US3683177A - Sterilization of a fluid by ultraviolet radiation - Google Patents

Abstract

A device for sterilizing water or another fluid, including a flexible bag through which the fluid is pumped and formed of a material transparent to ultraviolet radiation, with the bag extending first along one side of an ultraviolet lamp or lamps and then being doubled back along their opposite sides; and with the bag being pressed against the lamps by the pressure of the fluid being treated in a manner causing an inner wall of the bag to conform approximately to the shape of the lamp or lamps and thereby enhance or optimize the delivery of radiation to the fluid.

Description

United States Patent Veloz Aug. 8, 1972 [72] Inventor: Louis P. Veloz, 500 South Madison,

Pasadena, Calif. 15701 22 Filed: June30,1970

21 Appl.No.:51,065

[52] US. Cl. ..250/43, 21/102, 119/5, 250/48 [51] Int. Cl .JIOI] 37/00 [58] Field of Search ....250/43, 44, 45, 86, 51; 119/5; 21/102 [56] References Cited UNITED STATES PATENTS 3,535,513 10/1970 Cirami ..250/43 3,551,091 12/1970 Veloz ..250/43 3,447,892 6/1969 Watson ..250/51 Primary Examiner-James W. Lawrence Assistant Examiner-C. E. Church Attorney-William P. Green [57] ABSTRACT A device for sterilizing water or another fluid, including a flexible bag through which the fluid is pumped and formed of a material transparent to ultraviolet radiation, with the bag extending first along one side of an ultraviolet lamp or lamps and then being doubled back along their opposite sides; and with the bag being pressed against the lamps by the pressure of the fluid being treated in a manner causing an inner wall of the bag to conform approximately to the shape of the lamp or lamps and thereby enhance or optimize the delivery of radiation to the fluid.

20 Claims, 7 Drawing Figures so, 2I8 24 2'2 0'2 33 PATENTEDms' 8 1972 3,683,177

sum 1 BF 2 INVENTOR. L s P. YELOZ PATENTEDAUG 8 I972sum 2 or 2 LOU/S P. V54

Q firm/2 EV STERILIZATION OF A FLUID BY ULTRAVIOLET RADIATION BACKGROUND OF THE INVENTION This invention relates to improved devices for sterilizing water or another fluid by subjection to ultraviolet radiation. Though the invention in its broadest aspects is applicable to the sterilization of fluids for any of various different purposes, certain particular features of the invention are especially useful for sterilizing the water of an aquarium. To simplify and clarify the disclosure, the invention will be discussed primarily as applied to that use.

In an aquarium, the bacteria count in the water builds up very rapidly to an unacceptable level unless some means are provided for destroying or removing the bacteria. Among other means heretofore proposed for this purpose, it has been suggested that ultraviolet radiation be employed. However, though ultraviolet radiation is basically a very efiective and convenient way to sterilize water, the devices thus far suggested for utilizing such radiation to treat aquarium water have had certain distinct disadvantages rendering them essentially unacceptable for actual practical use. For example, in some of these prior devices the ultraviolet lamps have been directly immersed within a stream of water, in a manner introducing the danger of electrocution of the fish, and of persons touching the equipment. This hazard has been a very real one which prevents such equipment from passing the safety codes of many cities and other jurisdictions. Further, in those previously proposed types of aquarium sterilizing units which have been so devised as to overcome this electrocution hazard, the structures utilized in attempting to achieve this result have reduced the sterilizing effectiveness of the ultraviolet equipment so drastically that it becomes essentially worthless for the purpose; One such arrangement employs a flat quartz window between the lamp, and the water, but inherently by its structure permits use of radiation emitting from the bulb through only a very small angle, and therefore is very inefficient insofar as its use of the total emitted radiation is concerned.

SUMMARY OF THE INVENTION The present invention provides a unit which, in an extremely simple overall structure, is capable of completely eliminating all danger of electrocution, and at the same time attains maximum efliciency and effectiveness by directing through the fluid being treated substantially all of the radiation emitting in all directions from an ultraviolet lamp or lamps. Thus, lamps of very low wattage may be employed, and by continuous recirculation of the water within the aquarium can maintain that water continuously at a very low bacteria count level.

