IL43444A - Automatic tube cleaner for liquid (water) sterilizers - Google Patents

Abstract

A circular cleaning device which scours the external surface of an ultraviolet radiation tube, which acts as a radiation source for bacteria kill in ultraviolet radiation fluid sterilizers, removes deposits, which precipitate out of the sterilizable fluid, from the external surface of the ultraviolet radiation tube, or its surrounding shield, and thereby sustains the emanation of high intensity radiation flux from the tube into the fluid which is to be sterilized. [US3904363A]

Description

(O'DJO' T 13 npyn may »oeieiK m*nj's npaa Automatic Tube Cleaner for Liquid(Water) Sterilizers Naturvard Research(Canada)Ltd.

This invention relates to a cleaning liquid device for £t«i , particularily, water sterilizers.

More particularly, the present invention relates to a cleaning device for cleaning the outside surface of a protective sheath of a radiation tube of an ultraviolet radiation water sterilizer or the like, wherein the sterilizer employs a longitudinal ultraviolet radiation tube as a source of ultraviolet radiation or flux.

Water sterilizers may employ ultraviolet radiation tubes as a source of flux for the creation of ultraviolet radiation , and usually have a longitudinal ultraviolet tube, suspended coaxially along the axis of a cylindrical sterilization chamber. The water which is to be sterilized flows from one end of the cylinder (usually the bottom) in a vortex-like manner, to the other end of the cylinder (usually the top) such that a mean capture liquid · time of the -f-itti-d within the chamber is sufficient, in relation to the magnitude of the flux created by the ultraviolet radiation source, that a bacteria liquid stat Lu 4 is obtained at the outflow of the sterilization cylinder. When this "bacteria stat" condition is achieved, "a kill" is said to have been liquid imparted to the bacteria suspended in the f-l-tti-d ; that is, all the bacteria is killed.

It is known that the bacteria stat liquid condition can be achieved for a J¾Hrd- and in particular water, when the same is subjected to a minimum ultraviolet flux dose at a certain frequency, as those skilled in the art will know. It is also liquid known that the mean resident time of a ftuid within the sterilization chamber must be increased to maintain a bacteria stat dose of flux as a result of mineral deposits forming on the outside surface of the ultraviolet radiation source tube, or more accurately, the circumscribing protective sheath thereof, when a sheath is employed; as mineral deposits have a tendency to absorb the ultraviolet radiation. It is further known that a scraping device may be employed to scrap mineral deposits off the sheath, but such prior art devices suffer from such disadvantages as they have to be humanally activated with the appended result that a liquid human may forget to do the same and that f-luid- does not obtain the bacteria stat dose; or, further that such prior art devices are not sufficiently efficient to significantly clean the mineral deposits away to sustain the high flux intensity of the radiation penetrating through the sheath and liquid hence into the-fi«id-to be sterilized.

These deficiencies of the prior art have been avoided somewhat by either increasing the mean liquid resident time of the f¾«id flowing through the sterilization chamber, but this reduces the rate liquid or the volume of £i«*d flow and hence decreases the sterilization efficiency of the sterilizer as well as having its effect on increase manufacturing and operating costs.

The invention, therefore, contemplates an efficient cleaning device to scrape mineral and other deposits from the surrounding protective surface of an ultraviolet radiatio tube, the device , liquid being activated by the combined e ct of the -*1«14 flow through the ohamber on the one hand; and on the other* by the weight of the cleaning device itself* when low stops.

The cleaning device also contemplates providing a tigh piston*ype arrangement in the sterilizer between the oute sterilisation wall and the inner protective sheath so as to ensure adequate scraping of the deposits rom the protective surace of the sheath, whereupon high liquid flux intensifies into tho-^f-iid- can be sustained with minimum resident time of the¾^u&-i in the sterilizer for a kill* The invention, therefore, contemplates in combination with a liquid sterilization cylinder having an inner wall which defines a ohamber and positioned In said ohamber a coaxially-longitudinal located source of ultraviole radiation disposed behind a protective ultra-violet tran-emissive cylindrical sheath* a cleaning device adapted to pass to and fro within the chamber, during flow and non-flow of the liquid to be sterilized* characterized in tha the cleaning device comprises; (a) a first ring-like member having an orifice therein through which a liquid may low} (b) a lexible inner member attached to and disposed radially inward of the irst ring-like member with a segmen of its inner merging disposed on the locus of the$ circumference of a circle having a radius less than the exterior diameter of said sheath such (β) a flexible resilient outer member attached to and disposed radially outward o the irs ring-like member and having its outer circumference blasly urged agains the inner wall of the sterilisation cylinder whereby the weight o the cleaning device, during non-flow of th causes the cleaning device to fall whence the inner member sha es the ultra-violet transmissive cylindrical sheath again to clean said s*heath> and wherei durin such flow the orifice in said firs ring-like member ermita to pass from one side of the cleaning device to the other and hence through the said chamber. >£he present invention will now be described by wa of example with reference to the accompanying drawing in whichs liquid figure 1 is a perspective view of a portion of a fluid, particularityt a water storiliaation chambe employing the embodiments o the invention* figures 2 and 3 are longitudinal sections for explanation showing the profile of the cleaning device during flow and non-flow conditions* Figure 4 is a plan view of the cleaning device.

Figure 5 is a section along lines V-V of figure 4.

Figure 6 is an expanded section along lines VI-VI of figure 4.

