Method and apparatus for extending the life of an x-ray tube

The present invention teaches methods and apparatus for extending the life of an x-ray tube. An x-ray tube typically contains an insert for generating x-rays. The insert is housed in a housing wherein an insulating fluid circulates around the insert in the housing to provide thermal and electrical insulation. The present invention includes methods and apparatus for removing water from insulating oil. One embodiment of the invention includes a processor containing a coalescing element for removing water as a vapor from the oil. Other embodiments include methods and devices for drying the interior of the housing. Another embodiment of the invention includes a kit containing a processor having a coalescing element for removing water from the insulating oil. The portable kit allows the invention to be practiced on x-ray tubes maintained in gantry supports of x-ray machines, such as CT scanners.

BACKGROUND OF THE INVENTION
 The present invention relates to methods and devices for extending the life
 of an x-ray tube. Typically x-ray tubes are mounted inside a lead shielded
 radiation enclosure called a housing or casing. The housing is attachable
 to the x-ray machine, typically a CT, fluoroscopic, or rad machine. The
 housing is filled with a fluid of synthetic or petroleum derivative,
 generally referred to as insulating oil. The insulating oil acts to
 thermally and electrically insulate the tube. Heat is generally removed to
 air through fluid to water or fluid to water cooled air transfer.
 All such fluids, are damaged, from four major contributors: (1) heat; (2)
 radiation; (3) high voltage arcing; and (4) corona discharge.
 This heating oil is sold by two primary standards: (1) ASTM 877 for
 unprocessed oil; and (2) ASTM 1816 for processed oil. Insulating oil
 consists of perhaps 3500 separate hydrocarbons. The hydrocarbons having
 varying carbon bond lengths with many separate bonded molecules and ions,
 such as hydrogen, oxygen, hydroxyls, and many others.
 For most x-ray products, the end of life is primarily predicated by an
 arcing process. Failure is accentuated by deposition on the glass or metal
 window of the insert. Deposition on the high voltage hold off leads to
 collapse in the insert itself, leading to subsequent deterioration of
 rotor function. The arcing while starting out infrequently, increases in
 frequency as the oil deteriorates. As the arcing increases the oil
 deteriorates more rapidly which, in turn, leads to more arcing.
 It is commonly thought that the greases and waxes produced during the life
 of an x-ray tube are deleterious to the insulating oil, i.e. damaging.
 Such is the motivation behind U.S. Pat. No. 5,440,608 entitled "Method And
 System For Extending The Service Life Of An X-Ray Tube" by Peralta, et al.
 The method taught in Pat. '608, and subsequent patents by Peralta, U.S.
 Pat. Nos. 5,596,622 and 5,732,123. U.S. Pat. Nos. 5,440,608; 5,732,123;
 and 5,596,622 are collectively referred to herein as PERALTA. PERALTA
 describes methods and apparatus for removing the old oil and replacing it
 with new oil, and methods for filtering the greases and waxes produced
 during the life of an x-ray tube. As PERALTA points out, the financial
 risks involved in when working with x-ray tubes and CT scanners is
 substantial. Tubes are very delicate in some respects and require great
 care when repairing them.
 One problem encountered in the past has been the removal of bubbles which
 has come out of solution, or removal of those introduced into the system
 when oil has been replaced. For Siemens and Phillips manufactured tubes it
 has been quite common for many years to remove bubbles by replacing the
 oil. Circa 1984, General Electric introduced quick-disconnects into the
 hydraulic system, i.e. quick-disconnects in-line between the heat
 exchanger and the x-ray tube housing. This facilitated the removal of
 bubbles from the system. Since approximately 1985, this inventor has had
 occasion to open the hoses between the heat exchanger and the x-ray tube
 to remove bubbles, or replace oil, or both. PERALTA describes these well
 known techniques.
 This inventor believes the greases and waxes are not as damaging as is
 commonly believed. In fact, the addition of new oil, as taught by Peralta,
 is contrary to preferred embodiments of the present invention.
 SUMMARY OF THE INVENTION
 The present invention relates to methods and apparatus for extending the
 life of an x-ray tube. One embodiment of the present invention includes a
 method of extending the life of an x-ray tube having a housing and an
 insert located therein for producing x-rays. The method comprises the
 steps of providing the x-ray tube with an insulating oil in the housing;
 and processing the insulating oil to remove deleterious gases from the
 oil.