To achieve these results, I preferably employ a container or conduit through which the fluid being treated is passed, and having a wall which is exposed to radiation from an ultraviolet lamp, and is adapted to pass that radiation through the wall and into the fluid stream. In order to optimize the transmission of the will pass through the conforming flexible radiationtransparent wall and into the fluid. For maximum simplicity, the container or conduit may be formed as a flexible bag or series of bags, whose side walls are forced against the lamp or lamps by the pressure of the fluid being treated.

In a presently preferred arrangement, an elongated bag of this type extends first along one side of an ultraviolet lamp or lamps, and then curves back along the opposite side of the lamps, and upon application of pressure to the contained liquid is forced against the opposite sides of the lamps to substantially completely encircle them in an optimum fluid irradiating relationship. The bag may be contained within a confining housing, which supports the bag externally in its proper position, and which is formed of a. material opaque to the harmful radiation in ultraviolet light, to prevent escape of any of that radiation from the device.

This housing or a wall thereof may be transparent, however, to visible light, so that a pleasing blue light in the visible spectrum may pass from the device into the water of the aquarium to illuminate it in an attractive manner. The preferred material for forming the flexible bag or flexible wall is tetrafluoroethylene polymer (Teflon), which will pass substantially one hundred percent of the sterilizing radiation, but to which none of the bacteria or other impurities in the water will adhere, to thus maintain the bag clean and freely transparent to the radiation for a very extended period of time.

BRIEF DESCRIPTION OF THE DRAWING The above and other features and objects of the invention will be better understood from the following detailed description of the typical embodiment illustrated in the accompanying drawing in which:

FIG. 1 is a perspective view of a home aquarium having a water sterilizing unit constructed in accordance with the invention;

FIG. 2 is an enlarged vertical section taken on line 2-2 of FIG. 1;

FIG. 3 is a transverse vertical section taken on line 3-3 of FIG. 2;

FIG. 4 is a horizontal section taken on line 4-4 of FIG. 2;

FIGS. 5 and 6 are views taken in the vertical planes 5-5 and 6-45 respectively of FIG. 2; and

FIG. 7 is an exploded perspective view showing in separated condition the various difierent portions of the sterilizing unit.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring first to FIG. 1, I have shown at 10 a conventional rectangular home aquarium, having four vertical glass orplastic side walls 11 and a bottom wall, and containing a body ofwater 12 within which fish and/or other sea life are contained. The usualwater circulating pump 13 is mounted on a back wall of the aquarium, as by hangers orhooks 14 extending over the top edge of the back wall. This pump takes suction from the water in the aquarium through a hose l5, and is energized by electrical power from asupply line 16 to pump water slowly through anoutlet hose 17 to a sterilizingunit 18 embodying the present invention.

Thisunit 18 ultimately discharges the water through ahose 19 which extends over theupper edge 20 of therear wall 11. and then downwardly into the aquarium.Pump 13 may contain a built-in filter unit which removes particulate matter from the water before delivery to sterilizingunit 18.

Sterilizer 18 has ahousing 21 including anupper housing section 22 and alower housing section 23.Upper section 22 carries two downwardly projectingultraviolet lamps 24 which sterilize water pumped through a flexible bag orconduit 25 located in and supported by thebottom housing section 23.

Theupper section 22 of the housing may form a rectangular enclosure orchamber 122, defined by two parallel horizontal top andbottom walls 26 and 27, two parallel vertical inner andouter walls 28 and 29, and two parallel verticalopposite end walls 30 and 31 disposed perpendicular towalls 28 and 29.Top wall 26 may be rectangular, and projects inwardly beyond the plane of verticalinner wall 28, to form ahorizontal projection 32 which extends over the upper edge ofrear wall 11 of the aquarium, and which carries a downwardly projectinglip 33 for engaging the inner surface of therear wall 11 of the aquarium in a manner effectively supporting theentire sterilizer 18 in the position illustrated in H6. 1. Theouter wall 29 ofupper section 22 of the housing is rectangular and projects downwardly beneath the level ofbottom wall 27 of the upper housing section, and to a lowerhorizontal edge 34 ofwall 29 lying in essentially the same horizontal plane as theundersurface 35 ofbottom section 23 of the housing. This downwardly projectingportion 36 ofouter wall 29 is opaque to both visible and ultraviolet radiation, to shield the back side oflower housing section 23 against emission of radiation in that direction. Similarly, all of theother walls 26, 27, 28, the rest ofwall 29,walls 30 and 31 are desirably all opaque to both visible and ultraviolet radiation, to enclose and shield from view withincompartment 122 theelectrical ballast 36 and the upper portions of thesockets 37 and 38 into whichultraviolet lamps 24 are threadedly connectible.

