GB2368788A

GB2368788A - Salt water bathing pool with water flowing around central vertical axis

Info

Publication number: GB2368788A
Application number: GB0027726A
Authority: GB
Inventors: John Gerald Barley; Sean Michael Barley; Simon Paul William Brown
Original assignee: Nirvana SpA & Leisure Ltd
Current assignee: Nirvana SpA & Leisure Ltd
Priority date: 2000-11-14
Filing date: 2000-11-14
Publication date: 2002-05-15
Anticipated expiration: 2020-11-14
Also published as: GB2368788B; GB0027726D0

Abstract

A bathing pool (1) comprises a body of salt water and a means for rotating the body of water about a central vertical axis. Preferably the pool is circular and contains a central island around which the water flows. Velocity may be imparted to the water by jets (29) located below the water surface and spaced evenly around the perimeter of the pool. The pool may also include a system which extracts water from the pool which filters and sterilises the water before returning it to the pool.

Description

BATHING POOL

This invention relates to a bathing pool and in particular to a bathing pool for hydrotherapy, thalassotherapy, balneotherapy and the like, as well as for pleasurable leisure bathing.

It is an object of the present invention to provide means for combining the therapeutic aspects of mineral spa bathing with facilities for taking exercise in water which provides buoyancy to reduce stress on a patient's joints, a resistance to movement to promote muscular exercise, and water movement to provide both patient motivation and a stimulus to exercise.

In accordance with one aspect of the invention, there is provided a bathing pool comprising a body of salt water having a specific gravity of at least about 1.1 and means for rotating the body of water about a central vertical axis.

The salt water at high specific gravity provides both therapeutic benefits, well known from the medical literature, and buoyancy, which up to a certain depth allows a patient the choice of standing, with reduced weight, on the floor of the pool, or floating. The rotation of the body of water ensures that a standing patient is obliged to undertake muscular work, either walking to keep up with the current, or working to resist the current. In most circumstances, the current speed increases according to the patient's radial distance from the centre of rotation of the water, allowing a therapist

to control the force of the current by appropriate positioning of the patient in the pool.

The speed of rotation is preferably such as to give a water flow rate over the floor of the pool up to about 0.5 m/sec at the fastest point, normally the outside edge. This is just over 1 mph. Faster speeds may be appropriate for strenuous exercise, walking against the current over the floor of the pool. In many cases, a fastest flow rate of not less than 0.25 m/sec may be sufficient. For flotation, where relaxation is an objective, slower speeds still are suitable, with a maximum of from 0.025 m/sec upwards. This would correspond to a 20 minute circulation speed in a circular pool of 9m diameter.

Typically, the specific gravity of the water is not less than about 1.2 and not more than about 1.4. Excessive buoyancy and salinity are not generally desirable. The preferred specific gravity is from 1.26 to 1.32, which allows a patient to stand in a reasonable depth of water or to float.

Any salt dissolved in the water will contribute to the density or specific gravity of the water, and hence its buoyancy. The salt content of the water may include cations of which the major proportion by weight is sodium and anions of which the major proportion by weight is chloride. Sodium chloride is both plentiful and economical. Other cations and anions may be used for therapeutic reasons, in accordance with the medical literature. At pool temperatures, sodium chloride will be saturated with a content of about 370 g/l.

The water temperature is desirably in the range from 27 to 37OC, more preferably between 340 and 35OC.

Temperatures in the range 28'to 30'C are most suitable for an exercise regime, and in the range 350 to 36OC for relaxation, flotation and spa therapy.

A preferred depth of water in the pool is one which, according to the specific gravity, allows a patient to walk on the pool bottom or float at will. If it was for any reason desired to enforce floating, a depth of up to 2m could be provided. A depth of less than 1m would not be effective for adults, although could be beneficial for children. Optimum depths for patient treatment by walking or standing on the bottom of the pool are between 1100 and 1350mm. Greater depths up to about 1500mm may allow patients who are unable to walk into the pool to be launched from a wheeled stretcher or trolley.