 In a preferred embodiment the step of processing the oil to remove
 deleterious gases from the oil comprises removing water from the oil. The
 method also includes drying the housing. In one embodiment this is
 accomplished by circulating insulating oil which has been dried through
 the housing to absorb water in the housing and drying, or withdrawing,
 water from the oil.
 Another embodiment of the present invention includes an x-ray tube oil
 processor for extending the life of an x-ray tube. This is accomplished by
 processing the insulating oil for the x-ray tube. The x-ray tube oil
 processor includes a processing chamber having an oil inlet, an oil
 outlet, and a gas outlet. Preferably a coalescing element is positioned in
 the processing chamber. The coalescing element has a first end in fluid
 communication with the oil inlet.
 Generally a vacuum source is placed in fluid communication with the gas
 outlet to evacuate the processing chamber. An oil inlet hose and an oil
 outlet hose are respectively connected in fluid communication to the oil
 inlet and the oil outlet of the processing chamber. Oil then enters the
 oil inlet hose, passes through the coalescing element which removes gases,
 in particular water as a vapor, from the oil, and the oil then exits the
 oil outlet hose.
 Another embodiment of the present invention includes an x-ray tube
 processing kit for processing oil in an x-ray tube. The kit is important
 in the present invention because this allows the x-ray tube processor to
 be readily portable to a field location in which the x-ray tube is mounted
 on a gantry of an x-ray machine or CT scanner, and the like. The kit
 generally comprises a processing chamber containing a coalescent filter; a
 plurality of fluid hoses adapted to connect to the processing chamber.
 Preferably the kit also includes an oil pump adapter to connect to one of
 the plurality of fluid hoses; and a vacuum pump adapted to connect to the
 processing chamber.
 It is desirable to process the oil while the x-ray tube is mounted in the
 gantry to avoid the time, expense and potential risk of dismounting the
 x-ray tube, remounting the x-ray tube, calibrating the x-ray tube. It is
 also desirable because it avoids extended down time of the x-ray machine.
 One object of the present invention is to provide a means for extending the
 life of an x-ray tube. Another object of the present invention is to
 reduce healthcare costs. A further object of the invention is to encourage
 manufacturers to develop longer lasting tubes at lower costs.
 One object of the present invention is to provide a device for drying the
 housing of an x-ray tube. Another object of the present invention is to
 provide a device for removing water from the insulating oil of an x-ray
 tube.
 Another object of the present invention is to provide a device for
 improving the performance of x-ray tubes.
 Another object of the present invention is to provide a device for
 resurrecting "failed tubes."
 Another object is to teach a preventive maintenance program for extending
 the life of, and improving the performance of, an x-ray tube. A further
 objective is to provide a device for performing the preventive maintenance
 program.
 Another object of the present invention is to provide a device for drying
 insulating oil of an x-ray tube.
 Another object of the present invention is to provide a device for taking
 gases out of a solution wherein the gases are in the insulating oil of an
 x-ray tube.
 A further object of the present invention is to out-gas deleterious gases
 from the insulating oil.
 Another object of the present invention is to remove damaging gases from
 insulating oil by providing a device which processes the oil in an
 environment below atmospheric pressure.
 Another object is to provide a device for processing oil in a closed
 system.
 Another object of the present invention is to provide a device which forces
 bubbles back into solution while in the housing, then transfers the
 solution to a processing chamber, then allows the bubbles to be taken out
 of solution and removed as a gas by an evacuation process in a processing
 chamber. A coalescing element is employed in some embodiments to aid
 removal of the gases from the oil.
 Other objects and advantages of the present invention will be apparent to
 those of skill in the art from the teachings disclosed herein and by
 reference to the attached drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS
 The present invention relates to methods and apparatus for extending the
 life of an x-ray tube. FIG. 1 is a prior art drawing showing an x-ray tube
 10 fluidly connected to a heat exchanger 12. The x-rays are produced by an
 insert 14 shown in prior art drawing FIG. 2. A housing 18, shown in FIG.
 1, houses the insert 14. The insulating oil 16 shown in FIG. 2 circulates
 around the insert to provide thermal and electrical insulation. FIG. 3,
 prior art, depicts the x-ray tube 10 mounted on a gantry 20 of a computer
 tomography (CT) scanner 22. The machine depicted in FIG. 3 may also be any
 typical x-ray device.
 The following U. S. Patents, which discuss CT scanners, x-ray tubes, and
 cooling methods, are hereby incorporated herein by reference: U.S. Pat.