Theballast 36 and sockets are for best results secured to outervertical side wall 29 of theupper section 22 ofhousing 21. For this purpose,ballast 36 may have two alignedplanar mounting flanges 39 received against the inner side ofwall 29, and secured rigidly thereto byfasteners 40, typically screws or rivets. At its underside,ballast 36 may carry a horizontalsocket mounting plate 41, secured in any convenient manner to the ballast, withsockets 37 and 38 then being rigidly secured to the underside ofrigid plate 41 as byscrews 44. Anelectrical power line 45 is connectible to house current (preferably 110 volt, 60 cycle alternating current), and extends into the interior of the upper section of the housing through arubber grommet 46 connected into an opening in wall 3i, with the power line being connected withincompartment 122 to the ballast and sockets in the conventional series relationship.

Thesockets 37 and 38 have downwardly projecting tubular externally substantiallycylindrical portions 47 which are centered about parallelvertical axes 48, and project downwardly throughcircular openings 49 inbottom wall 27 of the upper section of the housing. These sockets contain internal threads centered about theaxes 48 and into which the upper threaded ends of thebulbs 24 are connectible.

In order to allow access to the interior of the upper hollow section ofhousing 21, for repair or replacement of the electrical parts, it is desirable that that upper housing section be formed in two parts appropriately secured together and adapted to be separated when desired. For this purpose, the previously discussedupper wall 26 andouter wall 29, as well as the downwardly projectinglip 33 onwall 26, may all be formed together as a first part of the upper housing section, while theremaining walls 27, 28, 30, and 31 may be formed as a second housing part, with this second part being securable to the first part byscrews 50 extending through apertures inwalls 30 and 31 and connecting into lugs orshoulders 51 projecting downwardly fromtop wall 26. If these twoscrews 50 are detached andbulbs 24 are removed from their sockets, the second part of the upper section of the housing may be removed downwardly from the upper part consisting ofwalls 26 and 29, to allow access to the sockets and ballast. Thewires connecting line 45 to the sockets and ballast may be sufficiently long or loose to enable such movement ofgrommet 46 and the wall by which it is carried relative to the sockets and ballast.

Thelower section 23 ofhousing 21 is of the essentially rectangular configuration illustrated in FIG. 7, having a horizontalrectangular bottom wall 53, two parallel vertical rectangular inner andouter walls 54 and 55, and two parallel verticalopposite end walls 56 and 57. Outer wall is received adjacent and parallel to the downwardly projectingshield portion 36 ofouter wall 29 ofupper section 22.inner wall 54 oflower section 23 is aligned vertically with theinner wall 28 of the upper section of the housing. Theupper edges 62 and 63 of inner andouter walls 54 and 55 of the lower section extend parallel to one another and horizontally, and are engageable upwardly against the underside ofbottom wall 27 of the top section, when the two sections are secured together in the normal FIG. 1 relationship. To attach the two sections together in the above manner, theopposite end walls 30 and 31 of the upper section may have downwardly projectingresilient tabs 58 containingrectangular openings 59 within whichdetent lugs 60 on coacting resilient upwardly projectingtabs 61 carried by theend walls 56 and 57 of the lower housing section are receivable in snap detenting relation.

