Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F24—HEATING; RANGES; VENTILATING
  • F24D—DOMESTIC- OR SPACE-HEATING SYSTEMS, e.g. CENTRAL HEATING SYSTEMS; DOMESTIC HOT-WATER SUPPLY SYSTEMS; ELEMENTS OR COMPONENTS THEREFOR
  • F24D3/00—Hot-water central heating systems
  • F24D3/10—Feed-line arrangements, e.g. providing for heat-accumulator tanks, expansion tanks ; Hydraulic components of a central heating system
  • F24D3/1008—Feed-line arrangements, e.g. providing for heat-accumulator tanks, expansion tanks ; Hydraulic components of a central heating system expansion tanks
  • F24D3/1016—Tanks having a bladder

Definitions

• the present invention relates to a bladder system for use in expansion tanks.
• the invention relates to a system consisting of a bladder, a rigid tubular body installed inside the bladder and a closing element, for example a cover to which both said elements, the bladder and the tubular body are linked.
• this bladder system in case of inspection or replacement of a defective bladder, this bladder can be replaced in a very simple manner so that the expansion tank is ready for use again.
• the invention also relates to expansion tanks wherein such bladder systems are installed, as well as a method for the replacement of said inventive bladder system in an expansion tank.
• An expansion tank is a pressure vessel that serves to limit variations in pressure in systems filled with a liquid.
• An expansion tank comprises two parts, separated by means of a diaphragm or a bladder. One part is filled with the same liquid as the system, whereas the other part is filled with a compressed gas, usually air.
• the working principle of an expansion tank is based on the principle that a gas, contrary to a liquid, is compressible. As soon as the pressure in the system goes up, the diaphragm will move in the direction of the gas, or the bladder filled with gas will decrease in volume, whereby the volume in the liquid system increases. In this manner the pressure will be reduced herein.
• Expansion tanks are applied amongst others in central heating systems.
• expansion tanks characterised by a fixed bladder, for households or small utility houses.
• expansion tanks characterised by a replaceable bladder or bellow, for use in medium-sized houses such as schools, offices, hospitals or smaller production entities.
• a third type of expansion tanks can be found in automatic expansion systems, steered by a compressor or a pump, for use in larger entities.
• a second problem is that in case of a sudden flow of liquid in an expansion tank with a bladder the liquid column and its related force, directed to that part of the bladder that is situated directly above said liquid column, can damage the bladder (column 2, lines 52-58).
• the solution proposed in this patent application comprises expansion tanks characterised by a special design of the pipe or duct. These are designed in such a way that a uniform transit of the liquid/solid mixture is enabled, whereby the problems described supra do not arise (column 1, lines 6-9).
• this pipe-construction is described for use in an expansion tank that is positioned vertically, whereby the liquid/solid mixture is added, resp. discharged at the bottom by means of an inlet/outlet opening (fig. 5).
• the bladder is situated between the liquid and the compression gas in such a way that the compression gas is situated between the bladder and the inner side of the expansion tank.
• This compression gas is set up according to a pressure set in advance; the liquid is at the inner side of the bladder (column 9, lines 34-36).
• a pressure meter and a valve for filling the gas At the outside of the expansion tank there is a pressure meter and a valve for filling the gas (Fig. 5, elements 96 and 92).
• the pressure gas in the expansion tank is situated between the bladder or the diaphragm and the inner side of the expansion tank.
• the liquid is situated inside the bladder.
• the replacement implies two handlings : on the one hand the bladder to be inspected or to be replaced has to be removed from the expansion tank through a usually narrow opening at the upper or lower side of the tank.
• Aim of the invention is the construction of an expansion tank with related bladder system, whereby the replacement of the bladder in an existing expansion tank is simplified.
• the aim of the invention is also the construction of an expansion tank, manufactured in a plastic material, with construction features such that the bladder system according to the invention can be easily placed inside and removed from the expansion tank.
• an expansion tank comprising a part filled with a compression gas and a part filled with liquid, a flexible pouch like bladder that separates both parts from each other, and a closing member connected to the bladder for an airtight sealing of the bladder to the expansion tank, whereby the bladder comprises a rigid tubular body, connected at at least one end to the bladder and the closing member, characterised in that the expansion tank is made of plastic and after commissioning the pressure gas is inside the bladder and the liquid is in the spacing between the bladder and the inside of the expansion tank.
• the expansion tank comprises an opening that is sufficiently large so that the closing member and the bladder connected thereto and the rigid tubular body can be installed, respectively can be removed through said opening in, resp. from said expansion tank.
• the inventors have designed a new concept for the inspection, respectively for the replacement of a bladder in an expansion tank.
• the method according to the invention for the replacement of a bladder in an expansion tank comprises the following steps :