 No. 5,086,449; entitled "Debubbler System for X-Ray Tubes" by Furbee, et
 al.; U.S. Pat. No. 4,115,697 entitled "X-Ray Tube Cooling Arrangement" by
 Hounsfield; U.S. Pat. No. 5,012,505 entitled "Fluidic Slip Ring For CT
 Scanners" by Zupancic, et al.; U.S. Pat. No. 4,622,687 entitled "Liquid
 Cooled Anode X-Ray Tubes" by Whitaker et al.; U.S. Pat. No. 4,688,239
 entitled "Heat Dissipation Means For X-Ray Generating Tubes" by Schaffner,
 et al.; U.S. Pat. No. 4,767,961 entitled "X-Ray Generator Cooling System"
 by Koller, et al.; U.S. Pat. No. 4,841,557 entitled "X-Radiator With
 Circulating Pump For Heat Dissipation" by Haberrecker, et al.; U.S. Pat.
 No. 4,866,743 entitled "Computer Tomography Apparatus With A Closed
 Circulation Cooling System" by Kroener; and U.S. Pat. No. 5,732,123
 entitled "Method and System For Extending The Service Life Of An X-Ray
 Tube" by Peralta et al.
 As mentioned in the background section, greases and waxes produced during
 the life of an x-ray tube are not particularly damaging. Gases, however,
 which are highly absorbable in oil can be particularly damaging to the
 process of producing x-rays. Because bubbles are a location of reduced
 insulation, but they can act as a pathway for electrical conduction
 through the insulating oil more readily than through regions lacking
 bubbles. Also, gas in solution provides opportunities for chemical
 disassociation by providing a source of hydrogen and oxygen ions.
 As mentioned in the background section the oil is made up of some 3500
 separate hydrocarbons. The oil is subjected to a chemical change due to
 the heat, radiation, arcing and corona phenomena within the x-ray tube.
 Longer chain molecules break down and recombine with other by-products to
 form longer and shorter chain molecules.
 A shorter chain of molecules may be pure gas, such as acetylene gas C.sub.2
 H.sub.6. C.sub.2 H.sub.6 is produced primarily during a major high voltage
 breakdown in oil. Other by-products include hydrogen, which is produced by
 stripping off a hydrogen ions by arcing or corona discharge. This is
 primarily due to a corona phenomena.
 Note that these gases are formed by manipulations of high voltage in the
 environment outside the actual x-ray tube insert. This is a key to
 understanding the nature of tube failure the x-ray machine. It is the
 insulating oil which is being altered and damaged. When the insulating oil
 becomes damaged, then the insert becomes damaged due to lack of proper
 insulation (via the effects of arcing).
 One of the keys to the invention is the realization that water is a
 component in oil which has been subjected to an operating x-ray machine
 environment. At room temperature the saturation level of water is about 62
 parts per million (ppm) in the insulating oil. During the x-ray process,
 and as the insulating oil breaks down, water can come out of solution
 (i.e. become a drop, or droplet, in the oil). The water can accumulate in
 minute droplets on the cooler surfaces of the x-ray tube housing. This is
 similar to condensation of water vapor on a cooler surface. Thus, water is
 accumulating inside the housing. The source of water is the oil itself.
 Water, while a neutral molecule, supports arcing because of the molecular
 nature of it. It has a 105.degree. angle between the centers of the
 molecules. This makes it act as a dipole in a static direct current (dc)
 field.
 In a CT tube, x-ray generation is thousands of times longer than in
 conventional tubes. In general, the x-ray in a CT scanner stays on for
 many seconds as opposed to the average milliseconds used in conventional
 tubes. This results in the insulating oil being exposed to radiation and
 higher temperatures for a longer time, in any given application. More
 time, and higher temperature, to expose and radiate the oil results in
 more disassociations and more water molecules formed to become aligned. A
 150 kV dc field is applied during the radiating process. Note that
 breakdown of the oil at a high field point of occurrence readily strips
 hydrogen ions from long molecules. The recombination and hydroxyl ions
 produces free water.
 Water is a by-product of some of these disassociations. Water is also a
 source of some of these disassociation problems. It is a damaging circular
 relationship during the production of radiation. Thus, it is desirable to
 remove water from the oil. It should also be noted that, generally
 speaking, the dielectric properties of the insulating oil (as a whole) are
 reduced by adding water.
 As mentioned, water will act as a dipole in a direct current field. Thus,
 to preserve, or increase, the dielectric properties of the insulating oil,
 it would be desirable to remove water. Prior art, adds water to the system
 by adding new oil. This is bad. Thus, water which has seeped out of the
 old oil and is clinging to the housing in the insert mixes with the new
 oil though the water is not absorbed because the new oil is likely
 saturated with water. That is, the oil is already at its saturation level
 for water. There is then even more water as a source for more
 disassociation problems.
