WO1995013853A1

WO1995013853A1 - Water treatment device

Info

Publication number: WO1995013853A1
Application number: PCT/US1994/012839
Authority: WO
Inventors: George H. Pankey
Original assignee: Whitehall Water Filtration Systems
Priority date: 1993-11-16
Filing date: 1994-11-08
Publication date: 1995-05-26
Also published as: AU1090995A

Abstract

A water purification unit (26) includes a cylindrical housing (36) which has a water pipe (42) and a water outlet (30). A sediment filter (24) is connected to the pipe (42) outside of the housing (36). On the inside of the housing (36), a stack helical coil of transparent tubing (48) is held in place inside the housing (36). An ultraviolet lamp (56) extends into the interior of the helical coil (48), for which power is obtained through a cord (28). The upper end of the coil (48) passes downwardly through the unit (26) as a tubing portion (50) that is connected to a water outlet pipe (30) out of the housing base (40).

Description

WATER TREATMENT DEVICE

BACKGROUND

Point-of-use water filtration systems are becoming increasingly popular to provide good tasting clean drinking water at the tap, where the water is to be consumed. Many such systems use a media filter, such as compressed charcoal, activated charcoal, or other types of materials for filtering out impurities from the water. Typically, such filters are used with water which already has been treated with chlorine for the purpose of killing bacteria and viruses in the water. The filters effectively remove the chlorine, chloramine, THM's, herbicides, pesticides, and other chemicals, along with metal such as lead. Such filters leave the trace minerals in the water; so that the water has a satisfying taste. A shortcoming of media filters, however, is that the particle sizes of bacteria and viruses in the water supply are smaller than the filtration capability; so that such filters do not remove bacteria and viruses from the untreated water.

A system which has been developed for providing water purification by removing bacteria and viruses, along with filtration of the water, is a reverse osmosis system. Reverse osmosis systems, however, are cumbersome, expensive and require steady maintenance. Furthermore, reverse osmosis systems waste large amounts of water (approximately three to five gallons or more to obtain one gallon of safe drinking water) . Reverse osmosis systems also remove the trace minerals, which are essential to good health; and the taste of the water is not as satisfying as natural or filtered water.

A third technique, which is utilized for purification of water, involves ultraviolet treatment. Systems employing ultraviolet treatment pass the water through a clear or transparent conductor in close proximity to a source of ultraviolet light to expose the bacteria in the water to the ultraviolet light. Ultraviolet light kills bacteria and viruses; but ultraviolet treatment does not treat the water for bad taste, odors, or contaminants of the type which are removed by media filtration devices.

Because of the relatively high expense of ultraviolet purification systems, they are not in widespread use. The bulb life of ultraviolet lamps typically is in the range of eight thousand hours. This is a relatively long life; but if the ultraviolet lamp is left on continuously, to ensure that filtration always takes place when water flows through the system, the life of the bulb is expended in less than one year. As a consequence, many ultraviolet purification systems employ a manually operated switch to switch on the ultraviolet lamp when the purification of water is desired, and to switch it off when purification is not desired. The danger of such a manually switched system is that if the switch inadvertently left on when it should be turned off, the life of the bulb is shortened. Conversely, if the switch is turned off and a person draws water from the system, no purification of that water takes place, which, many situations, can be dangerous to the health of the consumers of the water drawn through the system.

It is desirable to provide a water purification and filtration system, which overcomes the disadvantages of the prior art, which is inexpensive and easy to use.

SUMMARY OF THE INVENTION

It is an object of this invention to provide an improved water treatment system.

It is another object of this invention to provide an improved water purification system.

It is an additional object of this invention to provide an improved water purification system using an ultraviolet lamp for purification.

It is a further object of this invention to provide an improved ultraviolet water purification system which is compact in size, easy to use, and relatively inexpensive.

In accordance with a preferred embodiment of this invention, a water treatment device includes an enclosed hollow housing member, which has a water inlet and a water outlet. A length of ultraviolet-transparent tubing is helically wound and releaseably attached to the inside of the housing. An ultraviolet lamp extends into the interior of the helically wound ultraviolet-transparent tubing to expose water passing through the tubing to the ultraviolet light. A flow-responsive electrical switch is attached to close an electrical circuit to the ultraviolet lamp whenever water flow takes place through the tubing. When water flow is terminated, the switch is opened, thereby causing the lamp to be activated only when it is necessary to purify water passing through the helical tube around the lamp. BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a diagrammatic representation of a water treatment system employing a preferred embodiment of the invention;

Figure 2 is a cross-sectional view of a preferred embodiment of the invention;

Figure 3A and 3B are enlarged cross-sectional views of a portion of the embodiment of Figure 2 showing two different states of operation; and

Figure 4 is a cross-sectional view taken along the line 4-4 of Figure 2.