The body of water will normally be confined by a pool floor and a pool wall which, seen in plan, is desirably curved and presents no convex surface to the rotary water flow. Of course, the wall may be incidentally interrupted by entry and exit steps and the like.

If the rotating body of water is uninterrupted, it will normally have a centre of rotation where there is no linear flow. Partly to avoid a substantially non-flowing region of the pool, and partly to provide a convenient platform for a therapist, this region may be occupied by an island structure around which the water flows. Any central island structure would desirably present no concave surface to the rotary water flow, when viewed in plan. The outer confining wall is most commonly circular or oval (elliptical, ellipsoidal and the like) in plan

view. The whole body of water in the pool desirably rotates to the full depth of the pool, with a minimum of linear velocity variation with depth. Of course, frictional losses and the viscosity of the water will cause some slowing down of flow adjacent the floor and walls. Radially, there is preferably a velocity gradient in which the body of water rotates with greatest linear velocity adjacent the outer periphery of the rotating body, and progressively more slowly towards the centre.

In certain circumstances, if the centre is occupied by a relatively large island structure, there is a potential for equal linear velocity across the breadth of the stream between the inner and outer peripheral wall. If such an island structure is off centre, so that the breadth of the stream changes as the water flows around the island, the linear flow rate of the water may change.

Likewise, the linear velocity may change if the depth of the pool changes. The linear velocity is inversely proportional to the cross-sectional area of the pool in such a case. In accordance with the invention, it is preferred, for therapeutic purposes, to provide a geometry such that a steady overall water rotation rate allows a therapist to select different regions of the pool in which the linear flow rate of the water over the pool floor varies, in order to select the right exercise flow rate for the patient at any given time, without having to change the actual water circulation rate.

The means for rotating the body of water preferably comprise means for adding water to the pool with momentum in the direction of rotation. Suitable means comprise water jets below the pool surface, suitably in a confining wall, especially an outer peripheral wall, and/or in the floor of the pool. The means are

preferably evenly spaced around the rotary course of the body of water, and are also preferably spaced apart at different depths in the body of water. It is generally preferred that any vertical column of water should rotate at the same linear speed throughout its depth.

The added water is preferably recycled water that has been extracted from the pool, and preferably filtered and sterilised. Water may be extracted through sumps in the floor of the pool, through one or more wall outlets, and/or through one or more overflow channels outside one or more confining walls of the pool.

In general, the pool is desirably shaped so that substantially the whole of the body of water in the pool rotates in one rotary direction. It will be appreciated that minor eddies may occur on a small scale relative to the size of the users of the pool. The surface of the pool in particular should be of such a shape that, having regard to the effects of the means for rotating the body of water, all bathers floating freely in the pool should be carried by the current in a constant direction of rotation, and that eddies or dead calm areas where floating bathers might accumulate should be avoided.

The actual rotation rate of the body of water can be selected at will. However, when rotation is provided by the return through water jets of filtered and sterilised water previously extracted from the pool, the rate of extraction and return is preferably selected so that the volume extracted and returned to the pool in one hour is at least the volume contained by the pool. In other words, all the pool water is recycled on average at least once per hour.

One embodiment of the invention is illustrated, by way of example only, in the accompanying drawings, in which : Figure 1 is a plan view of a bathing pool in accordance with the invention, with dashed lines indicating the layout of hidden water ducts; and Figure 2 is a cross-section through the centre of the pool.

In the drawings, a pool 1 comprises a body of water 3 confined by a circular peripheral wall 5 and a floor 7.

The circular wall is interrupted by entry and exit steps 9 which do not intrude upon the line of the concave circular surface of the wall, seen in plan, that is presented to the bulk of the body of water.

The floor 7 is flat and is interrupted by two sumps 11, normally covered by gratings, through which water is extracted from the pool by pipework 13 for filtration and sterilisation. Water is also extracted through wall outlet 15 by pipework 17, for the same purpose. A further source of extracted water for filtration and purification is peripheral overflow channel 21 surrounding the wall 5 and steps 9, which channel is provided with drains 23 leading into pipework 25.