 The saturation level, or concentration, is a function of the oil
 temperature. As such, different amounts of gases will come out of solution
 at different temperatures. Also, different compounds form more readily at
 different temperatures. For example, acetylene, C.sub.2 H.sub.6, is
 believed to form more readily at cooler temperatures as compared to
 H.sub.2 at hotter temperature.
 Water, which is absorbable in oil to the level about 60 parts per million
 at room temperature, should be removed. Embodiments of the present
 invention remove oil down to 12-20 parts per million at room temperature.
 Other embodiments can reduce the water of down to 5 to 10 parts per
 million.
 At this point it is important to realize another aspect of the chemical
 breakdown in decomposition. Initially, all new housings are relatively
 similar, and new insulating oil is fairly standard. However, through the
 chemical breakdown which occurs during the x-radiation process, the
 particular parameters of the housing bond with the particular parameters
 of the oil in that housing. The more that particular insulating oil breaks
 down and bonds with that particular housing, the less the oil will break
 down and form new bonds. Essentially, the oil is subjected to a form of
 radiation hardening and is particularly tuned to that particular housing.
 Thus, it is actually preferred to use older oil, preferably oil which has
 undergone a bonding process, or has bonded, with that particular housing.
 This further reduces oil disassociation because there are less sources for
 disassociation. That is, the "parametric cross section" has been reduced.
 Each CT tube has an inherent set of parameters. Specific dimensions of oil
 through which the primary radiation passes for any given tube are wide and
 varying. Specific stray radiation varies from tube to tube also. Specific
 voltage setting for any generator have small variabilities as well. Each
 of these parameters, during the aging, or oil deteriorating process, is
 more sensitive to specific bonding energies over narrow domains. Many of
 the bonding energies are insensitive to the deterioration energies of
 radiation in thermal and corona sources. Thus as a class, bonds are
 reduced in number for a particular oil-housing pair or combination. Thus,
 the specific insulating oil in that specific housing has less
 opportunities to form new bonds.
 Accordingly, one embodiment of the present invention is for an x-ray tube
 oil processor 30 shown in FIG. 4. The x-ray tube oil processor 30 is for
 extending the life of an x-ray tube 10 by processing oil 16 for the x-ray
 tube 10, wherein the oil 16 is adapted to circulate around the insert 14
 in the housing 18 of the x-ray tube 10.
 The processor 30 comprises a processing chamber 32 having an oil inlet 34
 an oil outlet 36 a gas outlet 38. The processor 30 also includes a
 coalescing element 40 positioned in the processing chamber 32 wherein the
 coalescing element 40 has a first end 42 in fluid communication with the
 oil inlet 34. A vacuum source 44 is in fluid communication with the gas
 outlet 38. Preferably the gas outlet 38 is above the oil inlet 34 reduce
 the likelihood of drawing oil, or oil foam, through the gas outlet 38 and
 then through the vacuum source 44. This embodiment is shown in FIG. 4,
 FIGS. 5 and 6 show the gas outlet 38 below the coalescing element 40.
 An oil inlet hose 46 and an oil outlet hose 48 are respectively in fluid
 communication with the oil inlet 34 and the oil outlet 36 of the
 processing chamber 32. The oil 16 enters the oil inlet hose 46 and passes
 through the coalescing element 40 and exits the oil outlet hose 48 as
 processed oil 50. One preferred vacuum pump is produced by Robinair 15234
 using motor below.
 In the embodiment shown in FIG. 4 the processor 30 comprises a sump of oil
 52 in the processing chamber 32. In some embodiments, for some
 applications, it is preferred that the sump of oil 52 comprises radiation
 hardened oil. Radiation hardened oil being oil which has been exposed to
 x-rays. Preferably the oil has "bonded" with that housing by having been
 exposed to radiation over a period of time in that housing. However,
 exposing oil to radiation, of the same general category that the x-ray
 tube for which the insulating oil 16 is being processed produces
 radiation, is also useful.
 In a preferred embodiment the coalescing element 40 is located above the
 oil sump 52, as shown in FIG. 4.