DETAILED DESCRIPTION

Referring now to the drawing, the same reference numbers are used throughout the different figures to designate the same components.

Figure 1 illustrates a typical arrangement for an under- the-sink installation of a water purification and filtration system employing a preferred embodiment of the invention. As illustrated, a counter top 10 has faucet 15, with a hot water inlet 11 and a cold water inlet 13 connected, respectively, to suitable sources of hot and cold water through valves 12 and 14. This is a standard sink arrangement for water supplies in most homes, businesses and rest rooms throughout the world.

Also, as illustrated in Figure 1, the main cold water supply is obtained from an external water source (not shown) through a shut-off valve 19. This valve 19 supplies water to the valve 14; and, in addition, water is supplied through a "T" tap 20 through a line 22 to a sediment filter 24. The sediment filter 24 may be a conventional sediment trap or strainer, which may be opened to periodically remove sediment deposits from the trap. By utilizing a sediment trap in front of the other portions of the water purification and filtration system, the large sediment particles are prevented from adversely affecting the operation of the remainder of the system. By using a sediment trap 24 in front of the water purification unit 26, the turbidity of the water passing through the ultraviolet water purification unit 26, is reduced, thereby enhancing the effective operation of the ultraviolet purification unit 26.

Water passing through the unit 26 is exposed to ultraviolet light to kill viruses and bacteria; and the water then passes out of the unit 26 through an outlet line 30 to the inlet of a media filter 32, which may be filled with pressed carbon, activated carbon, KDF, silver carbon or the like for filtering dissolved contaminants from the purified water. After filtering, water at the outlet of the filter unit 32 is supplied over an outlet line 34 to a drinking water faucet 18, which also may be of a standard configuration. The sediment trap 24 and the media filter 32 may be of any suitable standard commercial design. For that reason, no details of these elements are illustrated.

The ultraviolet filter 26, however, is shown in detail in the cross-sectional view of Figure 2. In Figure 2 the unit 26 is shown consisting of an elongated cylindrical body 36, which is closed at its top end by a cap 38, and at its bottom end by a cap 40. The top cap 38 is removable to permit access to the interior for replacing the ultraviolet bulb 56, or for replacing the plastic tubing 46/48/50. The unit 36/38/40 typically is made of ultraviolet/opaque plastic, such as opaque CPVC. A typical size which has been incorporated into operating units is for the overall height of the hollow housing member 36/38/40 to be approximately eleven and one-half inches high, with a three and one-half inch diameter. PVC pipe materials are readily available in these sizes; so that the outer housing member 26 readily can be manufactured of inexpensive materials.

Water which passes through the sediment trap 24 is supplied to a water inlet of the housing member 26 through a suitable opening in the base 40, and passes through a pipe 42 to a flow sensitive switch unit 44. Water passing out of the switch unit 44 is supplied to one end of an ultraviolet-transparent plastic tubing 46, which is wound in tight, stacked helical coil 48. The upper end of the coil 48 then passes downwardly through the device (via tubing portion 50) and is connected to the water outlet pipe 30 on the opposite side of the base 40 of the housing member 26.

The helical coil 48 of transparent plastic tubing is held in place in the position shown in Figure 2 by means of four equally spaced elongated double-sided adhesive tape strips 49 (two of which are shown in Figure 2) extending parallel to the central axis of the cylindrical portion 36 of the housing member 26. The spiral coil 48 simply is pressed into place to engage the tacky surface of the adhesive on the strips 49 and is securely held in place, as illustrated in Figure 2, throughout the life of the device. To provide ultraviolet light for irradiating the water flowing through the tube 46/48/50, an elongated ultraviolet lamp 56 extends downwardly on the central axis of the housing portion 36 into the center of the helical coil 48 of the transparent tubing. Power for the lamp 56 is obtained from a conventional 110 Volt alternating current supply through a cord 28 passing through a grommet in the cap 38 of the housing 26 to a mounting base 54 for the lamp 56. Current to the lamp 56 passes through a switch in the flow-responsive switch unit 44, which is connected to the power supply for the lamp 56 in the base 54 by means of a wire pair 52.

The ultraviolet disinfection portion of the system shown in Figure 2 causes relatively high turbulence to be produced in the water flowing through the system, because of the spiral configuration of the tube portion 48 and the relatively small internal diameter of the tubes . An effective tube size has been found to be 3/16 inch od with a 1/8 inch id Material which has been found to be satisfactory for construction of the tube 46/48/50 is clear PVC or nylon. Effective operation has been obtained from a plastic tube constructed of Tygon^®, which has a high transmittance for short-wave ultraviolet light. The ultraviolet dosage from a 3^ Watt ultraviolet bulb exceeds thirty thousand UWS/CM². This dosage has been found sufficient to exceed the dosage required to kill cholera, for example. By employing the spiral motion for introducing high turbulence into the water flow through the tube section 48, microorganisms have an equal probability of being at a maximum exposure distance from the ultraviolet lamp source 56. In addition, the turbulence helps to mitigate shadowing effects caused by suspended solids in the fluid. Since the system is intended to be used with water, the potential for producing laminar flow, which results with fluids of high viscosity, is not likely, but even then the circular motion or spiral motion produced by the configuration of the tube portion 48 ensures exposure to effective dosages of ultraviolet light.

