Note: Descriptions are shown in the official language in which they were submitted.
- ~629L37
This invention relates to liquid sterilizers and
more particularly to water sterilizers employing ultra-violet
radiation to kill bacteria.
It is well known to sterilize water by exposing the `
water to ultra-violet radiation at a wavelength of approximately
2537 Angstroms. In a typical sterilizer, water is exposed to
ultra-violet radiation as it is introduced through an inlet
into a cylinder housing an ultra-violet tube, the water then ~ `
flowing through the length of the cylinder where it exits
through an outlet. The water is sterilized as it is exposed
to the ultra-violet radiation generated by the tube.
It is also known to sterilize water by exposing the
water to ozone at a waveIength of approximately 1880 Angstroms. `
The ozone can be generated by means of a tube of similar
construction to that of an ultra-violet radiation generator,
or by means of an electrical arc generated in the water. ~`
The known ozone generator leaves a residue of ozone in the
water, which continues to sterilize the water at it passes
through the cylinder.
It is also possible to sterilize water utilizing
gamma ray radiation. Thus, the principles of this invention ~~ "
apply to all of these known kinds of sterilizers. However,
the invention will be specifically described with reference to
embodiments employing ultra-violet radiation.
Although sterilization of water by use of
ultra-violet radiation has an excellent reputation for
killing bacteria, such sterilizers have tended to be expensive,
and also require specialized skills for installation and '~
maintenance. However, there ls a need for a water sterilizer
that a home or cottage owner can afford and can install and ;`
maintain without having specialized skills. ~
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One of the problems associated with known
sterilizers, which contributes to their complexity is that
they are designed as permanent installations, except for the
replacement of worn out or defective bulbs. As a consequency,
these sterilizers have complex mounting arrangements for the
tube, the end seal connections and the water inlet and outlet.
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Also? because the known sterilizers were designed as permanet ~ ;
installations, the water supply connections tended to be
complex, again requiring specialized skills for installation.
Since the tubes are also quite delicate, there is a serious
risk of tubes being broken on replacement, if done by anyone
other than a trained technician.
An example of a prior art sterilizer of complex
design is described in Canadian Patent 610,989, which issued
to Corn Products Company on December 20, 1960. This patented
sterilizer was clearly designed as a permanènt installation ~;~
except for replacement of the ultra-violet tubes. For axample,
the inlet and outlet ports are formed of conduits, nipples,
adapters, gaskets and screws. The ends of the ultra-violet
tubes are connected to electrical sockets that are mounted
on connector blocks slidably mounted on connector block plates
and locked in place. When a tube is to be replaced, these
connectors have to be removed from the connector blockplates.
It can be readlly appreciated that specialized sk:Llls are thus
required both for initial installation and maintenance.
Resealing of the sterilizer when replacing a lamp also poses
a problem.
, As is well known, ultra-violet tubes operate more
-I efficiently at higher temperatures. One known type of
water sterilizer, therefore, provides a protective quartz
sheath surrounding the tube, thereby leaving an air space
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~ between the sheath and the tube to provide insulation for
the tube from the water flowing around the sheath. However,
such sheaths suffer from the disadvantage of having to be
cleaned periodically to remove collected dust, which can
inhibit the penetration of light from the tube through the
sheath to the water, resulting in reduced efficiency and risk `~
of non-sterilization. Thus, the cleaning of the sheaths
has to be done by a skilled technician. Special handling
is also required, especially because the quartz is susceptible
to finger prints, and because the quality of quartz required
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produces a fragile sheath that can be broken very easily.
From the above discussion, it can be appreciated that prior
art water sterilizers employing sheaths are expensive and ;~ `
require specialized skills for their installation and
maintenance. Canadian Patent 610,989 employs such a quartz ; ;;
sheath, adding to the complexity, fragility and cost of
the sterilizer.
