Claims
- 1. A flexible portable plastic tubing mat adapted to be laid side-by-side with other similar mats for creating and maintaining an ice slab for skating and for preventing snow from melting on a ski slope and adapted to be laid end-to-end with other similar mats for creating an ice chute or trough for a toboggan slide or similar sliding purposes,
- a. said portable mat having a length many times greater than its width with a plurality of small diameter flexible plastic tubing members extending lengthwise of said mat adapted to have cooled anti-freeze liquid pumped therethrough,
- b. said flexible plastic tubing members having an inside diameter in the range from one-eighth to three-eighths of an inch,
- c. securing means connected to said tubing members for securing them in a grid pattern in said mat,
- d. said mat including supply and return sub-headers extending across one end of said mat with the ends of a plurality of said tubing members being connected respectively to said supply and return sub-headers with the direction of flow of the anti-freeze liquid being opposite in neighboring tubing members in the mat,
- e. said flexible portable mat being rollable into a roll for ease of transportation, and
- f. said sub-headers being adapted to be connected to main headers in an installation for interconnecting the plurality of said tubing members through the sub-headers to the main headers.
- 2. A flexible portable plastic tubing mat as claimed in claim 1 in which said small diameter plastic tubing members are co-extruded in pairs of such members and the ends of the tubing members are connected to said supply and return sub-headers to produce an opposite direction of the anti-freeze flow in the respective tubing members of each pair.
- 3. A flexible portable plastic tubing mat as claimed in claim 1 in which the mat is about 4 feet wide and at least 85 feet long.
- 4. A flexible portable plastic tubing mat as claimed in claim 1 in which supply and return sub-headers extend across both ends of said mat with the ends of a plurality of the tubing members connected respectively to supply and return sub-headers at opposite ends of the mat.
- 5. A flexible portable plastic tubing mat as claimed in claim 1 in which said small diameter plastic tubes are composed of ethylene vinyl acetate.
- 6. A flexible portable plastic tubing mat as claimed in claim 5 in which said securing means include tapes extending transversely along the mat at spaced positions along the length of said mat. .Iadd. 7. A flexible portable plastic tubing mat adapted to be laid side-by-side or end-to-end with other similar mats for creating and maintaining a frozen area,
- a. said portable mat having a length many times greater than its width with a plurality of small diameter flexible plastic tubing members extending lengthwise of said mat adapted to have cooled anti-freeze liquid pumped therethrough,
- b. said flexible plastic tubing members having an inside diameter in the range from one-eighth to three-eighth of an inch,
- c. securing means connected to said tubing members for securing them in a grid pattern in said mat,
- d. said mat including supply and return sub-headers extending across one end of said mat with the ends of a plurality of said tubing members being connected respectively to said supply and return sub-headers with the direction of flow of the anti-freeze liquid being opposite in neighboring tubing members in the mat,
- e. said flexible portable mat being rollable into a roll for ease of transportation, and
- f. said sub-headers being adapted to be connected to main headers in an installation for interconnecting the plurality of said tubing members through the sub-headers to the main headers. .Iaddend.
Parent Case Info
This application is a division of prior copending application Ser. No. 204,112, filed Dec. 2, 1971, which issued as U.S. Pat. No. 3,751,935 on Aug. 14, 1974.
The present invention relates to an apparatus for creating and maintaining an ice slab for skating purposes or for maintaining a layer of snow for skiing and in particular relates to a novel economic apparatus for providing portable system formed by multiple interconnected mats of small diameter flexible plastic tubes arranged in grids with the tubes placed close to one another and arranged with each input or supply tube portion closely adjacent to an outlet or return tube portion providing uniform temperature effect at a small distance above the tubes. The portable mats each include an individual supply sub-header and return sub-header for connection to main supply and return headers and the small plastic tubes are adapted to have a low temperature refrigerant pumped therethrough to provide the desired cooling effect.
In the prior art, ice skating rinks have commonly been frozen by the use of large diameter metal pipes having an internal diameter (I.D.) of approximately 1.25 inches, a wall thickness of one-eighth of an inch spaced 4.0 to 4.5 inches center-to-center spacing which have usually been embedded in concrete to provide a floor upon which the water was placed and thereafter frozen. These large diameter pipes in the prior art were filled with calcium chloride (CaCl.sub.2) brine as the cooling medium, and such a system involved a brine volume of about 3,200 gallons in the piping under the rink plus additional brine in the tanks and piping of the brine cooling equipment. In the prior art systems, the brine was passed through the refrigeration system to bring its temperature down to approximately 15.degree. to 18.degree. F. at the supply point entering the floor of the rink, and the return brine temperature was approximately 17.degree. to 20.degree. F. leaving the rink floor, depending upon the ambient temperature and the number of skaters. The ASHRAE Guide and Data Book on "Applications" (1968 Edition) published by the American Society of Heating, Refrigerating and Air-Conditioning Engineers, in Chapter 51, on Skating Rinks at page 616, states that the brine pump should be of sufficient capacity, so that the temperature difference between incoming and outgoing brine does not exceed 2.degree. F. under design conditions.
For many years, the prior art has assumed that the above type of under the floor cooling ice skating rink system is the "final word." And the book mentioned above confirms that such a system has been long considered by those skilled in the art to be the "final word." Nevertheless, such a conventional prior art system was very expensive in that the pipes must be assembled together piece-by-piece and welded, or otherwise laboriously and accurately connected and installed at the rink site by trained personnel. Thereafter, the assembled piping was usually embedded in concrete. With this prior art system, the ice rink was permanent and could not be moved from place to place. Additionally, large volumes of brine (about 3,200 gallons in the rink floor plus additional brine in the cooling system) had to be refrigerated and pumped through the pipe network in the floor to freeze the ice. A further problem which was encountered when a prior art system needed servicing was that the rusted metal pipes had to be laboriously chipped out from the concrete floor to be replaced. In addition, a large amount of pumping power was continuously consumed in a prior art system in circulating the large volume of brine at a sufficient velocity to hold a temperature difference between the supply point at entrance to the pipe network in the floor and the return point at exit from the floor at no more than about 2.degree. F.