Figure 4 is a top view, which illustrates the relative spacing between the lamp 56 and spiral tube portion 48 inside the cylindrical portion 36 of the outer housing member 26. As is readily apparent from Figure 4, the elongated ultraviolet lamp 56 is located on the central axis of the cylinder 36; so that the distance between the lamp 56 and the nearest portion of the walls of the spirally-wound part 48 of the clear plastic tubing is equal on all sides of the lamp 56.

Reference now should be made to Figures 3A and 3B, which are illustrated enlarged cross-sectional representations of the flow-sensitive switch used to control the operation of the ultraviolet lamp 56. As illustrated in both Figures 3A and 3B, the switch housing 44 includes a conventional reed switch 60, which is vertically oriented within the housing 44. The reed switch 60 has movable reed 61, and is normally in the open position, as illustrated in Figure 3A. As is readily apparent from an examination of both Figures 3A and 3B, the 110 Volt AC supply, which is obtained over the cord 28 (Figure 1) , is connected to one end of the reed or movable arm of the reed switch 61. The other contact at the upper end of the reed switch 60 is then connected through the lead 52 to the lamp 56, and from there back to ground. The ground wires also can extend from the switch 44 back into the housing 54 (via the wire pair 52 of Figure 2) ; but for purposes of illustration, the circuit shown in Figure 3A and 3B diagrammatically shows the electrical connections which are used.

To operate the reed switch 60 to its closed position, as shown in Figure 3B, a flow-responsive operator is employed. This is accomplished by connecting the inlet from the tube 42 at the bottom of the housing 44 through a connector 70 to one end of a vertical chamber 64 forming a portion of a "T" shaped flow tube. The outlet side of the flow tube is through a horizontal portion 66 extending approximately from the mid portion of the vertical portion 64. The portion 66 is connected through a connector 72 to the clear plastic tubing 46, as illustrated in both Figures 3A and 3B.

When the faucet 18 (Figure 1) is turned off, substantially equal pressure exists throughout the system; and no water flow takes place from the inlet 42 to the outlet 30. Under these circumstances, a magnet slug 68 drops by means of gravity (or, alternatively, by assistance of a repelling or attracting magnet, not shown) to the position shown in Figure 3A. In this position, the magnet slug 68 is located near the lower or pivoting end of the reed 61 of the switch 60. This location is sufficiently far away from the upper end of the reed 61 to permit the switch 60/61 to maintain its open position, as illustrated in Figure 3A.

When the tap 18 is opened to initiate withdrawal of water from the system, the pressure differential between the inlet pipe 42 and the outlet pipe 46 is such that substantially increased pressure is on the inlet side relative to the outlet side; and the water pressure pushes the magnet slug actuator 68 upwardly into the top part of the chamber 64, as illustrated in Figure 3B. Two things happen when this occurs. The position of the magnet slug 68 is opposite the upper end of the reed 61 of the switch 60 and pulls the switch reed 61 in the direction of the arrow shown in Figure 3B. The reed 61 makes electrical contact with the upper fixed contact to close the circuit from the voltage source to the ultraviolet lamp 56, thereby activating or illuminating the lamp 56. The second result of this operation is that water flow takes place in the direction shown by the arrows in Figure 3B upwardly through the lower portion of the vertical part 64 of the T-shaped chamber, and then outwardly through the horizontal part 66 to the tubing 46 to supply water to the system through the outlet pipe 30. As described previously, this causes water to flow from the pipe 30 through the filter 32, and finally to the outlet tap 18.

When the outlet tap 18 subsequently is turned off, the pressure differential between the inlet 42 and the outlet tube 46 terminates. Under these conditions, the magnet slug 68 drops under the weight of gravity to the position shown in Figure 3A; and the reed switch 60/61 once again resumes the open position shown in Figure 3A. This extinguishes the lamp 56.

Whenever the tap 18 is turned on again to draw water from it, the cycle of operation which has been described above once again is repeated. It is readily apparent that the lamp 56 also is illuminated whenever water flow takes place; and the lamp 56 always is automatically turned off whenever water flow through the system terminates. As a consequence, the useful lifetime of the lamp 56 is extended considerably, since the lamp is only energized when water is being withdrawn from the system.