The extracted, filtered and sterilised water is returned to the pool through pipework 27 leading to twelve inlet jets 29 arranged in four groups of three. Each group consists of a plurality of jets, three as illustrated, equally separated at different depths in the water, and circumferentially staggered within the group. The four

groups are evenly spaced around the circumference of the pool.

In order to impart anticlockwise rotation to the body of water 3, jets 29 are angled so that the momentum of the incoming water drives the rotation. The jets are suitably of the'eyeball'type, so that their angles can be adjusted for optimum effect.

In the illustrated pool, there is no central island structure. An instructor or therapist can stand and walk freely on a tiled poolside surround surface 30. The pool diameter in the illustrated example may be about 9m so that the instructor or therapist can easily keep sufficiently close to a patient, walking around the pool as necessary. The depth as illustrated is between 1200mm and 1250mm.

The water may have the following salt content, giving a specific gravity of around 1.28 :

Salt g/l NaCl 305.3 MgClz 0.5 Na2SO4 1.8 CaSO4 4.6 Total 312. 2

Ion g/l Na+ 120. 9 Mg 0. 1

Ca++ 1. 3 Cl-185. 5 SO4-- 4.5 Total 312. 2 In addition, sodium carbonate may be used as a pH buffer, to maintain a near neutral condition. Sterilisation may be maintained with a free bromine content of 2 to 4ppm.

Many variations in saline composition are of course possible; to give but one example, substantial concentrations of Epsom salts (magnesium sulphate) may be employed.

Claims

CLAIMS 1 A bathing pool comprising a body of salt water having a specific gravity of at least about 1.1 and means for rotating the body of water about a central vertical axis.
2 A pool according to claim 1 wherein the specific gravity of the water is not more than about 1.4
3 A pool according to claim 2 wherein specific gravity is from 1.26 to 1.32.
4 A pool according to any one of the preceding claims wherein the salt content of the water includes cations of which the major proportion by weight is sodium and anions of which the major proportion by weight is chloride.
5 A pool according to any one of the preceding claims wherein the fastest flow rate of the water over the floor of the pool is not less than 0.025 m/sec.
6 A pool according to any one of the preceding claims wherein the fastest flow rate of the water over the floor of the pool is not more than 0.5 m/sec.
7 A pool according to any one of the preceding claims wherein the water temperature is from 270 to 37OC.
8 A pool according to any one of the preceding claims wherein the water depth is from 1100 to 1500mm.
9 A pool according to any one of the preceding claims wherein the body of water is confined by a pool floor and a pool wall which, seen in plan, is curved and presents no convex surface to the rotary water flow.
10 A pool according to claim 9 wherein the pool is circular.
11 A pool according to any one of the preceding claims wherein the centre of rotation of the body of water is occupied by an island structure around which the water flows.
12 A pool according to claim 11 wherein the island structure presents no concave surface to the rotary water flow, when viewed in plan.
13 A pool according to any one of the preceding claims wherein the whole body of water in the pool rotates to the full depth of the pool.
14 A pool according to any one of the preceding claims wherein there is a radial velocity gradient in which the body of water rotates with greatest linear velocity adjacent the outer periphery of the rotating body, and progressively more slowly towards the centre.
15 A pool according to any one of the preceding claims wherein the means for rotating the body of water comprise means for adding water to the pool with momentum in the direction of rotation.
16 A pool according to claim 14 wherein the said means comprise water jets below the pool surface.
17 A pool according to claim 15 or claim 16 wherein the said means are evenly spaced around the rotary course of the body in water.
18 A pool according to any one of claims 15 to 17 wherein the said means are spaced apart at different depths in the body of water.
19 A pool according to any one of claims 15 to 18 wherein the added water is recycled water that has been extracted from the pool, filtered and sterilised.
20 A pool according to claim 19 wherein the rate of extraction and return is selected so that the volume extracted and returned to the pool in one hour is at least the volume contained in the pool.
21 A bathing pool substantially as herein described with reference to and as illustrated in the accompanying drawings.