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Other known prior art sterilizers employ sensing
devices to sense the amount of llght radiated by the ultra-
violet tube, coupled with a electro-magnetic control device
to control valves at the water inlet. Thus, if the tube
is not emi~ting sufficient light to sterilize, the valve at
the inlet is closed and the unit fails safe. Although
serving a useful purpose, such fail safe devices add to
the expense of a sterilizer unit. A prior art sterllizer
1 employing such a fail safe device is described in Canadian .
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Patent 674,555, which issued to Allsafe Water Srerilizer Ltd. ;- :
, on November 19, 1963. The Allsafe sterilizer is anothèr
example of one employing a protective sheath and designed
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;1 30 as a permanent installation except for replacement of lamps,
again involving a complex mechanical end cap arrangement '~
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requiring 9pecialized skills for maintenance. ':. ,' f~ '
- Canadian Patent 767,856 granted September 26, 1967
and Canadian Patent 841,135, granted May 5, 1970, and invented
by James W. Harrison, are further examples of sterilizers i
that are designed to fail safe. The sterilizers described
in these patents are of the permanent installation type
requiring the removal of end caps for replacement of ultra-
violet tubes.
Applicant has discovered that, by providing a
disposable sterilizer unit (comprising a jacket)
and tube), most of the above-noted problems and expenses can
be significantly reduced. Firstly, applicantls disposable `
or throw-away unit can be manufactured very inexpensively.
Secondly, the throw-away unit is designed to permit a person
with no specialized skills to install it and dispose of it
when the tube is defective or has worn out.
In the preferred embodiment of applicant's invention,
the protective quartz sheath is also eliminated by allowing
the tube to be directly exposed to the water within the
cylinder. This normally would reduce the capacity of the
sterilizer to kill bacteria, due to lack of insulation and
the resultant colder termperatures at the tube surface. However,
applicant has offset this deficiency by the provision of a
tube having more output power, i~e. a tube twice as long as
that normally required for s~andard water flow rates. In
other words, instead of utilizing a sheath to compensate for
inefficiencies of tubes at lower temperatures, applicant
utilizes a more efficient tube, thereby permiting the sheath
to be eliminated and avoiding its inherent problems outlined
above. In applicant's preferred embodiment, the water inlet
and outlet are restricted in size to provide a maximum flow
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rate of only 4 gallons per minute. This flow rate provides
an 3:1 safety factor for water at 2C. It i3 to be
understood, however, that the principles of this invention
also apply to sterllizers incorporating sheaths.
Other features of appllcant's preferred embodiment
are the provision of simple end seal connections that reduce
expense and-facllltate lnstallation; a simple mountlng for the
unit in its casing; and simple hose connections to the water
inlet and outlet. There is no resealing proble~ on replacement
since the disposable unit is f~ctory sealed. Although
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applicant's sterilizer would still suffer from the disadvantage
of the light source and jacket walls becoming coated with ~ ~`
residue from water over time, thus reducing efficiency, the
design is so inexpensive that it is economically practical to
dispose of the complete unit.
As can be appreciated from the above discussion,
applicant has provided a water sterilizer that is within the `
budget of most home and cottage owners. The sterilizer can
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be installed without specialized skills, and the sterilizer ,
unit can be economically thrown away when worn out, and readily
replaced with a new one at low cost. ;
In the light of the above, it can be seen that the
invention consists of a disposable unit for sterilizing a
liquid comprising: an elongated plastic jacket having an
inner surface and opposing ends, an elongated tube for gen- , ;
erating radiation to sterilize liquid in said jacket, said
tube extending longitudinally along the interior of said jacket
i and having an outer surface, said inner and outer surfaces
,1 forming a flow chamber within said jacket around said tube,
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said tube being non-removably received by said jacket, said
~ jacket being substantially opaque to said radiation, means
i adjacent said opposing ends of sald Jacket for providing an
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inlet and an outlet for flow of liquid from said inlet into ''`
said chamb~r and into direct contact with said tube for .~' '
sterilization by the radiation therefrom and Einally out of
said outlet, said jacket ends including liquid tight seals
engaging respective ends of said tube to prevent outflow of
liquid from said flow chamber except via said outlet, said '~
tube ends each terminating in electrically conductive ter-
minal means extending exteriorly of said jacket ends for
applying electric power to the tube and for providing mechanical ;
support to said unit.
