CA2481790C

CA2481790C - System for sanitizing a spa

Info

Publication number: CA2481790C
Application number: CA002481790A
Authority: CA
Inventors: Charles Mousseau
Original assignee: LECTRANATOR SYSTEMS Inc
Current assignee: LECTRANATOR SYSTEMS Inc
Priority date: 2004-09-16
Filing date: 2004-09-16
Publication date: 2006-11-14
Anticipated expiration: 2024-09-16
Also published as: CA2481790A1

Abstract

A system and method for maintaining adequate sanitizing of a spa or whirlpool, particularly those having volumes of about 200 to about 400 gallons of water, utilizes an electrolytic generator to provide sufficient chlorine or bromine during periods of low-to-no use. During periods of peak use, a buffered oxidizer is added to the spa water, either before use or immediately after use or both, to assist in removing organics and setting a pH in the spa which is conducive to maintaining adequate levels of active free chlorine or bromine to handle the increased organic load.

Description

1 °'SiIaTEM F~R oSAINIIT~ZINC ~1 SPA"

2

3 FIELD OF THE INVENTION

4 Embodiments of the invention relate to systems for treatment of water in swimming pools, spas and the like and morE= particularly to sanitizing 6 relatively small volume spas for residential use.

S BACKGR0~1ND ~F THE INVEN'T'ION
9 Halogens such as chlorine and bromine have long been used to sanitize water. The chemistry is well known to those skilled in the art.
11 Hypochlorous or hypobromous acid are typically the most effective species or 12 active free halide for sanitizing purposes Dissociation of these acids to the 13 less effective hypochlorite or hypobromite is pH and temperature dependant.
14 For example, at a pH of 8.0 only about 20% hypochlorous acid is present while at a pH of about ~.5 the amount of hypochlorous acid rises to about 50-16 60%. Further, sunlight and organic load can also significantly affect 17 disinfection capability.
18 Chlorine or bromine for sanitizing can be provided in a tablet, 19 liquid or powdered format or can be generated on site using known electrolytic methods. Applicant is aware that electrolytic systems are commercially 21 available which provide sufficient quantities of chlorine or bromine to 22 effectively sanitize large volume swimming pools and the like having 15,000 to 23 in excess of 100,000 DS gallons of water. While electrolytic units have been 24 successful in sanitizing commercial/municipal pools and spas having large volumes of water, residential spas or whirlpools having volumes of about 200 26 to about 400 US gallons present significant dif~cultie~s. Current electrolytic 1 systems are not reliably controllable to produce consistent and sufficiently 2 small volumes of halogen, particularly chlorine, to effectively sanitize without 3 over or under-chlorination. The limited volume, high operating temperature, 4 aeration and large organic loading or demand , when in use, combine to present challenges to keeping a constant pH and level of sanitizer.
6 Typically, prior art products and systems for sanitizing either 7 provide enough chlorine to satisfy needs when the spa is not in use or enough 8 to sanitize when it is in use and the organic load increases significantly.
9 Applicant is not aware however, of products that are capable of effectively handling both situations.
11 During use, organic materials such as hair oils, body oils, 12 sloughed skin and the like are added to the spa, causing the amount of 13 chlorine to begin to fail as the chlorine reacts with the organics, often to levels 14 where the chlorine level is no longer sufficient to handle the total dissolved solids and organics. In conventional spa maintenance, a periodic "shock" is 16 required to clear or sanitize the spa. The term "shock" is typically used to refer 17 to the addition of a high concentration of a sanitizer. Large amounts of 18 additional chlorine or products such as OXONE~ (available from Dupont~
19 Specialty Chemicals, Wilmington, Delaware 19898), a monopersulfate compound, are used to either raise the chlorine levels sufficient to sanitize the 21 increased level of organics or to oxidize the organics through the release of 22 oxygen. It is not recommended that the spa be used for significant periods of 23 time following a shock treatment as the pH is typicallly not optimum and will 24 result in irritation to the eyes and skin and potentially result in corrosion of metal in the spa.