• the bladder system comprises a flexible bladder, characterised in that the flexible bladder is foldable or compressible and, optionally, that the bladder is made of a flexible material, preferably an elastic material, more preferably thermoplastic polyurethane.
• the bladder can be made out of rubber, preferably butyl rubber, or it can comprise rubber, preferably butyl rubber.
• Thermoplastic polyurethane is a class of polyurethane plastics with very useful properties including elasticity and durability against oil, grease and wear and tear. Technically these plastics belong to the class of thermoplastic elastomers. Thermoplastic polyurethane is relatively cheap, easy to process, and shows a long operating life, is elastic and less sensitive to bacteria in comparison to alternative elastomers.
• the bladder is manufactured such that it follows the form, inclusive of the curves of the expansion tank with a small excess in dimensions as compared to the dimensions of the expansion tank.
• the bladder will press at its entire surface against the inner wall of the expansion tank, without the bladder itself being under pressure, even in the absence of water in the expansion tank, also in case the bladder of the air cell takes all of the available space in the expansion tank. This aspect has a beneficial influence on the life time of the bladder.
• the bladder system comprises a rigid tubular body made of a light metal or a plastic.
• Aluminium is particularly suited as light metal.
• a rigid or stiff thermoplastic material is an example of a material that can be selected as plastic material. Aluminium is a particularly preferred material in view of its easy process ability and it is also less vulnerable to deformation caused by temperature.
• the term thermoplastic material should be understood according to the present invention as a plastic material that can be elastically deformed at a high temperature above its material specific softening temperature.
• the rigid tubular body can also be made in a thermosetting plastic material.
• the rigid tubular body can for instance be made from a thermoplastic rigid plastic material selected from the following list : polyolefins, polyesters, pvc, polystyrene, thermoplastic polyurethanes, butyl-butadiene rubbers, elastomers, etc.
• this rigid tubular body comprises apertures. This results in an even pressure in this body, as well as in the remaining places of the bladder. Also the air is blown in the bladder from the air valve through these apertures.
• the bladder system is characterized by the fact that the bladder at both ends is connected to the rigid tubular body.
• the advantage hereof is that the bladder is positioned more accurately and steadily in the expansion tank, which has a beneficial effect on the life time of the bladder.
• the bladder system is characterized in that the bladder is made from welded pre-cut film materials.
• the elastic bladder material is manufactured using blow-moulding.
• the bladder is not manufactured by using such blow-moulding technique, but on the basis of welded pre-cut film materials.
• blow-moulding technique enables a uniform thickness and the possibility to reinforce the bladder at such places that are in need hereof.
• a further preferred embodiment of the invention is characterized by the fact that at the end of the bladder system opposite the closing member an adapter is present enabling this end of the bladder system to be accurately positioned relative to a collar of the expansion tank matching with such adapter.
• the effect is obtained as if the bladder itself at its upper and lower ends is secured to the expansion tank.
• This effect substantially enhances the life time of the bladder.
• the advantage hereof is also that this enables an easy installation and airtight connection of the bladder system to the expansion tank, as well as an easy removal of the bladder system out of the expansion tank.
• the bladder is secured at both ends of the plastic cover to the upper and lower end of the rigid tubular body.
• the closing member that connects the rigid tubular body and the flexible bladder can in principle be manufactured in any material, but preferably in a stiff thermoplastic material.
• thermoplastic material any of the following materials can be selected :
• polyolefins polyesters, pvc, polystyrene, thermoplastic polyurethanes, butyl-, butadiene rubbers, elastomeric materials, etc.
• the bladder and its pipe should be secured as a whole to this closing member, for example by means of a hollow screwed connection.
• the air valve is positioned in this hollow spacing.
• the bladder is designed to be used in combination with an expansion tank that is specifically designed to this end; differently phrased, the bladder is not suitable to be used with existing expansion tanks that are already in use; in principle such tanks are not suited for this purpose.
• Replacement of the bladder according to the invention can be effected either in case of breakdown of an existing bladder, or for instance at the occasion of a (yearly) preventive maintenance.
• the tank is characterised by the fact that it comprises at at least one end an aperture that is sufficiently large such that the bladder and the rigid tubular body of the bladder system can be installed in, resp. removed from the expansion tank through this end.
• the closing member abovementioned to which the bladder and the rigid tubular body are connected fits into this sufficiently large aperture of the expansion tank.
• the expansion tank at its end opposite the abovementioned closing member a collar is provided with which the adapter of the bladder system as described above, fits.