The bag orconduit 25 through which water to be sterilized is pumped, may be considered as taking the form essentially of an elongated tube formed of freely flexible film or sheet form material which is transparent to ultraviolet radiation, or at least to the wave lengths of such radiation which are capable of destroying bacteria (2000 to 2600 angstroms wave length). Thistubular bag 25 extends from afirst end 64 thereof longitudinally at 65 within the interior oflower housing section 23 and along the first side of the twolamps 24, and then forms a reverse bend at 66 adjacent the second end of the housing to curve back at 67 along the opposite side of the lamps to thesecond end 68 of the tube. At its two ends 64 and 68, thetube 25 may be cemerited continuously and peripherally to the outer surfaces of twoplastic connector elements 69 and 70, each of which extends a short distance into the corresponding end of the tube to allow such cementing to the tube in a permanently sealed relation. The twofittings 69 and 70 are received adjacent one of theend walls 56 oflower section 23 of the housing, and carry two short integrally formed horizontally projectingtubes 71 and 72 which extend out of the housing throughnotches 73 and 74 formed at opposite sides of one of the upwardly projectingdetent tabs 61. The inlet andoutlet hoses 17 and 19 of the sterilizer are then connected to thesetubes 71 and 72 at the outside of the housing.

As seen in FIGS. 5 and 6, theconnector elements 69 and 70 at opposite ends oftube 25 are elongated vertically, and therefore tend to give the tube 25 a correspondingly vertically extending cross-sectional shape, so that the tube may easily be received within the spaces betweenlamps 24 and the vertical side and end walls of the lower section of the housing.Tube 25 thus has a generally verticalinner wall 75 received adjacent the lamps, and a generally verticalouter wall 76 received adjacent the side walls and one end wall of the housing. The vertical height of tube and itsend pieces 69 and 70 is desirably approximately the same as the vertical height of the compartment formed within thelower section 23 of the housing.

As indicated previously, the film or sheet material from whichtube 25 is formed is a substance capable of passing at least the sterilizing portion of the ultraviolet radiation; .and preferably is also a material to which bacteria and other impurities in the water will not tend to adhere. For best results, this material forming tube orbag 25 is a thin film of a fluorocarbon polymer, preferably polytetrafluoroethylene, as sold by E. I. Du- Pont de Nemours under the trade name Teflon (FEP type). The film desirably has a thickness between about 2 and 3 mils, and for best results about 2 mils.

To now describe the manner of use of the discussed sterilizing device, assume that theunit 18 has been mounted on the side wall of an aquarium as illustrated at 10 in FIG. 1, and that it has been connected to the aquarium and apump 13 in the manner of FIG. 1. If both the pump and sterilizer are now energized electrically, the pump will commence to draw water from the aquarium throughline 15, and discharge it throughline 17 into one end of thetubular bag 25. This water flows longitudinally within the bag, first along one side of the twolamps 24, and then back along the opposite side of the lamps to ultimately discharge throughline 19 into the aquarium.

The pressure produced bypump 13 is great enough to force the inner initially generallyvertical wall 75 of tube orbag 25 inwardly against thelamps 24, as seen in FIGS. 2, 3 and 4 and with a force sufficient to cause theflexible wall 75 to conform closely to, and preferably substantially exactly to, the outer essentially spherical shape of each of thelamps 24. Thus, at each side of each lamp, the bag forms a substantially hemispherical recess containing and closely receiving a side of the inwardly at their upper sides far enough to contact the lamp sockets entirely about their peripheries, so that no portion of the lamp surfaces is left free of contact with a corresponding portion of the flexible bag wall. By virtue of this highly eflicient relationship between the flexible bag and the lamps, the radiation is utilized so eflectively that lamps of very small wattage (e. g., 4 watts each) can under continuous circulation conditions maintain an entire aquarium at an extremely low bacteria count level.

The confinement of the water being treated withinflexible bag 25 eliminates any danger of electrocution such as may occur when the lamps are immersed directly in the water. To further increase the safety of the apparatus,bottom wall 53 of thelower section 23 of the housing is provided withopenings 78 at its four comers to allow drainage from the housing of any water which may leak frombag 25. Thus, even if a leak were to develop in the bag, the water would immediately run out of thehousing section 23, and could not contact the electrical connections to the lamp sockets. To

assure such drainage of the water, the openings are made large enough to drain water by gravity fromsection 23 at a rate at least as great as, and preferably greater than, the rate at which pump 13 delivers water to the sterilizer. Further, it is preferred that the entire sterilizing unit, includingbag 25 and the housing compartment within which it is contained, be located above the level of the water in theaquarium tank 10, to additionally insure against any tendency for immersion of the lamps in water under any possible conditions.