1 Typically, shocking of the spa is performed on a scheduled basis 2 which is determined by the spa owner when testing the water quality. As 3 bromine and chlorine levels drop over time or are used up during peak usage 4 periods, the user must continuously test and retest the water to determine when treatment needs to be effected. As spa usage becomes more 6 infrequent, it becomes more diffcult to adjust levels of sanitizer to meet the 7 demands of both low usage and the sporadic higher demand. ~ver-8 chlorination during periods of low use or more frequent shocking in periods of 9 high use may result in corrosion of metal parts within the tub.
Clearly what is required is a system for maintaining a level of 11 sanitizer that is responsive to handle both low and high organic demand with 12 a minimum of testing and sanitizing procedures on the= part of the spa owner.

1 ~UMMAf~Y C3F THE INVENTION
2 A sanitizing method and system utilizes electrolytic generation of 3 halide alone to sanitize spa water during periods of low-to-no use and is 4 augmented in anticipation of or in reaction to periods of high usage and increased organic demand by the addition of a buffered oxidizer, which acts to 6 oxidize organics, generate active free halide from salt in the spa water and to 7 buffer the pH of the war to a range that is more favorable for maintaining a 8 higher concentration of hypochlorous or hypobromous acid for sanitizing the 9 increased organics.. Accordingly, there is no need to maintain sanitizer levels sufficient to control organics at peak or near peak levels when the spa is not 11 being used. The method is particularly useful for sanitizing water in spas 12 having a volume of water of about 200 to about 400 US gallons.
13 fn a broad aspect, a method for sanitizing water in a spa 14 comprises: providing a halide salt in a range from about 2800 ppm to about 3500 ppm into the relatively low volume of water; and in periods of low to-no 16 use, exposing the relatively low volume of water to an electrolytic apparatus 17 capable of generating a halide ion from the halide salt in the water at a pH of 18 about 8.0 or greater, the generation of halide ion being sufficient to maintain a 19 level of active free halide sufficient for sanitizing the relatively low volume of water during the periods of low to no organic demandi and in periods of 21 increased organic demand, providing a buffered oxidant at about pH 7.U to 22 oxidize at least a portion of the organics as a result c~f the increased organic 23 demand, for oxidizing the free halide to produce free active halide and for 24 maintaining a pH in a range from about 7.2 to about ~'.8 in combination with the electrolytic apparatus so as to permit optimum levels of active free halide.

1 In another broad aspect, a system for sanitizing a residential spa 2 comprises: a halide salt dissolved in a relative ly low volume of water in the 3 spa in a range of about 2500 ppm to about 3500 ppm per spa volume; an 4 electrolytic generator for generating a halide ion from the dissolved halide salt sufficient to maintain a level of active free halide optimum for sanitizing the 6 relatively low volume of water during periods of low to-no organic demand and 7 at a pH of about 8.0; and a buffered oxidizer, packaged for addition to the 8 water for periods of high organic demand, for oxidizing at least a portion of the 9 organics in the water, for oxidizing free halide to produce free active halide and for maintaining the pH in a range from about 7.2 to about 7.8 in 11 combination with the electrolytic generator, so as to permit optimum levels of 12 active free halide to be formed.
13 Preferably, the halide is either chloride or bromide and is 14 electrolyticaliy generated 'from sodium chloride or sodium bromide in water to produce hypochlorous acid or hypobromous acid. The pH following the 16 electrolytic generation is approximately pH 8Ø The dissociation of 17 hypochlorous acid to hypoclorite ion and hydrogen ion is particularly pH
18 dependant, white the dissociation of hypobromous acid is less so. At a pal of 19 8.0 or higher, a smaller percentage of hypochiorous acid exists relative to hypochiorite ion, however the electrolytic generation is relied upon only during 21 periods of very lowto-no usage of the spa and therefore, with relatively low to 22 non-existent levels of organics present, the amount of active free chlorine 23 (hypoclorous acid) or bromine (hypobromaus acid) is sufficient to sanitize the 24 spa.