 Refer now to FIG. 5 which shows a schematic layout of the oil processor 30
 connected to an x-ray tube 10. In the embodiment shown in FIG. 5, the
 processor 30 comprises an oil pump 54 in fluid communication with the oil
 outlet hose 48. Preferably the oil pump 54 is a gear pump. One acceptable
 gear pump is Tuthill DDS1.6
 A relief valve 56 is also shown fluidly connected to the oil outlet hose
 48. A relief hose fluidly connects the relief valve 56 to the oil inlet
 hose 46.
 A pressure gauge 60 is fluidly connected to the outlet hose 48. The
 pressure gauge can be used to determine the pressure in the housing. One
 acceptable pressure gauge is Ashcraft 1007PH.
 In some embodiments, as is shown in FIG. 5, the processor 30 comprises an
 outlet flow valve 62 in line with the oil outlet hose 48. An inlet flow
 valve 64 is shown in line with the oil inlet hose 46. The oil outlet hose
 48 shown in FIG. 5 is adapted to connect to the x-ray tube 10 housing 18,
 and the oil inlet hose 46 is adapted to connect to the x-ray tube 10
 housing 18. The x-ray tube housing 18 shown in FIG. 5 includes an oil in
 hose 66 and an oil out hose 68. The oil outlet hose 48 is connected to the
 oil in hose 66 and the oil inlet hose 46 is connected to the oil out hose
 68.
 As shown in FIG. 5, the processor 30 comprises a first quick-connect 70
 connecting the oil outlet hose 48 and the oil in hose 66, as well as a
 second quick-connect 72 connecting the oil inlet hose 46 and the oil out
 hose 68. FIG. 10 shows a representative quick-connect 70. The
 quick-connect (or quick-disconnect) 70 shown in FIG. 10 includes a double
 O-ring 100 around the perimeter and a bevel connection 102 at the
 interface of the conforming pieces 104 and 106. Conforming piece 106
 includes a triangular shaped lip 108 around its perimeter which abuts the
 edge of conforming piece 104 when the two pieces are mated.
 An acceptable hydraulic connector, which is a quick-coupling, is produced
 by Parker Fluid Connectors in the Quick-Coupling Division located in
 Minneapolis, Minn. Refer to FIG. 10
 Preferably the processor comprises a flow controller 74 proximate the
 coalescing element 40. The flow controller 74 has a discharge portion 76
 located away from the oil outlet 36. This is shown more clearly in FIG. 6.
 By locating the discharge portion 76 of the flow controller 74 away from
 the oil outlet 36 of the processing chamber 34 gas bubbles 78 are
 prevented from entering the oil outlet 36. If gas bubbles enter the oil
 outlet 36 and pass through the oil outlet hose 48 they will damage the
 gear pump 54 and prevent it from working. It is also desirable to prevent
 an air bubble from being transmitted into the housing 18 of the x-ray tube
 10. A bubble in an x-ray tube could be catastrophic to the tube, and
 damaging to the scanner. Since tube cost from $15,000 to $100,000, and the
 scanners cost from $300,000 to $1.2 M., the risk is very real.
 A vacuum gauge 80 is operably connected to the processing chamber 32. One
 preferred electronic vacuum gauge is that produced by JB Industries, Inc.
 of Aurora, Ill. 60507. When the oil processing is started pressure in the
 processing chamber 32 may typically be on the order of 700 microns. In
 some embodiments it is sufficient to evacuate the chamber down to 200
 microns. In some preferred embodiments it is desirable to evacuate the
 chamber down to 20 microns. Evacuation of the processing chamber 32
 removes gases from the processing chamber 32. Since the oil is processed,
 preferably, in a closed system the evacuation process is taking gases out
 of the oil. The reduced pressure in the chamber is an indication of this
 since the oil in the closed system is not reduced. In some preferred
 embodiments the processing chamber 32 is transparent. This allows the
 process to be visually monitored and to note the out-gassing from the oil.
 It is not required that the processing chamber 32 be transparent to
 monitor the process, however, because the process can be monitored by
 monitoring pressures in the processing chamber 32 as well as pressures in
 the housing 18.
 Preferably the processing chamber 32 comprises a length 82, shown in FIG.
 6, and the coalescing element 40 extends across the length 82 of the
 processing chamber 32.
 While a variety of coalescing filters will be apparent to those of skill in
 the art, the coalescing element 40 depicted in FIGS. 4 and 6 is a hollow
 cylindrical tube comprising very fine highly compressed shards and strips
 of fiberglass. The tube is then enclosed with a fine nylon wire mesh
 having openings on the order of 0.01 to 0.05 inch. The multitude of shards
 in the fiberglass act to create thin films which coalesce or collect the
 gases, preferably water, and out-gas the collected gas from the oil.