Referring to figure 1 a rf-l-«i-d-, liquid particularily water, sterilization chamber 10 includes a hollow cylindrical chamber 11. disposing ' coaxially to its inner longitudinal axis a protective exterior surface 52 of a circumscribing fused silica glass sheath 53 within which is disposed a longitudinal radiation source such as an ultraviolet lamp (not shown). The sheath of silica glass permits transmission of ultra-violet radiation into the region between the sheath 53 and the' interior wall of the chamber 11. Through it the liquid A cleaner 12 is disposed within this region (between sheath 53 and cylinder 11) and comprises a metal ring 13 to which is attached, on the outside circumference, radially projecting a flexible semi-rigid rubber-type membrane 14 of necessity ultraviolet (or whatever radiation is to be used) resistent, and on the inside circumference, radially projecting, a semi-rigid plastic or flexible metal membrane 15, also radiation resistent, and capable of providing a scrapping action against the protective surface 52 while at the same time retaining a reasonably good water metal rings 13 tight seal between the -flexible -memfe-pono 3r5- and surface' 52. The metal ring 13 preferably is in two halves, 13a and 13b, referring to figure 5, joined together by appropriate means (not shown) sandwiching the membranes 14 and 15 between them. Small holes or orifices 16 are drilled through the metal annulus 13 symmetrically about to allow the passage of water 54 across the cleaner through these holes.

The materials of construction of the two membranes 14 and 15 and of the metal ring 13 all require cleaner careful choice as the effective weight of the 12 is important as is the flex characteristics of the membrane 15 as will now be described. liquid In operation the fefaxrd 54 which is to be sterilized flows into the bottom of the chamber 11 at 22 and up in a vortex-like fashion through the cylinder to be discharged off the top (not shown) as those skilled in the art will know. With the water 54 flowing, since the cleaner 12 provides a reasonably good seal across the water flow region (only imperfections around the periphery of the membranes 14 and 15 and the plurality of holes 16 in the metal annulus 13 permitting water to by-pass the cleaner) pressure builds up underneath the cleaner (figure 2) and produces a force, F^, attempting to lift the cleaner upward. The seepage loss, L, reduces the force to an actual force, F^. Resisting the rise of the cleaner 12 are the weight, W, of the cleaner and the frictional force of cylindrical wall f and of the protective surface 52, f . If is greater that these opposing forces the protective surface 52 thus cleansing it. Careful choice of the inner membrane 15 will determine the cleaning efficiency, it has been found that a brushlike textured membrane of composite or plastic material is satisfactory. The cleaner 12 may be m'ade to rise strongly despite the losses L and the frictional forces, fp and fg and the cleaner weight, W.

Whiles the water 54 is flowing the cleaner 12 will be held at the top of the sterilizer 10. As soon as the flow stops the cleaner 12 will have the force FQ removed (the only force holding the cleaner 12 at the top of the sterilizer 10 when the cleaner is stationary) and the weight, W (see figure 3) will tend to pull the cleaner 12 to the bottom of the sterilizer 10. The forces resisting this movement are the frictional forces of the membranes 14 and 15 on the cylindrical wall 11, f_., and on the protective surface 52, f_, together P s with the water trapped beneath the cleaner 12.

However, the holes 16 through the metal annulus 13 will allow the water below the cleaner to seep through the cleaner 12 on its downward travel providing the weight, W, is great enough to overcome the frictional forces and resistance caused by the water flow through the holes 16; the cleaning device 12 will move boldly downward and the membrane 15 will flex and again scrape the protective surface 52 and clean it (figure 3) .

When a sterilization chamber having an inner diameter of three inches (7.62 cm.) with a of one inch (2.54 cm.) was used it has been found that the cleaning device 12 could have the following dimensions.

Metal annulus 13 [inner diameter 1-1/2" (3.675 cm.) outer diameter 2-1/2" (6.350 cm. ) ] . 1 5 Flexible annular membrane -t2- [inner diameter 7/8" (2.225 cm.) outer diameter 1-1/2" (3.675 cm.)]. 14 Flexible membrane -tir [inner diameter 2-1/2" (6.350 cm.) outer diameter 3-1/8" (7.937 cm. ) ] .

Diameter of orifices 16-1/16" (0.159 cm.).

Weight (W) of the cleaning device 12 approximately 1/2 pound (226.8 gms.).

Claims (1)

1. Claims In combination a liquid sterilisation cylinder an inner wall which defines a chamber and sitioned in chamber located source of ultraviolet radiation disposed a protective drical a cleaning adapted to pass to fro within during flo and of the liquid be cha cte that whic a liquid may flexible inner attached to and disposed o th firs with of its disposed on the locus of of circle having a less than the exterior of said sheat suc tha biaslngly said cylindrical resilient outer member attached to and radially outward of the it outer circumference urged agains the wall the cylinder the weight of the cleaning during liquid of the causes the cleanin device to f ll whence inner member scapes transiaissivs cylindrical sheath to clean said and wherein during such orifice member liquid permits pass one side of the device to Claim wherein the member a plurality of orifices disposed cleaning according to 1 wherein the member plurality of ereatially positioned in cleaning according to any of 1 to wherein th first a according to an of Claims 1 to the resilient a solid of a o cleaning device or to any of Claims 1 3 wherein the inne ring is a plastic radia ion a de according to any of 1 to the inner member io composed of flexible sheet of A combination of liquid cylinder a cleaning device substantially as hereinbe described with to the accompanying the Applicant Hess insufficientOCRQuality