GB1590630A - Fluid flow silencing device - Google Patents

Description

(54) A FLUID FLOW SILENCING DEVICE (71) We, DERWENT-MACDEE- LIMITED, formerly called Mac Dee Plastics Limited, a British company of The Ryedale Building, Piccadilly York YO1 iPA,- do hereby declare the invention, for which we pray that a patent may be granted to isis, and the- method by Which it is to be performed, to be particularly described in and by the following statement:: The present invention relates to fluid flow silencing devices and more' particularly to fluid flow silencing devices for' use in refil valves for water cisterns to reduce the noise generated when water is fed into the cistern through the refil valve.

In many applications, for example with domestic central heating systems and water closets, the noise generated when liquid is fed into a cistern is unacceptably high and various attempts have been made to reduce this noise.Hitherto, in attempting to Solve this problem, it has been assumed that most of the noise has been generated as a result of liquid which issues from the supply mains to the cistern receptacle impacting with the surface of liquid already in the rec-eptacle and it is generally accepted that cistern noise is appreciably less when incoming liquid is discharted below the surface Of the- liquid already in the cistern teceptacle. However, in cisterns supplied front drinking water mains, there is a risk of back-syphoning of water from the cistern receptacle into the main water supply as a result of some pres- sure loss in the cistern. This is deatly dangerous because of the possibility of con tamination of the main Water supply and so in many countries, including the United Kingdom, civil regulations have been enacted to prohibit the use of water cisterns which are not designed to prevent back-syphoning-.

Thus, in the United Kingdom, it- is not per- mitted to use a cistern which is connected to the' water mains by water supply means which discharge below the water Level in the cistern receptacle. This has meant that most attempts at- noise reduction i-n- cistems have relied on sound insulation by the use of heavier gauge materials for the water supply means and for the cistern receptacles and also to the use of sound insulating material in the walls of the cistern receptacles, but both of these expedients have considerably increased the cost of production. Moreover, the reduction in noise achieved by these techniques still leaves much to be desired.

It is therefore an object of the present invention to provide a more effective and economical reduction in ciStern noise than has hitherto been obtained and this object has been achieved by exploiting the' dis- covery that the most unacceptable component of cistern noise does riot noise as a result of the liquid jet from the supply means impacting on the surface of liquid already in the cistern receptacle, a's formerly accepted, but as a result of turbulence in the liquid itself as it flows into the cistern receptacle.

It has been found that the necessary reduction in turbulence can be obtained by the use of means for aerating. the liquid flowing through the bait valve outlet pipe into the liquid receptacle and it is' believed that this is because the presence of entrained air in the liquid flowing through the outlet pipe inhibits any turbulence in this flow.

In cisterns in which the liquid supply means are provAed with flow control m'eans, such as a ball or float valve, for confrolling the- flow of liquid into the receptacle' and where the receptacle is provided with an over-flow passage for ensuring that the Surface of liquid in the receptacle does not exceed a maximum height, it is convenie'nt to provide the turbulence reducing' means downstream of the flow control means because, with this form of arangement, the turbulence reducing means may be readily removed for cleaning without necessarily removing the flow control means.It is also possible to provide this form- of consfruction merely by attaching a suitable form of túr- bulence- reducing means to the outlet of the flow control means of a conventional cistern.

Moreover an additional advantage is obtained where it is desired to position the outlet of the liquid supply means above the maximum height of the liquid surface in the cistern receptable, in conformity with United Kingdom regulations for cisterns connecting to water mains. In this case, the air entrained in the liquid issuing from the liquid supply means ensures that the jet of fluid impinging on the liquid already in the cistern receptacle is much less dense than the liquid itself and so the noise generated is much less than the noise generated by a jet of liquid which has not been aerated.

According to the invention there is provided a silencing device for a water cistern refil valve comprising a conduit for liquid flow mounted at an outlet of the valve and having a multi-apertured plate arranged to divide the liquid flow into a plurality of jets, a liquid permeable flow retarding screen mounted downstream of said plate, and means for admitting air to the space between said plate and said screen to effect aeration of said fluid jets issuing from said plate to pass through said screen.

It is preferred that the screen of liquid permeable flow retarding material comprises at least one sheet of wire gauze. In addition, an upwardly domed sheet of wire gauze may be mounted over the plate formed with a pluarality of apertures so as to prevent the apertures being blocked. Particles trapped by this domed sheet of wire gauze tend to be displaced, by the liquid flow, radially outwardly, over the surface of the domed sheet of gauze material so as to collect at the outer rim of this sheet. The domed sheet of wire gauze therefore serves as a self-clearing device which prevents blockage of the perforations formed in the perforated plate.