 Adjusting the pressure in the processing chamber, via evacuation, aids
 out-gassing.
 In one preferred embodiment the relief valve 56 comprises an inport 84, an
 outport 86, and a relief port 88. The relief hose 58 connects the relief
 port 88 to the oil inlet hose 46. Preferably the oil pump 54 is downstream
 of the outlet valve 62 and the relief valve 56 is downstream of the oil
 pump 54. The pressure gauge 60 is connected to the oil outlet hose 48
 downstream of the relief valve 56 in the configuration shown in FIG. 5.
 In many instances it will be desirable to maintain the x-ray tube 10 on the
 gantry 20 of the CT scanner 22. Thus the oil outlet 36 of the processing
 chamber 32 is attached to the housing 18 and the oil inlet 34 is attached
 to the housing 18 while the housing 18 is mounted in the gantry 20. This
 is shown in FIG. 7.
 Since it will be desirable to perform the oil processing while the x-ray
 tube is mounted on a gantry, it will be desirable to have the oil
 processor portable. Accordingly, one embodiment of the present invention
 is for an x-ray tube processing kit 90 for processing oil 16 in an x-ray
 tube 10 housing 18 wherein the housing 18 is mounted on a gantry.
 Referring to FIG. 8 the kit 90 comprises a processing chamber 32 containing
 a coalescing element 40; a plurality of fluid hoses 92 adapted to connect
 to the processing chamber 32; an oil pump 54 adapted to connect to one of
 the plurality of fluid hoses 92; and a vacuum pump 44 adapted to connect
 to the processing chamber 32. A one preferred source of fluid hoses is
 Ritchie In one embodiment the plurality of fluid hoses 92 comprises at
 least two hoses fluidly connected to valves (see FIG. 5) including the one
 hose being adapted to connect to the oil pump 54.
 Preferably the kit 90 includes a plurality of quick-connectors (not shown
 in FIG. 8). Also it will be desirable if the kit 90 includes a
 quick-connector kit for positioning a quick-connector in-line between the
 housing 18 and a heat exchanger 12, wherein the heat exchanger 12 is
 mounted on the gantry 20, and wherein the oil 16 is adapted to circulate
 through the heat exchanger 12 and the housing 18.
 Preferably the kit 90 comprises a carrying case 94 for transporting the
 processing chamber 32. Generally it will be desirable if the carrying case
 94 comprises foam padding 96 for securing the kit components in place.
 Preferably the carrying case 94, the oil pump 54, the vacuum pump 44, and
 the processing chamber 32 are sized such that the processing chamber 32,
 the vacuum pump 44, and the oil pump simultaneously fit in the carrying
 case 94. It is desirable to have the kit weight less than 40 kilos. This
 facilitates international transportation of the kit.
 More generally the present invention includes a method of extending the
 life of an x-ray tube 10 having a housing 18 and an insert 14 located
 therein for producing x-rays. The method comprises the steps of providing
 the x-ray tube 10 with an insulating oil 16 in the housing 18; and
 processing the insulating oil 16 to remove deleterious gases 98 from the
 oil. See FIG. 6.
 Preferably the step of processing the oil 16 to remove deleterious gases 98
 from the oil 16 comprises removing water from the oil wherein the water is
 removed as a gas.
 The method may also include the step of drying the housing by removing
 water. This is accomplished when processed oil 50 circulates through the
 housing 18. Since the processed oil 50 is dryer than the housing 18 the
 processed oil will absorb water in the housing 18 which will then be
 removed from the oil by the coalescing element 40 (in some preferred
 embodiments).
 Typically the deleterious gas 98 includes water vapor and the step of
 processing includes transporting the oil through a coalescing element 40,
 out-gassing the deleterious gases 98 from the oil 16 (or 50) and removing
 water from the oil 16 (or 50). Recall, the 50 indicates oil which has
 passed through the coalescing element 40 and has been "processed."
 However, the oil 16 and the processed oil 50 readily mix. So it is
 desirable to continually circulate and process the oil until a desired
 dryness is reached. The desired dryness can be "measured" by reference to
 pressures in the processing chamber 32. Thus, the terms oil 16 and oil 50
 are used interchangeably except where reference to processed oil 50
 facilitates understanding of the invention. One exemplary apparatus for
 accomplishing this is shown in FIGS. 5 and 6.