It has previously been noted that theupper section 22 ofhousing 21 is formed of a material opaque to both ultraviolet and visible radiation. Thelower section 23 of the housing is, on the other hand, preferably formed of a material which, while opaque to ultraviolet radiation of the bacteria-destroying wave lengths, is nevertheless transparent to visible light. As a result, the small amount of violet and blue light in the visible range which is normally produced by an ultraviolet lamp can pass through the walls of thelower housing section 23 and into the aquarium, to give the water and contents of the aquarium a very attractive appearance. A suitable substance having this characteristic of not transmitting the undesired ultraviolet light while transmitting visible light may be an appropriate transparent acrylic material, such as methylmethacrylate. If desired, theinner wall 62 oflower housing section 23 may be formed of this type material to pass blue light into the interior of the aquarium, while the other walls of the lower housing section may be formed of a material opaque to both visible and ultraviolet light.

Thetubular bag 25 may be formed of an initially flat sheet of material folded to a tubular shape and seamed longitudinally. In order to facilitate attachment of the opposite ends of the tube tofittings 69 and 70, the

the end of the housing in a relation closing off the flow of liquid at that point. For this purpose, thebag 75 may be initially formed as a simple tube in which the overall horizontal lengths ofwalls 75 and 76 between their opposite ends are identical, but withouter wall 76 subsequently being stretched longitudinally (horizontally) at 66, to the desired increased length greater than that ofwall 75. In operation, when the pressure withintube 25 forces theinner wall 75 inwardly against the lamps, the same pressure forces theouter wall 76 outwardly against the vertical walls of thelower housing section 23, so that the tube then is externally essentially rectangular in shape, and internally of a shape corresponding to the configuration of the twolamps 24.

If it becomes desirable to clean or replace thebag 75, the pump may first be stopped and thenlower housing section 23 may be easily released for downward separation from the upper housing section, by pressing inwardly on and thereby releasingdetent tabs 61. Assection 23 is moved downwardly, it carries with it thebag 75, which may then be easily removed fromsection 23 through its open upper side for cleaning or replacement.

While a certain specific embodiment of the present invention has been disclosed as typical, the invention is of course not limited to this particular form, but rather is applicable broadly to all such variations as fall within the scope of the appended claims.

I claim:

1. A sterilizer comprising at least one lamp adapted to produce ultraviolet radiation, a container through which a fluid to be sterilized is passed and having a wall exposed to said radiation formed of a material through which the radiation will pass into the fluid to sterilize it, said wall being flexible and being positioned to be urged against said lamp by said fluid and to conform approximately in shape to a portion of the lamp in a relation enhancing transmission of radiation to the fluid.

2. A sterilizer as recited inclaim 1, in which said wall is formed of a flexible film of tetrafluoroethylene polymer.

3. A sterilizer as recited inclaim 1, in which said container is a flexible bag extending along a first side of the lamp and then doubled back to return along its opposite side and having said wall in engagement with and conforming in shape approximately to opposite sides of the lamp.

4. A sterilizer as recited inclaim 1, including a housing having a portion extending about and holding said container.

5. A sterilizer as recited inclaim 1, including a body structure carrying said lamp, and a housing holding said container and detachably connectible to said body structure in a position locating said flexible wall of the container adjacent the lamp.

6. A sterilizer as recited inclaim 1, in which said lamp projects downwardly, and said container is a generally U-shaped flexible bag having a first portion extending along one side of the lamp and then doubled back to form a second portion extending along the opposite side of the lamp, with the lamp projecting downwardly between said portions.

7. A sterilizer as recited inclaim 1, including a housing having an upper hollow first section and a lower hollow second section, means for securing said lower section of the housing detachably to said first section, a socket mounted to said upper housing section and carrying said lamp in downwardly projecting position, said container being a generally U-shaped flexible bag contained in said lower housing section and having two portions between which said lamp is receivable.

8. A sterilizer as recited in claim 7, in which said wall of the bag engages and conforms at least partially to both of two opposite sides of the lamp.

9. A sterilizer as recited inclaim 1, including a housing which said container is located and having a wall which is opaque to ultraviolet radiation but is adapted to pass visible light from said lamp to the exterior of the housing for illuminating an associated aquarium.

10. A sterilizer as recited inclaim 1, including a housing having a first section which carries said container and is opaque to ultraviolet radiation but transparent to visible light to pass visible light from said lamp to the exterior of said first section at a first side, said housing including a second section having a wall which is opaque to visible light and is received at a second side of the first section as a shield.