• the step of disconnecting, respectively re-connecting the closing member of the bladder system to the expansion tank is effected by unscrewing, resp. screwing of a V- connection or a bolt/nut connection.
• the disconnection, resp. the re- connection of the closing member of the bladder system to the rigid tubular body is effected by the unscrewing, resp. the screwing of a nut connection.
• Figure 1 shows a schematic presentation of an exemplary embodiment of a bladder system according to the invention, positioned in an expansion tank.
• Figure 2 shows a more detailed representation of the positioning of a bladder system according to the invention in an expansion tank.
• Figure 3 shows a schematic representation of a bladder system according to the invention when positioned in an expansion tank.
• Figure 4 shows the various steps to be followed when a preferred embodiment of a bladder system according to the invention has to be replaced in an expansion tank.
• Figure 5 shows a detailed representation of a preferred embodiment of a bladder system according to the invention.
• Figure 6 shows a cross-section of a preferred embodiment of an expansion tank in working condition according to the invention.
• Figure 7 shows a cross-section of an alternate preferred embodiment of a bladder as installed for use in an expansion tank according to the invention.
• Figure 8 shows a cross-section of an alternate preferred embodiment of a bladder as disassembled for use in an expansion tank according to the invention, (in both figures the bladder is shown in blown-up or expanded position for the clarity of the figure.)
• the bladder should be able to adapt in a flexible manner to the compressibility of the air as opposite to the non-compressible characteristic of the water, such that the bladder can exercise its buffering capacity.
• the material of the bladder should be flexible, but not necessarily elastic.
• the bladder can be foldable, or compressible. It suffices that the design of the bladder is such that it can exercise its buffering capacity in an expansion tank under practical circumstances.
• the material of the bladder comprises an elastic material such as rubber, but this is not necessary; the bladder can also be manufactured entirely from such elastic material.
• Bladder systems according to the invention preferably are positioned in expansion tanks made out of plastic.
• Expansion tanks made out of plastic or composite material constitute a preferred embodiment, amongst others in view of their lower weight and resistance to corrosion or rust, and consequently their more easy maintenance.
• thermoplastic materials These are - as opposite to thermosetting materials - completely recyclable. On top hereof they are characterized by a high impact resistance.
• the bladder according to the invention can be used in combination with expansion tanks made out of steel, on condition there is a sufficiently large inlet- aperture for the bladder with the pipe.
• expansion tanks made out of steel, on condition there is a sufficiently large inlet- aperture for the bladder with the pipe.
• plastic expansion tanks are those marketed under the brand Wellmate by the company Pentair Residential Filtration, LLC, USA.
• expansion tanks produced by Covess N.V., Belgium, on the basis of pure thermoplastic materials.
• the water - or more generally the liquid the pressure whereof should be controlled - resides in these apparatus in the spacing between the outer plastic shell of the expansion tank and the diaphragm or bladder.
• the latter is usually made of thermoplastic polyurethane.
• the gas usually air, resides in the diaphragm or bladder.
• Expansion tanks produced in steel are usually characterized by the inverse situation : in this case the water or the liquid usually resides in the bladder; the air then resides in the spacing between the bladder and the steel cover. This is the situation in each of the expansion tanks described in the prior art set forth above.
• the latter construction has the advantage that the bladder is connected at its upper- and lower ends at the steel cover and this generally enhances the life time of the bladder.
• FIG. 5 shows a drawing of a preferred embodiment of a bladder system according to the invention.
• 5 represents a spacer (to keep distance between various parts); 6 represents the bladder;
• the air is pressed in the bladder by opening the air valve situated on top of the tank, up until a pressure of for example 3 bar is reached.
• the air valve is locked; water is introduced in the expansion tank at its lower end, until a pressure of for example 6 bar is reached.
• the filling pump is stopped.
• the bladder is compressed until a pressure of 6 bar is equally reached. Water can then be consumed; in case of water consumption, the bladder will expand as a function of the amount of water consumed; the pressure in the bladder and the expansion tank will gradually decrease until the level of 3 bar has been reached. At that point the tank need to be refilled.
• a signal is sent to the filling pump indicating water should be added through an opening consisting for example of a T- valve or a C- bend at the lower end of the tank.
• the bladder systems and expansion tanks according to the invention can be offered in a wide range of applications.
• the capacity can vary from quite compact tanks for limited use in households, up until tanks of a larger volume for larger industrial users.
• the capacity expressed in litres of liquid, can vary from 5 until 5 000 litre. Preferably between 100 (25.8 Gallons) up to 500 (129 gallons), which represent quite usual values.