 One embodiment of the method comprises locating the coalescing element 40
 in a processing chamber 32; fluidly connecting the housing 18 to an inlet
 34 of the processing chamber 32. The method also includes the step of
 evacuating the processing chamber 32 as oil 16 in the housing 18 is
 transported through the processing chamber 32 inlet 34 and through the
 coalescing element 40, wherein the oil 16 exiting the coalescing element
 is processed oil 50. See FIG. 6.
 Referring to FIG. 5 as an exemplary embodiment, the method also comprises
 the step of fluidly connecting an outlet 36 of processing chamber 32 to
 the housing 18 and transporting the processed oil 50 to the housing 18.
 Referring to FIG. 6, some embodiments of the method comprise the steps of
 placing a sump of oil 52 in the processing chamber 32; and allowing the
 processed oil 50 to mix with the oil in the sump. Thus the step of
 transporting the processed oil to the housing includes transporting sump
 oil to the housing. Preferably the method comprises utilizing radiation
 hardened oil in the sump of oil.
 Thus it will be apparent to those of skill in the art that the method in
 some embodiments will comprise the steps of circulating oil 16 from the
 housing 18 through the coalescing element 40 through the sump of oil 52
 and back to the housing 18. Also included in the method are steps of
 removing gases from the oil 16 as it passes through the coalescing element
 40; and continuing to circulate the oil 16 until a desirable level of gas
 has been removed from the oil.
 In some preferred embodiments the method comprises the steps of aligning a
 first end 42 of the coalescing element 40 over the processing chamber
 inlet 34; supporting the coalescing element 40 above the sump of oil 52.
 The step of transporting the oils 50 to the housing 18 includes pumping
 the oil 50 to the housing 18. The step of evacuating the processing
 chamber 32 includes evacuating the deleterious gases 98 out-gased from the
 oil 16. This is shown in FIG. 6.
 It is desirable to prevent a bubble 78 from being sucked through the
 processing chamber outlet 36 for the reasons previously discussed. This is
 most easily accomplished by locating the processing chamber outlet 36 away
 from where the oil exiting the coalescing element 40 enters the sump of
 oil 52. In FIG. 6 this is accomplished by use of a flow controller 74.
 In some embodiments it is preferred that the step of circulating the oil
 through the housing is at a positive pressure. This prevents bubbles from
 coming out of solution while they are in the housing. The step of
 circulating the oil 16 in a positive pressure occurs prior to evacuating
 the deleterious gases 98 from the processing chamber 32, in some preferred
 embodiments. This helps prevent a bubble from forming in the housing 18.
 Some embodiments of the method comprise the step of adjusting pressure in
 the housing by regulating oil flow into and out of the housing. In some
 instances, it is desirable to build up to a positive pressure of about 15
 psi in the housing, then begin processing, then operate at a neutral or
 slightly positive pressure, or thereabouts, in the housing.
 Preferably, the method of processing the oil comprises maintaining the xray
 tube 10 on the gantry 20 of the x-ray machine 22.
 It will be apparent to those of skill in the art that the method also
 comprises the steps of locating the coalescing element 40 in a processing
 chamber 32 having an inlet 34 an outlet 36 and an evacuation port 38. The
 evacuation port 38 is also referred to as a gas outlet. The method also
 comprises fluidly connecting the housing 18 to the processing chamber
 inlet 34; fluidly connecting the housing 18 to the processing chamber
 outlet 36; and connecting a vacuum source 44 to the processing chamber
 evacuation port 38. The method also includes evacuating gases 98 from the
 processing chamber 32 and circulating oil 16 and 50 through the processing
 chamber. Preferably the steps of fluidly connecting the housing 18 to the
 inlet 34 and the outlet 36 of the processing chamber 32 comprises the step
 of inserting quick-connects 70 and 72 in oil flow lines between the
 housing 18 and a heat exchanger 12 on a gantry 20. See FIG. 7.
 In some embodiments the method of processing the oil 16 comprises the steps
 of locating the coalescing element 40 above a sump of oil 52 in the
 processing chamber 32. The method also comprises positioning the
 coalescing element 40 relative to the processing chamber 32 inlet 34 such
 that oil 16 entering the processing chamber 32 through the processing
 chamber inlet 34 must pass through the coalescing element 40.
 Preferably the step of circulating the oil at a positive pressure through
 the housing comprises the step of pumping the oil into the housing to
 increase pressure in the housing prior to allowing oil to flow out of the
 housing. Thus, oil from the sump of oil is forced into the housing to
 increase pressure in the housing and aid forcing any bubbles in the
 housing back into solution. The oil is then allowed to flow through the
 lines and through the coalescing filter. When the oil flows through the
 coalescing element, water and other gases are out-gased from the oil. This
 processed oil is then transported back to the housing.