In the preferred embodi'ment of applicant's invention, 1
the generating means is an ultra-violet tube designed to'gener~te
ultra-violet radiation at a wavelength of approximately
2537 Angstroms. An acrylic rod is threaded lnto the side of '~
the jacket to be exposed to the light generated by the tube, '
and to thereby provide a viewport e'xternally of the ~acket for ~'
determining if the'tube is operating. In~another embodiment ~'
a circuit includingan LED is provided for determining if the -
tube is operating. `
Also in the preferred embodiment, the plastic jacket
comprises a central portion and two end portions fixed thereto,
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each end portion comprising an integral injection moulded .
part, including respective inlet and outlet connections. An
'~ 0-rlng is mounted in each end portion in annular grooves to
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'~ provlde a seal against water flow from the chamber to the
exterior of the jacXet. ;~
~nother embodiment provides a novel means for
stopping the flow of liquid to the sterilizer unit when the
tube fails to operate. ~'
~ 30 Embodiments of thls invention wlll now be descr~bed,
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by way of example, with reference to tl~e accompanying ,~
drawings in which:
- Figure 1 is a perspective view of a disposable
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water sterili~er unit;
Figure 2 is a plan view of the same unit;
Figure 3 is a horizontal sectional~view of the "
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~062~37
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unit taken along lines III-III of Figure 1, showing the
- ultra-violet tube and the end sealing arrangements;
Figure 4 is a sectional view taken along line ~.
IV-IV of Figure 3 showing details of a water inlet or outlet .
connection;
Figure 5 is a plan view of a water sterilizer casing
with the unit re~oved;
Figure 6 is a similar view of the casing with the
sterilizer unit installed;
Figure 7 is a view taken along line VII-VII of
Figure 6 showing details of the mounting receptacle in the
casing; .
Figure 8 is a view taken along line VIII-VIII of
Figure 6 showing more details;
Figure 9 is an end view of the casing with che
cover mounted thereon;
Figure 10 is a perspective view of a sterilizer
assembly incasing a sterilizer unit;
Figure 11 is a front view of the sterilizer assembly; ,`
Figure 12, which is located on the same sheet as
. . Figures 8 and 9, is a schematic diagram of a water filtering system;
Figure 13 shows a circuit arrangement for providing
a visual means to detect failure of the tube;
I Figure 14 i9 a plan view of a case (with cover removed)
,, showing the mounting and connections of the circuit components
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of Figure 13;
i, Figure 15 shows a circuit arrangement for providing .
:~ a stoppage of water flow upon failure of the tube; and
, 30 Figure 16 is a plan view of a case (with cover
1 removed) showing the mounting and connections of the circuit :
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components of Figure 15.
Description of Embodiments
Figures 1 to 4 show an embodiment of a disposable
water sterilizer unit 20, which essentially comprises an
elongated cylindrical plastic jacket 21, typically made of
ABS tubing, and an ultra-violet tube 22 designed to radiate
light at a wavelength of approximately 2537 Angstroms to `
sterilize water exposed to the ultra-violet radiation.
The jacket 21 is composed of a central portion 21' -~
and end portions 23 and 24. These end portions are injection
moulded parts and are fixed to the central portion 22 at 25 i ;
and 26 by means of a suitable adhesive. Of course, the jacket '
21 can be formed of a single moulded part.