To provide a visual external indication of the proper operation of the lamp 56, a end light fiber optic sensor 74 is extended through the wall of the cylindrical portion 36 in a position to receive light from the lamp 56 passing through the transparent coil 48. The sensor 74 provides a quick visual indication of the operation of the lamp 56, without having to remove the cover 38 to determine whether it is functioning. The sensor 74 has a very small diameter; so that only a small amount of light passes through the sensor 74 during operation of the device.

When microorganisms, such as viruses and bacteria, are subjected to ultraviolet light, a constant fraction of the number present die in each time increment. The fraction of the initial number of microorganisms present at a given time is called the survival ratio. This survival ratio is determined by the number of organisms initially present, the number surviving at any given time (the time of exposure) , the intensity of ultraviolet light impinging on the microorganisms, and a constant which depends upon the type of microorganisms and the wavelength of the ultraviolet light being used. Basically, for each given microorganism and ultraviolet light wavelength, the fraction of microorganisms killed depends upon the product of the ultraviolet light intensity and the exposure time. This product is known as the dosage; and it is the single most important parameter for rating any ultraviolet disinfection equipment .

The dosage obviously is dependent upon the strength and wavelength of the ultraviolet lamp, and the time of exposure is directly dependent upon the flow rate of the water through the system, as well as the number of turns of the transparent coil around the lamp, which determines the total amount of time any given unit of water is exposed to the light from the ultraviolet lamp. Consequently, the design parameters of the unit may be adjusted to ensure that microorganisms of the type expected to be encountered by the unit will be destroyed or killed in normal operation of the unit.

Dosage requirements for bacteria range from 2,500 to 25,000 UWS/CM². Yeast dosage requirements range from 6,600 to 17,000 UWS/CM². Mold, spore, fungi and algae dosage requirements range from 11,000 to 330,000 UWS/CM². Viruses, with the exception of the tobacco mosaic (not normally found in water) , have dosage requirements in the same range as bacteria. Protozoa and nematode eggs have extremely high dosage requirements.

The system which is described above is particularly useful in regions of the world which do not have good water purification systems. Even in areas of the world which use chlorine and ozone for purification, some viruses, such as polio and coxsackie require very high doses of chlorine and ozone to be effective. High chlorine dosages result in unhealthy, bad tasting water. For those parts of the world, however, where chlorine and ozone water purification are not used, or are ineffectively used, a system of the type described above is essential . When the unit shown in Figure 2 is interconnected in a series system of the type illustrated in Figure 1, the maximum effectiveness of good tasting pure water is realized. The system of the type illustrated in Figure 1 may be used with water supplies which are untreated or badly contaminated, and still provide good tasting water at the drinking water faucet 18. By trapping the sediment in the sediment trap 24 first, the turbidity which results from sediment in the water is significantly reduced. As a consequence, the effectiveness of the ultraviolet exposure of the water flowing through the coil 48 is enhanced. By removing the bacteria and viruses from the water before it passes through the media filter 33, the breeding of additional bacteria and viruses in the media filter 32 is eliminated. If the filter 32 were connected in the water flow chain in front of the ultraviolet purification unit 26, breeding of bacteria and viruses could take place in the filter 32, particularly during times when no water flow takes place. The result would be increased quantities of bacteria and viruses being supplied to the purification unit 26, which would increase the chance for the passage of viruses and bacteria to the faucet 18. By placing the units in the order shown in Figure 1, namely having water first flowing through the sediment trap, then through the ultraviolet purification unit 26, and finally, through the media filter 32, the most effective water purification and filtration system is obtained.

Various changes and modifications will occur to those skilled in the art, without departing from the true scope of the invention as defined in the appended claims.

Claims

1. A water treatment device housed in a source of electrical power and having an ultraviolet lamp for connection to an enclosed housing member having a water inlet and a water outlet, characterized by: a predetermined length of ultraviolet transparent tubing connected at a first end with the water inlet of the housing member and connected at a second end with the water outlet of the housing member, and physically located in proximity to the ultraviolet lamp which illuminates the tubing when the ultraviolet lamp is activated; a normally open electric switch connected in series circuit between the source of electric power and the ultraviolet lamp; and means for closing the normally open electric switch in response to water flow through the ultraviolet-transparent tubing.

2. The device according to Claim 1 further characterized in that the predetermined length of ultraviolet-transparent tubing is wound in a stacked spiral coil around the ultraviolet lamp.

3. The device according to Claim 2 further characterized in that the spiral coil of ultraviolet-transparent tubing is attached to the interior wall of the housing member.

4. The device according to Claim 3 further characterized in that the ultraviolet-transparent tubing is attached to the interior wall of said housing member with elongated strips of double sided adhesive tape.

5. The device according to any of Claims 1 to 4 further characterized in that the normally open electric switch comprises a reed switch closed by a magnetic actuator located adjacent the reed switch, wherein the actuator is moved from a first position, when no water flow takes place, to a second position in response to water flow through the ultraviolet- transparent tubing to cause the reed switch to close.