• the working range in terms of temperature of the liquids to be handled can equally well vary between broad ranges. For most applications the temperature of the liquid to be treated is situated between 1° and 90 ° Celsius.
• the working pressure inside the expansion tank can equally vary between broad ranges, depending upon the application. Working pressures up until 10 bar are quite usual.
• thermoplastic expansion tank with a nominal capacity of 150 Litre is around 18. Kg, and its dimensions are 18 inch as regards its diameter and 101 cm high.
• the closing member to which the bladder and the rigid tubular body enclosed therein are connected at one end, comprise an air valve.
• This valve enables the bladder to be put under pressure according to a technique known to the person skilled in the art, namely through the introduction of air that is distributed inside the entire flexible bladder through this air valve and through the pipe and its apertures.
• a technique known to the person skilled in the art namely through the introduction of air that is distributed inside the entire flexible bladder through this air valve and through the pipe and its apertures.
• the manufacturer takes care that this tank already shows an air pressure in the bladder. This air pressure in a large number of applications amounts to 3 bar.
• the commissioning is very easy : the expansion tank simply is connected to the system, the water inlet is opened and the operation starts. The expansion tank is then ready for use.
• connection to the system of the customer can take place for instance by means of the in/outlet of the expansion tank, that may comprise a screw thread connection to this end.
• a 5/4 inch connection is provided, that can be reduced to a lower value by means of a reduction element, if required.
• Step 1
• This first step consists in locking the water inlet from the system of the customer to the expansion tank. To this end, the expansion tank need not to be disconnected from the system of the customer.
• Step 2
• the air inside the bladder is allowed to escape by pressing the air valve on the closing member of the tank.
• Step 3
• Step 4
• V-connection clamp
• bolt/nut connection by means whereof the closing member is connected to the expansion tank, is screwed off.
• Step 5
• the closing member to which the bladder with pipe is connected at at least one end, is removed from the expansion tank. In this way the bladder and the pipe connected thereto are easily removed from the expansion tank.
• Step 6
• Step 7 In case of replacement of the bladder and the pipe connected thereto, the new bladder and the pipe combination need to be connected to the closing member by tightly screwing again this connection nut.
• Step 8
• Step 10 The V-connection or bolt/nut connection is placed again and screwed tightly.
• the expansion tank is ready for being used again, and consequently the inlet/outlet openings can be re-opened, and the system of the customer can anew be put in use.
• a pipe of for instance 1003 mm can be used for an expansion tank of 150 litre. This is relatively high, since the diameter of a tank of 150 litre sometimes is chosen less than for instance for a tank of for instance 230 litre.
• Figure 6 shows how in a preferred embodiment of an expansion tank according to the invention, the bladder at the lower side of the expansion tank is pressed against the rigid tubular body, and the spacing between the bladder and the inner side of the plastic expansion tank is filled with liquid, in this case water.
• the water is pumped inside the tank at its lower end, and the upper part of the bladder remains pressed against the inner side of the expansion tank.
• water is pressed in the tank with an upper limit of 4 bar.
• the compressed pressure gas usually air
• the bladder is designed such that its dimensions slightly exceed the dimensions of the expansion tank.
• the bladder is not subjected to any tension, in view of its dimensions and form that is designed slightly larger in comparison with the dimensions and form of the corresponding surrounding expansion tank.
• Figure 7 shows in cross-section an alternate preferred embodiment of a bladder as installed for use in an expansion tank according to the invention.
• thermoplastic polyurethane TPU
• TPU thermoplastic polyurethane
• a coupling piece is visible that ends up sharply so as to fit at the lower end of the expansion tank in a collar or fitting, and to keep the pipe and bladder at its position.
• a connection piece is visible that fits in a cover or closing member to seal the pipe and bladder to the expansion tank in a air-tight manner.
• This piece also comprises an air valve to blow air into the bladder, and in case of removal of the bladder, to have the air escape therefrom.
• Figure 8 shows in cross-section an alternate preferred embodiment of a bladder in dis-assembled state for use in an expansion tank according to the invention.

Landscapes

• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Supply Devices, Intensifiers, Converters, And Telemotors (AREA)
• Diaphragms And Bellows (AREA)
• Filling Or Discharging Of Gas Storage Vessels (AREA)

Applications Claiming Priority (2)

Publications (2)

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Family Applications (1)

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Cited By (3)

Citations (4)

Family Cites Families (3)

• 2012
  • 2012-05-17 BE BE201200329A patent/BE1020694A5/nl not_active IP Right Cessation
• 2013
  • 2013-05-14 WO PCT/BE2013/000026 patent/WO2013170323A2/fr not_active Ceased

Patent Citations (4)

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