The screen of liquid permeable flow retarding material and the multi-apertured plate may be mounted in a spout extending from the free end of the conduit and the spout surrounded by a tubular shroud which, at one end, is sealingly connected to the spout above or below one or more vents in the spout for admitting air to the space between the plate and screen, and which, with the outer surface of the spout, defines an annular flow path for air to flow into the or each vent. This form of construction further reduces noise emanating from the cistern in that it masks the sound resulting from the entrainment of air in liquid passing through the spout. This is particularly true where the shroud is connected to the spout above the or each vent and it has a downwardly directed opening.It has also been found more convenient to control the induction of air by varying the dimensions of this shroud and by varying the dimensions of the vents themselves.

An embodiment of the invention is hereinafter described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a schematic part-sectional elevation of a refil valve for a domestic water closet cistern provided with a flow silencing device according to an embodiment of the invention; Figure 2 is an end elevation of the refil valve shown in Figure 1; and Figure 3 is a sectional elevation, on an enlarged scale, illustrating the construction of aerating a preferred form of the flow silencing device attached to the refil valve shown in Figures 1 and 2.

As shown in Figure 1, a refil ball operated valve 1, forming part of the water supply means for the receptacle (not shown) of a domestic water closet cistern is fed from an inlet pipe 2 and is provided with a narrowbore valve seat member 3 which is cooperable with a valve member 4 to close the valve 1 when the arm 5 of a ball or float 11 (see Figure 2) connected to the end of the arm 5 is raised as a result of the liquid level a-b rising within the receptacle.

When the valve is open, as shown in Figure l, water passes through the outlet 10 of the body 10a of the valve 1 and flows into an extension conduit 12 which, as shown in Figure 2, extends laterally of the axis of the inlet pipe 2. The water then issues from a shroud 13 depending from the underside of the free end of the extension conduit 12.

As shown in Figure 3, a removable spout 15, for controlling turbulence in water flow, is arranged coaxially in the shroud 13. The spout 15 comprises a tubular casing 16 retained by an upper end 17 in an opening 14 formed in the extension conduit 12 and terminates substantially in the plane containing the lower edge of the shroud 13.

The shroud 13 is radially spaced from the tubular exterior of the casing 16 and thereby cooperates with the casing 16 to form an annular passage 18 which is closed at the top by the upper end 17, but having at the bottom, an inlet 19 formed between the shroud 13 and the casing 16. The passage 18 provides communication between the inlet and circumferentially extending vents 20 (one being shown) in the wall of the casing 16, towards its upper end 17. The end 17 may be formed with diametral lugs 17a to retain it in the opening 14, the shroud 13 being shown slightly raised in the opening 14 with the lugs spaced from their seat on the conduit 12 for sake of illustration. The interior of the shroud 13 is formed with diametrically opposed grooves (not shown) which permit the lugs 17a to pass on insertion or removal of the spout 15.The lugs 17a are normally retained in corresponding recesses radiating from the opening 14 and angularly separated from the grooves. At the upper end 17 of the casing 16, across its flow area, are retained a multiperforated disc 21 and a surmounting fine wire mesh dome 22, the peripheries of the disc 21 and the dome 22 contacting each other. At the bottom end of the casing 16, across the flow area of its outlet opening 23, is a horizontal fine wire mesh insert 24 retained by an internal bead 25 at the opening 23. Two or more inserts 24 may be provided. The disc 21 and mesh insert 24 define between them a mixing space 26 for air and water as hereinafter described.

The extension conduit 12 is rigid and the opening 23 is above the water level a-b at all times.

When the water in the cistern has fallen below the level at which the ball valve closes, the float 11 descends correspondingly and causes the valve to open. Water for recharging the cistern flows through the outlet 10 of the valve body 10a and into the extension conduit 12. The water reaches the mesh dome 22 in a random, turbulent state, but after flowing through the dome 22 and the perforated disc 21, the turbulence tends to be controlled and subdued. The water flows through the mixing space 26 as a series of fine jets issuing, respectively, from the perforations in the disc 21 and friction between the water and air admitted by the vents 20 from the passage 18 and inlet 19 causes the air to be entrained in the water in the space 26. The controlled turbulence of the water in the space 26 breaks the air down into very fine bubbles.Water leaving the space 26 through the mesh insert 24 and out through the opening 23 therefore has a chalky appearance because of the fine air bubbles entrained in it and tends not to splash as it strikes the bottom of the cistern receptacle or the rising water level in it.

Moreover, the water discharging from the opening 23 has a tolerable, low noise level.

The casing 16, disc 21 and mesh parts 22 and 24 may be of plastics material and two or more of these components may be moulded in one piece, if consistent with quick assembly and insertion or removal and disassembly for cleaning.