5 1 In anticipation of, or in reaction to, increased usage of the spa 2 and the increased organics caused therefrom, a buffered oxidizer is added to 3 the spa to oxidize at least a portion of the organics, the pH of the buffered 4 oxidizer being such that in combination with the pH of the electrolytic generation of halide ion being 8.0, the fine! pH of the spa water is in a range

6 of pH 7.2 - 7.8 and preferably 7.4 - 7.6. At a pE-1 of about 7.2 to about

7.8, a 7 greater amount of hypochlorous or hypobromous acid is present and is

8 therefore capable of sanitizing the increased organics in the spa. Further, the

9 buffered oxidizer acts to oxidize the free halide to increase levels of active free halide.
11 A generator cell in the electrolytic generator is preferably small 12 in size and capable of producing sufficient halide iorr from the salt and water 13 to maintain a free available chlorine or bromine kevel of between 1 - 5 14 ppmlvoiume with no to very low organics present in tlhe spa water.
Preferably, the free chlorine level is maintained in a range between 2.0 ~-- 3.0 ppmlvolume 16 and the free bromine level is maintained in a range between 2.0 - 4.0 17 ppm/volume.
18 Preferably, the oxidizer is a monopersLdfate such as OXONE~
19 (pH less than or about 3.0} buffered with an alkaline salt such as sodium carbonate or sodium bicarbonate. The addition of the buffered oxidizer, 21 having a final pH of about 7.0, to the water containing electrolytically 22 generated halide at about pH 8.0, results in a final 19H of about pH 7.4-7.6, 23 optimum for preventing dissociation of the hypochlorous acid or hypobromous 24 acid.

1 BRIEF DESCRIPTION OF THE DR,4WINCS
2 Figures 1 a-c are schematic views illustrating an embodiment of 3 the method and system of the Invention for sanitizing a residential spa using a 4 retrofit electrolytic generator and the addition of a buffered oxidizer, more particularly 6 Figure 1 a is a schematic illustrating sanitizing during periods of 7 low to no usage;
8 Figure 1b is a schematic illustrating sanitizing before a high 9 organic demand; and Figure 1c is a schematic illustrating sanitizing after use where 11 there is a high organic demand;
12 Figure 2 is a schematic of the retrofit electrolytic generator far 13 according to Fig. 1, for installation over a side wall of a spa; and 14 Figure 3 is a sectional view of a spa wall having the electrolytic generator installed therein for use in the system according to Figs. 1 a-c.

1 DETAILED DESCRIPT14N ~F THE PREFERRED EP~B~DIIVIENT
2 As shown in Flgs. 1a-c, and in embodiments of the invention, an 3 electrolytic generator 10, capable of generating free active halide from a 4 halide salt, is installed in a spa 11, such as a residential spa, having a volume of approximately 200 -- 400 lJS gallons c750 -~ 1500 L) and typically 6 supporting from 1 - 10 bathers at the same time. "fhe active free halide is 7 most effective if it is in the acid form.
8 Preferably, the halide is either chloride or bromide and is 9 electrolytically generated from sodium chloride or sadium bromide in water to produce hypochlorous acid or hypobromous acid. The halide salt is added to 11 the spa water to maintain a concentration in the range oB about 2500 - 3500 12 ppmlspa volume and more preferably about 3000 ppm/spa volume. The pH
13 following the electrolytic generation is approximately pH 8Ø The dissociation 14 of hypochlorous acid to hypoclorite ion and hydrogen ion is particularly pH
dependant, while the dissociation of hypobromous acid is less so.
16 During periods of !ow-to-no usage of the spa 11 where there is 17 minimal organic load, the electrolytic generator is capable of providing 18 sufficient active free halide to sanitize the spa 1. Typically, the effective range 19 is approximately 1.0 - 5.0 ppm/spa volume. At a pH of 8.0 or higher, a smaller percentage of hypochlorous acid exists relative to hypochlorite ion than at 21 lower pH, however as the electrolytic generation is relied Lapon only during 22 periods of very low to no usage of the spa, the amount of active free chlorine 23 (hypochlorous acid) or bromine (hypobromous acid) is sufFcient to sanitize the 24 spa.

