion of one of the potable water tanks is located below the level of a single-port drain mast. 
         FIG. 3  depicts an embodiment of the present invention in which a portion of the plumbing lines that interconnect the auxiliary water tank to the primary water tank are above the level of the top of the water tanks. 
         FIG. 4  depicts an embodiment of the present invention with a single potable water tank where a portion of the potable water distribution lines are routed below the level of a single port drain mast and a three position selector valve is used to control distribution of the water and drainage of the system. In  FIG. 4 , the three position selector valve is set to allow distribution of the water throughout the system, while preventing water from draining through the drain mast. 
         FIG. 5  depicts the embodiment of  FIG. 4  with a different setting for the three position selector valve. In  FIG. 5 , the three position selector valve is set to allow water to drain from the potable water tank and the interconnect lines between the potable water tank and the three position selector valve. 
         FIG. 6  depicts the embodiment of  FIG. 4  with another different setting for the three position selector valve. In  FIG. 6 , the three position selector valve is set to allow water to drain from the distribution lines between the check valve and the three position selector valve. 
         FIG. 7  depicts an embodiment of the present invention with a single potable water tank where a portion of the potable water distribution lines are routed below the level of a single port drain mast and three individual valves are used to control distributing and draining water. 
         FIG. 8  depicts an embodiment of the present invention with two potable water tanks, primary and auxiliary, in which a portion of the potable water distribution lines are routed below the level of a single port drain mast and a three position selector valve is used to control the draining of the system. In  FIG. 8 , the three position selector valve is set to allow distribution of the water throughout the system, while preventing water from draining through the drain mast. 
         FIG. 9  depicts the embodiment of  FIG. 8  with a different setting for the three position selector valve. In  FIG. 9 , the three position selector valve is set to allow water to drain from the potable water tanks and the interconnect lines between the potable water tanks and the three position selector valve. 
         FIG. 10  depicts the embodiment of  FIG. 8  with another different setting for the three position selector valve. In  FIG. 10 , the three position selector valve is set to allow water to drain from the distribution lines between the check valve and the three position selector valve. 
         FIG. 11  depicts an embodiment of the present invention with two potable water tanks, primary and auxiliary, in which a portion of the potable water distribution lines are routed below the level of a single port drain mast and three individual valves are used to control the draining of the system. 
         FIG. 12  depicts and embodiment of the present invention with a single water tank, in which a portion of the tank and a portion of the plumbing lines connecting the tank to a dual port drain mast are located below the level of the dual port drain mast. 
     
    
    
     DETAILED DESCRIPTION OF INVENTION 
     If a user of an aircraft desires to drain a potable water system in flight, and the drain point is above the lowest level of the water system, whether the lowest level of the water system is the lowest point of the potable water tank, the supply lines, the interconnect lines, or any other portion of the water system, the water must be forced uphill to be adequately drained. The preferred embodiment of the current invention uses the pressure source from the potable water system, e.g., a compressor, a pump, or bleed air from the aircraft engines, to push the water from the lowest portion of the water system up to the drain point, which can be a multiple-port drain mast or a dedicated single port drain mast. 
       FIG. 1  shows a schematic representing a configuration of an aircraft water system in which a portion of a potable water tank is below the top of the drain mast as well as portions of its interconnecting plumbing. This positioning is in contrast to a drain mast that is located below the water tank and its interconnecting plumbing such that the tank would sufficiently drain from the force of gravity. But, physical constraints of the aircraft sometimes dictate that the drain mast be installed in a location where the tank and interconnecting plumbing cannot sufficiently drain using the force of gravity. As such some other force must be used to adequately drain the tank and interconnect line.  FIG. 1  depicts a drain mast and interconnecting plumbing placement in which the tank cannot sufficiently drain using gravity. As such, some other force must be used if the tank is to be sufficiently drained. The embodiment depicted in  FIG. 1  uses the pressure system associated with delivering water throughout the plane to drain the tank and interconnecting plumbing. 
     During normal use of the system shown in  FIG. 1 , water is delivered as needed to portions of the aircraft by pressure that is supplied to the system through the pressure supply line  104  into tank  103 . During the normal supply of water, valve  107  is closed, and check valve  105  is closed with check valve  105  being closed by the pressure on the system. Water is then forced to the points of use through the supply line  106 . When the operator wishes to drain the water system, valve  107  is opened and pressure from the supply line forces water out of tank  103  through drain mast interconnect line  102  to drain mast  101 . 
     On aircraft that operate with a pressurized cabin, the difference between the internal cabin pressure and the pressure outside the aircraft may be as high as 8 pounds per square inch. This is known as cabin differential pressure. When a water tank is being drained, pressure in the tank may fall below the cabin differential pressure. When this occurs, check valve  105  will open allowing pressure from the cabin to enter the tank  103 . 