As can be clearly seen from Figure 3, the jacket 21
is concentrically mounted about the tube 22 to provide a
chamber 27 between the internal surface of the jacket and
the external surface of the tube for the flow of water to
be sterilized. The tube 22 passes through and beyond the
end portions 23 and 24 of the jacket. The tube 22 is supported '
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by the end portions 23 and 24 by means of- a close fit between
the extreme ends of reduced diameter and the surface of the .
tube, and by means of neoprene 0-rings 28 and 29 located in
grooves 30 and 31 of the end portions 23 and 24. These rings
j also provide a seal against water flow Erom the chamber 27 to
¦ the exterior of the jacket 21.
Water inlet and outlet connections 32 and 33 are
also moulded as part of the end portions 23 and 24 respectively,
to provide connections to and from a water supply with access
to the chamber 27.
iO Prongs 34 and 35 at the ends of the tube 22 serve
~ as electrical connection means externally of the jacket
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to make electrical connection with electrical connections
in a casing. An acrylic rod 36 is threaded into the wall
of the jacket 21, and is exposed to the light generated ~rom
the tube 22 to provide a viewport for visually monitoring the
operation of the tube. Acrylic has been chosen as the
material for the rod, since it provides good stability in
the presence of ultra-viGlet radiation.
As can best be seen in Figure 4, ~he end portion 24
has moulded therewith a fin 37, which imparts turbulence
to the water flowing in and out of the jacket via the
connections 32 and 33. It can also be seen thatthe connections
32 and 33 are threaded at their ends with a 3/4 inch
National Hose thread for easy connection to an ordinary
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automatic washing machine fill hose.
Turning now to Figures 5 to 9, an elongated, ~ i
rectangular shaped casing 40 is shown for incasing the ,~
disposable sterilizer unit 20. The casing has mounted thereon r"
a standard electrical outlet 41, a standard ballast 42, a
standard starter 43 and mounting receptacles 44 and 45 for
the tube 22, together with their appropriate interconnected
electrical wiring. The casing also includes three hemispherical
notches 46, 47 and 48 in one side thereof.
As shown in Figure 6, a sterilizer unit 20 of the kind
shown in Figures 1 to 4 is placed in the casing 40 with the
inlet connection 32, viewport 36 and outlet connection 33
facing up, so that the prongs 34 and 35 are in vertical -~
alignment and fit into a slot 44' in the receptacles 44 and 45,
respectively. The unit 20 is then rotated 90 to assume the
~l position shown in Figures 6 and 7. The inlet connection 32, ``~-
l~ 30 viewport 36 and outlet connection 33 fit into the slots 46, ~
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ii 47 and 48, and the prongs are in horizontal alignment and in ~; `
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electrical contact with metallic springs 49, which are in turn
connected to terminals located at the bottom of the receptacles ~ -
44 and 45. A cover 50 (see Figures 10 and 11), having
hemispherical slots 51 to 53 complementary to the slots 46 to
48, is then fitted over the casing and fi~ed thereto by means
of screws 54 at each end.
Figure 12 shows in schematic form a water sterilizing . -~
system employing applicant's invention. A water source inlet
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is connected to a water pipe 60, the water being diverted
by means of a connection 61 and valves 62 and 6~ through an ~ ;~
activated carbon filter 64, and then through a sterilizer
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assembly 65 according to applicant's invention. By means of
a valve 66 and a connection 67 the sterilized water is passed
back to the pipe 60 to an outlet leading to the house water
supply. It is found to be desirable in practice to locate
an activated carbon filter ahead of applicant's sterilizer ~;
to remove particles from the water. However, applicant's ;~
sterilizer is still required following such filtering to
kil]. bacteria, known to grow in activated carbon filters.
In the embodiment just described, a viewport for
visually monitoring the operation of the tube is provided.
However, there may be circumstances in which the tube may
I still generate light but not enough radiation to sterilize ``-
j the liquid. Accordingly, the embodiments of Figures 13 and 14 ~r ' ,'
provide for electrically sensing the flow o current through
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the tube.