11. A sterilizer as recited inclaim 1, including a housing structure carrying said lamp and said container and having a mounting portion adapted to hook over the upper edge of an aquarium wall to hang the sterilizer thereon.

12. A sterilizer as recited inclaim 1, including a housing having a first section carrying said lamp and a second section carrying said container, and interfitting snap detents on said two sections for releasably securing them together in a sterilizing condition.

13. A sterilizer as recited inclaim 1, including a housing having an upper hollow first section with a mounting portion adapted to hook over and be supported by the wall of an aquarium, a socket carried by said first housing section and carrying said lamp in downwardly projecting position, said housing having a lower hollow second section, releasable detents on said two sections for securing said second section detachably to the underside of said first section, said container being a generally U-shaped bag of flexible tetrafluoroethylene polymer which extends along a first side of said lamp and then doubles back along the opposite side thereof and which conforms approximately in shape to opposite sides of the lamp, a ballast for said lamp in said first housing section, said second section being formed of a substance which'is opaque to ultraviolet but transparent to visible light, said lamp producing some visible light which passes to the exterior of said lower section at a first side thereof to enter an associated aquarium, said upper section being formed of a material opaque to visible light and forming a shield opaque to such visible light and projecting downwardly at a second side of the first section.

14. A sterilizer comprising a housing, a flexible bag contained in and supported by said housing and having a flexible wall adapted to pass ultraviolet radiation, inlet and outlet means for conducting a fluid to be sterilized through said bag, and at least one ultraviolet lamp positioned to pass ultraviolet radiation through said wall and into said fluid to sterilize it, said flexible wall of said bag being positioned to be urged against said lamp by said fluid.

l5. A sterilizer as recited inclaim 14, in which said bag is generally U-shaped and extends first along one side of said lamp and is then doubled back along the opposite side of said lamp.

16. A sterilizer as recited inclaim 14, in which said housing has a drain opening through which any leakage from the bag may escape to the exterior of the housing.

17. A sterilizer as recited inclaim 14, in which said housing has an upper section carrying said lamp and a lower section carrying said bag and secured detachably to the upper section.

18. A sterilizer as recited inclaim 14, in which said housing has an upper section carrying said lamp and a lower section carrying said bag and secured detachably to the upper section, said lower section having a wall opaque to ultraviolet but transparent to visible light, said upper section having a wall which is opaque to visible light projecting downwardly along an outer side of the lower section.

19. A sterilizer as recited inclaim 14, in which said bag first extends along one side of said lamp and is then doubled back in a return bend to extend along the opposite side of the lamp, said bag having inner and outer walls the latter of which is longer than the former to avoid closure of the fluid passage through the bag at said return bend.

20. The method of manufacture that comprises forming a tubular bag of flexible material adapted to pass ultraviolet radiation, positioning said bag to extend first along one side of an ultraviolet lamp and then be doubled back in a return bend to extend along the opposite side of the lamp, and at some time during said method stretching an outer wall of said bag to a greater length than an inner wall thereof to avoid closure of the bag at said return bend by contact of said inner wall with said outer wall.

Claims (20)

1. A sterilizer comprising at least one lamp adapted to produce ultraviolet radiation, a container through which a fluid to be sterilized is passed and having a wall exposed to said radiation formed of a material through which the radiation will pass into the fluid to sterilize it, said wall being flexible and being positioned to be urged against said lamp by said fluid and to conform approximately in shape to a portion of the lamp in a relation enhancing transmission of radiation to the fluid.

2. A sterilizer as recited in claim 1, in which said wall is formed of a flexible film of tetrafluoroethylene polymer.

3. A sterilizer as recited in claim 1, in which said container is a flexible bag extending along a first side of the lamp and then doubled back to return along its opposite side and having said wall in engagement with and conforming in shape approximately to opposite sides of the lamp.

4. A sterilizer as recited in claim 1, including a housing having a portion extending about and holding said container.

5. A sterilizer as recited in claim 1, including a body structure carrying said lamp, and a housing holding said container and detachably connectible to said body structure in a position locating said flexible wall of the container adjacent the lamp.