1 As shown in Fig. 1 b, in anticipation of increased usage of the 2 spa 11 and the increased organics caused therefrom, a buffered oxidizer 12 is 3 added to the spa 11 to oxide at least a portion of the organics, the pH of the 4 buffered oxidizer 12 being such that in combination with the pH of the electrolytic generation of halide, the final pH of the spa water is in a range of 6 about 7.2 to about 7.8 and preferably about 7.4 to about 7.6. At the pH of 7 about 7.2 to about 7.8, an increased amount of chlorine or bromi ne, existing 8 as hypochlorous or hypobromous acid, is present for main~aining a relatively 9 constant level of chlorine or bromine in the water and is therefore capable of sanitizing the increased organics in the spa 11.
11 Further, the buffered oxidizer oxidizes the free halide present as 12 a result of the halide salt which in turn exists as hypochlorous or 13 hypobromous acid at a pH of about 7.2 to about 7.8. Thus, the addition of the 14 buffered oxidizer also acts to increase the active free halide in the spa water.
Preferably, an active free chlorine level is maintained in a range 16 between 2.0 - 3.0 ppmlvolume and an active free bromine level is maintained 17 in a range between 2.0-4.0 ppmlvolume.
18 Alternatively, as shown in Fig. 1 c, the buffered oxidizer 12 may 19 be added after the spa 11 has been used and the organic load 13 has increased or the buffered oxidizer 12 can be added both immediately before 21 and after use. In each case the levels of chlorine and bromine remain 22 relatively consistently within the effective ranges of active free halide.
23 Advantageously, as a result, bathers can immediately use the spa as there is 24 no large pH shift experienced with conventional sanitizing or shocking regimes.

1 As shown in Figs 2 and 3, a generator cell 20 in the electrolytic 2 generator 10 is preferably small in size and capable of producing sufficient 3 active free halide from the salt and water to maintain the effective ranges of 4 active free halide with no to very low organics present in the spa water. As well known to those skilled in the art, the cell 20 comprises blades 21 of a 6 metal, such as, titanium preferably coated with a noble metal such as 7 platinum or iridium or preferably, ruthenium. The blades 21 are sandwiched 8 between end caps 22,23 and are housed in a perforated, transparent plastic 9 tube 24, such as polyvinyl chloride (PVC), to protect the blades 21 from damage to the coating. The perforations in the tube 24 permit contact of the 11 blades 21 with the water.
12 In an embodiment of the invention, the electrolytic generator 10 13 has an output control dial 25 which is manually set to control the active free 14 halide output relative to the spa volume. Set, for example at 100%, the generator 10 is capable of producing the equivalent of approximately 15 16 grams of chlorine in a 24 hour period which would satisfy a spa having a 17 volume of 400 tJS gal (1500 L) during periods of low-to-no use.
18 As shown in Figs 1a-c and 2, the generator 10 is available as a 19 retrofit unit wherein the cel! 20 is suspended in the water over a wall 30 of the spa 11 and a control module 31 is mounted on or adjacent an outside surface 21 32 of the spa 11.
22 Alternatively, as shown in Fig. 3, the generator 10 may be 23 installed within the wall 30 of the spa 11 at the factory, the control module 31 24 being integrated into the spa controls (not shown).

1 Further, the generator 10 is programmed to reverse polarity at 2 regularly scheduled intervals which assists in cleaning of the ceA blades 21.
3 Preferably, the bufFered oxidizer is a monopersulfate such as 4 OXONE~ available from Dupont~ Specialty chemicals, Wilmington, Delaware 19898) (pFl less than or about 3.0) buffered with an alkaline salt, 6 such as sodium carbonate or sodium bicarbonate. 'the addition of the 7 buffered oxidizer 12, having a final pH of about 7.0, to the water containing 8 electrolytically generated halide at about pH 8.0, results in a final pH of about 9 pH '7.4-7.6, optimum for preventing dissociation of the hypochlorous acid or hypobromous acid and maintaining a constant, reproducible level of active 11 free halide within the spa during periods of peak usage.
12 Most preferably, the buffered oxidizer 12 is prepackaged in 13 convenient pouches 14 such as a gel capsule for addition to the spa 11. One 14 or more pouches 14 may be added depending upon the volume of the spa 11 or based ~n bather/organic loading.
16 For example in a 250 gal (1000L) spa containing 3000ppm 1? sodium chloride, the addition of about 15g of OXONE~ will produce 18 approximately 3ppm free chlorine in demand-free water. lr~ the presence of an 19 organic demand, the amount of free chlorine produced will be less as a portion of the OXONEC~ will act to oxidize the organics.
21 !n the case of a 250ga1 (1000L) spa containing 3000ppm halide 22 salt (97% sodium chloride and 3% sodium bromide), t:he halide will react with 23 the OXONE~ and any free chlorine will also act to oxidize br~mide to 24 bromine, 'thus, virtually all of the halogen produced will be bromine. A
concentration of 15g of OXONEO will produce about 6.8ppm of free bromine 1 in demand-free water which is in excess of the normal amount of bromine 2 added to a spa.
3 As with conventional spa maintenance regimes in spas 11 using 4 chlorine as the active halide, Cyanuric acid may be added to the spa to stabilize the chlorine, particularly if exposed direotly to tJV rays.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN
EXCLUSIVE PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS
FOLLOWS:

1. A method for sanitizing water in a spa comprising:
providing about 2800 ppm to about 3500 ppm halide salt into the water; and in periods of low-to-no use, exposing the water to an electrolytic apparatus capable of generating a halide ion from the halide salt in the water at a pH of about 8.0, the generation of halide ion being sufficient to maintain a level of active free halide sufficient for sanitizing the relatively low volume of water during the periods of low-to-no organic demand; and in periods of increased organic demand, additionally adding a buffered oxidant at about pH 7.0 to oxidize at least a portion of the organics as a result of the increased organic demand, to oxidize a portion of the halide ion to generate active free halide and for maintaining a pH in a range from about 72 to about 7.8 in combination with the electrolytic apparatus so as to permit optimum levels of active free halide.

2. The method as described in claim 1 wherein the halide salt is sodium chloride, the halide ion is chlorine and the active free halide is hypochlorous acid.

3. The method as described in claim 1 wherein the halide salt is sodium bromide, the halide ion is bromine and the active free halide is hypobromous acid.

4. The method as described in claim 1 wherein the oxidant is potassium monopersulfate.

5. The method as described in claim 4 wherein the oxidant further comprises an alkaline salt for buffering the oxidant.

6. The method as described in claim 5 wherein the alkaline salt is sodium carbonate or sodium bicarbonate.

7. The method as described in claim 5 wherein the buffered oxidant is prepackaged for addition to the water.

8. The method as described in claim 1 wherein the electrolytic generator produces halide ion in a range from about 1 ppm to about 5 ppm per spa volume when the spa is not in use.

9. The method as described in claim 1 further comprising providing a buffered oxidant immediately before and after periods of high organic demand.

10. The method as described in claim 1 wherein the pH is maintained in a range from about 7.4 to about 7.6.

11. The method as described in claim 1 wherein the water has a volume from about 200 US gallons to about 400 US gallons.

12. A system for sanitizing water in a spa comprising:
a halide salt dissolved in the water in the spa in a range of about 2500 ppm to about 3500 ppm per spa volume;
an electrolytic generator for generating a halide ion from the dissolved halide salt sufficient to maintain a level of active free halide optimum for sanitizing the water during periods of low-to-no organic demand and at a pH of about 8.0; and a buffered oxidizer, packaged for addition to the water for periods of high organic demand, for oxidizing at least a portion of the organics in the water, to oxidize a portion of the halide ion to generate active free halide and for maintaining the pH in a range from about 7.2 to about 7.8 in combination with the electrolytic generator, so as to permit optimum levels of active free halide to be formed.

13. The system as described in claim 12 wherein the halide salt is sodium chloride, the halide ion is chlorine and the active free halide is hypochlorous acid.

14. The system as described in claim 12 wherein the halide salt is sodium bromide, the halide ion is bromine and the active free halide is hypobromous acid.

15. The system as described in claim 12 wherein the oxidant is a monopersulfate.

16. The system as described in claim 15 wherein the oxidant further comprises an alkaline salt for buffering the oxidant.

17. The system as described in claim 15 wherein the alkaline salt is sodium carbonate or sodium bicarbonate.

18. The system as described in claim 16 wherein the buffered oxidant is prepackaged for addition to the water.

19. The system as described in claim 12 wherein the electrolytic generator produces halide ion in a range from about 1 ppm to about 5 ppm per spa volume when the spa is not in use.

20. The system as described in claim 12 further comprising providing a buffered oxidant before and after periods of high organic demand.

21. The system as described in claim 12 wherein the pH is maintained in a range from about 7.4 to about 7.6.

22. The method as described in claim 12 wherein the water has a volume from about 200 US gallons to about 400 US gallons