WHAT WE CLAIM IS:- 1. A silencing device for a water cistern refil valve comprising a conduit for liquid flow mounable at an outlet of the valve and having a multi-apertured plate arranged to divide the liquid flow into a plurality of jets, a liquid permeable flow retarding screen mounted downstream of said plate, and means for admitting air to the space between said plate and said screen to effect aeration of said liquid jets issuing from said plate to pass through said screen.

2. A device as claimed in Claim 1, wherein said screen is composed of at least one sheet of wire gauze.

3. A device as claimed in Claim 1 or 2, wherein a domed sheet of wire gauze is mounted over said plate and upstream thereof.

4. A device as claimed in any preceding claim wherein said plate and said screen are mounted in a spout which is detachably secured to the conduit, said spout being provided with one or more vents for admitting air to the space between said screen and said plate.

5. A device as claimed in Claim 4, wherein a tubular shroud surrounds said spout to define an annular flow path for air to flow into the or each said vent.

6. A refil valve for a water cistern comprising an inlet, an outlet for delivering water to the cistern entering said inlet, valve means operably responsive to water level in the cistern to control flow of water from said inlet to said outlet, and a flow silencing device as claimed in any preceding claim arranged at said outlet.

7. A cistern provided with a refil valve according to Claim 6, with the outfall from said silencing device being above a level of water in the cistern determined by said valve means.

8. A refil valve for a water cistern substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

9. A fluid flow silencing device substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (9)

**WARNING** start of CLMS field may overlap end of DESC **. on insertion or removal of the spout 15. The lugs 17a are normally retained in corresponding recesses radiating from the opening 14 and angularly separated from the grooves. At the upper end 17 of the casing 16, across its flow area, are retained a multiperforated disc 21 and a surmounting fine wire mesh dome 22, the peripheries of the disc 21 and the dome 22 contacting each other. At the bottom end of the casing 16, across the flow area of its outlet opening 23, is a horizontal fine wire mesh insert 24 retained by an internal bead 25 at the opening 23. Two or more inserts 24 may be provided. The disc 21 and mesh insert 24 define between them a mixing space 26 for air and water as hereinafter described. The extension conduit 12 is rigid and the opening 23 is above the water level a-b at all times. When the water in the cistern has fallen below the level at which the ball valve closes, the float 11 descends correspondingly and causes the valve to open. Water for recharging the cistern flows through the outlet 10 of the valve body 10a and into the extension conduit 12. The water reaches the mesh dome 22 in a random, turbulent state, but after flowing through the dome 22 and the perforated disc 21, the turbulence tends to be controlled and subdued. The water flows through the mixing space 26 as a series of fine jets issuing, respectively, from the perforations in the disc 21 and friction between the water and air admitted by the vents 20 from the passage 18 and inlet 19 causes the air to be entrained in the water in the space 26. The controlled turbulence of the water in the space 26 breaks the air down into very fine bubbles.Water leaving the space 26 through the mesh insert 24 and out through the opening 23 therefore has a chalky appearance because of the fine air bubbles entrained in it and tends not to splash as it strikes the bottom of the cistern receptacle or the rising water level in it. Moreover, the water discharging from the opening 23 has a tolerable, low noise level. The casing 16, disc 21 and mesh parts 22 and 24 may be of plastics material and two or more of these components may be moulded in one piece, if consistent with quick assembly and insertion or removal and disassembly for cleaning. WHAT WE CLAIM IS:-

1. A silencing device for a water cistern refil valve comprising a conduit for liquid flow mounable at an outlet of the valve and having a multi-apertured plate arranged to divide the liquid flow into a plurality of jets, a liquid permeable flow retarding screen mounted downstream of said plate, and means for admitting air to the space between said plate and said screen to effect aeration of said liquid jets issuing from said plate to pass through said screen.

2. A device as claimed in Claim 1, wherein said screen is composed of at least one sheet of wire gauze.

3. A device as claimed in Claim 1 or 2, wherein a domed sheet of wire gauze is mounted over said plate and upstream thereof.

4. A device as claimed in any preceding claim wherein said plate and said screen are mounted in a spout which is detachably secured to the conduit, said spout being provided with one or more vents for admitting air to the space between said screen and said plate.

5. A device as claimed in Claim 4, wherein a tubular shroud surrounds said spout to define an annular flow path for air to flow into the or each said vent.

6. A refil valve for a water cistern comprising an inlet, an outlet for delivering water to the cistern entering said inlet, valve means operably responsive to water level in the cistern to control flow of water from said inlet to said outlet, and a flow silencing device as claimed in any preceding claim arranged at said outlet.

7. A cistern provided with a refil valve according to Claim 6, with the outfall from said silencing device being above a level of water in the cistern determined by said valve means.

8. A refil valve for a water cistern substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

9. A fluid flow silencing device substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.