The present invention is a radical departure from the prior art, an important technological jump which represents a real breakthrough in the ice skating rink field. Instead of 2.degree. F. differential in the supply and return temperatures, a differential from 15.degree. up to 25.degree. F. or more can be employed. Instead of heavy walled metal pipes having an I.D. of 1.25 inches and an O.D. of 1.50 inches, thin-walled, flexible, small diameter plastic tubing is used having an I.D. of between one-eighth and three-eighth of an inch, such tubing having a wall thickness of about one-thirty-second of an inch. Instead of using 3,200 gallons of brine in the rink floor, only 300 gallons of low temperature anti-freeze liquid, such as ethylene glycol, is used and operating at a supply temperature of no more than 10.degree. and preferably no more than 5.degree. F., instead of 15.degree. to 18.degree. F., as required in the conventional prior art. Moreover, instead of utilizing a high level of pumping power to circulate brine, only one-third or less pump power is utilized, which represents a great saving in electricity extending into the future; typically $6,000 to $7,000 per year savings or more in a full size rink application. Instead of using large diameter headers to supply and return the brine, the present invention enables the use of headers which are only about one-tenth of the cross-sectional area of the prior art headers.
The present invention advantageously enables the use of small diameter flexible plastic tubing which can be pre-assembled into portable mats in a factory and thereafter conveniently rolled up and carried to a site to be quickly coupled together with other mats to form the cooling grid for an ice rink. Manufacturing these plastic tubing mats in a factory each with a supply and return sub-header adapted to be easily coupled together with the main supply and return header enables the initial cost of a system embodying this invention to be drastically lower than that of the prior art. Advantageously, once these plastic tubing mats are formed at the factory, they can be rolled up so as to form a conveniently portable roll, similar to a roll of carpeting, and which can be taken by pick-up truck or station wagon from the factory to the rink site to be unrolled and laid down like strips of carpet. This, therefore, means that the present invention gives to the user practicable and economic portability.
Further, by virtue of the fact that the plastic tubing has been pre-assembled in mats, servicing is much easier to perform and far less costly because one mat can be quickly and conveniently removed and exchanged for another. Additionally, the present system enables much smaller header piping and related equipment to be employed because of the smaller volume of liquid involved, thus representing a further savings because all of the valves and fittings are only about one-tenth as large as in the prior art.
The plastic tubing mats which can be employed in practice of the present invention are many times greater in length than they are in width. For example, in a flexible plastic tubing mat adapted to extend the length of a full-size skating rink, the mat is generally 200 feet in length and four feet wide. In the case where the flexible plastic tubing mat is to extend transversely of such a rink, the mat is generally 85 feet long and 4 feet wide. The circulation in the tubing is arranged to double back on itself such that both the supply and return sub-headers are at the same end of the 85 foot mat for all of the tubing therein.
For mats extending the length of the rink, the small diameter, flexible plastic tubes are arranged to run the length of the mat in closely spaced parallel relationship with the ends of the tubes being connected to supply and return sub-headers at opposite ends of the mat. The direction of liquid flow is in opposite directions in closely spaced adjacent tubes to provide uniform cooling action in the ice in spite of the temperature differentials of 15.degree. to 25.degree., so keeping the temperature of the ice as uniform as is possible across its face. Fastening means in transverse relation to the axis of the small plastic tubes are arranged so as to form the plastic tubing into a grid-like form. Supply sub-headers each having a length approximately equal to the width of the mat are arranged so as to supply each tube with cold anti-freeze liquid and similar return sub-headers are arranged so as to receive the refrigerant after it has passed through the tubes. Thereafter, the fluid is transferred from the return sub-header into cooling apparatus to be again refrigerated and, thereafter, recirculated through the system.
These flexible plastic tubing mats embodying the present invention can be constructed and assembled in the factory where mass production techniques can be used. In the presently preferred embodiments, these mats are formed from plastic tubes of ethylene vinyl acetate (EVA). Fastening means running transverse to the direction of the axis of the tubing forms the tubing into a grid-like form. After assembly with their sub-headers, the tubing mats can be rolled into an easily portable form and transported to the location wherein the skating rink is to be assembled. The ice rink is formed on a level and approximately rectangular area of ground with a layer of insulating material preferably separating the flexible tubing mat from the ground. Several of these mats, each of which comprises a plurality of plastic tubes arranged in grid-like form, are arranged on the rectangular area that will form the ice rink. The sub-headers of the individual mats, thereafter, are interconnected with appropriate headers and freezing equipment so as to complete the ice freezing system. The tubing mats are usually covered with a thin layer of sand or other similar material, so as to prevent a skater's blade from penetrating the ice surface and thereby cutting, tearing, or otherwise damaging the plastic tubing. When these preparations are complete, water is sprayed onto this surface and allowed to freeze. Because of the low temperature of the anti-freeze liquid passed through the tubes, the ice is quickly frozen and the ice rink formed.
US Referenced Citations (6)
Divisions (1)
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Date |
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204112 |
Dec 1971 |
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Reissues (1)
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Number |
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387148 |
Aug 1973 |
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Patent Grant
RE29438