In Figure 13, a conventional starter 70 for firing a
tube i9 connected in a circuit with an ultra-violet tube 71,
a resistor 72, a conventional ballast 73 and terminals 74 for
connection to a conventional source of A.C. voltage. When
~ current flows through the tube 71, a voltage drop is produced
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11~62437
across the resistor, with a portion of the current flowing
through a diode 75 during the negative half cycle of the A.C.
voltage. This current flows through a current limiting resistor
76 and a light emitting diode (LED) 77. The parameters of the `
circuit are chosen so that as long as there is sufficient
current flowing through the tube 71 to sterilize the water,
the LED 77 remains on. When there is insufficient current or
if the tube 71 is off,~the LED also goes off, giving an
indication that sterilization is not being achieved.
For a G30T8 tube, employing a ~S4 starter and a
L140FTPC ballast, applicant has found that the following
circuit components provide satisfactory results: ;~
resistor 72: 10 W 6.8 ohms
diode 75: lN4006
resistor 76: 1/2 W 27 ohms
LED 77: OL30
Turning to Figure 14, a casing 78 for housing
the tube 71 is provided, including the starter 70, and the
ballast 73. A terminal 79 is mounted on the casing for
providing interconnections among the circuit components.
The LED 77 is mounted to the wall of the casing and protrudes
from the exterior thereof so that the light can be readily ;
observed.
If the surfaces of the ultra-violet tube in contact
with the water become coated with deposi~s, the effectiveness
of the ultra-violet radiation can be seriously retarded.
Thus, some sterili~ers are provided with means to prevent S
1 the flow of water when insufficient light is being radiated i
; by the tube.
One such arrangement is disclosed in Canadian Patent
!
l 674,555 referred to above. The patent uses a photocell that
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6243g7
is sensitive to ultra-vi~let light. The cell is connected
in series with a current sensing relay, which in turn operates
a valve that opens and closes the water inlet, depending on `
whether sufficient radiation is being received by the cell
from the tube.
The embodiment of Figures lS and 16 does not use `
a photo cell or a relay, but instead directly senses the ` "
current flowing through the ultra-violet tube. A normally open `
spring return push button switch 80 for firing a tube is
connected in circuit with an ultra-violet tube 81, a full wave
rectifier 82, a conventional ballast 83 and terminals 84 for
connection to a conventional source of A.C. voltage. The
current flowing through the tube 81 is tapped off by the ;
rectifier 82, with the rectified current flowing through the r
coil of a solenoid-operated,water control valve 85. -
As long as su~ficient D.C. current is flowihg
through the solenoid, the valve remains open, and the water
continues to flow through the unit. However, if the current !`-
drops due to a failure or defect in the tube 81, the valve
closes and the water flow is stopped. If the tube fails
for any reason and the valve closes, the steriliæer cannot
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start again without operating the switch 80. ~ "
In Figure 16, a casing 86 for housing the tube 81
is provided, including the starter 80 having its button
protruding from the exterior of the casing and the ballast 83.
~ A terminal 87 is mounted on the casing for providing
¦ ` interconnections and for mounting the rectifier 82. A water
¦ inlet 88 is connected to one side of the valve 85, which is
mounted to the exterior of the casing 86. The output side of
~ 30 the valve 85 is connected by a short piece of hose 90 through
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~ an aperture in the casing (not shown) to the inlet connection
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of the disposable sterilizer unit. A conduit 89 houses the
- electrical leads that connect to the solenoid coil.
Thus, applicant has satisfied a need for an
inexpensive water sterilizer assembly that is of simple
construction, easy to install without special skills, and
which advantageously employs a disposable water sterilizer
unit. Although applicant's preferTed embodiment does not
utilize a sheath or a fail-safe device, it is to be understood
that such features could readily be added to applicant's
embodiment without departing from the spirit and scope of ,
the invention as claimed.
Applicant has also provided sterilizers with
mechanisms for sensing the failure of the tube, either by t '
producing a visual indication or by stopping the flow of !;' ,~
water to the tube.
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