 Some preferred embodiments of the present invention comprise placing a
 relief valve 56 in line between the oil pump 54 in the housing 18;
 connecting a relief port 88 on the relief valve 56 to the processing
 chamber inlet.
 Preferably the method also includes adjusting an inlet valve 64, also
 referred to as an inlet flow valve, 64 and an outlet flow valve, also
 referred to as an outlet flow valve, 62 to regulate pressure in the
 housing 18. The inlet valve 64 is in-line between the housing 18 and the
 processing chamber inlet 34, and the outlet valve 62 is in line between
 the housing 18 and the processing chamber outlet 36. The processing
 chamber inlet is also referred to as the oil inlet and the processing
 chamber outlet is also referred to as the oil outlet.
 Due to the damage which may be caused by excessive or minimal pressure in
 the housing, one embodiment in the method comprises monitoring pressure in
 the housing. Another embodiment comprises the step of monitoring pressure
 in the processing chamber. Typically, the step of monitoring pressure in
 the housing is accomplished via an oil pressure gauge. The step of
 monitoring pressure in the processing chamber is accomplished via a vacuum
 gauge.
 Since different out-gases come out of solution at different temperatures
 one embodiment comprises the step of out-gassing gases formed at higher
 temperatures by heating the oil. Another comprises the step of out-gassing
 gases formed at colder temperatures by cooling the oil.
 Another method of extending the life of an x-ray tube having a housing and
 an insert located therein for producing x-rays comprises the step of
 providing an insulating oil in the housing; and drying insulating oil.
 In some embodiments the step of drying the insulating oil comprises
 removing water from the insulating oil. Oil is highly deliquescent,
 similar to pure grain alcohol. The oil seeks water which is has condensed
 onto the outer cooler housing wall in the form of microscopic droplets.
 Thus, changing oil can aid the removal of saturated water, but it cannot
 remove absorbed water, except for what has gone into solution. Therefore,
 drying the oil, similar to wringing out a towel, allows the, now dryer,
 oil to absorb more water, which is in turn "wrung out" of the oil. The
 process is repeated until a sufficient level of dryness is achieved, i.e.
 water is removed. As has previously been discussed, this may be
 accomplished through use of a coalescing element, though other devices and
 methods will be apparent to those of skill in the art.
 In some embodiments the step of removing water comprises reducing the water
 saturated in the oil. In one embodiment this includes reducing a parts of
 water per million parts of oil level to at least twenty parts of water per
 million parts of oil. The standard for most x-ray tube oil is on the order
 of thirty parts per million, wherein this is considered "dry." Thus, one
 embodiment of the invention is to improve performance by providing
 improved oil.
 As will be clear from the teachings herein, the method may also comprise
 the step of drying an interior (not shown) of the housing 18. This may be
 accomplished by circulating the insulating oil 16 through the housing 18,
 wherein the insulating oil 16 is drier than the housing 18; and allowing
 the drier insulating oil to absorb water in the housing. The method also
 includes the step of removing the absorbed water from the insulating oil.
 In many instances it is preferred that the step of drying the insulating
 oil occurs while maintaining the x-ray tube on a gantry of an x-ray
 machine.
 Another embodiment comprises the removal of aromatic hydrocarbons. This is
 beneficial because the insulating qualities of hydrocarbons is generally
 not suitable.
 Another embodiment comprises the steps of hardening oil and introducing the
 hardened oil into an environment or chamber. In one version, the
 environment is a cooling chamber of a nuclear power plant. The hardening
 is carried out using a radiation source in treatment chamber, wherein the
 treatment chamber is separate from the cooling chamber.
 Another embodiment comprises the steps of out-gassing gases and capturing
 the gases. In one embodiment, the gases are captured in a balloon-trap to
 more readily illustrate the quantity of gases taken out of solution.
 One embodiment of the processing kit comprises a processing chamber
 containing a coalescent filter; and a plurality of fluid hoses adapted to
 connect to the processing chamber. The kit preferably includes an oil pump
 wherein both the processing chamber and the oil pump are adapted to allow
 oil to be maintained in both elements during shipping while preventing oil
 from spilling out. Upon set up, the oil will be gravity feed into the
 respective components.
 Thus, although there have been described particular embodiments of the
 present invention of a new and useful X-Ray Tube Processor, it is not
 intended that such references be construed as limitations upon the scope
 of this invention except as set forth in the following claims.