     The use of either the cabin differential pressure from line  108  or the potable water pressurization from line  104  will force the water from water tank  103  through drain mast interconnect line  102  to drain mast  101 . In comparison to using only one of the cabin differential pressure from line  108  or the potable water pressurization from line  104 , the use of both the cabin differential pressure from line  108  or the potable water pressurization from line  104  will increase the rate at which the tank and water lines will drain. 
     The aircraft water system depicted in  FIG. 2  is comprised of both a primary water tank  203  and an auxiliary water tank  209 . In this case, a portion of the auxiliary water tank  209 ; the interconnect line  207  that connects the auxiliary water tank to the primary water tank; and the line  202  that connect the primary water tank  203  to the drain mast  201  are below the level of the drain mast  201 . 
     When water is distributed throughout the aircraft, pressure is supplied to the system through the pressure supply line  204  which forces water from the auxiliary water tank  209  into the primary water tank  203  and then through the distribution line  206  to the points of use. When the operator wishes to drain the potable water system, valve  208  is opened, which causes pressure from pressure supply line  204  to force water from the auxiliary water tank  209  through interconnect line  207  into the primary water tank  203  where it then travels through the drain mast interconnect line  202  to the drain mast  201 . 
     As in the system shown in  FIG. 1 , if the pressure in the tanks in  FIG. 2  falls below the cabin differential pressure, the check valve  205  will open allowing air from the cabin to enter the auxiliary water tank  209  through the cabin vent line  210  and force water from auxiliary water tank  209  through the interconnect line  207  into the primary water tank  203  where it then travels through the drain mast interconnect line  202  to the drain mast  201 . 
     The use of either the cabin differential pressure from line  210  or the potable water pressurization from line  204  will force the water from auxiliary water tank  209  through the interconnect line  207  into the primary water tank  203  where it then travels through the drain mast interconnect line  202  to the drain mast  201 . In comparison to using only one of the cabin differential pressure from line  210  or the potable water pressurization from line  204 , the use of both the cabin differential pressure from line  210  or the potable water pressurization from line  204  will increase the rate at which the tanks and water lines will drain. 
     The aircraft water system depicted in  FIG. 3  is comprised of a primary water tank  303  and auxiliary water tank  309  where the interconnect line between the two tanks  307  is routed such that it is above the level of both water tanks. When water is distributed throughout the aircraft, pressure is supplied to the system through the pressure supply line  304  which forces water from the auxiliary water tank  309  through the primary to auxiliary water tank interconnect line  307  into the primary water tank  303  and then through the distribution line  306  to the points of use. When the operator wishes to drain the potable water system, valve  308  is opened, which causes pressure from pressure supply line  304  to force water from the auxiliary water tank  309  through interconnect line  307  into the primary water tank  303  where it then travels through the drain mast interconnect line  302  to the drain mast  301 . 
     As in the system shown in  FIG. 1 , if the pressure in the tanks falls below the cabin differential pressure the check valve  305  will open allowing pressure from the cabin to enter the auxiliary water tank  309 . The use of either the cabin differential pressure from line  310  or the potable water pressurization from line  304  will force the water from auxiliary water tank  309  through the interconnect line  307  into the primary water tank  303  where it then travels through the drain mast interconnect line  302  to the drain mast  301 . In comparison to using only one of the cabin differential pressure from line  310  or the potable water pressurization from line  304 , the use of both the cabin differential pressure from line  310  or the potable water pressurization from line  304  will increase the rate at which the tanks and water lines will drain. 
     The system depicted in  FIG. 4  is comprised of a system with a potable water tank  403  and a potable water interconnect line  406  which is routed such that it will not adequately gravity drain through drain mast  401 . When water is distributed throughout the aircraft, pressure is supplied to the system through the pressure supply line  404  which forces water from the water tank  403  through the water interconnect line  406  to the three position selector valve  407  which is in the position to allow water to pass through to distribution line  410  and on to points of use. In that position, shown in  FIG. 4 , the three position selector valve disconnects line  406  from line  402 . 
     When the operator wishes to drain the water system in-flight, the three position selector valve  407  is then set to a position that connects interconnect line  406  to interconnect line  402  allowing water from water tank  403  and interconnect lines  406  and  402  to drain through drain mast  401 , as shown in  FIG. 5 . In that position pressure from the pressure supply line  404  forces water to flow through a portion of the distribution line  406  through interconnect line  402  and out the drain mast  401 .  FIG. 5  also shows the three position selector valve in a position that disconnects distribution line  410  from both lines  402  and  406 . 
     Once the water tank  403  and water distribution line  406  are sufficiently drained, the three position selector valve is repositioned such that distribution line  410  can be drained, as shown in  FIG. 6 . In  FIG. 6 , three position selector valve  407  connects distribution line  410  to interconnect line  402  and the water is drained through the drain mast  401  through cabin differential pressure. Cabin differential pressure opens the check valve  409  which forces the water in distribution line  410  to be drained through interconnect line  402  and out the drain mast  401 . Cabin differential pressure is supplied through line  408  through check valve  409 . In  FIG. 6  three position selector valve  407  is positioned such that interconnect line  406  is disconnected from lines  402  and  410 . The use of the water system pressure in conjunction with the cabin differential pressure will force the potable water tank  403  and the distribution lines  406  and  410  to be adequately drained in flight. The three position selector valve  407  may be replaced by three individual valves  707 ,  709 , and  710  as shown in  FIG. 7 . 