6. A sterilizer as recited in claim 1, in which said lamp projects downwardly, and said container is a generally U-shaped flExible bag having a first portion extending along one side of the lamp and then doubled back to form a second portion extending along the opposite side of the lamp, with the lamp projecting downwardly between said portions.

7. A sterilizer as recited in claim 1, including a housing having an upper hollow first section and a lower hollow second section, means for securing said lower section of the housing detachably to said first section, a socket mounted to said upper housing section and carrying said lamp in downwardly projecting position, said container being a generally U-shaped flexible bag contained in said lower housing section and having two portions between which said lamp is receivable.

8. A sterilizer as recited in claim 7, in which said wall of the bag engages and conforms at least partially to both of two opposite sides of the lamp.

9. A sterilizer as recited in claim 1, including a housing within which said container is located and having a wall which is opaque to ultraviolet radiation but is adapted to pass visible light from said lamp to the exterior of the housing for illuminating an associated aquarium.

10. A sterilizer as recited in claim 1, including a housing having a first section which carries said container and is opaque to ultraviolet radiation but transparent to visible light to pass visible light from said lamp to the exterior of said first section at a first side, said housing including a second section having a wall which is opaque to visible light and is received at a second side of the first section as a shield.

11. A sterilizer as recited in claim 1, including a housing structure carrying said lamp and said container and having a mounting portion adapted to hook over the upper edge of an aquarium wall to hang the sterilizer thereon.

12. A sterilizer as recited in claim 1, including a housing having a first section carrying said lamp and a second section carrying said container, and interfitting snap detents on said two sections for releasably securing them together in a sterilizing condition.

13. A sterilizer as recited in claim 1, including a housing having an upper hollow first section with a mounting portion adapted to hook over and be supported by the wall of an aquarium, a socket carried by said first housing section and carrying said lamp in downwardly projecting position, said housing having a lower hollow second section, releasable detents on said two sections for securing said second section detachably to the underside of said first section, said container being a generally U-shaped bag of flexible tetrafluoroethylene polymer which extends along a first side of said lamp and then doubles back along the opposite side thereof and which conforms approximately in shape to opposite sides of the lamp, a ballast for said lamp in said first housing section, said second section being formed of a substance which is opaque to ultraviolet but transparent to visible light, said lamp producing some visible light which passes to the exterior of said lower section at a first side thereof to enter an associated aquarium, said upper section being formed of a material opaque to visible light and forming a shield opaque to such visible light and projecting downwardly at a second side of the first section.

14. A sterilizer comprising a housing, a flexible bag contained in and supported by said housing and having a flexible wall adapted to pass ultraviolet radiation, inlet and outlet means for conducting a fluid to be sterilized through said bag, and at least one ultraviolet lamp positioned to pass ultraviolet radiation through said wall and into said fluid to sterilize it, said flexible wall of said bag being positioned to be urged against said lamp by said fluid.

15. A sterilizer as recited in claim 14, in which said bag is generally U-shaped and extends first along one side of said lamp and is then doubled back along the opposite side of said lamp.

16. A sterilizer as recited in claim 14, in which said housing has a drain opeNing through which any leakage from the bag may escape to the exterior of the housing.

17. A sterilizer as recited in claim 14, in which said housing has an upper section carrying said lamp and a lower section carrying said bag and secured detachably to the upper section.

18. A sterilizer as recited in claim 14, in which said housing has an upper section carrying said lamp and a lower section carrying said bag and secured detachably to the upper section, said lower section having a wall opaque to ultraviolet but transparent to visible light, said upper section having a wall which is opaque to visible light projecting downwardly along an outer side of the lower section.

19. A sterilizer as recited in claim 14, in which said bag first extends along one side of said lamp and is then doubled back in a return bend to extend along the opposite side of the lamp, said bag having inner and outer walls the latter of which is longer than the former to avoid closure of the fluid passage through the bag at said return bend.

20. The method of manufacture that comprises forming a tubular bag of flexible material adapted to pass ultraviolet radiation, positioning said bag to extend first along one side of an ultraviolet lamp and then be doubled back in a return bend to extend along the opposite side of the lamp, and at some time during said method stretching an outer wall of said bag to a greater length than an inner wall thereof to avoid closure of the bag at said return bend by contact of said inner wall with said outer wall.

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