     The aircraft system depicted in  FIG. 8  is comprised of both a primary water tank  803  and auxiliary water tank  809 , primary to auxiliary water tank interconnect line  807  and distribution line  806  routed such that they will not adequately gravity drain through drain mast  801 . When water is distributed throughout the aircraft, pressure is supplied through the pressure supply line  804  which forces water from the auxiliary tank  809  through interconnect line  807  and into the primary water tank  803  and then through the interconnect line  806  to the three position selector valve which is set to a position that allows water to pass through to distribution line  812  and on to the points of use. In that position, shown in  FIG. 8 , the three position selector valve disconnects line  806  from line  802 . 
     When the operator wishes to drain the potable water system in-flight, the three position selector valve  808  is repositioned to connect the drain mast  801  through the drain mast interconnect line  802  to the interconnect line  806 , as shown in  FIG. 9 . In  FIG. 9  pressure from line  804  is supplied to auxiliary water tank  809 , which forces water to flow from the auxiliary potable water tank  809  through the primary to auxiliary water tank interconnect line  807  and into the primary water tank  803  and then through interconnect line  806 , and through the drain mast interconnect line  802 , and out the drain mast  801 . The position of three position selector valve  808  shown in  FIG. 9  disconnects distribution line  812  from lines  802  and  806 . 
     Once the primary water tank  803  and auxiliary water tank  809 , as well as the primary to auxiliary water tank interconnect line  807  and interconnect line  806  are drained, the three position selector valve  808  is repositioned such that distribution line  812  can be drained, as shown in  FIG. 10 . In  FIG. 10  three position selector valve  808  connects distribution line  812  to the drain mast interconnect line  802  and the water is drained through the drain mast  801  using cabin differential pressure. Cabin differential pressure opens the check valve  811  which forces the water in distribution line  812  to be drained through drain mast interconnect line  802  and out the drain mast  801 . Cabin pressure enters the check valve  811  through vent line  810 . In  FIG. 10  three position selector valve  808  is positioned such that interconnect line  806  is disconnected from lines  802  and  812 . Three position selector valve  808  may be replaced by three individual valves  1108 ,  1111 , and  1114  as shown in  FIG. 11 . The use of the water system pressure in conjunction with the cabin differential pressure will force the potable water tank  803 , auxiliary water tank  809 , the interconnect line  807 , the interconnect line  806 , the drain mast interconnect line  802 , and distribution line  812  to be adequately drained in-flight. 
       FIG. 12  depicts an aircraft water system as shown in  FIG. 1 , except that the drain mast in  FIG. 12  is a dual port drain mast, which can be used to separately drain potable water through line  102  and gray water through line  1202 . This configuration can be applied to any of the embodiments described herein, such that a dual-port drain mast is used to allow the separate drainage of both potable water and gray water through the same mast. It should also be noted that multiple drain masts, consisting of more than two ports, can be used in kind to drain more than two different liquids separately. Furthermore, the drain masts, either single or multiple-port, can be heated to help prevent liquids from freezing upon exiting the drain. 
     Although the invention has been shown and described with respect to a certain preferred embodiment or embodiments, it is obvious that equivalent alterations and modifications will occur to others skilled in the art upon the reading and understanding of this specification and the annexed drawings. In particular regard to the various functions performed by the above described components (assemblies, devices, circuits, etc.), the terms (including a reference to a “means”) used to describe such components are intended to correspond, unless otherwise indicated, to any component which performs the specified function of the described component (i.e., that is functionally equivalent), even though not structurally equivalent to the disclosed structure which performs the function in the herein illustrated exemplary embodiments of the invention. 
     Specific reference has been made in the description of embodiments of this invention as they relate to potable water drainage of an aircraft in-flight. It should be noted, however, that one of ordinary skill in the art would understand that this invention could be applied to drain other liquids of aircraft and those liquids could be drained either in-flight or on the ground. Furthermore, the representation of the embodiments of this invention are not limited to the specific number of water tanks, plumbing lines, pressure lines, or any other component of an aircraft system that requires drainage as described herein. One of ordinary skill in the art would understand that an aircraft system that requires drainage may be comprised of any number of those components and that this invention encompasses such variations. 
     In addition, while a particular feature of the invention may have been disclosed with respect to only one of several embodiments, such feature may be combined with one or more other features of the other embodiments as may be desired. Additionally, specific details may have been omitted inasmuch as such details are not considered necessary to obtain a complete understanding of the present invention, and are considered to be within the understanding of persons of ordinary skill in the relevant art. 
     It is therefore contemplated that the claims will cover any such modifications or embodiments that fall within the true scope of the invention.